Carbonates

This study was made to solve the following questions: (1) Which of the three crystal forms of calcium carbonate (calcite, aragonite and vaterite) is produced most predominantly from sea water by inorganic processes. (2) Which of the chemical constituents of sea water has the greatest influence on the polymorphic formation of calcium carbonate? The experimental results show that aragonite alone is favored in sea water media because of the strong influence of magnesium in the water on the crystal formation of calcium carbonate.

@article{doi105928kaiyou194218141,
    author = "Kitano, Yasushi and Hood, Donald W.",
    title = "Calcium Carbonate Crystal Forms Formed from Sea Water by Inorganic Processes",
    year = "1962",
    journal = "Journal of Engineering Physics and Thermophysics",
    abstract = "This study was made to solve the following questions: (1) Which of the three crystal forms of calcium carbonate (calcite, aragonite and vaterite) is produced most predominantly from sea water by inorganic processes. (2) Which of the chemical constituents of sea water has the greatest influence on the polymorphic formation of calcium carbonate? The experimental results show that aragonite alone is favored in sea water media because of the strong influence of magnesium in the water on the crystal formation of calcium carbonate.",
    url = "https://doi.org/10.5928/kaiyou1942.18.141",
    doi = "10.5928/kaiyou1942.18.141",
    openalex = "W921874498"
}

ABSTRACT On two Florida reefs, submarine reef 10-12 feet high and up to 50 feet wide were dissected with explosives so that internal structures could be examined. Millepora and alga-coated were found to be composed mainly of in-situ coral (Acropora palmata). Comparison of A. palmata with encrusted suggests that a new interpretation of spur and groove formation is necessary. A. palmata growing in less than 20 feet of water on the seaward slope of reefs which face prevailing seas modifies its growth form so that the branches can accommodate the forward thrust of impinging waves. The branches become oriented in the direction of wave movement, and degree of modification is proportional to the wave strength. Continued unidirectional growth causes individual colonies to coalesce into fingerlike that project as much as 200 feet into oncoming seas. These living spurs die from crowding when they reach the surface and subsequently become completely masked with calcareous algae and Millepora. Moving sand, in the grooves between spurs, prevents coral attachment, and periodic hurricane seas remove accumulating debris derived from the overhanging walls of adjoining spurs.

@article{doi10130674d70e342b2111d78648000102c1865d,
    author = "Shinn, Eugene A.",
    title = "Spur and Groove Formation on the Florida Reef Tract",
    year = "1963",
    journal = "Journal of Sedimentary Research",
    abstract = "ABSTRACT On two Florida reefs, submarine reef 10-12 feet high and up to 50 feet wide were dissected with explosives so that internal structures could be examined. Millepora and alga-coated were found to be composed mainly of in-situ coral (Acropora palmata). Comparison of A. palmata with encrusted suggests that a new interpretation of spur and groove formation is necessary. A. palmata growing in less than 20 feet of water on the seaward slope of reefs which face prevailing seas modifies its growth form so that the branches can accommodate the forward thrust of impinging waves. The branches become oriented in the direction of wave movement, and degree of modification is proportional to the wave strength. Continued unidirectional growth causes individual colonies to coalesce into fingerlike that project as much as 200 feet into oncoming seas. These living spurs die from crowding when they reach the surface and subsequently become completely masked with calcareous algae and Millepora. Moving sand, in the grooves between spurs, prevents coral attachment, and periodic hurricane seas remove accumulating debris derived from the overhanging walls of adjoining spurs.",
    url = "https://doi.org/10.1306/74d70e34-2b21-11d7-8648000102c1865d",
    doi = "10.1306/74d70e34-2b21-11d7-8648000102c1865d",
    openalex = "W2168929794"
}

@misc{postnikov1964about3,
    author = "Postnikov, V. G. and Postnikova, I. Y",
    title = "About the possibilities of reef formations in lower Cambrian deposits in Markovskaya reconnaissance area (Irkutskii region)",
    year = "1964",
    howpublished = "Academy of Sciences of the USSR Reports, v. 158, no. 3, p. 605-608; English translation by American Geological Institute, 1965, Academy of Science, USSR Reports, v.158, p. 57-59",
    note = "talkorigins\_source = {true}; raw\_reference = {Postnikov, V. G., and Postnikova, I. Y., 1964, About the possibilities of reef formations in lower Cambrian deposits in Markovskaya reconnaissance area (Irkutskii region): Academy of Sciences of the USSR Reports, v. 158, no. 3, p. 605-608; English translation by American Geological Institute, 1965, Academy of Science, USSR Reports, v.158, p. 57-59.}"
}

@misc{lokhmatov1966change2,
    author = "Lokhmatov, G. I",
    title = "Change of contents of lower Cambrian carbonate deposits under the influence of consediment formation of geological structures (south of Siberian Platform)",
    year = "1966",
    howpublished = "Academy of Sciences of the USSR Reports, v. 170, no. 3, p. 661-664; English translation by American Geological Institute, 1967, Academy of Science, USSR Doklady, v.170, p.88-90",
    note = "talkorigins\_source = {true}; raw\_reference = {Lokhmatov, G. I., 1966, Change of contents of lower Cambrian carbonate deposits under the influence of consediment formation of geological structures (south of Siberian Platform): Academy of Sciences of the USSR Reports, v. 170, no. 3, p. 661-664; English translation by American Geological Institute, 1967, Academy of Science, USSR Doklady, v.170, p.88-90.}"
}

ABSTRACT Distribution coefficient data for the coprecipitation of Sr+2 with aragonite and calcite at low temperatures enable the Sr+2 concentrations of carbonate minerals and rocks to be interpreted in terms of the strontium/calcium ratio of the precipitating solution and the temperature of precipitation. Sea water and a variety of other natural waters have been analyzed to provide the necessary solution data. The best value of the ratio mSr+2/mCa+2 in sea water has been determined to be (0.86 ± 0.04) 10-2. Predicted Sr+2 concentrations of aragonite precipitated from sea water are 8290 ± 850 ppm for the Bahamas and 8200 ± 1110 ppm for the Persian Gulf. Bahaman and Persian Gulf oolitic aragonite contains 9800 ± 500 ppm and 9590 ± 500 ppm Sr+2 respectively, some 17-18 percent higher than predicted values. Bahaman grapestone aragonite contains 9520 ± 600 ppm Sr+2 It is suggested that organic complexing of cations at the sites of precipitation may account for these differences. Reef coral aragonites from the Bahamas and Persian Gulf contain 7980 ± 300 and 7740 ± 300 ppm Sr+2 respectively. Bahaman codiacean algal aragonites contain 8740 ± 600 ppm Sr+2 The uptake of Sr+2 by both corals and algae seems to be affected only slightly by biochemical fractionation, in comparison with most molluscan aragonites which show very strong biochemical fractionation of cations. The predicted Sr+2 concentration of calcite precipitated from sea water is about 1200 ppm. Biogenic calcites of pelagic foraminifera and some molluscs have closely similar Sr+2 concentrations and thus exhibit minimal biochemical fractionation. Lagoonal aragonite muds from the Persian Gulf have a Sr+2 concentration of 9390 ± 500 ppm, a value very similar to that of oolitic aragonite. This similarity and the lack of any obvious skeletal breakdown or abrasion source strongly suggest that the aragonite is a non-skeletal (inorganic) precipitate, although a bacterial, or indirect algally induced precipitation mechanism, cannot be ruled out. The Sr+2 concentrations of diagenetically altered limestones are demonstrated to be of potential value in indicating the mechanisms of diagenesis. Two simple diagenetic analogues are discussed in detail, the system and the open-system recrystallization of carbonate sediments in the presence of an aqueous solution. In closed-the diagenetic alteration of typical aragonitic sediments the former process may give rise to calcites with 700-10,000 ppm Sr+2 whereas calcites with much lower Sr+2 concentrations may result from the latter process (350 ppm or less). The rather low Sr+2 concentrations of ancient limestones and the relatively low solubility of CaCO3 minerals dictate that an open system prevailed through which rather large volum s of pore fluid migrated during diagenesis (probably > 105 pore volumes). These low Sr+2 concentrations also suggest that even if diagenetic alteration does occur with a sea-water pore fluid, later fresh-water diagenesis largely masks these early changes.

@article{doi10130674d71cb72b2111d78648000102c1865d,
    author = "Kinsman, David J. J.",
    title = "Interpretation of Sr+2 Concentrations in Carbonate Minerals and Rocks",
    year = "1969",
    journal = "Journal of Sedimentary Research",
    abstract = "ABSTRACT Distribution coefficient data for the coprecipitation of Sr+2 with aragonite and calcite at low temperatures enable the Sr+2 concentrations of carbonate minerals and rocks to be interpreted in terms of the strontium/calcium ratio of the precipitating solution and the temperature of precipitation. Sea water and a variety of other natural waters have been analyzed to provide the necessary solution data. The best value of the ratio mSr+2/mCa+2 in sea water has been determined to be (0.86 ± 0.04) 10-2. Predicted Sr+2 concentrations of aragonite precipitated from sea water are 8290 ± 850 ppm for the Bahamas and 8200 ± 1110 ppm for the Persian Gulf. Bahaman and Persian Gulf oolitic aragonite contains 9800 ± 500 ppm and 9590 ± 500 ppm Sr+2 respectively, some 17-18 percent higher than predicted values. Bahaman grapestone aragonite contains 9520 ± 600 ppm Sr+2 It is suggested that organic complexing of cations at the sites of precipitation may account for these differences. Reef coral aragonites from the Bahamas and Persian Gulf contain 7980 ± 300 and 7740 ± 300 ppm Sr+2 respectively. Bahaman codiacean algal aragonites contain 8740 ± 600 ppm Sr+2 The uptake of Sr+2 by both corals and algae seems to be affected only slightly by biochemical fractionation, in comparison with most molluscan aragonites which show very strong biochemical fractionation of cations. The predicted Sr+2 concentration of calcite precipitated from sea water is about 1200 ppm. Biogenic calcites of pelagic foraminifera and some molluscs have closely similar Sr+2 concentrations and thus exhibit minimal biochemical fractionation. Lagoonal aragonite muds from the Persian Gulf have a Sr+2 concentration of 9390 ± 500 ppm, a value very similar to that of oolitic aragonite. This similarity and the lack of any obvious skeletal breakdown or abrasion source strongly suggest that the aragonite is a non-skeletal (inorganic) precipitate, although a bacterial, or indirect algally induced precipitation mechanism, cannot be ruled out. The Sr+2 concentrations of diagenetically altered limestones are demonstrated to be of potential value in indicating the mechanisms of diagenesis. Two simple diagenetic analogues are discussed in detail, the system and the open-system recrystallization of carbonate sediments in the presence of an aqueous solution. In closed-the diagenetic alteration of typical aragonitic sediments the former process may give rise to calcites with 700-10,000 ppm Sr+2 whereas calcites with much lower Sr+2 concentrations may result from the latter process (350 ppm or less). The rather low Sr+2 concentrations of ancient limestones and the relatively low solubility of CaCO3 minerals dictate that an open system prevailed through which rather large volum s of pore fluid migrated during diagenesis (probably > 105 pore volumes). These low Sr+2 concentrations also suggest that even if diagenetic alteration does occur with a sea-water pore fluid, later fresh-water diagenesis largely masks these early changes.",
    url = "https://doi.org/10.1306/74d71cb7-2b21-11d7-8648000102c1865d",
    doi = "10.1306/74d71cb7-2b21-11d7-8648000102c1865d",
    openalex = "W1997248638"
}

Abstract Pore systems in sedimentary carbonates are generally complex in their geometry and genesis, and commonly differ markedly from those of sandstones. Current nomenclature and classifications appear inadequate for concise description or for interpretation of porosity in sedimentary carbonates. In this article we review current nomenclature, propose several new terms, and present a classification of porosity which stresses interrelations between porosity and other geologic features. The time and place in which porosity is created or modified are important elements of a genetically oriented classification. Three major geologic events in the history of a sedimentary carbonate form a practical basis for dating origin and modification of porosity, independent of the stage of lithification. These events are (1) creation of the sedimentary framework by clastic accumulation or accretionary precipitation (final deposition), (2) passage of a deposit below the zone of major influence by processes related to and operating from the deposition surface, and (3) passage of the sedimentary rock into the zone of influence by processes operating from an erosion surface (unconformity). The first event, final deposition, permits recognition of predepositional, depositional, and postdeposilional stages of porosity evolution. Cessation of final deposition is the most practical basis for distinguishing primary and secondary (postdeposilional) porosity. Many of the key postdepositionol changes in sedimentary carbonates and their pore systems occur near the surface, either very early in burial history or at a penultimate stage associated with uplift and erosion. Porosity created or modified at these times commonly can be differentiated. On the basis of the three major events heretofore distinguished, we propose to term the early burial stage “eogenetic,” the late stage “telogenetic,” and the normally very long intermediate stage “mesogenetic.” These new terms ore also applicable to process, zones of burial, or porosity formed in these times or zones (e.g., eogenetic cementation, mesogenetic zone, telogenetic porosity). The proposed classification is designed to aid in geologic description and interpretation of pore systems and their carbonate host rocks. It is a descriptive and genetic system in which 15 basic porosity types are recognized: seven abundant types (interparticle, intraparticle, intercrystal, moldic, fenestral, fracture, and vug), and eight more specialized types. Modifying terms are used to characterize genesis, size and shape, and abundance of porosity. The genetic modifiers involve (1) process of modification (solution, cementation, and internal sedimentation), (2) direction or stage of modification (enlarged, reduced, or filled), and (3) time of porosity formation (primary, secondary, predepositional, depositional, eogenetic, mesogenetic, and telogenetic). Used with the basic porosity type, these genetic modifiers permit explicit designation of porosity origin and evolution. Pore shapes are classed as irregular or regular, and the latter ore subdivided into equant, tubular, and platy shapes. A grade scale for size of regular-shaped pores, utilizing the overage diameter of equant or tubular pores and the width of platy pores, has three main classes: micropores (< 1/16 mm), mesopores (1/16–4 mm), and megopores (4–256 mm). Megopores and mesopores ore divided further into small and large subclasses. Abundance is noted by percent volume and/or by ratios of porosity types. Most porosity in sedimentary carbonates can be related specifically to sedimentary or diagenetic components that constitute the texture or fabric (fabric-selective porosity). Some porosity cannot be related to these features. Fabric selectivity commonly distinguishes pore systems of primary and early postdepositional (eogenetic) origin from those of later (telogenetic) origin that normally form after extensive diagenesis has transformed the very porous assemblage of stable and unstable carbonate minerals into a much less porous aggregate of ordered dolomite and/or calcite. Porosity in most carbonate facies, including most carbonate petroleum reservoir rocks, is largely fabric selective.

@article{doi1013065d25c98b16c111d78645000102c1865d,
    author = "Choquette, Philip W. and Pray, Lloyd C.",
    title = "Geologic Nomenclature and Classification of Porosity in Sedimentary Carbonates",
    year = "1970",
    journal = "AAPG Bulletin",
    abstract = "Abstract Pore systems in sedimentary carbonates are generally complex in their geometry and genesis, and commonly differ markedly from those of sandstones. Current nomenclature and classifications appear inadequate for concise description or for interpretation of porosity in sedimentary carbonates. In this article we review current nomenclature, propose several new terms, and present a classification of porosity which stresses interrelations between porosity and other geologic features. The time and place in which porosity is created or modified are important elements of a genetically oriented classification. Three major geologic events in the history of a sedimentary carbonate form a practical basis for dating origin and modification of porosity, independent of the stage of lithification. These events are (1) creation of the sedimentary framework by clastic accumulation or accretionary precipitation (final deposition), (2) passage of a deposit below the zone of major influence by processes related to and operating from the deposition surface, and (3) passage of the sedimentary rock into the zone of influence by processes operating from an erosion surface (unconformity). The first event, final deposition, permits recognition of predepositional, depositional, and postdeposilional stages of porosity evolution. Cessation of final deposition is the most practical basis for distinguishing primary and secondary (postdeposilional) porosity. Many of the key postdepositionol changes in sedimentary carbonates and their pore systems occur near the surface, either very early in burial history or at a penultimate stage associated with uplift and erosion. Porosity created or modified at these times commonly can be differentiated. On the basis of the three major events heretofore distinguished, we propose to term the early burial stage “eogenetic,” the late stage “telogenetic,” and the normally very long intermediate stage “mesogenetic.” These new terms ore also applicable to process, zones of burial, or porosity formed in these times or zones (e.g., eogenetic cementation, mesogenetic zone, telogenetic porosity). The proposed classification is designed to aid in geologic description and interpretation of pore systems and their carbonate host rocks. It is a descriptive and genetic system in which 15 basic porosity types are recognized: seven abundant types (interparticle, intraparticle, intercrystal, moldic, fenestral, fracture, and vug), and eight more specialized types. Modifying terms are used to characterize genesis, size and shape, and abundance of porosity. The genetic modifiers involve (1) process of modification (solution, cementation, and internal sedimentation), (2) direction or stage of modification (enlarged, reduced, or filled), and (3) time of porosity formation (primary, secondary, predepositional, depositional, eogenetic, mesogenetic, and telogenetic). Used with the basic porosity type, these genetic modifiers permit explicit designation of porosity origin and evolution. Pore shapes are classed as irregular or regular, and the latter ore subdivided into equant, tubular, and platy shapes. A grade scale for size of regular-shaped pores, utilizing the overage diameter of equant or tubular pores and the width of platy pores, has three main classes: micropores (\< 1/16 mm), mesopores (1/16–4 mm), and megopores (4–256 mm). Megopores and mesopores ore divided further into small and large subclasses. Abundance is noted by percent volume and/or by ratios of porosity types. Most porosity in sedimentary carbonates can be related specifically to sedimentary or diagenetic components that constitute the texture or fabric (fabric-selective porosity). Some porosity cannot be related to these features. Fabric selectivity commonly distinguishes pore systems of primary and early postdepositional (eogenetic) origin from those of later (telogenetic) origin that normally form after extensive diagenesis has transformed the very porous assemblage of stable and unstable carbonate minerals into a much less porous aggregate of ordered dolomite and/or calcite. Porosity in most carbonate facies, including most carbonate petroleum reservoir rocks, is largely fabric selective.",
    url = "https://doi.org/10.1306/5d25c98b-16c1-11d7-8645000102c1865d",
    doi = "10.1306/5d25c98b-16c1-11d7-8645000102c1865d",
    openalex = "W2029837300",
    references = "doi101002gj3350050104, doi10113000167606196677843tsbp20co2, doi1013060bda5c3616bd11d78645000102c1865d, openalexw2761886851"
}

@article{thrailkill1972carbonate5,
    author = "Thrailkill, J. V",
    title = "Carbonate chemistry of aquifer and stream water in Kentucky",
    year = "1972",
    journal = "Journal of Hydrology, v. 16, p. 93-104",
    note = "talkorigins\_source = {true}; raw\_reference = {Thrailkill, J. V., 1972, Carbonate chemistry of aquifer and stream water in Kentucky: Journal of Hydrology, v. 16, p. 93-104.}"
}

ABSTRACT Calcite cements of the Lake Valley Formation (Osagean) consist of clear syntaxial and granular cements in non-biohermal facies; cements in bioherms are dominated by distinctive cloudy cements, but also include clear cements. The clear cements show compositional zoning that comprises an early iron-free zone and a later iron-poor to iron-rich zone. Cathodoluminescence of the non-ferroan calcite cements reveals as many as four zones containing varying amounts of MnII. Three of these zones are correlative within single measured sections through about 200 ft of stratigraphic interval; and are correlative laterally for a distance of at least 10 mi. Petrography of the non-ferroan cements from samples inmediately adjacent to post-Lake Valley unconformities dates the oldest of these three zones as pre-Meramecian, and the younger two as post-Meramecian and pre-Atokan. Ferroan calcites largely precipitated during post-early Atokan; a minor amount precipitated in pre-Atokan time. Cloudy biohermal cements are older than the clear cements, and precipitated contemporaneonsly with sedimentation of the bioherm facies--they are interpreted by this and previous work to be marine cements. Clear cements are interpreted to have precipitated in the phreatic zone. Evidence includes crystal and zonal geometry, absence of marine hardgrounds, differences from marine cements, and MnII and FeII content. The stratigraphic and geographic distribution of the non-ferroan clear cement zones is interpreted to reflect ancient phreatic lenses established during pre-Meramec and pre-Atokan subaerial exposures of the Lake Valley Formation.

@article{doi101306212f6bc22b2411d78648000102c1865d,
    author = "Meyers, William J.",
    title = "Carbonate Cement Stratigraphy of the Lake Valley Formation (Mississippian) Sacramento Mountains, New Mexico",
    year = "1974",
    journal = "Journal of Sedimentary Research",
    abstract = "ABSTRACT Calcite cements of the Lake Valley Formation (Osagean) consist of clear syntaxial and granular cements in non-biohermal facies; cements in bioherms are dominated by distinctive cloudy cements, but also include clear cements. The clear cements show compositional zoning that comprises an early iron-free zone and a later iron-poor to iron-rich zone. Cathodoluminescence of the non-ferroan calcite cements reveals as many as four zones containing varying amounts of MnII. Three of these zones are correlative within single measured sections through about 200 ft of stratigraphic interval; and are correlative laterally for a distance of at least 10 mi. Petrography of the non-ferroan cements from samples inmediately adjacent to post-Lake Valley unconformities dates the oldest of these three zones as pre-Meramecian, and the younger two as post-Meramecian and pre-Atokan. Ferroan calcites largely precipitated during post-early Atokan; a minor amount precipitated in pre-Atokan time. Cloudy biohermal cements are older than the clear cements, and precipitated contemporaneonsly with sedimentation of the bioherm facies--they are interpreted by this and previous work to be marine cements. Clear cements are interpreted to have precipitated in the phreatic zone. Evidence includes crystal and zonal geometry, absence of marine hardgrounds, differences from marine cements, and MnII and FeII content. The stratigraphic and geographic distribution of the non-ferroan clear cement zones is interpreted to reflect ancient phreatic lenses established during pre-Meramec and pre-Atokan subaerial exposures of the Lake Valley Formation.",
    url = "https://doi.org/10.1306/212f6bc2-2b24-11d7-8648000102c1865d",
    doi = "10.1306/212f6bc2-2b24-11d7-8648000102c1865d",
    openalex = "W2024583597"
}

ABSTRACT Earlier interpretations of textural alteration affecting Great Salt Lake ooids have greatly influenced concepts of ooid diagenesis. Scanning electron microscope study shows, however, that the coarse radial aragonite rays are depositional, that no recrystallization of pellet cores has occurred, and that Great Salt Lake ooids have not suffered noticeable diagenesis. As suggested by Kahle (1974), radial texture in ancient calcitic ooids is probably mainly original, not diagenetic. Retention of such fine textures has been attributed to organic matter (since found to be equivalent in modern skeletal and non‐skeletal grains) or to paramorphic replacement (proposed for non‐skeletal grains whose original aragonite mineralogy was only inferred from modern analogs). Pleistocene ooids known to have been aragonite alter like aragonite shells to coarse neomorphic calcite, often with aragonite relics. The striking uniformity of that coarse texture in neomorphic calcite replacing known skeletal aragonites throughout the geologic record has been noted for over 100 years. In contrast, Mississippian ooids retain fine texture as do calcite layers of coexisting gastropods, but unlike the strongly altered aragonite layers of these same gastropods. Therefore, inferences of original aragonitic mineralogy of ancient non‐skeletal carbonate grains (including muds) which are now calcite but retain fine texture appear unwarranted, as do assumptions of differential diagenetic behaviour of ancient aragonitic skeletal and non‐skeletal grains. Accordingly, modern depositional environments of marine ooids and carbonate muds must be rejected as chemically unrepresentative of comparable ancient environments. It is inferred that ancient non‐skeletal carbonates were originally predominantly or exclusively calcite because of an earlier lower oceanic Mg/Ca ratio (<2/1) which altered progressively to values favouring aragonite (modern Mg/Ca value = 5/1). Major influencing factors are: selective removal of calcium by planktonic foraminifers and coccolithophorids since Jurassic‐Cretaceous time and by abundant younger, Mg‐poor aragonite skeletons and an erratic trend toward decreasing dolomite formation (decreasing removal of oceanic Mg). The change to aragonite dominance over calcite for non‐skeletal carbonates was probably during early to middle Cenozoic time.

@article{doi101111j136530911975tb00244x,
    author = "Sandberg, Philip A.",
    title = "New interpretations of Great Salt Lake ooids and of ancient non‐skeletal carbonate mineralogy",
    year = "1975",
    journal = "Sedimentology",
    abstract = "ABSTRACT Earlier interpretations of textural alteration affecting Great Salt Lake ooids have greatly influenced concepts of ooid diagenesis. Scanning electron microscope study shows, however, that the coarse radial aragonite rays are depositional, that no recrystallization of pellet cores has occurred, and that Great Salt Lake ooids have not suffered noticeable diagenesis. As suggested by Kahle (1974), radial texture in ancient calcitic ooids is probably mainly original, not diagenetic. Retention of such fine textures has been attributed to organic matter (since found to be equivalent in modern skeletal and non‐skeletal grains) or to paramorphic replacement (proposed for non‐skeletal grains whose original aragonite mineralogy was only inferred from modern analogs). Pleistocene ooids known to have been aragonite alter like aragonite shells to coarse neomorphic calcite, often with aragonite relics. The striking uniformity of that coarse texture in neomorphic calcite replacing known skeletal aragonites throughout the geologic record has been noted for over 100 years. In contrast, Mississippian ooids retain fine texture as do calcite layers of coexisting gastropods, but unlike the strongly altered aragonite layers of these same gastropods. Therefore, inferences of original aragonitic mineralogy of ancient non‐skeletal carbonate grains (including muds) which are now calcite but retain fine texture appear unwarranted, as do assumptions of differential diagenetic behaviour of ancient aragonitic skeletal and non‐skeletal grains. Accordingly, modern depositional environments of marine ooids and carbonate muds must be rejected as chemically unrepresentative of comparable ancient environments. It is inferred that ancient non‐skeletal carbonates were originally predominantly or exclusively calcite because of an earlier lower oceanic Mg/Ca ratio (<2/1) which altered progressively to values favouring aragonite (modern Mg/Ca value = 5/1). Major influencing factors are: selective removal of calcium by planktonic foraminifers and coccolithophorids since Jurassic‐Cretaceous time and by abundant younger, Mg‐poor aragonite skeletons and an erratic trend toward decreasing dolomite formation (decreasing removal of oceanic Mg). The change to aragonite dominance over calcite for non‐skeletal carbonates was probably during early to middle Cenozoic time.",
    url = "https://doi.org/10.1111/j.1365-3091.1975.tb00244.x",
    doi = "10.1111/j.1365-3091.1975.tb00244.x",
    openalex = "W1973082754"
}

ABSTRACT The complex pattern of biological accretion, internal sedimentation, early lithification, and biological destruction, that characterizes modern reefs and many fossil reefs has been recognized in archaeocyathid‐rich patch reefs of Lower Cambrian age in the Forteau Formation, southern Labrador. Patch reefs occur as isolated masses or complex associations of many discrete masses of archaeocyathid‐rich limestone and skeletal lime sands, surrounded by well‐bedded skeletal limestones and shales. Each reef is composed of many loafshaped mounds stacked on top of one another. The limestone of each mound comprises archaeocyathids and Renalcis or Renalcis ‐like structures in a matrix of argillaceous lime mud rich in sponge spicules, trilobite and salterellid skeletons. Numerous growth cavities roofed by pendant Renalcis ‐like organisms and Renalcis are partially to completely filled with geopetal sediment indicating that much of the matrix was deposited as internal sediment. Two stages of diagenetic alteration are recognized: (1) syn‐depositional, which affected only the reefs, and (2) post‐depositional, which affected both reefs and inter‐reef sediments. On the sea floor reef sediments were pervasively cemented and fibrous carbonate was precipitated in intraskeletal and growth cavities. These limestones and cements as well as archaeocyathid skeletons, were subsequently bored by endolithic organisms. Later post‐depositional subaerial diagenesis resulted first in dissolution of certain skeletons and precipitation of calcite cement above the water table, followed by extensive precipitation of pore‐filling calcite below the water table. These carbonate reefs are similar in structure to the basal pioneer accumulations of much younger lower and middle Palaeozoic reefs. They did not develop into massive ‘ecologic’ reefs because archaeocyathids never developed the necessary large, massive, hemispherical skeletons. This occurrence indicates that reefs developed more or less coincident with, and not long after, the appearance of skeletal metazoans in the Lower Cambrian.

@article{doi101111j136530911978tb00299x,
    author = "James, Noël P. and Kobluk, David R.",
    title = "Lower Cambrian patch reefs and associated sediments: southern Labrador, Canada",
    year = "1978",
    journal = "Sedimentology",
    abstract = "ABSTRACT The complex pattern of biological accretion, internal sedimentation, early lithification, and biological destruction, that characterizes modern reefs and many fossil reefs has been recognized in archaeocyathid‐rich patch reefs of Lower Cambrian age in the Forteau Formation, southern Labrador. Patch reefs occur as isolated masses or complex associations of many discrete masses of archaeocyathid‐rich limestone and skeletal lime sands, surrounded by well‐bedded skeletal limestones and shales. Each reef is composed of many loafshaped mounds stacked on top of one another. The limestone of each mound comprises archaeocyathids and Renalcis or Renalcis ‐like structures in a matrix of argillaceous lime mud rich in sponge spicules, trilobite and salterellid skeletons. Numerous growth cavities roofed by pendant Renalcis ‐like organisms and Renalcis are partially to completely filled with geopetal sediment indicating that much of the matrix was deposited as internal sediment. Two stages of diagenetic alteration are recognized: (1) syn‐depositional, which affected only the reefs, and (2) post‐depositional, which affected both reefs and inter‐reef sediments. On the sea floor reef sediments were pervasively cemented and fibrous carbonate was precipitated in intraskeletal and growth cavities. These limestones and cements as well as archaeocyathid skeletons, were subsequently bored by endolithic organisms. Later post‐depositional subaerial diagenesis resulted first in dissolution of certain skeletons and precipitation of calcite cement above the water table, followed by extensive precipitation of pore‐filling calcite below the water table. These carbonate reefs are similar in structure to the basal pioneer accumulations of much younger lower and middle Palaeozoic reefs. They did not develop into massive ‘ecologic’ reefs because archaeocyathids never developed the necessary large, massive, hemispherical skeletons. This occurrence indicates that reefs developed more or less coincident with, and not long after, the appearance of skeletal metazoans in the Lower Cambrian.",
    url = "https://doi.org/10.1111/j.1365-3091.1978.tb00299.x",
    doi = "10.1111/j.1365-3091.1978.tb00299.x",
    openalex = "W2067371960",
    references = "doi101002gj3350050104, doi101007978364265923211, doi1010160012825272900724, doi101086627696, doi1010970001069419650700000019, doi101111j136530911970tb00191x, doi101111j1469185x1969tb00609x, doi101306212f6bc22b2411d78648000102c1865d, doi102475ajs275101121, doi1035767gscpgbull194730"
}

ABSTRACT Shelf edge, foreslope, and slope facies in the Lower to Middle Cambrian Shady Dolomite (600-1300 m thick) are exposed southeast of Austinville, southwestern Virginia, Valley and Ridge Province of the Appalachians. The Shady-Rome beds constitute an important type of Lower Paleozoic platform margin. The upward-shallowing platform sequence consists of shallow subtidal ribbon-laminated carbonates (Patterson Member) overlain by shoal water to tidal flat massive dolomites and fenestral cryptalgal carbonates (Austinville and Ivanhoe Members) that pass up into red mudcracked clastic and carbonate rocks (Rome Formation). The platform-margin is characterized by 1) shelf edge Epiphyton boundstone reefs, grainstone/packstones and rudites; these pass seaward into 2) thick sequences of fores ope, bedded limeclast packstone/grainstone, minor interbedded breccias and thin, black, shaly limestones; downslope these grade into 3) thin bedded, black, shaly limestone sequences that contain grainstone/packstone beds, downslope bioherms and blocks of Epiphyton boundstone and polymictic and oligomictic breccias composed of platform, foreslope and slope derived detritus; further seaward, these pass into 4) slope deposits that lack bioherms and are dominated by black shaly limestones, thin grainstone/packstones and oligomictic breccias containing slope-derived black shaly limestone clasts. The southeastern Shady Dolomite facies are important in that they provide information on the character of the Cambrian carbonate platform margin in eastern North America. Further, the presence of blocks and bioherms of Epiphyton boundstone in the deeper-water, Shady breccias suggests that other deeper-water breccias in the Appalachians might also contain similar in-place or allochthonous Epiphyton reef limestones. The similarity of some of the slope lithofacies to relict features of metamorphosed carbonates in the southern Appalachian Piedmont, suggests that the Valley and Ridge rocks might provide useful information on protoliths and depositional processes for rocks in the Appalachian-Piedmont province.

@article{doi101306212f79782b2411d78648000102c1865d,
    author = "Pfeil, R. W.",
    title = "Cambrian Carbonate Platform Margin Facies, Shady Dolomite, Southwestern Virginia, U.S.A.",
    year = "1980",
    journal = "Journal of Sedimentary Research",
    abstract = "ABSTRACT Shelf edge, foreslope, and slope facies in the Lower to Middle Cambrian Shady Dolomite (600-1300 m thick) are exposed southeast of Austinville, southwestern Virginia, Valley and Ridge Province of the Appalachians. The Shady-Rome beds constitute an important type of Lower Paleozoic platform margin. The upward-shallowing platform sequence consists of shallow subtidal ribbon-laminated carbonates (Patterson Member) overlain by shoal water to tidal flat massive dolomites and fenestral cryptalgal carbonates (Austinville and Ivanhoe Members) that pass up into red mudcracked clastic and carbonate rocks (Rome Formation). The platform-margin is characterized by 1) shelf edge Epiphyton boundstone reefs, grainstone/packstones and rudites; these pass seaward into 2) thick sequences of fores ope, bedded limeclast packstone/grainstone, minor interbedded breccias and thin, black, shaly limestones; downslope these grade into 3) thin bedded, black, shaly limestone sequences that contain grainstone/packstone beds, downslope bioherms and blocks of Epiphyton boundstone and polymictic and oligomictic breccias composed of platform, foreslope and slope derived detritus; further seaward, these pass into 4) slope deposits that lack bioherms and are dominated by black shaly limestones, thin grainstone/packstones and oligomictic breccias containing slope-derived black shaly limestone clasts. The southeastern Shady Dolomite facies are important in that they provide information on the character of the Cambrian carbonate platform margin in eastern North America. Further, the presence of blocks and bioherms of Epiphyton boundstone in the deeper-water, Shady breccias suggests that other deeper-water breccias in the Appalachians might also contain similar in-place or allochthonous Epiphyton reef limestones. The similarity of some of the slope lithofacies to relict features of metamorphosed carbonates in the southern Appalachian Piedmont, suggests that the Valley and Ridge rocks might provide useful information on protoliths and depositional processes for rocks in the Appalachian-Piedmont province.",
    url = "https://doi.org/10.1306/212f7978-2b24-11d7-8648000102c1865d",
    doi = "10.1306/212f7978-2b24-11d7-8648000102c1865d",
    openalex = "W1983310554"
}

ABSTRACT Understanding the processes and products of carbonate diagenesis is essential to exploration for, and optimum development of, hydrocarbon reservoirs in carbonate rocks. Much (and perhaps most) cementation and formation of secondary porosity (except fractures) in carbonates occurs at relatively shallow depths in one of four major diagenetic environments: the vadose zone, meteoric phreatic zone, mixing zone, and marine phreatic zone. Each of these zones may be divided into several parts on the basis of rate of water movement and saturation of the water with respect to calcium carbonate. Most carbonates are deposited in and begin their diagenetic history in the marine phreatic environment. This zone may be divided into two end members of a continuous spectrum: a zone of relatively little water circulation in which micritization and minor intragranular cementation occur, and a zone of good water circulation near the sediment/water interface of shelf margins or the upper shoreface in which extensive intergranular and cavity-filling cementation occur. Fibrous aragonite and micritic Mg-calcite are the dominant cements. With subaerial exposure, fresh water will replace sea water in the pores of shallow-water carbonates, and a zone of mixed fresh and marine waters may form. In long-lived mixing zones, dolomite may form if the water is of relatively low salinity, whereas bladed Mg-calcite may form if the water is relatively marine. Active water circulation in the mixing zone, which may be caused by seasonal rainfall, is necessary for dolomitization or cementation. Diagenesis in the freshwater phreatic environment may involve leaching in the zone of solution, neomorphism of grains accompanied by extensive intergranular calcite cementation in the active saturated zone, or neomorphism of grains without cementation in the stagnant saturated zone. Syntaxial overgrowths on echinoderm fragments and interlocking crystals of equant calcite that coarsen toward pore centers are typical of cementation in the active freshwater phreatic zone. The freshwater vadose environment is the zone with both air and meteoric water in the pores and may be divided into the zone of solution and the zone of precipitation. CO2 from the atmosphere and soil contributes to solution which generally occurs near the soil zone and forms vugs, molds, and etched grains. When the water becomes saturated with respect to calcite, evaporation or CO2 loss may cause precipitation of fine equant calcite in the form of pendant and meniscus cements. Grains may be altered to calcite, particularly in humid climates, and caliche crusts may be produced by evaporation and/or biologic (generally algal) factors. Climate plays an important role in early diagenesis if subaerial exposure occurs. In arid climates, cementation in freshwater environments may be limited and primary intergranular porosity may be preserved. In humid climates, little primary porosity is likely to escape cementation, but significant amounts of secondary moldic and vuggy porosity may form. Interpretation of diagenesis in carbonates is complicated by the fact that diagenetic environments may change many times in the history of a carbonate rock. By recognizing the processes leading to the formation or preservation of porosity, and the distribution of diagenetic environments in which those processes acted, the distribution of porosity in subsurface carbonates can often be predicted.

@article{doi1013062f918a6316ce11d78645000102c1865d,
    author = "Longman, Mark W.",
    title = "Carbonate Diagenetic Textures from Nearsurface Diagenetic Environments",
    year = "1980",
    journal = "AAPG Bulletin",
    abstract = "ABSTRACT Understanding the processes and products of carbonate diagenesis is essential to exploration for, and optimum development of, hydrocarbon reservoirs in carbonate rocks. Much (and perhaps most) cementation and formation of secondary porosity (except fractures) in carbonates occurs at relatively shallow depths in one of four major diagenetic environments: the vadose zone, meteoric phreatic zone, mixing zone, and marine phreatic zone. Each of these zones may be divided into several parts on the basis of rate of water movement and saturation of the water with respect to calcium carbonate. Most carbonates are deposited in and begin their diagenetic history in the marine phreatic environment. This zone may be divided into two end members of a continuous spectrum: a zone of relatively little water circulation in which micritization and minor intragranular cementation occur, and a zone of good water circulation near the sediment/water interface of shelf margins or the upper shoreface in which extensive intergranular and cavity-filling cementation occur. Fibrous aragonite and micritic Mg-calcite are the dominant cements. With subaerial exposure, fresh water will replace sea water in the pores of shallow-water carbonates, and a zone of mixed fresh and marine waters may form. In long-lived mixing zones, dolomite may form if the water is of relatively low salinity, whereas bladed Mg-calcite may form if the water is relatively marine. Active water circulation in the mixing zone, which may be caused by seasonal rainfall, is necessary for dolomitization or cementation. Diagenesis in the freshwater phreatic environment may involve leaching in the zone of solution, neomorphism of grains accompanied by extensive intergranular calcite cementation in the active saturated zone, or neomorphism of grains without cementation in the stagnant saturated zone. Syntaxial overgrowths on echinoderm fragments and interlocking crystals of equant calcite that coarsen toward pore centers are typical of cementation in the active freshwater phreatic zone. The freshwater vadose environment is the zone with both air and meteoric water in the pores and may be divided into the zone of solution and the zone of precipitation. CO2 from the atmosphere and soil contributes to solution which generally occurs near the soil zone and forms vugs, molds, and etched grains. When the water becomes saturated with respect to calcite, evaporation or CO2 loss may cause precipitation of fine equant calcite in the form of pendant and meniscus cements. Grains may be altered to calcite, particularly in humid climates, and caliche crusts may be produced by evaporation and/or biologic (generally algal) factors. Climate plays an important role in early diagenesis if subaerial exposure occurs. In arid climates, cementation in freshwater environments may be limited and primary intergranular porosity may be preserved. In humid climates, little primary porosity is likely to escape cementation, but significant amounts of secondary moldic and vuggy porosity may form. Interpretation of diagenesis in carbonates is complicated by the fact that diagenetic environments may change many times in the history of a carbonate rock. By recognizing the processes leading to the formation or preservation of porosity, and the distribution of diagenetic environments in which those processes acted, the distribution of porosity in subsurface carbonates can often be predicted.",
    url = "https://doi.org/10.1306/2f918a63-16ce-11d7-8645000102c1865d",
    doi = "10.1306/2f918a63-16ce-11d7-8645000102c1865d",
    openalex = "W1982339776",
    references = "doi101002gj3350020103, doi101111j136530911970tb00191x, doi10130674d711952b2111d78648000102c1865d"
}

@misc{zapivalov1980formation6,
    author = "Zapivalov, N. P",
    title = "Formation of oil pools in deep Paleozoic carbonates of the intermediate stage in the south of the West Siberian Platform [in Russian], in Osobennosti formirovaniya zalezhey nefti i gaza v glubokozalegayuschchick plastakh",
    year = "1980",
    howpublished = "Moscow, Nedra, p. 23-228; English Summary in Petroleum Geology, v.19, no.6, 1981, p.292-295",
    note = "talkorigins\_source = {true}; raw\_reference = {Zapivalov, N. P., 1980, Formation of oil pools in deep Paleozoic carbonates of the intermediate stage in the south of the West Siberian Platform [in Russian], in Osobennosti formirovaniya zalezhey nefti i gaza v glubokozalegayuschchick plastakh: Moscow, Nedra, p. 23-228; English Summary in Petroleum Geology, v.19, no.6, 1981, p.292-295.}"
}

ABSTRACT The Nolichucky Formation (0–300 m thick) formed on the Cambrian pericratonic shelf in a shallow intrashelf basin bordered along strike and toward the regional shelf edge by shallow water carbonates and by nearshore clastics toward the craton. Lateral facies changes from shallow basinal rocks to peritidal carbonates suggest that the intrashelf basin was bordered by a gently sloping carbonate ramp. Peritidal facies of the regional shelf are cyclic, upward‐shallowing stromatolitic carbonates. These grade toward the intrashelf basin into shallow ramp, cross‐bedded, ooid and oncolitic, intraclast grain‐stones that pass downslope into deeper ramp, subwave base, ribbon carbonates and thin limestone conglomerate. Ribbon limestones are layers and lenses of trilobite packstone, parallel and wave‐ripple‐laminated, quartzose calcisiltite, and lime mudstone arranged in storm‐generated, fining upward sequences (1–5 cm thick) that may be burrowed. Shallow basin facies are storm generated, upward coarsening and upward fining sequences of green, calcareous shale with open marine biota; parallel to hummocky laminated calcareous siltstone; and intraformational flat pebble conglomerate. There are also rare debris‐flow paraconglomerate (10–60 cm thick) and shaly packstone/wackestone with trace fossils, glauconite horizons and erosional surfaces/hardgrounds. A 15‐m thick tongue of cyclic carbonates within the shale package contains subtidal digitate algal bioherms which developed during a period of shoaling in the basin. Understanding the Nolichucky facies within a ramp to intrashelf basin model provides a framework for understanding similar facies which are widely distributed in the Lower Palaeozoic elsewhere. The study demonstrates the widespread effects of storm processes on pericratonic shelf sedimentation. Finally, recognition of shallow basins located on pericratonic shelves is important because such basins influence the distribution of facies and reservoir rocks, whose trends may be unrelated to regional shelf‐edge trends.

@article{doi101111j136530911981tb01702x,
    author = "Markello, James R. and Read, J. F.",
    title = "Carbonate ramp‐to‐deeper shale shelf transitions of an Upper Cambrian intrashelf basin, Nolichucky Formation, Southwest Virginia Appalachians",
    year = "1981",
    journal = "Sedimentology",
    abstract = "ABSTRACT The Nolichucky Formation (0–300 m thick) formed on the Cambrian pericratonic shelf in a shallow intrashelf basin bordered along strike and toward the regional shelf edge by shallow water carbonates and by nearshore clastics toward the craton. Lateral facies changes from shallow basinal rocks to peritidal carbonates suggest that the intrashelf basin was bordered by a gently sloping carbonate ramp. Peritidal facies of the regional shelf are cyclic, upward‐shallowing stromatolitic carbonates. These grade toward the intrashelf basin into shallow ramp, cross‐bedded, ooid and oncolitic, intraclast grain‐stones that pass downslope into deeper ramp, subwave base, ribbon carbonates and thin limestone conglomerate. Ribbon limestones are layers and lenses of trilobite packstone, parallel and wave‐ripple‐laminated, quartzose calcisiltite, and lime mudstone arranged in storm‐generated, fining upward sequences (1–5 cm thick) that may be burrowed. Shallow basin facies are storm generated, upward coarsening and upward fining sequences of green, calcareous shale with open marine biota; parallel to hummocky laminated calcareous siltstone; and intraformational flat pebble conglomerate. There are also rare debris‐flow paraconglomerate (10–60 cm thick) and shaly packstone/wackestone with trace fossils, glauconite horizons and erosional surfaces/hardgrounds. A 15‐m thick tongue of cyclic carbonates within the shale package contains subtidal digitate algal bioherms which developed during a period of shoaling in the basin. Understanding the Nolichucky facies within a ramp to intrashelf basin model provides a framework for understanding similar facies which are widely distributed in the Lower Palaeozoic elsewhere. The study demonstrates the widespread effects of storm processes on pericratonic shelf sedimentation. Finally, recognition of shallow basins located on pericratonic shelves is important because such basins influence the distribution of facies and reservoir rocks, whose trends may be unrelated to regional shelf‐edge trends.",
    url = "https://doi.org/10.1111/j.1365-3091.1981.tb01702.x",
    doi = "10.1111/j.1365-3091.1981.tb01702.x",
    openalex = "W2145649605",
    references = "doi1010079783642814983, doi1010160025322767900515, doi1010160037073868900249, doi1010160040195175901390, doi101016s0070457108x70451, doi101130001676061970811031lpmtat20co2, doi101139e79156, doi101306212f79782b2411d78648000102c1865d, doi10130674d7185c2b2111d78648000102c1865d, doi1023071796776, openalexw1575605242, openalexw630270902"
}

@article{zapivalov1981identifying7,
    author = "Zapivalov, N. P. and Pekhtereva, I. A. and Serdyuk, Z. Y. and Shmatalyuk, G. F",
    title = "Identifying and mapping Paleozoic reef massifs in western Siberia",
    year = "1981",
    journal = "International Geology Review, v. 23, p. 956-962",
    note = "talkorigins\_source = {true}; raw\_reference = {Zapivalov, N. P., Pekhtereva, I. A., Serdyuk, Z. Y., and Shmatalyuk, G. F., 1981, Identifying and mapping Paleozoic reef massifs in western Siberia: International Geology Review, v. 23, p. 956-962.}"
}

@incollection{pemberton1983carbonates,
    author = "Pemberton, H. Earl",
    title = "Carbonates",
    year = "1983",
    booktitle = "Minerals of California",
    url = "https://doi.org/10.1007/978-1-4684-6638-6\_6",
    doi = "10.1007/978-1-4684-6638-6\_6",
    pages = "198-235"
}

@misc{aitken1984the1,
    author = "Aitken, J. D. and McIlreath, J. A",
    title = "The Cathedral Reef escarpment, a Cambrian great wall with humble origins",
    year = "1984",
    howpublished = "Geos: Energy Mines and Resources, Canada, v. 13, no. 1, p. 17-19",
    note = "talkorigins\_source = {true}; raw\_reference = {Aitken, J. D., and McIlreath, J. A., 1984, The Cathedral Reef escarpment, a Cambrian great wall with humble origins: Geos: Energy Mines and Resources, Canada, v. 13, no. 1, p. 17-19.}"
}

@incollection{crossref1984carbonates,
    title = "Carbonates",
    year = "1984",
    booktitle = "SEM Petrology Atlas",
    url = "https://doi.org/10.1306/mth4442c10",
    doi = "10.1306/mth4442c10",
    pages = "154-175"
}

@misc{saller1984petrologic4,
    author = "Saller, A",
    title = "Petrologic and geochemical constraints on the origin of subsurface dolomite, Enewetak Atoll",
    year = "1984",
    howpublished = "Geology, v. 12, p. 217-220",
    note = "talkorigins\_source = {true}; raw\_reference = {Saller, A., 1984, Petrologic and geochemical constraints on the origin of subsurface dolomite, Enewetak Atoll: Geology, v. 12, p. 217-220.}"
}

Summary Shallow-marine carbonate sediments occur in three settings: platforms, shelves and ramps. The facies patterns and sequences in these settings are distinctive. However, one type of setting can develop into another through sedimentational or tectonic processes and, in the geologic record, intermediate cases are common. Five major depositional mechanisms affect carbonate sediments, giving predictable facies sequences: (1) tidal flat progradation, (2) shelf-marginal reef progradation, (3) vertical accretion of subtidal carbonates, (4) migration of carbonate sand bodies and (5) resedimentation processes, especially shoreface sands to deeper subtidal environments by storms and off-shelf transport by slumps, debris flows and turbidity currents. Carbonate platforms are regionally extensive environments of shallow subtidal and intertidal sedimentation. Storms are the most important source of energy, moving sediment on to shoreline tidal flats, reworking shoreface sands and transporting them into areas of deeper water. Progradation of tidal flats, producing shallowing upward sequences is the dominant depositional process on platforms. Two basic types of tidal flat are distinguished: an active type, typical of shorelines of low sediment production rates and high meteorologic tidal range, characterized by tidal channels which rework the flats producing grainstone lenses and beds and shell lags, and prominent storm layers; and a passive type in areas of lower meteorologic tidal range and higher sediment production rates, characterized by an absence of channel deposits, much fenestral and cryptalgal peloidal micrite, few storm layers and possibly extensive mixing-zone dolomite. Fluctuations in sea-level strongly affect platform sedimentation. Shelves are relatively narrow depositional environments, characterized by a distinct break of slope at the shelf margin. Reefs and carbonate sand bodies typify the turbulent shelf margin and give way to a shelf lagoon, bordered by tidal flats and/or a beach-barrier system along the shoreline. Marginal reef complexes show a fore-reef—reef core—back reef facies arrangement, where there were organisms capable of producing a solid framework. There have been seven such phases through the Phanerozoic. Reef mounds, equivalent to modern patch reefs, are very variable in faunal composition, size and shape. They occur at shelf margins, but also within shelf lagoons and on platforms and ramps. Four stages of development can be distinguished, from little-solid reef with much skeletal debris through to an evolved reef-lagoon-debris halo system. Shelf-marginal carbonate sand bodies consist of skeletal and oolite grainstones. Windward, leeward and tide-dominated shelf margins have different types of carbonate sand body, giving distinctive facies models. Ramps slope gently from intertidal to basinal depths, with no major change in gradient. Nearshore, inner ramp carbonate sands of beach-barrier-tidal delta complexes and subtidal shoals give way to muddy sands and sandy muds of the outer ramp. The major depositional processes are seaward progradation of the inner sand belt and storm transport of shoreface sand out to the deep ramp. Most shallow-marine carbonate facies are represented throughout the geologic record. However, variations do occur and these are most clearly seen in shelf-margin facies, through the evolutionary pattern of frame-building organisms causing the erratic development of barrier reef complexes. There have been significant variations in the mineralogy of carbonate skeletons, ooids and syn-sedimentary cements through time, reflecting fluctuations in seawater chemistry, but the effect of these is largely in terms of diagenesis rather than facies.

@article{doi101144gslsp19850180108,
    author = "Tucker, M. E.",
    title = "Shallow-marine carbonate facies and facies models",
    year = "1985",
    journal = "Geological Society London Special Publications",
    abstract = "Summary Shallow-marine carbonate sediments occur in three settings: platforms, shelves and ramps. The facies patterns and sequences in these settings are distinctive. However, one type of setting can develop into another through sedimentational or tectonic processes and, in the geologic record, intermediate cases are common. Five major depositional mechanisms affect carbonate sediments, giving predictable facies sequences: (1) tidal flat progradation, (2) shelf-marginal reef progradation, (3) vertical accretion of subtidal carbonates, (4) migration of carbonate sand bodies and (5) resedimentation processes, especially shoreface sands to deeper subtidal environments by storms and off-shelf transport by slumps, debris flows and turbidity currents. Carbonate platforms are regionally extensive environments of shallow subtidal and intertidal sedimentation. Storms are the most important source of energy, moving sediment on to shoreline tidal flats, reworking shoreface sands and transporting them into areas of deeper water. Progradation of tidal flats, producing shallowing upward sequences is the dominant depositional process on platforms. Two basic types of tidal flat are distinguished: an active type, typical of shorelines of low sediment production rates and high meteorologic tidal range, characterized by tidal channels which rework the flats producing grainstone lenses and beds and shell lags, and prominent storm layers; and a passive type in areas of lower meteorologic tidal range and higher sediment production rates, characterized by an absence of channel deposits, much fenestral and cryptalgal peloidal micrite, few storm layers and possibly extensive mixing-zone dolomite. Fluctuations in sea-level strongly affect platform sedimentation. Shelves are relatively narrow depositional environments, characterized by a distinct break of slope at the shelf margin. Reefs and carbonate sand bodies typify the turbulent shelf margin and give way to a shelf lagoon, bordered by tidal flats and/or a beach-barrier system along the shoreline. Marginal reef complexes show a fore-reef—reef core—back reef facies arrangement, where there were organisms capable of producing a solid framework. There have been seven such phases through the Phanerozoic. Reef mounds, equivalent to modern patch reefs, are very variable in faunal composition, size and shape. They occur at shelf margins, but also within shelf lagoons and on platforms and ramps. Four stages of development can be distinguished, from little-solid reef with much skeletal debris through to an evolved reef-lagoon-debris halo system. Shelf-marginal carbonate sand bodies consist of skeletal and oolite grainstones. Windward, leeward and tide-dominated shelf margins have different types of carbonate sand body, giving distinctive facies models. Ramps slope gently from intertidal to basinal depths, with no major change in gradient. Nearshore, inner ramp carbonate sands of beach-barrier-tidal delta complexes and subtidal shoals give way to muddy sands and sandy muds of the outer ramp. The major depositional processes are seaward progradation of the inner sand belt and storm transport of shoreface sand out to the deep ramp. Most shallow-marine carbonate facies are represented throughout the geologic record. However, variations do occur and these are most clearly seen in shelf-margin facies, through the evolutionary pattern of frame-building organisms causing the erratic development of barrier reef complexes. There have been significant variations in the mineralogy of carbonate skeletons, ooids and syn-sedimentary cements through time, reflecting fluctuations in seawater chemistry, but the effect of these is largely in terms of diagenesis rather than facies.",
    url = "https://doi.org/10.1144/gsl.sp.1985.018.01.08",
    doi = "10.1144/gsl.sp.1985.018.01.08",
    openalex = "W2001962979",
    references = "doi101111j136530911981tb01702x"
}

@incollection{wenk1985carbonates,
    author = "WENK, H.-R.",
    title = "Carbonates",
    year = "1985",
    booktitle = "Preferred Orientation in Deformed Metal and Rocks",
    url = "https://doi.org/10.1016/b978-0-12-744020-0.50022-5",
    doi = "10.1016/b978-0-12-744020-0.50022-5",
    pages = "361-384"
}

ABSTRACT The St George Group consists of peritidal carbonate rocks deposited on the continental shelf of North America bordering the ancient Iapetus Ocean. These Lower Ordovician rocks are similar to other lower Palaeozoic limestones and dolostones that accumulated in epeiric seas and veneer cratonic areas worldwide. A wide variety of facies in the St George is grouped into seven lithotopes, interpreted to represent supratidal, intertidal and shallow, high‐ and low‐energy subtidal environments. Rapid lateral facies changes can be observed in some field exposures, and demonstrated by correlation of closely spaced sections. The stratigraphic array of these lithotopes, although too irregular to be simplified into shallowing‐upward cycles, suggests that they were deposited as small tidal flat islands and banks. Shallow subtidal areas around islands generated sediment and permitted tidal exchange. Tidal flat islands were somewhat variable in character at any one time, and evolved with changing regional hydrographic conditions. The St George rocks suggest an alternative theory of carbonate sedimentation in large, shallow epeiric seas, namely as small islands and banks built by processes that operated in a tidal regime. Furthermore, this island model provides a framework for a mechanism of cyclic carbonate sedimentation, by which small‐scale, peritidal cycles represent tidal flat islands that accreted vertically and migrated laterally as local sediment supply from neighbouring subtidal areas waxed and waned during relatively constant subsidence.

@article{doi101111j136530911986tb00540x,
    author = "Pratt, Brian R. and James, Noël P.",
    title = "The St George Group (Lower Ordovician) of western Newfoundland: tidal flat island model for carbonate sedimentation in shallow epeiric seas",
    year = "1986",
    journal = "Sedimentology",
    abstract = "ABSTRACT The St George Group consists of peritidal carbonate rocks deposited on the continental shelf of North America bordering the ancient Iapetus Ocean. These Lower Ordovician rocks are similar to other lower Palaeozoic limestones and dolostones that accumulated in epeiric seas and veneer cratonic areas worldwide. A wide variety of facies in the St George is grouped into seven lithotopes, interpreted to represent supratidal, intertidal and shallow, high‐ and low‐energy subtidal environments. Rapid lateral facies changes can be observed in some field exposures, and demonstrated by correlation of closely spaced sections. The stratigraphic array of these lithotopes, although too irregular to be simplified into shallowing‐upward cycles, suggests that they were deposited as small tidal flat islands and banks. Shallow subtidal areas around islands generated sediment and permitted tidal exchange. Tidal flat islands were somewhat variable in character at any one time, and evolved with changing regional hydrographic conditions. The St George rocks suggest an alternative theory of carbonate sedimentation in large, shallow epeiric seas, namely as small islands and banks built by processes that operated in a tidal regime. Furthermore, this island model provides a framework for a mechanism of cyclic carbonate sedimentation, by which small‐scale, peritidal cycles represent tidal flat islands that accreted vertically and migrated laterally as local sediment supply from neighbouring subtidal areas waxed and waned during relatively constant subsidence.",
    url = "https://doi.org/10.1111/j.1365-3091.1986.tb00540.x",
    doi = "10.1111/j.1365-3091.1986.tb00540.x",
    openalex = "W2132300109",
    references = "cisne1982facies, doi101002gj3350190402, doi1010079783642814983, doi1010160025322779900860, doi1010160025322781901183, doi101029eo063i023p0052906, doi101086628416, doi101111j136530911977tb00134x, doi101111j136530911982tb01733x, doi1011300016760619637493sitcio20co2, doi10113000167606198192197tpodra20co2, doi101139e79070, doi1013060bda5c3616bd11d78645000102c1865d, doi10130674d7185c2b2111d78648000102c1865d, openalexw2761886851, openalexw597633443"
}

@article{park1987middle,
    author = "Park, Byong-Kwon and Han, Sang-Joon",
    title = "Middle Cambrian Back-Reef Deposits: Carbonates Interbedded in the Lower Part of Pungchon Limestone Formation, Korea",
    year = "1987",
    journal = "Journal of the Geological Society of Korea",
    url = "https://doi.org/10.14770/jgsk.1987.23.4.287",
    doi = "10.14770/jgsk.1987.23.4.287",
    number = "4",
    openalex = "W7124454945",
    pages = "287-305",
    volume = "23"
}

@article{doi1023073514525,
    author = "Rowland, Stephen and Gangloff, Roland A.",
    title = "Structure and Paleoecology of Lower Cambrian Reefs",
    year = "1988",
    journal = "Palaios",
    url = "https://doi.org/10.2307/3514525",
    doi = "10.2307/3514525",
    openalex = "W2322534427"
}

ABSTRACT The Shackleton Limestone formed a carbonate platform that bordered part of the Greater Antarctic craton in middle and late Early Cambrian time. In the Holyoake Range of the central Transantarctic Mountains, this unit records deposition on a stable shelf on which flourished ecological reefs composed of microorganisms and archaeocyathans. Burrow‐mottled lime mudstone, wackestone and packstone with patch reefs represent accumulation in shelf areas of relatively low to moderate energy. Thick ooidal grainstone units reflect deposition in higher energy shoals and as sand sheets that were associated with extensive reef complexes. The framework of these reefs was principally the product of micro‐organisms, by inference mostly cyanobacteria. Archaeocyathans constitute as much as 30% of some reefs, but commonly they form less than 10% and are absent from some. On the basis of microbial composition, three reef types are recognized. The first type is a Renalcis boundstone that lacks archaeocyathans. Within these, abundant upward‐directed thalii of Renalcis formed a framework that trapped fine‐grained sediment. The second type, which forms the core of some larger reefs, is composed of stromatactis‐bearing, microbial boundstone. The third, yet most common, reef type is variable in composition. It is characterized by the presence of abundant Epiphyton, but may include archaeocyathans, and the microbial microfossils Girvanella and Renalcis as well as cryptomicrobial clotted micrite. In this type of reef, frame‐building organisms typically constructed highly porous structures that had small interparticle and fenestral pores and large growth‐framework cavities, as well as rare metre‐sized caverns. Within these spaces, Epiphyton and, less commonly Renalcis, encrusted framework elements, fine‐grained sediments accumulated, and pervasive sea‐floor cements were precipitated. Boundstone fabrics in the Shackleton Limestone are highly complex, with fabrics analogous to younger, more metazoan‐rich reefs, as well as deep‐water stromatactis‐bearing mud‐mounds. The Epiphyton‐Girvanella ‐archaeocyathan frameworks and stromatactis‐bearing boundstones, both of which seemingly first appeared in the middle Early Cambrian, are regarded as the precursors, in structure, composition, and preferred hydrologic setting, of the more extensive reefs and complex framework styles of later Phanerozoic time.

@article{doi101111j136530911989tb00611x,
    author = "Rees, Margaret N. and Pratt, Brian R. and Rowell, A. J.",
    title = "Early Cambrian reefs, reef complexes, and associated lithofacies of the Shackleton Limestone, Transantarctic Mountains",
    year = "1989",
    journal = "Sedimentology",
    abstract = "ABSTRACT The Shackleton Limestone formed a carbonate platform that bordered part of the Greater Antarctic craton in middle and late Early Cambrian time. In the Holyoake Range of the central Transantarctic Mountains, this unit records deposition on a stable shelf on which flourished ecological reefs composed of microorganisms and archaeocyathans. Burrow‐mottled lime mudstone, wackestone and packstone with patch reefs represent accumulation in shelf areas of relatively low to moderate energy. Thick ooidal grainstone units reflect deposition in higher energy shoals and as sand sheets that were associated with extensive reef complexes. The framework of these reefs was principally the product of micro‐organisms, by inference mostly cyanobacteria. Archaeocyathans constitute as much as 30\% of some reefs, but commonly they form less than 10\% and are absent from some. On the basis of microbial composition, three reef types are recognized. The first type is a Renalcis boundstone that lacks archaeocyathans. Within these, abundant upward‐directed thalii of Renalcis formed a framework that trapped fine‐grained sediment. The second type, which forms the core of some larger reefs, is composed of stromatactis‐bearing, microbial boundstone. The third, yet most common, reef type is variable in composition. It is characterized by the presence of abundant Epiphyton, but may include archaeocyathans, and the microbial microfossils Girvanella and Renalcis as well as cryptomicrobial clotted micrite. In this type of reef, frame‐building organisms typically constructed highly porous structures that had small interparticle and fenestral pores and large growth‐framework cavities, as well as rare metre‐sized caverns. Within these spaces, Epiphyton and, less commonly Renalcis, encrusted framework elements, fine‐grained sediments accumulated, and pervasive sea‐floor cements were precipitated. Boundstone fabrics in the Shackleton Limestone are highly complex, with fabrics analogous to younger, more metazoan‐rich reefs, as well as deep‐water stromatactis‐bearing mud‐mounds. The Epiphyton‐Girvanella ‐archaeocyathan frameworks and stromatactis‐bearing boundstones, both of which seemingly first appeared in the middle Early Cambrian, are regarded as the precursors, in structure, composition, and preferred hydrologic setting, of the more extensive reefs and complex framework styles of later Phanerozoic time.",
    url = "https://doi.org/10.1111/j.1365-3091.1989.tb00611.x",
    doi = "10.1111/j.1365-3091.1989.tb00611.x",
    openalex = "W2032375048"
}

Low latitude carbonates in massive and clinoform bedded sheets, termed ramps, occur throughout the Tertiary Tethyan realm, and are characterized by recurring biofacies usually including large foraminifera, rhodolithic algae, coralgal patch-reef and gastropod dominated sequences. All can be interpreted broadly within a standardized Tertiary carbonate ramp model. Biota can be used to define precise palaeobathymetric zones which have a predictive utility in palaeoenvironmental modelling, especially where data are limited. The carbonate ramp model of earlier authors, has been elaborated by Read (1982) and ramp formation occurs mostly in passive margin and extensional tectonic settings. Ramps are characterized by slope gradients of less than 1 degree and, once established, are conservative to change. Much use has been made of the ramp model for Palaeozoic and Mesozoic lithofacies modelling. In contrast, published work on Cenozoic ramps is limited, however, Tethyan ramps are particularly widespread and extend tens to hundreds of kilometres along strike and occupy tens of kilometres of slope. Many studies have dealt with Cenozoic ramp associations and sequences (e.g. Pedley 1983; Reiss & Hottinger 1984; Purser 1973) and have demonstrated the diversity of biotal and sediment detail, but without ascribing them to a ramp model. Biota were quick to adapt to the Tertiary environments left vacant after the K–T boundary extinction events. New genera of Foraminifera, Mollusca, Bryozoa and Echinoder-mata rapidly replaced the extinct forms in bursts of innovative opportunism. Codiacean algae, Rhodophyta and marine angiosperms were equally adaptive colonizers of the carbonate platforms. Novel biofacies associations were derived from

@article{doi101144gsjgs14650746,
    author = "Buxton, Mike and Pedley, H.M.",
    title = "Short Paper: A standardized model for Tethyan Tertiary carbonate ramps",
    year = "1989",
    journal = "Journal of the Geological Society",
    abstract = "Low latitude carbonates in massive and clinoform bedded sheets, termed ramps, occur throughout the Tertiary Tethyan realm, and are characterized by recurring biofacies usually including large foraminifera, rhodolithic algae, coralgal patch-reef and gastropod dominated sequences. All can be interpreted broadly within a standardized Tertiary carbonate ramp model. Biota can be used to define precise palaeobathymetric zones which have a predictive utility in palaeoenvironmental modelling, especially where data are limited. The carbonate ramp model of earlier authors, has been elaborated by Read (1982) and ramp formation occurs mostly in passive margin and extensional tectonic settings. Ramps are characterized by slope gradients of less than 1 degree and, once established, are conservative to change. Much use has been made of the ramp model for Palaeozoic and Mesozoic lithofacies modelling. In contrast, published work on Cenozoic ramps is limited, however, Tethyan ramps are particularly widespread and extend tens to hundreds of kilometres along strike and occupy tens of kilometres of slope. Many studies have dealt with Cenozoic ramp associations and sequences (e.g. Pedley 1983; Reiss \& Hottinger 1984; Purser 1973) and have demonstrated the diversity of biotal and sediment detail, but without ascribing them to a ramp model. Biota were quick to adapt to the Tertiary environments left vacant after the K–T boundary extinction events. New genera of Foraminifera, Mollusca, Bryozoa and Echinoder-mata rapidly replaced the extinct forms in bursts of innovative opportunism. Codiacean algae, Rhodophyta and marine angiosperms were equally adaptive colonizers of the carbonate platforms. Novel biofacies associations were derived from",
    url = "https://doi.org/10.1144/gsjgs.146.5.0746",
    doi = "10.1144/gsjgs.146.5.0746",
    openalex = "W2088261594",
    references = "doi1010160040195182901299"
}

ABSTRACT Carbonate buildups in the Flinders Ranges of mid‐Early Cambrian age grew during a period of high archaeocyath diversity and are of two types: (1) low‐energy, archaeocyath‐sponge‐spicule mud mounds, and (2) high‐energy, archaeocyath‐calcimicrobe (calcified microbial microfossil) bioherms. Mud mounds are composed of red carbonate mudstone and sparse to abundant archaeocyath floatstone, have a fenestral fabric, display distinct stromatactis, contain abundant sponge spicules and form structures up to 150m wide and 80 m thick. Bioherms are either red or dark grey limestone and occur as isolated small structures 2–20 m in size surrounded by cross‐bedded calcarenites and calcirudites or as complexes of mounds and carbonate sands several hundreds of metres across. Red bioherms comprise masses of white Epiphyton with scattered archaeocyaths and intervening areas of archaeocyath‐rich lime mudstone. Grey bioherms are complex intergrowths of archaeocyaths, encrusting dark grey Renalcis and thick rinds of fibrous calcite cement. The bioherms were prone to synsedimentary fracturing and exhibit large irregular cavities, up to 1.5 m across, lined with fibrous calcite. The buildups are isolated or in contiguous vertical succession. Mud mounds occur alone in low‐energy, frequently nodular, limestone facies. Individual bioherms and bioherm complexes occur in high‐energy on‐shelf and shelf‐margin facies. The two types also form large‐scale, shallowing‐upward sequences composed of basal (deep water) mud mounds grading upward into archaeocyath‐calcimicrobe bioherm complexes and bioherms in cross‐bedded carbonate sands. The uppermost sequence is capped by ooid grainstone and/ or fenestral to stromatolitic mudstone. The calcimicrobe and metazoan associations form the two major biotic elements which were to dominate reefs throughout much of subsequent Phanerozoic time.

@article{doi101111j136530911990tb00147x,
    author = "James, Noël P. and Gravestock, David",
    title = "Lower Cambrian shelf and shelf margin buildups, Flinders Ranges, South Australia 1",
    year = "1990",
    journal = "Sedimentology",
    abstract = "ABSTRACT Carbonate buildups in the Flinders Ranges of mid‐Early Cambrian age grew during a period of high archaeocyath diversity and are of two types: (1) low‐energy, archaeocyath‐sponge‐spicule mud mounds, and (2) high‐energy, archaeocyath‐calcimicrobe (calcified microbial microfossil) bioherms. Mud mounds are composed of red carbonate mudstone and sparse to abundant archaeocyath floatstone, have a fenestral fabric, display distinct stromatactis, contain abundant sponge spicules and form structures up to 150m wide and 80 m thick. Bioherms are either red or dark grey limestone and occur as isolated small structures 2–20 m in size surrounded by cross‐bedded calcarenites and calcirudites or as complexes of mounds and carbonate sands several hundreds of metres across. Red bioherms comprise masses of white Epiphyton with scattered archaeocyaths and intervening areas of archaeocyath‐rich lime mudstone. Grey bioherms are complex intergrowths of archaeocyaths, encrusting dark grey Renalcis and thick rinds of fibrous calcite cement. The bioherms were prone to synsedimentary fracturing and exhibit large irregular cavities, up to 1.5 m across, lined with fibrous calcite. The buildups are isolated or in contiguous vertical succession. Mud mounds occur alone in low‐energy, frequently nodular, limestone facies. Individual bioherms and bioherm complexes occur in high‐energy on‐shelf and shelf‐margin facies. The two types also form large‐scale, shallowing‐upward sequences composed of basal (deep water) mud mounds grading upward into archaeocyath‐calcimicrobe bioherm complexes and bioherms in cross‐bedded carbonate sands. The uppermost sequence is capped by ooid grainstone and/ or fenestral to stromatolitic mudstone. The calcimicrobe and metazoan associations form the two major biotic elements which were to dominate reefs throughout much of subsequent Phanerozoic time.",
    url = "https://doi.org/10.1111/j.1365-3091.1990.tb00147.x",
    doi = "10.1111/j.1365-3091.1990.tb00147.x",
    openalex = "W2163469278",
    references = "doi1010160012825290900595, doi10108003115518608619151, doi101111j136530911978tb00299x, doi101111j136530911982tb01733x, doi101111j136530911989tb00611x, doi101306212f853f2b2411d78648000102c1865d, doi101306m26490, doi101306m33429, doi102110pec85360109, doi1023073514525, doi1035767gscpgbull194730"
}

@article{crossref1992carbonates,
    title = "Carbonates",
    year = "1992",
    journal = "Physics and Chemistry of the Earth",
    url = "https://doi.org/10.1016/0079-1946(92)90024-n",
    doi = "10.1016/0079-1946(92)90024-n",
    pages = "211-220",
    volume = "18"
}

ABSTRACT Reefal buildups in western Mongolia of mid‐Early Cambrian (late Atdabanian) age flourished during a period when shelf seas were globally widespread. The succession at Zuune Arts records the transition from shallow marine siliciclastic sediments (Bayan Gol Formation) to shallow marine, but still clastic‐influenced, carbonates (Salaany Gol Formation). The Salaany Gol Formation is interpreted as having been deposited as a series of shallowing upwards cycles on a shallow, gently inclined shelf in a rapidly subsiding epicontinental sea. Cycles commenced with the growth of subtidal metazoan‐calcimicrobe aggregative communities on an open shelf. The resultant buildups were commonly engulfed by extensive, massive microbial stromatolites when they grew in agitated intertidal conditions. Latterly, they were smothered by ooid shoals in response to rapid sea level rise. Four types of reefal buildup are distinguished: (1) green‐coloured calcimicrobe (Tarthinia, Epiphyton, Gordonophyton and Renalcis) boundstones; (2) red‐or green‐coloured Cambrocyathellus‐Tarthinia‐Epiphyton bafflestones; (3) red‐coloured Okulitchicyathus bindstones; and (4) red‐coloured radiocyath‐archaeocyath‐cribricyath bioherms. Each is interpreted as having grown at increasing depths and possibly sedimentation rates. The buildups are commonly enclosed within graded and planar bedded bioclastic grainstones and packstones, and are best developed towards the top of the formation, when sea level was high. Thickets of large, solitary archaeocyaths are also inferred in the deeper interbiohermal areas. These buildups had synoptic relief and constructed porous structures with growth‐framework cavities housing diverse coelobiontic communities. Extensive synsedimentary cements are present, including pseudomorphed aragonitic fans and possible pseudomorphed aragontic botryoids. These early reefs thus have geological fabrics similar to later Phanerozoic representatives. It is proposed however, that this ecosystem was largely composed of generalist and opportunistic filter and suspension feeders which were dependent upon a far higher input of nutrients than modern day reefal developments. Bacteria were probably the main primary producers, from both planktic and benthic cyanobacterial communities. The diversity of each buildup assemblage appears to be controlled by primary cavity size, the richest fauna belonging to the highly tiered radiocyath‐dominated community inferred to have lived in the deepest waters. The communities at Zuune Arts can be compared with other buildups from the early Cambrian, and with Lower Ordovician receptaculid‐calcimicrobe‐solitary sponge bioherms known from the USA and Siberia.

@article{doi101111j136530911993tb01364x,
    author = "Wood, Rachel and Zhuravlev, Andrey Yu. and ANAAZ, CHIMED TSEREN",
    title = "The ecology of Lower Cambrian buildups from Zuune Arts, Mongolia: implications for early metazoan reef evolution",
    year = "1993",
    journal = "Sedimentology",
    abstract = "ABSTRACT Reefal buildups in western Mongolia of mid‐Early Cambrian (late Atdabanian) age flourished during a period when shelf seas were globally widespread. The succession at Zuune Arts records the transition from shallow marine siliciclastic sediments (Bayan Gol Formation) to shallow marine, but still clastic‐influenced, carbonates (Salaany Gol Formation). The Salaany Gol Formation is interpreted as having been deposited as a series of shallowing upwards cycles on a shallow, gently inclined shelf in a rapidly subsiding epicontinental sea. Cycles commenced with the growth of subtidal metazoan‐calcimicrobe aggregative communities on an open shelf. The resultant buildups were commonly engulfed by extensive, massive microbial stromatolites when they grew in agitated intertidal conditions. Latterly, they were smothered by ooid shoals in response to rapid sea level rise. Four types of reefal buildup are distinguished: (1) green‐coloured calcimicrobe (Tarthinia, Epiphyton, Gordonophyton and Renalcis) boundstones; (2) red‐or green‐coloured Cambrocyathellus‐Tarthinia‐Epiphyton bafflestones; (3) red‐coloured Okulitchicyathus bindstones; and (4) red‐coloured radiocyath‐archaeocyath‐cribricyath bioherms. Each is interpreted as having grown at increasing depths and possibly sedimentation rates. The buildups are commonly enclosed within graded and planar bedded bioclastic grainstones and packstones, and are best developed towards the top of the formation, when sea level was high. Thickets of large, solitary archaeocyaths are also inferred in the deeper interbiohermal areas. These buildups had synoptic relief and constructed porous structures with growth‐framework cavities housing diverse coelobiontic communities. Extensive synsedimentary cements are present, including pseudomorphed aragonitic fans and possible pseudomorphed aragontic botryoids. These early reefs thus have geological fabrics similar to later Phanerozoic representatives. It is proposed however, that this ecosystem was largely composed of generalist and opportunistic filter and suspension feeders which were dependent upon a far higher input of nutrients than modern day reefal developments. Bacteria were probably the main primary producers, from both planktic and benthic cyanobacterial communities. The diversity of each buildup assemblage appears to be controlled by primary cavity size, the richest fauna belonging to the highly tiered radiocyath‐dominated community inferred to have lived in the deepest waters. The communities at Zuune Arts can be compared with other buildups from the early Cambrian, and with Lower Ordovician receptaculid‐calcimicrobe‐solitary sponge bioherms known from the USA and Siberia.",
    url = "https://doi.org/10.1111/j.1365-3091.1993.tb01364.x",
    doi = "10.1111/j.1365-3091.1993.tb01364.x",
    openalex = "W2096124414",
    references = "doi1010079783642523359, doi1010160012825272900633, doi1010160022098174900057, doi101038305019a0, doi101038324055a0, doi101111j136530911978tb00299x, doi10113000917613198715111rproaa20co2, doi1035767gscpgbull194730, openalexw1558464430, openalexw2754161204, openalexw587905045"
}

Abstract Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wixaxia, best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wixaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wixaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid—brachiopod—mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.

@article{doi101098rstb19950029,
    author = "Morris, Simon Conway and Peel, John S.",
    title = "Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution",
    year = "1995",
    journal = "Philosophical Transactions of the Royal Society B Biological Sciences",
    abstract = "Abstract Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wixaxia, best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wixaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wixaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid—brachiopod—mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.",
    url = "https://doi.org/10.1098/rstb.1995.0029",
    doi = "10.1098/rstb.1995.0029",
    openalex = "W2001586405",
    references = "doi101007978148992427812, doi1010160301926885900518, doi101017s0022336000037057, doi101038326181a0, doi101038345802a0, doi101038361219a0, doi101098rstb19790006, doi101098rstb19850005, doi101111j143904691975tb00509x, doi101111j146363951991tb00312x, doi101111j146364091991tb00303x, doi101111j150239311969tb01258x, doi101111j150239311993tb01502x, doi101126science2224620163, doi101126science2464928339, doi101126science3277277, doi101144gsjgs14940631, doi101146annureves10110179001551, doi105962bhltitle8596, morris1979the, morris1987a, openalexw2138270429, openalexw2302261279, openalexw2754161204, openalexw589153876"
}

Late Permian reefs of the Capitan complex, west Texas; the Magnesian Limestone, England; Chuenmuping reef, south China; and elsewhere contain anomalously large volumes of aragonite and calcite marine cements and sea-floor crusts, as well as abundant microbial precipitates. These components strongly influenced reef growth and may have been responsible for the construction of rigid, open reefal frames in which bryozoans and sponges became encrusted and structurally reinforced. In some cases, such as the upper biostrome of the Magnesian Limestone, precipitated microbialites and inorganic crusts were the primary constituents of the reef core. These microbial and inorganic reefs do not have modern marine counterparts; on the contrary, their textures and genesis are best understood through comparison with the older rock record, particularly that of the early Precambrian. Early Precambrian reefal facies are interpreted to have formed in a stratified ocean with anoxic deep waters enriched in carbonate alkalinity. Upwelling mixed deep and surface waters, resulting in massive seafloor precipitation of aragonite and calcite. During Mesoproterozoic and early Neoproterozoic time, the ocean became more fully oxidized, and seafloor carbonate precipitation was significantly reduced. However, during the late Neoproterozoic, sizeable volumes of deep ocean water once again became anoxic for protracted intervals; the distinctive "cap carbonates" found above Neoproterozoic tillites attest to renewed upwelling of anoxic bottom water enriched in carbonate alkalinity and 12C. Anomalous late Permian seafloor precipitates are interpreted as the product, at least in part, of similar processes. Massive carbonate precipitation was favored by: 1) reduced shelf space for carbonate precipitation, 2) increased flux of Ca to the oceans during increased continental erosion, 3) deep basinal anoxia that generated upwelling waters with elevated alkalinities, and 4) further evolution of ocean water in the restricted Delaware, Zechstein, and other basins. Temporal coincidence of these processes resulted in surface seawater that was greatly supersaturated by Phanerozoic standards and whose only precedents occurred in Precambrian oceans.

@article{doi1023073515096,
    author = "Grotzinger, J. P. and Knoll, Andrew H.",
    title = "Anomalous Carbonate Precipitates: Is the Precambrian the Key to the Permian?",
    year = "1995",
    journal = "Palaios",
    abstract = {Late Permian reefs of the Capitan complex, west Texas; the Magnesian Limestone, England; Chuenmuping reef, south China; and elsewhere contain anomalously large volumes of aragonite and calcite marine cements and sea-floor crusts, as well as abundant microbial precipitates. These components strongly influenced reef growth and may have been responsible for the construction of rigid, open reefal frames in which bryozoans and sponges became encrusted and structurally reinforced. In some cases, such as the upper biostrome of the Magnesian Limestone, precipitated microbialites and inorganic crusts were the primary constituents of the reef core. These microbial and inorganic reefs do not have modern marine counterparts; on the contrary, their textures and genesis are best understood through comparison with the older rock record, particularly that of the early Precambrian. Early Precambrian reefal facies are interpreted to have formed in a stratified ocean with anoxic deep waters enriched in carbonate alkalinity. Upwelling mixed deep and surface waters, resulting in massive seafloor precipitation of aragonite and calcite. During Mesoproterozoic and early Neoproterozoic time, the ocean became more fully oxidized, and seafloor carbonate precipitation was significantly reduced. However, during the late Neoproterozoic, sizeable volumes of deep ocean water once again became anoxic for protracted intervals; the distinctive "cap carbonates" found above Neoproterozoic tillites attest to renewed upwelling of anoxic bottom water enriched in carbonate alkalinity and 12C. Anomalous late Permian seafloor precipitates are interpreted as the product, at least in part, of similar processes. Massive carbonate precipitation was favored by: 1) reduced shelf space for carbonate precipitation, 2) increased flux of Ca to the oceans during increased continental erosion, 3) deep basinal anoxia that generated upwelling waters with elevated alkalinities, and 4) further evolution of ocean water in the restricted Delaware, Zechstein, and other basins. Temporal coincidence of these processes resulted in surface seawater that was greatly supersaturated by Phanerozoic standards and whose only precedents occurred in Precambrian oceans.},
    url = "https://doi.org/10.2307/3515096",
    doi = "10.2307/3515096",
    openalex = "W1972548568",
    references = "doi1010160009254185900233, doi101029eo067i035p00649, doi101038367231a0, doi101306m26490c5, doi101306m56578, doi1023073514973"
}

@incollection{crossref1998carbonates,
    title = "Carbonates",
    year = "1998",
    booktitle = "Backscattered Scanning Electron Microscopy and Image Analysis of Sediments and Sedimentary Rocks",
    url = "https://doi.org/10.1017/cbo9780511628894.007",
    doi = "10.1017/cbo9780511628894.007",
    pages = "98-118"
}

The primary mineralogy of oolites and early marine carbonate cements led Sandberg [Nature 305 (1983), 19–22] to divide the Phanerozoic Eon into three intervals of `aragonite seas' and two intervals of `calcite seas'. Hardie [Geology 24 (1996), 279–283] has shown that these oscillations, together with synchronous oscillations in the mineralogy of marine potash evaporites, can be explained by secular shifts in the Mg/Ca ratio of seawater driven by changes in spreading rates along mid-ocean ridges. The Hardie model also predicts that high-Mg calcite should precipitate along with aragonite, as it does in today's aragonite sea. We have uncovered oscillations in the carbonate mineralogy of hypercalcifying organisms (ones that have produced massive skeletons, large reefs, or voluminous bodies of sediment) that correspond to Sandberg's aragonite seas and calcite seas and that are predicted by the Hardie model. Particular groups of corals, sponges, and algae appear to have been dominant reef builders only when favored by an appropriate Mg/Ca ratio in seawater. In early and middle Paleozoic calcite seas (Calcite I), reefs were dominated by calcitic tabulate, heliolitid, and rugose corals and calcitic stromatoporoids. In contrast, during the period of late Paleozoic–early Mesozoic aragonite seas (Aragonite II), aragonitic groups of sponges, scleractinian corals, and phylloid algae, as well as high-Mg calcitic red algae, were principal reef builders. During Late Cretaceous time, at the acme of Calcite II, massive rudists displaced aragonitic hermatypic corals. In today's aragonite sea (Aragonite III) scleractinian corals are again dominant reef builders, along with high-Mg calcitic coralline algae. Major sediment-producing algae exhibit temporal patterns similar to those of reef builders. Calcitic receptaculitids flourished during Calcite I, whereas aragonitic dasycladaceans did not become dominant rock formers until Aragonite II. During Calcite II, calcitic nannoplankton formed massive coccolith chalks in warm shallow seas of the Late Cretaceous, after the Mg/Ca ratio of seawater had reached a very low value and calcium concentration, a very high value. As the Mg/Ca ratio of seawater rose and calcium concentration fell during the Cenozoic Era, individual coccoliths, on average, became less massive and encrusted cells less thickly. By Pliocene time, during Aragonite III, the prominent genus Discoaster secreted only narrow-rayed coccoliths that covered less than 25% of the cell surface. Also during Aragonite III, the aragonitic green alga Halimeda emerged as the dominant skeletal sediment producer in reef tracts. The influence of seawater chemistry on skeletal secretion appears to have been especially strong for morphologically simple taxa that exert relatively weak control over their own calcification. Such groups include algae, sponges, corals, and bryozoans. Morphological simplicity also permits these groups to adopt vegetative or colonial modes of growth that confer success in competition for space on reefs. This linkage, in addition to the basic chemical demands of hypercalcification, has given the Mg/Ca ratio of seawater strong control over the success of individual reef-building taxa. More generally, this ratio appears to have strongly influenced evolutionary changes in the skeletal mineralogy of sponges and cheilostome bryozoans throughout their history. We conclude that throughout Phanerozoic time a chain of causation has extended from mid-ocean ridge processes, via seawater chemistry, to the mineralogical and biological composition of reef communities and bioclastic carbonate deposits.

@article{doi101016s0031018298001096,
    author = "Stanley, Steven M. and Hardie, Lawrence A.",
    title = "Secular oscillations in the carbonate mineralogy of reef-building and sediment-producing organisms driven by tectonically forced shifts in seawater chemistry",
    year = "1998",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    abstract = "The primary mineralogy of oolites and early marine carbonate cements led Sandberg [Nature 305 (1983), 19–22] to divide the Phanerozoic Eon into three intervals of `aragonite seas' and two intervals of `calcite seas'. Hardie [Geology 24 (1996), 279–283] has shown that these oscillations, together with synchronous oscillations in the mineralogy of marine potash evaporites, can be explained by secular shifts in the Mg/Ca ratio of seawater driven by changes in spreading rates along mid-ocean ridges. The Hardie model also predicts that high-Mg calcite should precipitate along with aragonite, as it does in today's aragonite sea. We have uncovered oscillations in the carbonate mineralogy of hypercalcifying organisms (ones that have produced massive skeletons, large reefs, or voluminous bodies of sediment) that correspond to Sandberg's aragonite seas and calcite seas and that are predicted by the Hardie model. Particular groups of corals, sponges, and algae appear to have been dominant reef builders only when favored by an appropriate Mg/Ca ratio in seawater. In early and middle Paleozoic calcite seas (Calcite I), reefs were dominated by calcitic tabulate, heliolitid, and rugose corals and calcitic stromatoporoids. In contrast, during the period of late Paleozoic–early Mesozoic aragonite seas (Aragonite II), aragonitic groups of sponges, scleractinian corals, and phylloid algae, as well as high-Mg calcitic red algae, were principal reef builders. During Late Cretaceous time, at the acme of Calcite II, massive rudists displaced aragonitic hermatypic corals. In today's aragonite sea (Aragonite III) scleractinian corals are again dominant reef builders, along with high-Mg calcitic coralline algae. Major sediment-producing algae exhibit temporal patterns similar to those of reef builders. Calcitic receptaculitids flourished during Calcite I, whereas aragonitic dasycladaceans did not become dominant rock formers until Aragonite II. During Calcite II, calcitic nannoplankton formed massive coccolith chalks in warm shallow seas of the Late Cretaceous, after the Mg/Ca ratio of seawater had reached a very low value and calcium concentration, a very high value. As the Mg/Ca ratio of seawater rose and calcium concentration fell during the Cenozoic Era, individual coccoliths, on average, became less massive and encrusted cells less thickly. By Pliocene time, during Aragonite III, the prominent genus Discoaster secreted only narrow-rayed coccoliths that covered less than 25\% of the cell surface. Also during Aragonite III, the aragonitic green alga Halimeda emerged as the dominant skeletal sediment producer in reef tracts. The influence of seawater chemistry on skeletal secretion appears to have been especially strong for morphologically simple taxa that exert relatively weak control over their own calcification. Such groups include algae, sponges, corals, and bryozoans. Morphological simplicity also permits these groups to adopt vegetative or colonial modes of growth that confer success in competition for space on reefs. This linkage, in addition to the basic chemical demands of hypercalcification, has given the Mg/Ca ratio of seawater strong control over the success of individual reef-building taxa. More generally, this ratio appears to have strongly influenced evolutionary changes in the skeletal mineralogy of sponges and cheilostome bryozoans throughout their history. We conclude that throughout Phanerozoic time a chain of causation has extended from mid-ocean ridge processes, via seawater chemistry, to the mineralogical and biological composition of reef communities and bioclastic carbonate deposits.",
    url = "https://doi.org/10.1016/s0031-0182(98)00109-6",
    doi = "10.1016/s0031-0182(98)00109-6",
    openalex = "W2147427800",
    references = "doi101038305019a0, doi101038308231a0, doi10108011035898209455245, doi101144gsjgs14960979, doi1023072992562, openalexw2989964553"
}

@incollection{crossref2000carbonates,
    title = "Carbonates",
    year = "2000",
    booktitle = "High Temperature Properties and Thermal Decomposition of Inorganic Salts with Oxyanions",
    url = "https://doi.org/10.1201/9781420042344-5",
    doi = "10.1201/9781420042344-5",
    pages = "35-72"
}

Summary Deposits produced by microbial growth and metabolism have been important components of carbonate sediments since the Archaean. Geologically best known in seas and lakes, microbial carbonates are also important at the present day in fluviatile, spring, cave and soil environments. The principal organisms involved are bacteria, particularly cyanobacteria, small algae and fungi, that participate in the growth of microbial biofilms and mats. Grain‐trapping is locally important, but the key process is precipitation, producing reefal accumulations of calcified microbes and enhancing mat accretion and preservation. Various metabolic processes, such as photosynthetic uptake of CO 2 and/or HCO 3 – by cyanobacteria, and ammonification, denitrification and sulphate reduction by other bacteria, can increase alkalinity and stimulate carbonate precipitation. Extracellular polymeric substances, widely produced by microbes for attachment and protection, are important in providing nucleation sites and facilitating sediment trapping. Microbial carbonate microfabrics are heterogeneous. They commonly incorporate trapped particles and in situ algae and invertebrates, and crystals form around bacterial cells, but the main component is dense, clotted or peloidal micrite resulting from calcification of bacterial cells, sheaths and biofilm, and from phytoplankton‐stimulated whiting nucleation. Interpretation of these texturally convergent and often inscrutable fabrics is a challenge. Conspicuous accumulations are large domes and columns with laminated (stromatolite), clotted (thrombolite) and other macrofabrics, which may be either agglutinated or mainly composed of calcified or spar‐encrusted microbes. Stromatolite lamination appears to be primary, but clotted thrombolite fabrics can be primary or secondary. Microbial precipitation also contributes to hot‐spring travertine, cold‐spring mound, calcrete, cave crust and coated grain deposits, as well as influencing carbonate cementation, recrystallization and replacement. Microbial carbonate is biologically stimulated but also requires favourable saturation state in ambient water, and thus relies uniquely on a combination of biotic and abiotic factors. This overriding environmental control is seen at the present day by the localization of microbial carbonates in calcareous streams and springs and in shallow tropical seas, and in the past by temporal variation in abundance of marine microbial carbonates. Patterns of cyanobacterial calcification and microbial dome formation through time appear to reflect fluctuations in seawater chemistry. Stromatolites appeared at ∼3450 Ma and were generally diverse and abundant from 2800 to 1000 Ma. Inception of a Proterozoic decline variously identified at 2000, 1000 and 675 Ma, has been attributed to eukaryote competition and/or reduced lithification. Thrombolites and dendrolites mainly formed by calcified cyanobacteria became important early in the Palaeozoic, and reappeared in the Late Devonian. Microbial carbonates retained importance through much of the Mesozoic, became scarcer in marine environments in the Cenozoic, but locally re‐emerged as large agglutinated domes, possibly reflecting increased algal involvement, and thick micritic reef crusts in the late Neogene. Famous modern examples at Shark Bay and Lee Stocking Island are composite coarse agglutinated domes and columns with complex bacterial–algal mats occurring in environments that are both stressed and current‐swept: products of mat evolution, ecological refugia, sites of enhanced early lithification or all three?

@article{doi101046j13653091200000003x,
    author = "Riding, Robert",
    title = "Microbial carbonates: the geological record of calcified bacterial–algal mats and biofilms",
    year = "2000",
    journal = "Sedimentology",
    abstract = "Summary Deposits produced by microbial growth and metabolism have been important components of carbonate sediments since the Archaean. Geologically best known in seas and lakes, microbial carbonates are also important at the present day in fluviatile, spring, cave and soil environments. The principal organisms involved are bacteria, particularly cyanobacteria, small algae and fungi, that participate in the growth of microbial biofilms and mats. Grain‐trapping is locally important, but the key process is precipitation, producing reefal accumulations of calcified microbes and enhancing mat accretion and preservation. Various metabolic processes, such as photosynthetic uptake of CO 2 and/or HCO 3 – by cyanobacteria, and ammonification, denitrification and sulphate reduction by other bacteria, can increase alkalinity and stimulate carbonate precipitation. Extracellular polymeric substances, widely produced by microbes for attachment and protection, are important in providing nucleation sites and facilitating sediment trapping. Microbial carbonate microfabrics are heterogeneous. They commonly incorporate trapped particles and in situ algae and invertebrates, and crystals form around bacterial cells, but the main component is dense, clotted or peloidal micrite resulting from calcification of bacterial cells, sheaths and biofilm, and from phytoplankton‐stimulated whiting nucleation. Interpretation of these texturally convergent and often inscrutable fabrics is a challenge. Conspicuous accumulations are large domes and columns with laminated (stromatolite), clotted (thrombolite) and other macrofabrics, which may be either agglutinated or mainly composed of calcified or spar‐encrusted microbes. Stromatolite lamination appears to be primary, but clotted thrombolite fabrics can be primary or secondary. Microbial precipitation also contributes to hot‐spring travertine, cold‐spring mound, calcrete, cave crust and coated grain deposits, as well as influencing carbonate cementation, recrystallization and replacement. Microbial carbonate is biologically stimulated but also requires favourable saturation state in ambient water, and thus relies uniquely on a combination of biotic and abiotic factors. This overriding environmental control is seen at the present day by the localization of microbial carbonates in calcareous streams and springs and in shallow tropical seas, and in the past by temporal variation in abundance of marine microbial carbonates. Patterns of cyanobacterial calcification and microbial dome formation through time appear to reflect fluctuations in seawater chemistry. Stromatolites appeared at ∼3450 Ma and were generally diverse and abundant from 2800 to 1000 Ma. Inception of a Proterozoic decline variously identified at 2000, 1000 and 675 Ma, has been attributed to eukaryote competition and/or reduced lithification. Thrombolites and dendrolites mainly formed by calcified cyanobacteria became important early in the Palaeozoic, and reappeared in the Late Devonian. Microbial carbonates retained importance through much of the Mesozoic, became scarcer in marine environments in the Cenozoic, but locally re‐emerged as large agglutinated domes, possibly reflecting increased algal involvement, and thick micritic reef crusts in the late Neogene. Famous modern examples at Shark Bay and Lee Stocking Island are composite coarse agglutinated domes and columns with complex bacterial–algal mats occurring in environments that are both stressed and current‐swept: products of mat evolution, ecological refugia, sites of enhanced early lithification or all three?",
    url = "https://doi.org/10.1046/j.1365-3091.2000.00003.x",
    doi = "10.1046/j.1365-3091.2000.00003.x",
    openalex = "W2150772200",
    references = "bertrandsarfati1981stromatolite, doi101002gj3350050104, doi10100797814757115239, doi10100797836426651652, doi101016030192688590066x, doi101016s0012825297834848, doi101016s0070457108711373, doi101017cbo9780511601064, doi1010381911032b0, doi101038269209a0, doi101038324055a0, doi101038333313a0, doi101038377220a0, doi101038383423a0, doi101038scientificamerican017886, doi10108011035898209455245, doi101086626965, doi101111j136530911982tb01733x, doi101126science1631544, doi101126science1744011825, doi101126science28554301033, doi101130gsab481873, doi101139e79088, doi101144gsjgs14960979, doi101146annurevearth271313, doi101146annurevmi49100195003431, doi102216i003188842244561, doi1023073514631, doi1023073514674, doi1023073514973, doi102475ajs26791017, doi105860choice295709, doi105860choice304422, openalexw2026796374, openalexw2508765924, openalexw2601700276, openalexw599354073, schidlowski1988a, semikhatov2000proterozoic"
}

Reefs containing abundant calcified metazoans occur at several stratigraphic levels within carbonate platforms of the terminal Proterozoic Nama Group, central and southern Namibia. The reef-bearing strata span an interval ranging from approximately 550 Ma to 543 Ma. The reefs are composed of thrombolites (clotted internal texture) and stromatolites (laminated internal texture) that form laterally continuous biostromes, isolated patch reefs, and isolated pinnacle reefs ranging in scale from a meter to several kilometers in width. Stromatolite-dominated reefs occur in depositionally updip positions within carbonate ramps, whereas thrombolite-dominated reefs occur broadly across the ramp profile and are well developed as pinnacle reefs in downdip positions. The three-dimensional morphology of reef-associated fossils was reconstructed by computer, based on digitized images of sections taken at 25-micron intervals through 15 fossil specimens and additionally supported by observations of over 90 sets of serial sections. Most variation observed in outcrop can be accounted for by a single species of cm-scale, lightly calcified goblet-shaped fossils herein described as Namacalathus hermanastes gen. et sp. nov. These fossils are characterized by a hollow stem open at both ends attached to a broadly spheroidal cup marked by a circular opening with a downturned lip and six (or seven) side holes interpreted as diagenetic features of underlying biological structure. The goblets lived atop the rough topography created by ecologically complex microbial-algal carpets; they appear to have been sessile benthos attached either to the biohermal substrate or to soft-bodied macrobenthos such as seaweeds that grew on the reef surface. The phylogenetic affinities of Namacalathus are uncertain, although preserved morphology is consistent with a cnidarian-like bodyplan. In general aspect, these fossils resemble some of the unmineralized, radially symmetric taxa found in contemporaneous sandstones and shales, but do not appear to be closely related to the well-skeletonized bilaterian animals that radiated in younger oceans. Nama reefs demonstrate that biohermal associations of invertebrates and thrombolite-forming microorganisms antedate the Cambrian Period.

@article{doi1016660094837320000260334cmitsr20co2,
    author = "Grotzinger, J. P. and Watters, W. A. and Knoll, Andrew H.",
    title = "Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia",
    year = "2000",
    journal = "Paleobiology",
    abstract = "Reefs containing abundant calcified metazoans occur at several stratigraphic levels within carbonate platforms of the terminal Proterozoic Nama Group, central and southern Namibia. The reef-bearing strata span an interval ranging from approximately 550 Ma to 543 Ma. The reefs are composed of thrombolites (clotted internal texture) and stromatolites (laminated internal texture) that form laterally continuous biostromes, isolated patch reefs, and isolated pinnacle reefs ranging in scale from a meter to several kilometers in width. Stromatolite-dominated reefs occur in depositionally updip positions within carbonate ramps, whereas thrombolite-dominated reefs occur broadly across the ramp profile and are well developed as pinnacle reefs in downdip positions. The three-dimensional morphology of reef-associated fossils was reconstructed by computer, based on digitized images of sections taken at 25-micron intervals through 15 fossil specimens and additionally supported by observations of over 90 sets of serial sections. Most variation observed in outcrop can be accounted for by a single species of cm-scale, lightly calcified goblet-shaped fossils herein described as Namacalathus hermanastes gen. et sp. nov. These fossils are characterized by a hollow stem open at both ends attached to a broadly spheroidal cup marked by a circular opening with a downturned lip and six (or seven) side holes interpreted as diagenetic features of underlying biological structure. The goblets lived atop the rough topography created by ecologically complex microbial-algal carpets; they appear to have been sessile benthos attached either to the biohermal substrate or to soft-bodied macrobenthos such as seaweeds that grew on the reef surface. The phylogenetic affinities of Namacalathus are uncertain, although preserved morphology is consistent with a cnidarian-like bodyplan. In general aspect, these fossils resemble some of the unmineralized, radially symmetric taxa found in contemporaneous sandstones and shales, but do not appear to be closely related to the well-skeletonized bilaterian animals that radiated in younger oceans. Nama reefs demonstrate that biohermal associations of invertebrates and thrombolite-forming microorganisms antedate the Cambrian Period.",
    url = "https://doi.org/10.1666/0094-8373(2000)026<0334:cmitsr>2.0.co;2",
    doi = "10.1666/0094-8373(2000)026<0334:cmitsr>2.0.co;2",
    openalex = "W2179498155",
    references = "doi101016030192688590066x, doi101111j136530911986tb00540x, doi101826182003741571989, doi1023073514631, doi102475ajs2728752, doi102475ajs275101121"
}

ABSTRACT Photosynthetic uptake of inorganic carbon can raise the pH adjacent to cyanobacterial cells, promoting CaCO 3 precipitation. This effect is enhanced by CO 2 concentrating mechanisms that actively transport into cells for carbon fixation. CO 2 concentrating mechanisms presumably developed in response to atmospheric decrease in CO 2 and increase in O 2 over geological timescales. In present‐day cyanobacteria, CO 2 concentrating mechanisms are induced when the atmospheric partial pressure of CO 2 (p CO2) falls below ∼0.4%. Reduction in p CO2 during the Proterozoic may have had two successive effects on cyanobacterial calcification. First, fall in p CO2 below ∼1% (33 times present atmospheric level, PAL) resulted in lower dissolved inorganic carbon (DIC) concentrations that reduced pH buffering sufficiently for isolated CaCO 3 crystals to begin to nucleate adjacent to cyanobacterial cells. As a result, blooms of planktic cyanobacteria induced precipitated ‘whitings’ of carbonate mud in the water column whose sedimentary accumulation began to dominate carbonate platforms ∼1400–1300 Ma. Second, fall in p CO2 below ∼0.4% (10 PAL) induced CO 2 ‐concentrating mechanisms that further increased pH rise adjacent to cells and promoted in vivo cyanobacterial sheath calcification. Crossing of this second threshold is indicated in the fossil record by the appearance of Girvanella 750–700 Ma. Coeval acquisition of CO 2 concentrating mechanisms by planktic cyanobacteria further stimulated whiting production. These inferences, that p CO2 fell below ∼1%∼1400–1300 Ma and below ∼0.4% 750–700 Ma, are consistent with empirical and modelled palaeo‐atmosphere estimates. Development of CO 2 concentrating mechanisms was probably temporarily slowed by global cooling ∼700–570 Ma that favoured diffusive entry of CO 2 into cells. Lower levels of temperature and DIC at this time would have reduced seawater carbonate saturation state, also hindering cyanobacterial calcification. It is suggested that as Earth emerged from ‘Snowball’ glaciations in the late Neoproterozoic, global warming and O 2 rise reactivated the development of CO 2 concentrating mechanisms. At the same time, rising levels of temperature, calcium ions and DIC increased seawater carbonate saturation state, stimulating widespread cyanobacterial in vivo sheath calcification in the Early Cambrian. This biocalcification event promoted rapid widespread development of calcified cyanobacterial reefs and transformed benthic microbial carbonate fabrics.

@article{doi101111j14724669200600087x,
    author = "Riding, Robert",
    title = "Cyanobacterial calcification, carbon dioxide concentrating mechanisms, and Proterozoic–Cambrian changes in atmospheric composition",
    year = "2006",
    journal = "Geobiology",
    abstract = "ABSTRACT Photosynthetic uptake of inorganic carbon can raise the pH adjacent to cyanobacterial cells, promoting CaCO 3 precipitation. This effect is enhanced by CO 2 concentrating mechanisms that actively transport into cells for carbon fixation. CO 2 concentrating mechanisms presumably developed in response to atmospheric decrease in CO 2 and increase in O 2 over geological timescales. In present‐day cyanobacteria, CO 2 concentrating mechanisms are induced when the atmospheric partial pressure of CO 2 (p CO2) falls below ∼0.4\%. Reduction in p CO2 during the Proterozoic may have had two successive effects on cyanobacterial calcification. First, fall in p CO2 below ∼1\% (33 times present atmospheric level, PAL) resulted in lower dissolved inorganic carbon (DIC) concentrations that reduced pH buffering sufficiently for isolated CaCO 3 crystals to begin to nucleate adjacent to cyanobacterial cells. As a result, blooms of planktic cyanobacteria induced precipitated ‘whitings’ of carbonate mud in the water column whose sedimentary accumulation began to dominate carbonate platforms ∼1400–1300 Ma. Second, fall in p CO2 below ∼0.4\% (10 PAL) induced CO 2 ‐concentrating mechanisms that further increased pH rise adjacent to cells and promoted in vivo cyanobacterial sheath calcification. Crossing of this second threshold is indicated in the fossil record by the appearance of Girvanella 750–700 Ma. Coeval acquisition of CO 2 concentrating mechanisms by planktic cyanobacteria further stimulated whiting production. These inferences, that p CO2 fell below ∼1\%∼1400–1300 Ma and below ∼0.4\% 750–700 Ma, are consistent with empirical and modelled palaeo‐atmosphere estimates. Development of CO 2 concentrating mechanisms was probably temporarily slowed by global cooling ∼700–570 Ma that favoured diffusive entry of CO 2 into cells. Lower levels of temperature and DIC at this time would have reduced seawater carbonate saturation state, also hindering cyanobacterial calcification. It is suggested that as Earth emerged from ‘Snowball’ glaciations in the late Neoproterozoic, global warming and O 2 rise reactivated the development of CO 2 concentrating mechanisms. At the same time, rising levels of temperature, calcium ions and DIC increased seawater carbonate saturation state, stimulating widespread cyanobacterial in vivo sheath calcification in the Early Cambrian. This biocalcification event promoted rapid widespread development of calcified cyanobacterial reefs and transformed benthic microbial carbonate fabrics.",
    url = "https://doi.org/10.1111/j.1472-4669.2006.00087.x",
    doi = "10.1111/j.1472-4669.2006.00087.x",
    openalex = "W2161489818",
    references = "doi101017s0022336000030663, doi101126science1057204, doi101144gsjgs14960979, doi1016690883135120000150087tcomie20co2, doi102110palo2003p0396"
}

The depositional age and stratigraphic correlations of metamorphosed and variably deformed rocks of Mount Everest are poorly known because of limited recovery of diagnostic fossils. Detailed study of Cambrian and Ordovician strata from along the length of the Himalaya has produced a coherent stratigraphy that stretches from northern India to Tibet. Our work also demonstrates that the North Col Formation rocks (= Everest series), between the Qomolangma and Lhotse detachments of the South Tibetan detachment system, still locally preserve sedimentary textures and primary stratigraphy that match those within Cambrian strata ~1100 km to the west in northern India. This demonstrates a coherency of depositional systems and stratigraphic architecture for Cambrian deposits along much of the Himalaya Tethyan margin. It also allows, for the fi rst time, identifi cation of precise depositional ages of several units in the Everest region, in particular, the Yellow Band carbonate and directly underlying siliciclastic strata, which are both shown to be late Middle Cambrian in age. Detrital zircon data presented herein for a sample from these siliciclastic strata contain a similar age spectrum to those from Middle Cambrian strata in northern India, as well as grains as young as ca. 526 Ma, both of which support the depositional age and continuity of depositional systems along the length of the Himalaya. Highly fractured rocks of the Ordovician lower Chiatsun Group in the hanging wall of the South Tibetan detachment system in Nyalam, 75 km to the west of Everest, correlate with Ordovician strata of the Mount Qomolangma Formation on Mount Everest. Our correlations indicate that the base of the summit pyramid of Everest, the foot of the "Third Step," is composed of a 60-m-thick, white-weathering thrombolite bed. The top of this ancient microbial deposit crops out only 70 m below the summit of Mount Everest.

@article{doi101130b263841,
    author = "Myrow, Paul M. and Hughes, Nigel C. and Searle, M. P. and Fanning, C. Mark and Peng, Shanchi and Parcha, S. K.",
    title = "Stratigraphic correlation of Cambrian–Ordovician deposits along the Himalaya: Implications for the age and nature of rocks in the Mount Everest region",
    year = "2008",
    journal = "Geological Society of America Bulletin",
    abstract = {The depositional age and stratigraphic correlations of metamorphosed and variably deformed rocks of Mount Everest are poorly known because of limited recovery of diagnostic fossils. Detailed study of Cambrian and Ordovician strata from along the length of the Himalaya has produced a coherent stratigraphy that stretches from northern India to Tibet. Our work also demonstrates that the North Col Formation rocks (= Everest series), between the Qomolangma and Lhotse detachments of the South Tibetan detachment system, still locally preserve sedimentary textures and primary stratigraphy that match those within Cambrian strata \textasciitilde 1100 km to the west in northern India. This demonstrates a coherency of depositional systems and stratigraphic architecture for Cambrian deposits along much of the Himalaya Tethyan margin. It also allows, for the fi rst time, identifi cation of precise depositional ages of several units in the Everest region, in particular, the Yellow Band carbonate and directly underlying siliciclastic strata, which are both shown to be late Middle Cambrian in age. Detrital zircon data presented herein for a sample from these siliciclastic strata contain a similar age spectrum to those from Middle Cambrian strata in northern India, as well as grains as young as ca. 526 Ma, both of which support the depositional age and continuity of depositional systems along the length of the Himalaya. Highly fractured rocks of the Ordovician lower Chiatsun Group in the hanging wall of the South Tibetan detachment system in Nyalam, 75 km to the west of Everest, correlate with Ordovician strata of the Mount Qomolangma Formation on Mount Everest. Our correlations indicate that the base of the summit pyramid of Everest, the foot of the "Third Step," is composed of a 60-m-thick, white-weathering thrombolite bed. The top of this ancient microbial deposit crops out only 70 m below the summit of Mount Everest.},
    url = "https://doi.org/10.1130/b26384.1",
    doi = "10.1130/b26384.1",
    openalex = "W2164664612",
    references = "doi1016690883135120000150087tcomie20co2"
}

Modern Ca:Mg carbonate stromatolites form in association with the microbial mat in the hypersaline coastal lagoon, Lagoa Vermelha (Brazil). The stromatolites, although showing diversified fabrics characterized by thin or crude lamination and/or thrombolitic clotting, exhibit a pervasive peloidal microfabric. The peloidal texture consists of dark, micritic aggregates of very high-Mg calcite and/or Ca dolomite formed by an iso-oriented assemblage of sub-micron trigonal polyhedrons and organic matter. Limpid acicular crystals of aragonite arranged in spherulites surround these aggregates. Unlike the aragonite crystals, organic matter is present consistently in the dark, micritic carbonate comprising the peloids. This organic matter is observed as sub-micron flat and filamentous mucus-like structures inside the interspaces of the high-Mg calcite and Ca dolomite crystals and is interpreted as the remains of degraded extracellular polymeric substances. Moreover, many fossilized bacterial cells are associated strictly with both carbonate phases. These cells consist mainly of 0·2 to 4 μm in diameter, sub-spherical, rod-like and filamentous forms, isolated or in colony-like clusters. The co-existence of fossil extracellular polymeric substances and bacterial bodies, associated with the polyhedrons of Ca:Mg carbonate, implies that the organic matter and microbial metabolism played a fundamental role in the precipitation of the minerals that form the peloids. By contrast, the lack of extracellular polymeric substances in the aragonitic phase indicates an additional precipitation mechanism. The complex processes that induce mineral precipitation in the modern Lagoa Vermelha microbial mat appear to be recorded in the studied lithified stromatolites. Sub-micron polyhedral crystal formation of high-Mg calcite and/or Ca dolomite results from the coalescence of carbonate nanoglobules around degraded organic matter nuclei. Sub-micron polyhedral crystals aggregate to form larger ovoidal crystals that constitute peloids. Subsequent precipitation of aragonitic spherulites around peloids occurs as micro-environmental water conditions around the peloids change.

@article{doi101111j13653091200901083x,
    author = "Spadafora, Alessandra and Perri, Edoardo and McKenzie, Judith A. and VASCONCELOS, CRISÓGONO",
    title = "Microbial biomineralization processes forming modern Ca:Mg carbonate stromatolites",
    year = "2009",
    journal = "Sedimentology",
    abstract = "Modern Ca:Mg carbonate stromatolites form in association with the microbial mat in the hypersaline coastal lagoon, Lagoa Vermelha (Brazil). The stromatolites, although showing diversified fabrics characterized by thin or crude lamination and/or thrombolitic clotting, exhibit a pervasive peloidal microfabric. The peloidal texture consists of dark, micritic aggregates of very high-Mg calcite and/or Ca dolomite formed by an iso-oriented assemblage of sub-micron trigonal polyhedrons and organic matter. Limpid acicular crystals of aragonite arranged in spherulites surround these aggregates. Unlike the aragonite crystals, organic matter is present consistently in the dark, micritic carbonate comprising the peloids. This organic matter is observed as sub-micron flat and filamentous mucus-like structures inside the interspaces of the high-Mg calcite and Ca dolomite crystals and is interpreted as the remains of degraded extracellular polymeric substances. Moreover, many fossilized bacterial cells are associated strictly with both carbonate phases. These cells consist mainly of 0·2 to 4 μm in diameter, sub-spherical, rod-like and filamentous forms, isolated or in colony-like clusters. The co-existence of fossil extracellular polymeric substances and bacterial bodies, associated with the polyhedrons of Ca:Mg carbonate, implies that the organic matter and microbial metabolism played a fundamental role in the precipitation of the minerals that form the peloids. By contrast, the lack of extracellular polymeric substances in the aragonitic phase indicates an additional precipitation mechanism. The complex processes that induce mineral precipitation in the modern Lagoa Vermelha microbial mat appear to be recorded in the studied lithified stromatolites. Sub-micron polyhedral crystal formation of high-Mg calcite and/or Ca dolomite results from the coalescence of carbonate nanoglobules around degraded organic matter nuclei. Sub-micron polyhedral crystals aggregate to form larger ovoidal crystals that constitute peloids. Subsequent precipitation of aragonitic spherulites around peloids occurs as micro-environmental water conditions around the peloids change.",
    url = "https://doi.org/10.1111/j.1365-3091.2009.01083.x",
    doi = "10.1111/j.1365-3091.2009.01083.x",
    openalex = "W1563041753",
    references = "doi101016s0012825201000897, doi101016s0070457108711373"
}

@article{doi101016jsedgeo201302001,
    author = "Chen, Jitao and Lee, Hyun Suk",
    title = "Soft-sediment deformation structures in Cambrian siliciclastic and carbonate storm deposits (Shandong Province, China): Differential liquefaction and fluidization triggered by storm-wave loading",
    year = "2013",
    journal = "Sedimentary Geology",
    url = "https://doi.org/10.1016/j.sedgeo.2013.02.001",
    doi = "10.1016/j.sedgeo.2013.02.001",
    openalex = "W2035267172",
    references = "doi101016jsedgeo201011002, doi101016s0037073896000577"
}

@incollection{stirling2014carbonates,
    author = "Stirling, C. H.",
    title = "Carbonates, Marine Carbonates, (U-Series)",
    year = "2014",
    booktitle = "Encyclopedia of Scientific Dating Methods",
    url = "https://doi.org/10.1007/978-94-007-6326-5\_242-1",
    doi = "10.1007/978-94-007-6326-5\_242-1",
    pages = "1-8"
}

@incollection{stirling2015carbonates,
    author = "Stirling, Claudine H.",
    title = "Carbonates, Marine Carbonates (U-Series)",
    year = "2015",
    booktitle = "Encyclopedia of Earth Sciences Series",
    url = "https://doi.org/10.1007/978-94-007-6304-3\_242",
    doi = "10.1007/978-94-007-6304-3\_242",
    pages = "136-141"
}

@article{doi101016jpalaeo201606018,
    author = "Lee, Jeong‐Hyun and Hong, Jongsun and Choh, Suk‐Joo and Lee, Dong‐Jin and Woo, Jusun and Riding, Robert",
    title = "Early recovery of sponge framework reefs after Cambrian archaeocyath extinction: Zhangxia Formation (early Cambrian Series 3), Shandong, North China",
    year = "2016",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2016.06.018",
    doi = "10.1016/j.palaeo.2016.06.018",
    openalex = "W2413423943",
    references = "doi101016jearscirev201503002"
}

Geological mapping in 1970 of lower Cambrian outcrop in the eastern Flinders Ranges of South Australia included the description and naming of the Moorowie Formation, representing the uppermost Hawker Group. The mapping is supported by 885 m of measured sections. An early Cambrian regressive-marine shelf-margin succession is described, from the massive Wilkawillina Limestone (base), the grey laminated limestones, syndepositional slump-induced intraformational folds and breccias, collapse talus, and graded sediment gravity flow deposits of the Mernmerna Formation, terrace-edge attrition megabreccias and reefs of the Moorowie Formation, passing up to the red beds of the Billy Creek Formation (top). Rapid changes in sedimentary facies are attributed to basement block movements and diapiric influence on sedimentation with abrupt vertical relief and paleoslope indicated by syndepositional slumping and platform margin collapse. Tuffs in the Mernmerna Formation record contemporaneous volcanism. Massive archaeocyathan limestones, ooid grainstones, peloid limestones, reef-sourced megabreccias and red shales define five members in the overlying Moorowie Formation, signalling shallow-marine regressive conditions and the development of a biologically diverse carbonate platform seaward of evaporitic lagoons and supratidal sabkhas. The megabreccias of the Moorowie Formation formed as thin semi-autochthonous debris aprons or shallow tidal-channel infills resulting from gradual and persistent wave attrition and repeated collapse of a carbonate terrace that was vigorously reworked by tidal currents. Shale interbeds within the Moorowie Formation represent lightly channelised shallow-marine ramp deposits, with adjacent mud flats, as easterly equivalents of the Oraparinna Shale, the earliest of which formed the substrate to the attrition megabreccias. Emergent evaporite diapirs near Mt John and Mt Frome are the probable sources of coarse siliciclastics within the carbonates. Some of the siliciclastics were likely transported onto the carbonate platform by sandstorms or migrating dunes. Late in the Cambro-Ordovician Delamerian Orogeny, earlier salt diapirs at depth were compressed and reactivated as highly mobile evaporite-rubble breccias and intruded as small plugs and dykes into fissures in a lithified and folded cover. The intrusive breccias include metasediment and metabasic xenoclasts attributable to the Callanna Group, while diapir-related faults also host minor copper, lead and barite mineralisation. Documentation of this unique record contributes to wider investigations of the Ediacaran-to-early-Cambrian succession of the Flinders Ranges sector of the Arrowie Basin, adding to its global heritage values, effective management and appreciation by the wider community.

@misc{mount2019geological,
    author = "Mount, T. J. and Jago, J. B. and Langsford, N. R. and Dalgarno, C. R.",
    title = "Geological setting of the Moorowie Formation, lower Cambrian Hawker Group, Mt Chambers Gorge, eastern Flinders Ranges, South Australia",
    year = "2019",
    publisher = "Taylor \& Francis",
    abstract = "Geological mapping in 1970 of lower Cambrian outcrop in the eastern Flinders Ranges of South Australia included the description and naming of the Moorowie Formation, representing the uppermost Hawker Group. The mapping is supported by 885 m of measured sections. An early Cambrian regressive-marine shelf-margin succession is described, from the massive Wilkawillina Limestone (base), the grey laminated limestones, syndepositional slump-induced intraformational folds and breccias, collapse talus, and graded sediment gravity flow deposits of the Mernmerna Formation, terrace-edge attrition megabreccias and reefs of the Moorowie Formation, passing up to the red beds of the Billy Creek Formation (top). Rapid changes in sedimentary facies are attributed to basement block movements and diapiric influence on sedimentation with abrupt vertical relief and paleoslope indicated by syndepositional slumping and platform margin collapse. Tuffs in the Mernmerna Formation record contemporaneous volcanism. Massive archaeocyathan limestones, ooid grainstones, peloid limestones, reef-sourced megabreccias and red shales define five members in the overlying Moorowie Formation, signalling shallow-marine regressive conditions and the development of a biologically diverse carbonate platform seaward of evaporitic lagoons and supratidal sabkhas. The megabreccias of the Moorowie Formation formed as thin semi-autochthonous debris aprons or shallow tidal-channel infills resulting from gradual and persistent wave attrition and repeated collapse of a carbonate terrace that was vigorously reworked by tidal currents. Shale interbeds within the Moorowie Formation represent lightly channelised shallow-marine ramp deposits, with adjacent mud flats, as easterly equivalents of the Oraparinna Shale, the earliest of which formed the substrate to the attrition megabreccias. Emergent evaporite diapirs near Mt John and Mt Frome are the probable sources of coarse siliciclastics within the carbonates. Some of the siliciclastics were likely transported onto the carbonate platform by sandstorms or migrating dunes. Late in the Cambro-Ordovician Delamerian Orogeny, earlier salt diapirs at depth were compressed and reactivated as highly mobile evaporite-rubble breccias and intruded as small plugs and dykes into fissures in a lithified and folded cover. The intrusive breccias include metasediment and metabasic xenoclasts attributable to the Callanna Group, while diapir-related faults also host minor copper, lead and barite mineralisation. Documentation of this unique record contributes to wider investigations of the Ediacaran-to-early-Cambrian succession of the Flinders Ranges sector of the Arrowie Basin, adding to its global heritage values, effective management and appreciation by the wider community.",
    url = "https://tandf.figshare.com/articles/dataset/Geological\_setting\_of\_the\_Moorowie\_Formation\_lower\_Cambrian\_Hawker\_Group\_Mt\_Chambers\_Gorge\_eastern\_Flinders\_Ranges\_South\_Australia/8275202/1",
    doi = "10.6084/m9.figshare.8275202.v1",
    openalex = "W4394105290"
}

Geological mapping in 1970 of lower Cambrian outcrop in the eastern Flinders Ranges of South Australia included the description and naming of the Moorowie Formation, representing the uppermost Hawker Group. The mapping is supported by 885 m of measured sections. An early Cambrian regressive-marine shelf-margin succession is described, from the massive Wilkawillina Limestone (base), the grey laminated limestones, syndepositional slump-induced intraformational folds and breccias, collapse talus, and graded sediment gravity flow deposits of the Mernmerna Formation, terrace-edge attrition megabreccias and reefs of the Moorowie Formation, passing up to the red beds of the Billy Creek Formation (top). Rapid changes in sedimentary facies are attributed to basement block movements and diapiric influence on sedimentation with abrupt vertical relief and paleoslope indicated by syndepositional slumping and platform margin collapse. Tuffs in the Mernmerna Formation record contemporaneous volcanism. Massive archaeocyathan limestones, ooid grainstones, peloid limestones, reef-sourced megabreccias and red shales define five members in the overlying Moorowie Formation, signalling shallow-marine regressive conditions and the development of a biologically diverse carbonate platform seaward of evaporitic lagoons and supratidal sabkhas. The megabreccias of the Moorowie Formation formed as thin semi-autochthonous debris aprons or shallow tidal-channel infills resulting from gradual and persistent wave attrition and repeated collapse of a carbonate terrace that was vigorously reworked by tidal currents. Shale interbeds within the Moorowie Formation represent lightly channelised shallow-marine ramp deposits, with adjacent mud flats, as easterly equivalents of the Oraparinna Shale, the earliest of which formed the substrate to the attrition megabreccias. Emergent evaporite diapirs near Mt John and Mt Frome are the probable sources of coarse siliciclastics within the carbonates. Some of the siliciclastics were likely transported onto the carbonate platform by sandstorms or migrating dunes. Late in the Cambro-Ordovician Delamerian Orogeny, earlier salt diapirs at depth were compressed and reactivated as highly mobile evaporite-rubble breccias and intruded as small plugs and dykes into fissures in a lithified and folded cover. The intrusive breccias include metasediment and metabasic xenoclasts attributable to the Callanna Group, while diapir-related faults also host minor copper, lead and barite mineralisation. Documentation of this unique record contributes to wider investigations of the Ediacaran-to-early-Cambrian succession of the Flinders Ranges sector of the Arrowie Basin, adding to its global heritage values, effective management and appreciation by the wider community.

@misc{mount2020geological,
    author = "Mount, T. J. and Jago, J. B. and Langsford, N. R. and Dalgarno, C. R.",
    title = "Geological setting of the Moorowie Formation, lower Cambrian Hawker Group, Mt Chambers Gorge, eastern Flinders Ranges, South Australia",
    year = "2020",
    publisher = "Taylor \& Francis",
    abstract = "Geological mapping in 1970 of lower Cambrian outcrop in the eastern Flinders Ranges of South Australia included the description and naming of the Moorowie Formation, representing the uppermost Hawker Group. The mapping is supported by 885 m of measured sections. An early Cambrian regressive-marine shelf-margin succession is described, from the massive Wilkawillina Limestone (base), the grey laminated limestones, syndepositional slump-induced intraformational folds and breccias, collapse talus, and graded sediment gravity flow deposits of the Mernmerna Formation, terrace-edge attrition megabreccias and reefs of the Moorowie Formation, passing up to the red beds of the Billy Creek Formation (top). Rapid changes in sedimentary facies are attributed to basement block movements and diapiric influence on sedimentation with abrupt vertical relief and paleoslope indicated by syndepositional slumping and platform margin collapse. Tuffs in the Mernmerna Formation record contemporaneous volcanism. Massive archaeocyathan limestones, ooid grainstones, peloid limestones, reef-sourced megabreccias and red shales define five members in the overlying Moorowie Formation, signalling shallow-marine regressive conditions and the development of a biologically diverse carbonate platform seaward of evaporitic lagoons and supratidal sabkhas. The megabreccias of the Moorowie Formation formed as thin semi-autochthonous debris aprons or shallow tidal-channel infills resulting from gradual and persistent wave attrition and repeated collapse of a carbonate terrace that was vigorously reworked by tidal currents. Shale interbeds within the Moorowie Formation represent lightly channelised shallow-marine ramp deposits, with adjacent mud flats, as easterly equivalents of the Oraparinna Shale, the earliest of which formed the substrate to the attrition megabreccias. Emergent evaporite diapirs near Mt John and Mt Frome are the probable sources of coarse siliciclastics within the carbonates. Some of the siliciclastics were likely transported onto the carbonate platform by sandstorms or migrating dunes. Late in the Cambro-Ordovician Delamerian Orogeny, earlier salt diapirs at depth were compressed and reactivated as highly mobile evaporite-rubble breccias and intruded as small plugs and dykes into fissures in a lithified and folded cover. The intrusive breccias include metasediment and metabasic xenoclasts attributable to the Callanna Group, while diapir-related faults also host minor copper, lead and barite mineralisation. Documentation of this unique record contributes to wider investigations of the Ediacaran-to-early-Cambrian succession of the Flinders Ranges sector of the Arrowie Basin, adding to its global heritage values, effective management and appreciation by the wider community.",
    url = "https://tandf.figshare.com/articles/dataset/Geological\_setting\_of\_the\_Moorowie\_Formation\_lower\_Cambrian\_Hawker\_Group\_Mt\_Chambers\_Gorge\_eastern\_Flinders\_Ranges\_South\_Australia/8275202/2",
    doi = "10.6084/m9.figshare.8275202.v2"
}

Skeletal–microbial–cement reefs are a triple hybrid carbonate that mainly formed during the Pennsylvanian to Mid-Triassic, when a marked increase in microbial carbonate formation coincided with extensive precipitation of crystalline crusts on the seafloor. We report a new type of reef-building association from Middle–Upper Ordovician strata of western North China, in which erect thin tubes of tetradiids (coralomorph) are encrusted by the calcimicrobes Renalcis and Angusticellularia and then by a large amount of early marine cement that is presumably high-Mg calcite or aragonite in composition. The resulting meter-scale mound is embedded within intraclastic–bioclastic grainstone, implying high-energy shallow-marine conditions. The thin tetradiid tubes, which would have been unable to physically withstand strong waves and currents, are interpreted to have been consolidated by encrusting calcimicrobes and then by extensive early marine cementation. Tetradiid-bearing reefs have generally been reported from muddy successions; the results of the present study suggest that consolidators were important in reef-building in high-energy environments during the later Ordovician. Considering also the coeval bivalve–sponge–microbial–cement reef reported from the same area and a sponge–microbial–cement reef from Arctic Canada, early marine cementation appears to have been at least locally important in the late Ordovician, similar to the Pennsylvanian through the Mid-Triassic. These triple hybrid carbonates may have formed by a combination of: (1) emergence of newly evolved skeletal reef-builders during the Great Ordovician Biodiversification Event; (2) development of CO2-concentrating mechanisms in calcimicrobes induced by a decrease in atmospheric CO2; and (3) an increase in the calcium saturation state in seawater resulting in extensive abiotic cementation as well as calcification of microbes. All of these factors might have been induced by global cooling throughout the Mid–Late Ordovician.

@article{doi101016jgloplacha2021103462,
    author = "Lee, Jeong‐Hyun and Lee, Dong‐Jin",
    title = "Mid–Late Ordovician tetradiid–calcimicrobial–cement reef: A new, peculiar reef-building consortium recording global cooling",
    year = "2021",
    journal = "Global and Planetary Change",
    abstract = "Skeletal–microbial–cement reefs are a triple hybrid carbonate that mainly formed during the Pennsylvanian to Mid-Triassic, when a marked increase in microbial carbonate formation coincided with extensive precipitation of crystalline crusts on the seafloor. We report a new type of reef-building association from Middle–Upper Ordovician strata of western North China, in which erect thin tubes of tetradiids (coralomorph) are encrusted by the calcimicrobes Renalcis and Angusticellularia and then by a large amount of early marine cement that is presumably high-Mg calcite or aragonite in composition. The resulting meter-scale mound is embedded within intraclastic–bioclastic grainstone, implying high-energy shallow-marine conditions. The thin tetradiid tubes, which would have been unable to physically withstand strong waves and currents, are interpreted to have been consolidated by encrusting calcimicrobes and then by extensive early marine cementation. Tetradiid-bearing reefs have generally been reported from muddy successions; the results of the present study suggest that consolidators were important in reef-building in high-energy environments during the later Ordovician. Considering also the coeval bivalve–sponge–microbial–cement reef reported from the same area and a sponge–microbial–cement reef from Arctic Canada, early marine cementation appears to have been at least locally important in the late Ordovician, similar to the Pennsylvanian through the Mid-Triassic. These triple hybrid carbonates may have formed by a combination of: (1) emergence of newly evolved skeletal reef-builders during the Great Ordovician Biodiversification Event; (2) development of CO2-concentrating mechanisms in calcimicrobes induced by a decrease in atmospheric CO2; and (3) an increase in the calcium saturation state in seawater resulting in extensive abiotic cementation as well as calcification of microbes. All of these factors might have been induced by global cooling throughout the Mid–Late Ordovician.",
    url = "https://doi.org/10.1016/j.gloplacha.2021.103462",
    doi = "10.1016/j.gloplacha.2021.103462",
    openalex = "W3133560117",
    references = "doi101016jearscirev201804003, doi101016jearscirev2020103300, doi102110palo2010p10097r, openalexw607087370"
}

ABSTRACT Microbial carbonates formed stromatolitic, thrombolitic, dendrolitic and maceriate (mazelike) fabrics in shallow marine Cambrian–Early Ordovician carbonates encircling Laurentia. However, poor preservation often hinders recognition of their specific components. Well‐preserved examples of normal shallow marine limestones in the ca 490 Ma upper Cambrian Point Peak Member, Wilberns Formation, central Texas, include stromatolitic cones, steep‐sided laminated rimmed columns with grainy interiors, and laminated and maceriate domes. Together these form decimetre to metre‐thick biostromes. In these examples, a single component, microstromatolite, on its own or with minor calcimicrobes, creates macroscopic stromatolitic, dendrolitic, thrombolitic and maceriate fabrics. Microstromatolites constructed upward widening stromatolitic cones that developed into columns with laminated rims surrounding slightly depressed interiors. These columns accumulated allochthonous sediment by a ‘bucket effect’. Their interiors contain either clusters of dendrolitic microstromatolite or ragged columns of laminated stromatolite–sponge biolithite, and are often characterized by a ‘mottled’ fabric that superficially resembles thrombolite. This mottling was formed by localized dolomitization around millimetric burrows that otherwise do not appear to have significantly influenced the biolithite fabric. Calcimicrobes, including cyanobacteria (Razumovskia) and microproblematica (Renalcis and Tarthinia), impart a mesoscopic clotted appearance to maceriate fabric, and locally to column rims, both of which are dominated by microstromatolite. Similar component‐fabric relationships should be recognizable in rimmed columns and domes that were locally abundant elsewhere in Cambrian–Early Ordovician shallow carbonate seas.

@article{doi101111sed13048,
    author = "Lee, Jeong‐Hyun and Riding, Robert",
    title = "Stromatolite‐rimmed thrombolite columns and domes constructed by microstromatolites, calcimicrobes and sponges in late Cambrian biostromes, Texas, USA",
    year = "2022",
    journal = "Sedimentology",
    abstract = "ABSTRACT Microbial carbonates formed stromatolitic, thrombolitic, dendrolitic and maceriate (mazelike) fabrics in shallow marine Cambrian–Early Ordovician carbonates encircling Laurentia. However, poor preservation often hinders recognition of their specific components. Well‐preserved examples of normal shallow marine limestones in the ca 490 Ma upper Cambrian Point Peak Member, Wilberns Formation, central Texas, include stromatolitic cones, steep‐sided laminated rimmed columns with grainy interiors, and laminated and maceriate domes. Together these form decimetre to metre‐thick biostromes. In these examples, a single component, microstromatolite, on its own or with minor calcimicrobes, creates macroscopic stromatolitic, dendrolitic, thrombolitic and maceriate fabrics. Microstromatolites constructed upward widening stromatolitic cones that developed into columns with laminated rims surrounding slightly depressed interiors. These columns accumulated allochthonous sediment by a ‘bucket effect’. Their interiors contain either clusters of dendrolitic microstromatolite or ragged columns of laminated stromatolite–sponge biolithite, and are often characterized by a ‘mottled’ fabric that superficially resembles thrombolite. This mottling was formed by localized dolomitization around millimetric burrows that otherwise do not appear to have significantly influenced the biolithite fabric. Calcimicrobes, including cyanobacteria (Razumovskia) and microproblematica (Renalcis and Tarthinia), impart a mesoscopic clotted appearance to maceriate fabric, and locally to column rims, both of which are dominated by microstromatolite. Similar component‐fabric relationships should be recognizable in rimmed columns and domes that were locally abundant elsewhere in Cambrian–Early Ordovician shallow carbonate seas.",
    url = "https://doi.org/10.1111/sed.13048",
    doi = "10.1111/sed.13048",
    openalex = "W4303043607",
    references = "doi101016jearscirev2020103300, doi101016jgloplacha2021103586, doi104095123903, openalexw633053001"
}

Review paper on authigenic carbonates associated with gas hydrates, with particular focus on their recognition in the geological record.

@misc{bojanowski2026authigenic,
    author = "Bojanowski, Maciej and Argentino, Claudio and Conti, Stefano and Dela Pierre, Francesco and Fontana, Daniela and Giunti, Stefani and Martire, Luca and Natalicchio, Marcello",
    title = "Authigenic carbonates as archives of past hydrates: Definitions, identifications, and research directions",
    year = "2026",
    publisher = "Institute of Geological Sciences Polish Academy of Sciences",
    abstract = "Review paper on authigenic carbonates associated with gas hydrates, with particular focus on their recognition in the geological record.",
    url = "https://dataportal.ing.pan.pl/citation?persistentId=doi:10.60871/INGPAN/9MVWRZ",
    doi = "10.60871/ingpan/9mvwrz"
}

@misc{crossrefNonecarbonates,
    title = "Carbonates",
    year = "None",
    booktitle = "SpringerReference",
    url = "https://doi.org/10.1007/springerreference\_187240",
    doi = "10.1007/springerreference\_187240"
}