Cyclothems

The Speiser shale, Wreford limestone, and Wymore shale member of the Matfield formation were studied in east-central Kansas. More than 200 exposures were examined, of which 138 were measured and described. The results of this stratigraphic work have been incorporated into a correlation chart. Several completely exposed sections were sampled, representative specimens from each distinctive lithologic unit being collected for laboratory analysis. Samples of rock from six key sections were examined in detail to collate information derived from observation of outcrops, polished surfaces of chert, polished and etched limestone surfaces, insoluble residues of limestones, washed shales, sand/shale ratio studies, and pipette analyses. In addition, thin sections were made of sandstones, limestones, and cherts; large blocks of limestone were etched in an acid bath; and three subsurface sections were examined. A complete stratigraphic description of the outcropping rocks of the Wreford limestone and adjacent shales is presented. The sequence exhibits repetition of lithologies and faunas that is attributed to cyclic sedimentation. Two nearly complete cycles of deposition are recognized, the rocks of each constituting a cyclothem. The two cyclothems, which include strata extending from the middle of the Speiser shale to the middle of the Wymore shale, comprise the Wreford megacyclothem. Each of the major types of sedimentary rock is characterized by a distinctive fossilized biota (or lack of one) and is the product of a particular environment. Sandstones and red shales are continental deposits. The sandstones are unfossiliferous, representing accumulation in ancient river channels; red shale, bearing sparse charophyte oogonia, accumulated in interfluve areas of a broad low plain that bordered the early Permian sea. Green shales, grayish-yellow mudstones, and molluscan limestones were deposited in the area between the shoreline and the outer limit of marine waters of less-than-normal salinity. Ostracodes and fragmentary remains of other kinds of invertebrates are characteristic of the first two lithologies; Aviculopecten and Septimyalina characterize the third. Calcareous shales represent deposition moderately far from shore in marine waters of normal salinity. These rocks contain the most abundant and taxonomically varied fauna of the megacyclothem. Derbyia, Dictyoclostus, Composita, and Chonetes are the dominant megafossils. Cherty limestones were deposited during the stage of maximum transgression of the sea. Lack of inorganic clastic constituents suggests deposition in clear water far from shore. The fauna includes bryozoans and brachiopods as the dominant types. Chalky limestones bearing little chert are a special development of the cherty-limestone phase of deposition. They locally form relatively thick reefs, which are dominantly composed of bryozoans and algal remains. The environment of deposition shoreward from the reefs is believed to have been governed partly by their presence. Algal limestones are present in the regressive hemicycles of sedimentation and correspond in relative position to the transgressive molluscan phases. Some algal limestones are believed to be the product of a hypersaline environment. Algal limestones that contain large burrowing clams and are situated shoreward from the ancient reefs are interpreted as having accumulated in a somewhat brackish environment, because the associated invertebrate fossils are similar to those seen in transgressive molluscan limestones. In the limestones that were deposited during maximum transgression there are two types of chert. Compact noncalcareous cherts are believed to be primary chemical precipitates; layered or laminated calcareous cherts formed from silica deposited more slowly than the noncalcareous cherts and owe their present appearance to changes that occurred during diagenesis. The typical transgressive hemicycle in the Wreford megacyclothem begins with red shale (locally with a sandstone) followed, in upward order, by green shale, mudstone, molluscan limestone, calcareous shale, and cherty limestone (including local chalky-limestone reef development). The typical regressive hemicycle includes the same rock types in reverse stratigraphic order except that the molluscan limestone equivalent is commonly algal. Neither of the Wreford cyclothems is complete. Subsurface sections in which the end members of the hemicycles can be detected indicate widespread distribution of the environments controlling the different phases of sedimentation. Similar repetitions of lithologic types, each with its particular faunal assemblage, are seen in the stratigraphic sequence above the Wreford limestone up to and including the Winfield limestone.

@article{hattin1956depositional,
    author = "Hattin, Donald E.",
    title = "Depositional Environment of the Wreford Megacyclothem (Lower Permian) of Kansas",
    year = "1956",
    journal = "Bulletin (Kansas Geological Survey)",
    abstract = "The Speiser shale, Wreford limestone, and Wymore shale member of the Matfield formation were studied in east-central Kansas. More than 200 exposures were examined, of which 138 were measured and described. The results of this stratigraphic work have been incorporated into a correlation chart. Several completely exposed sections were sampled, representative specimens from each distinctive lithologic unit being collected for laboratory analysis. Samples of rock from six key sections were examined in detail to collate information derived from observation of outcrops, polished surfaces of chert, polished and etched limestone surfaces, insoluble residues of limestones, washed shales, sand/shale ratio studies, and pipette analyses. In addition, thin sections were made of sandstones, limestones, and cherts; large blocks of limestone were etched in an acid bath; and three subsurface sections were examined. A complete stratigraphic description of the outcropping rocks of the Wreford limestone and adjacent shales is presented. The sequence exhibits repetition of lithologies and faunas that is attributed to cyclic sedimentation. Two nearly complete cycles of deposition are recognized, the rocks of each constituting a cyclothem. The two cyclothems, which include strata extending from the middle of the Speiser shale to the middle of the Wymore shale, comprise the Wreford megacyclothem. Each of the major types of sedimentary rock is characterized by a distinctive fossilized biota (or lack of one) and is the product of a particular environment. Sandstones and red shales are continental deposits. The sandstones are unfossiliferous, representing accumulation in ancient river channels; red shale, bearing sparse charophyte oogonia, accumulated in interfluve areas of a broad low plain that bordered the early Permian sea. Green shales, grayish-yellow mudstones, and molluscan limestones were deposited in the area between the shoreline and the outer limit of marine waters of less-than-normal salinity. Ostracodes and fragmentary remains of other kinds of invertebrates are characteristic of the first two lithologies; Aviculopecten and Septimyalina characterize the third. Calcareous shales represent deposition moderately far from shore in marine waters of normal salinity. These rocks contain the most abundant and taxonomically varied fauna of the megacyclothem. Derbyia, Dictyoclostus, Composita, and Chonetes are the dominant megafossils. Cherty limestones were deposited during the stage of maximum transgression of the sea. Lack of inorganic clastic constituents suggests deposition in clear water far from shore. The fauna includes bryozoans and brachiopods as the dominant types. Chalky limestones bearing little chert are a special development of the cherty-limestone phase of deposition. They locally form relatively thick reefs, which are dominantly composed of bryozoans and algal remains. The environment of deposition shoreward from the reefs is believed to have been governed partly by their presence. Algal limestones are present in the regressive hemicycles of sedimentation and correspond in relative position to the transgressive molluscan phases. Some algal limestones are believed to be the product of a hypersaline environment. Algal limestones that contain large burrowing clams and are situated shoreward from the ancient reefs are interpreted as having accumulated in a somewhat brackish environment, because the associated invertebrate fossils are similar to those seen in transgressive molluscan limestones. In the limestones that were deposited during maximum transgression there are two types of chert. Compact noncalcareous cherts are believed to be primary chemical precipitates; layered or laminated calcareous cherts formed from silica deposited more slowly than the noncalcareous cherts and owe their present appearance to changes that occurred during diagenesis. The typical transgressive hemicycle in the Wreford megacyclothem begins with red shale (locally with a sandstone) followed, in upward order, by green shale, mudstone, molluscan limestone, calcareous shale, and cherty limestone (including local chalky-limestone reef development). The typical regressive hemicycle includes the same rock types in reverse stratigraphic order except that the molluscan limestone equivalent is commonly algal. Neither of the Wreford cyclothems is complete. Subsurface sections in which the end members of the hemicycles can be detected indicate widespread distribution of the environments controlling the different phases of sedimentation. Similar repetitions of lithologic types, each with its particular faunal assemblage, are seen in the stratigraphic sequence above the Wreford limestone up to and including the Winfield limestone.",
    url = "https://doi.org/10.17161/kgsbulletin.no.124.22120",
    doi = "10.17161/kgsbulletin.no.124.22120",
    openalex = "W4406783997",
    pages = "1-150"
}

@book{cuffey1967bryozoan1,
    author = "Cuffey, R. J",
    title = "Bryozoan Tabulipora carbonaria in Wreford Megacyclothem (Lower Permian) of Kansas",
    year = "1967",
    publisher = "University of Kansas Paleontological Contributions, p. 1-96",
    note = "talkorigins\_source = {true}; raw\_reference = {Cuffey, R. J., 1967, Bryozoan Tabulipora carbonaria in Wreford Megacyclothem (Lower Permian) of Kansas: University of Kansas Paleontological Contributions, p. 1-96.}"
}

Abstract Continued lithologic and paleontologic considerations of Kansas Upper Pennsylvanian megacyclothems more firmly establish the basic ascending sequence of: outside (nearshore) shale—middle (transgressive) limestone—core (offshore) shale—upper (regressive) limestone—outside (nearshore) shale, as representing a single transgressive-regressive sequence; this sequence is thus considered simply a cyclothem. Lateral facies change along the 500-km Iowa-Kansas outcrop belt is greatest in upper parts of upper limestones and outside shales, as would be expected in shallow-water to shoreline deposits; it is least in middle limestones, core shales, and bases of upper limestones, as would be expected in deeper water deposits. The widespread phosphatic black shale facies that commonly accompanies maximum transgression in the core shale is explained by water becoming deep enough to develop a thermocline strong enough to prevent bottom oxygenation by wind-driven vertical circulation. Pennsylvanian position of Mid-Continent North America, in the trade-wind belt north of the paleoequator along the Appalachians, allowed establishment of large-scale quasi-estuarine circulation in the Mid-Continent epicontinental sea. Cold, deep, oxygen-poor, phosphate-rich water from the western ocean was drawn in along the bottom through the basins of West Texas eventually to upwell in the eastern Mid-Continent and replace the surface water moved westward out of the sea by the prevailing winds. Upwelling greatly increased surface-water production of organic matter, which continually settled (while being carried westward) into the deeper incoming current, where it decayed and depleted the remaining oxygen while continually enriching the already high phosphate in a circulatory trap. In this way substantial organic matter and phosphorite were deposited on the anoxic sea bottom to produce the phosphatic black shale facies. This model for offshore phosphatic black shale deposition obviates the difficulty of explaining in shallow tropical water the combination of nonskeletal phosporite production, and widespread lateral uniformity of a quiet anoxic environment between two marine limestones. It supports large-scale Pennsylvanian transgressions and regressions in the Mid-Continent sea, but remains compatible with the local cyclic sedimentary process of delta outbuilding and abandonment along the shoreline. In fact, large-scale marine transgressions and regressions account for the widespread distribution of delta-shoreline deposits from the Appalachians to Kansas. The offshore black shale model can be expanded to a more general depositional model that not only explains the lateral variation in black-shale-bearing Pennsylvanlan cyciothems from the Appalachians to West Texas, but also accounts for the scarcity of black shales in younger Pennsylvanlan and Permian Mid-Continent cyciothems by suggesting that water depths at maximum transgression during that time were generally too shallow to establish an effective thermocline.

@article{doi101306c1ea43c416c911d78645000102c1865d,
    author = "Heckel, Philip H.",
    title = "Origin of Phosphatic Black Shale Facies in Pennsylvanian Cyclothems of Mid-Continent North America",
    year = "1977",
    journal = "AAPG Bulletin",
    abstract = "Abstract Continued lithologic and paleontologic considerations of Kansas Upper Pennsylvanian megacyclothems more firmly establish the basic ascending sequence of: outside (nearshore) shale—middle (transgressive) limestone—core (offshore) shale—upper (regressive) limestone—outside (nearshore) shale, as representing a single transgressive-regressive sequence; this sequence is thus considered simply a cyclothem. Lateral facies change along the 500-km Iowa-Kansas outcrop belt is greatest in upper parts of upper limestones and outside shales, as would be expected in shallow-water to shoreline deposits; it is least in middle limestones, core shales, and bases of upper limestones, as would be expected in deeper water deposits. The widespread phosphatic black shale facies that commonly accompanies maximum transgression in the core shale is explained by water becoming deep enough to develop a thermocline strong enough to prevent bottom oxygenation by wind-driven vertical circulation. Pennsylvanian position of Mid-Continent North America, in the trade-wind belt north of the paleoequator along the Appalachians, allowed establishment of large-scale quasi-estuarine circulation in the Mid-Continent epicontinental sea. Cold, deep, oxygen-poor, phosphate-rich water from the western ocean was drawn in along the bottom through the basins of West Texas eventually to upwell in the eastern Mid-Continent and replace the surface water moved westward out of the sea by the prevailing winds. Upwelling greatly increased surface-water production of organic matter, which continually settled (while being carried westward) into the deeper incoming current, where it decayed and depleted the remaining oxygen while continually enriching the already high phosphate in a circulatory trap. In this way substantial organic matter and phosphorite were deposited on the anoxic sea bottom to produce the phosphatic black shale facies. This model for offshore phosphatic black shale deposition obviates the difficulty of explaining in shallow tropical water the combination of nonskeletal phosporite production, and widespread lateral uniformity of a quiet anoxic environment between two marine limestones. It supports large-scale Pennsylvanian transgressions and regressions in the Mid-Continent sea, but remains compatible with the local cyclic sedimentary process of delta outbuilding and abandonment along the shoreline. In fact, large-scale marine transgressions and regressions account for the widespread distribution of delta-shoreline deposits from the Appalachians to Kansas. The offshore black shale model can be expanded to a more general depositional model that not only explains the lateral variation in black-shale-bearing Pennsylvanlan cyciothems from the Appalachians to West Texas, but also accounts for the scarcity of black shales in younger Pennsylvanlan and Permian Mid-Continent cyciothems by suggesting that water depths at maximum transgression during that time were generally too shallow to establish an effective thermocline.",
    url = "https://doi.org/10.1306/c1ea43c4-16c9-11d7-8645000102c1865d",
    doi = "10.1306/c1ea43c4-16c9-11d7-8645000102c1865d",
    openalex = "W2070496895",
    references = "doi1013063d93436d16b111d78645000102c1865d, openalexw2601695287"
}

@article{lutzgarihan1979stratigraphy,
    author = "Lutz-Garihan, Anne B and Cuffey, Roger J.",
    title = "Stratigraphy of the Lower Permian Wreford Megacyclothem in Southernmost Kansas and Northern Oklahoma",
    year = "1979",
    journal = "Bulletin (Kansas Geological Survey)",
    url = "https://doi.org/10.17161/kgsbulletin.no.i216.22266",
    doi = "10.17161/kgsbulletin.no.i216.22266",
    openalex = "W4406784003",
    pages = "1-19"
}

Vertebrates occur together with marine-indicating invertebrates in the same facies of the WrefOrd Megacyclothem, Gearyan Stage, Lower Permian, of Kansas.The vertebrates include typically marine (petalodont, cladodont) taxa and those usually considered to be freshwater indicators (xenacanths, acanthodians).The consistent association of xenacanths and acanthodians with marine invertebrates and vertebrates in the Lower Permian of Kansas as well as their presence in both marine and freshwater lit hofacies at other localities indicate that xenacanths and acanthodians were euryhaline, anadromous or catadromous, and so cannot be used as freshwater indicators.Burrows with the lungfish Gnathorhiza and the amphibians Lysorophus and Diplocaulus occur in nearshore green deposits, thus indicating that Gnathorhiza and late Paleozoic tetrapods of E. C. Olson's aquatic community were tolerant of salt water.THE INVERTEBRATE FAUNA of parts of the Lower Permian of Kansas has been intensively studied with regard to its relationship to lithofacies and paleoenvironments.The Lower Permian Wreford Megacyclothem (Gearyan) has been particularly well investigated (Hattin, 1957; Cuffey, 1967; Lutz-Garihan and Cuffey, 1979).The environmental parameters show a change from fully marine to coastal (high-intertidal) ' %limns(rip! re(rived.lantiary I. 1985.conditions.Vertebrates are common throughout the sequence, but all are fragmentary, with the exception of the lungfish Gnathorhiza and tetrapods at the base of the sequence (Speiser Shale); the latter occur in, or close to, burrows in close proximity to red deposits.Lower Permian rocks in New Mexico, Texas, and Oklahoma yield an abundant and taxonomically diverse fauna of lower verte-

@article{openalexw334282282,
    author = "Schultze, Hans‐Peter",
    title = "Marine to onshore vertebrates in the Lower Permian of Kansas and their paleoenvironmental implications",
    year = "1985",
    journal = "KU ScholarWorks (The University of Kansas)",
    abstract = "Vertebrates occur together with marine-indicating invertebrates in the same facies of the WrefOrd Megacyclothem, Gearyan Stage, Lower Permian, of Kansas.The vertebrates include typically marine (petalodont, cladodont) taxa and those usually considered to be freshwater indicators (xenacanths, acanthodians).The consistent association of xenacanths and acanthodians with marine invertebrates and vertebrates in the Lower Permian of Kansas as well as their presence in both marine and freshwater lit hofacies at other localities indicate that xenacanths and acanthodians were euryhaline, anadromous or catadromous, and so cannot be used as freshwater indicators.Burrows with the lungfish Gnathorhiza and the amphibians Lysorophus and Diplocaulus occur in nearshore green deposits, thus indicating that Gnathorhiza and late Paleozoic tetrapods of E. C. Olson's aquatic community were tolerant of salt water.THE INVERTEBRATE FAUNA of parts of the Lower Permian of Kansas has been intensively studied with regard to its relationship to lithofacies and paleoenvironments.The Lower Permian Wreford Megacyclothem (Gearyan) has been particularly well investigated (Hattin, 1957; Cuffey, 1967; Lutz-Garihan and Cuffey, 1979).The environmental parameters show a change from fully marine to coastal (high-intertidal) ' \%limns(rip! re(rived.lantiary I. 1985.conditions.Vertebrates are common throughout the sequence, but all are fragmentary, with the exception of the lungfish Gnathorhiza and tetrapods at the base of the sequence (Speiser Shale); the latter occur in, or close to, burrows in close proximity to red deposits.Lower Permian rocks in New Mexico, Texas, and Oklahoma yield an abundant and taxonomically diverse fauna of lower verte-",
    url = "https://openalex.org/W334282282",
    openalex = "W334282282"
}

Recognition of ontogeny within a stenolaemate bryozoan colony requires separating the individualistic aspects of a zooid's growth from those of its neighbors. The ancestrula is the only zooid within a colony that always displays a partially independent ontogeny that ceases when it starts to experience shared changes with its neighboring daughter zooids during subsequent accretionary skeletal growth. Stenolaemate astogeny (shared changes across multiple zooids during the growth of both the ancestrular zooid and its asexual descendants) includes all coordinated changes in the size, shape, number, and calcification of autozooids, polymorphs, and extrazooidal structures, as well as changes within autozooids or polymorphs, such as the formation of basal diaphragms and brown bodies. Despite the fact that many of these directional changes occur within individual zooids, they are not part of ontogeny because they are taking place simultaneously across zooids that share a common skeleton, extrazooidal tissues, and pseudocoelomic spaces. Shared directional multizooidal changes occurring during colony growth provide a confirmatory test for the existence of astogeny. Astogeny was statistically evaluated in 6–15 characters measured within the exozones of four colonies of Tabulipora carbonaria (Worthen in Worthen and Meek, 1875). Statistically significant (at P ≤ 0.05) directional changes took place across growth stages within the exozone in the following morphometric characters: zooecial density, zooecial wall surface area, acanthostyle density, zooecial wall thicknesses, maximum acanthostyle diameters, and intrazooecial diaphragm abundances. Overall, earlier exozonal growth stages differ statistically from those of the later exozone, with characteristics of intermediate growth stages intergrading between the two. Discriminant function analysis segregated intervals of exozonal growth into early-, intermediate-, and late-stage clusters, confirming patterns delineated by univariate statistical tests. Based on these exozonal growth patterns, heterochronic changes in exozone astogeny characterized evolution within and across species of Tabulipora. Onshore populations of T. carbonaria were astogenetically progenetic relative to offshore ones along an environmental gradient across Kansas, whereas local populations became temporally more hypermorphic in a short-term stratigraphic succession of similar environments. Tabulipora carbonaria originated by astogenetic recapitulation in populations of its probable ancestor, T. ramosa. Therefore, speciation, microevolution, and clinal variation in Tabulipora all involved heterochronic modifications of exozone astogeny.

@article{doi101017s0022336000020448,
    author = "Pachut, Joseph F. and Cuffey, Roger J. and Anstey, Robert L.",
    title = "The concepts of astogeny and ontogeny in stenolaemate bryozoans, and their illustration in colonies of Tabulipora carbonaria from the Lower Permian of Kansas",
    year = "1991",
    journal = "Journal of Paleontology",
    abstract = "Recognition of ontogeny within a stenolaemate bryozoan colony requires separating the individualistic aspects of a zooid's growth from those of its neighbors. The ancestrula is the only zooid within a colony that always displays a partially independent ontogeny that ceases when it starts to experience shared changes with its neighboring daughter zooids during subsequent accretionary skeletal growth. Stenolaemate astogeny (shared changes across multiple zooids during the growth of both the ancestrular zooid and its asexual descendants) includes all coordinated changes in the size, shape, number, and calcification of autozooids, polymorphs, and extrazooidal structures, as well as changes within autozooids or polymorphs, such as the formation of basal diaphragms and brown bodies. Despite the fact that many of these directional changes occur within individual zooids, they are not part of ontogeny because they are taking place simultaneously across zooids that share a common skeleton, extrazooidal tissues, and pseudocoelomic spaces. Shared directional multizooidal changes occurring during colony growth provide a confirmatory test for the existence of astogeny. Astogeny was statistically evaluated in 6–15 characters measured within the exozones of four colonies of Tabulipora carbonaria (Worthen in Worthen and Meek, 1875). Statistically significant (at P ≤ 0.05) directional changes took place across growth stages within the exozone in the following morphometric characters: zooecial density, zooecial wall surface area, acanthostyle density, zooecial wall thicknesses, maximum acanthostyle diameters, and intrazooecial diaphragm abundances. Overall, earlier exozonal growth stages differ statistically from those of the later exozone, with characteristics of intermediate growth stages intergrading between the two. Discriminant function analysis segregated intervals of exozonal growth into early-, intermediate-, and late-stage clusters, confirming patterns delineated by univariate statistical tests. Based on these exozonal growth patterns, heterochronic changes in exozone astogeny characterized evolution within and across species of Tabulipora. Onshore populations of T. carbonaria were astogenetically progenetic relative to offshore ones along an environmental gradient across Kansas, whereas local populations became temporally more hypermorphic in a short-term stratigraphic succession of similar environments. Tabulipora carbonaria originated by astogenetic recapitulation in populations of its probable ancestor, T. ramosa. Therefore, speciation, microevolution, and clinal variation in Tabulipora all involved heterochronic modifications of exozone astogeny.",
    url = "https://doi.org/10.1017/s0022336000020448",
    doi = "10.1017/s0022336000020448",
    openalex = "W2477758535",
    references = "doi1010079781489935335, doi101016b978012763150950012x, doi101017s0094837300006588, doi101017s0094837300013786, doi101111j155856461987tb02473x, doi1023073225581, hattin1956depositional, openalexw1499955781, openalexw2506868775, openalexw586512518"
}

Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall.

@article{doi1017161cresv0i23511848,
    author = "Miller, Keith and West, Ronald R.",
    title = "Reevaluation of Wolfcampian Cyclothems in Northeastern Kansas",
    year = "1993",
    journal = "Current Research in Earth Sciences",
    abstract = "Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall.",
    url = "https://doi.org/10.17161/cres.v0i235.11848",
    doi = "10.17161/cres.v0i235.11848",
    openalex = "W3201334289",
    references = "doi1010160037073888900565, doi1010160166516284900193, doi10108011035898709454746, doi10113000167606198798475lpgeig20co2, doi1011300016760619901020535dccslc23co2, doi1011300091761319900180533pcosro23co2, doi101130gsab471177, doi102110pec88010039, openalexw1973279175"
}

ABSTRACT Columnar structured horizons have been recognized in ancient coastal palaeosols of several Lower Permian (Asselian) stratigraphic units of north‐central Kansas. These strongly developed columnar, polygonal‐shaped peds are characteristic of sodium‐influenced (natric) argillic horizons, and are commonly indicative of semi‐arid to arid environments. Evaporite features above and below these palaeosols support the conclusion for a dry palaeoclimate. The columnar peds are typically 3–15 cm in diameter and exhibit domed tops. Fine clay fills the cracks between the columnar peds, and is generally of a darker colour than the peds. Each natric horizon has a low value and chroma colour, apparently the result of carbonate accumulation. The natric horizons in these Permian palaeosols appear to have been partially influenced by sodium‐rich groundwaters. Root traces and root moulds are found between peds in all natric horizons, indicating plant succession after columnar ped formation. These sodium‐influenced palaeosol profiles occur as part of a spectrum of palaeosol types that indicate cyclical climate change associated with glacioeustatic sea‐level fluctuations.

@article{doi101111j136530911997tb00427x,
    author = "McCahon, Thomas J. and Miller, Keith",
    title = "Climatic significance of natric horizons in Permian (Asselian) palaeosols of north‐central Kansas, USA",
    year = "1997",
    journal = "Sedimentology",
    abstract = "ABSTRACT Columnar structured horizons have been recognized in ancient coastal palaeosols of several Lower Permian (Asselian) stratigraphic units of north‐central Kansas. These strongly developed columnar, polygonal‐shaped peds are characteristic of sodium‐influenced (natric) argillic horizons, and are commonly indicative of semi‐arid to arid environments. Evaporite features above and below these palaeosols support the conclusion for a dry palaeoclimate. The columnar peds are typically 3–15 cm in diameter and exhibit domed tops. Fine clay fills the cracks between the columnar peds, and is generally of a darker colour than the peds. Each natric horizon has a low value and chroma colour, apparently the result of carbonate accumulation. The natric horizons in these Permian palaeosols appear to have been partially influenced by sodium‐rich groundwaters. Root traces and root moulds are found between peds in all natric horizons, indicating plant succession after columnar ped formation. These sodium‐influenced palaeosol profiles occur as part of a spectrum of palaeosol types that indicate cyclical climate change associated with glacioeustatic sea‐level fluctuations.",
    url = "https://doi.org/10.1111/j.1365-3091.1997.tb00427.x",
    doi = "10.1111/j.1365-3091.1997.tb00427.x",
    openalex = "W2071767377",
    references = "doi1010160012825294900027, doi101086628978, doi1010970001069419780400000019, doi1011300016760619931050129cop23co2, doi101144gsjgs15061109, doi101306ad462b4616f711d78645000102c1865d, doi1017161kgsbulletinno23520441, doi102110pec88010039, doi102136sssaj196903615995003300020006x, openalexw1601939319"
}

@incollection{crossref1999stratigraphic,
    title = "Stratigraphic distribution of paleozoic nonmarine ostracoda devonian",
    year = "1999",
    booktitle = "Developments in Palaeontology and Stratigraphy",
    url = "https://doi.org/10.1016/s0920-5446(99)80003-x",
    doi = "10.1016/s0920-5446(99)80003-x",
    pages = "3-271"
}

Studies of bryozoans from the Wreford Megacyclothem have provided an extensive species-level database with which to examine paleoecologic patterns using multivariate statistical methods. Detrended correspondence (DCA) or gradient analysis was applied to fractional abundances of 17 species across 85 sampling intervals primarily within calcareous lithologies of the Wreford strata of Kansas.

@article{doi1017161pcns18083773,
    author = "Pachut, Joseph F. and Cuffey, Roger J.",
    title = "Stratigraphic and Geographic Bryozoan Abundance Gradients in the Calcareous Shales of the Wreford Megacyclothem (Lower Permian, Kansas)",
    year = "1999",
    journal = "Paleontological Contributions New Series (1992-2009)",
    abstract = "Studies of bryozoans from the Wreford Megacyclothem have provided an extensive species-level database with which to examine paleoecologic patterns using multivariate statistical methods. Detrended correspondence (DCA) or gradient analysis was applied to fractional abundances of 17 species across 85 sampling intervals primarily within calcareous lithologies of the Wreford strata of Kansas.",
    url = "https://doi.org/10.17161/pcns.1808.3773",
    doi = "10.17161/pcns.1808.3773",
    openalex = "W2140821910",
    references = "doi101016001669959180043y, doi101017s0022336000036921, doi101111j146918091975tb00129x, doi101111j150239311978tb01893x, doi101111j150239311985tb00697x, doi101111j150239311986tb01898x, doi101126science16338741419, doi1015159781400860180203, doi1023073515180, openalexw1543350971"
}

@article{doi101016s0031018203006643,
    author = "Hembree, Daniel I. and Martin, Larry D. and Hasiotis, Stephen T.",
    title = "Amphibian burrows and ephemeral ponds of the Lower Permian Speiser Shale, Kansas: evidence for seasonality in the midcontinent",
    year = "2003",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/s0031-0182(03)00664-3",
    doi = "10.1016/s0031-0182(03)00664-3",
    openalex = "W2026603680",
    references = "doi1010029780470698716, doi1010160031018287900307, doi1010160031018288900545, doi101016c20090021126, doi10108010420949309380105, doi1023071447109, doi1023071931798, doi105860choice493882, openalexw101633874, openalexw1996683265, openalexw334282282"
}

ABSTRACT ‘Microsaurs’ (Lepospondyli) were a group of tetrapods whose fossil record spanned the Mississippian–Early Permian, and have sometimes been implicated in the origins of lissamphibians (especially the fossorial caecilians). Although common in the well-sampled Permian deposits of Texas and Oklahoma, little is known of conservative recumbirostran ‘microsaurs’ from more northerly localities (Kansas/Nebraska). Data on a new, well-preserved recumbirostran, Huskerpeton englehorni, gen. et sp. nov., from the Eskridge Formation, Nebraska, reveal affinities to the purported gymnarthrid ‘Euryodus’ bonneri (here moved to a new genus, Proxilodon) from the Speiser Formation, Kansas. High resolution micro-computed tomography reveals important endocranial data, including an ossified ‘supraoccipital’ that is usually absent in gymnarthrids, a dorsal sinus separating the synotic tectum from the dermal skull roof as in ostodolepids, ventral flanges of the frontals articulating directly with the ascending lamina of the sphenethmoid, and tall, ossified ‘pleurosphenoids,’ thereby providing useful comparison with morphologically derived recumbirostrans. A cladistic analysis of 60 taxa and 227 characters recovered a monophyletic clade of Huskerpeton, Proxilodon, and the recently described Tambaroter within a more inclusive clade that includes gymnarthrids and ostodolepids (both nested members of the Recumbirostra and putative outgroups to caecilians). Whereas other lepospondyls (i.e., lysorophians) are abundant in the region, the records of Huskerpeton and Proxilodon reveal that only two ‘microsaur’ genera are adequately known from the lowermost Permian of Kansas/Nebraska and demonstrate similarities between the Eskridge and Speiser faunas. Moreover, these forms may represent the ground plan from which more specialized fossorial forms (gymnarthrids and ostodolepids) evolved. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

@article{doi101080027246342013728998,
    author = "Huttenlocker, Adam K. and Pardo, Jason D. and Small, Bryan J. and Anderson, Jason S.",
    title = "Cranial morphology of recumbirostrans (Lepospondyli) from the Permian of Kansas and Nebraska, and early morphological evolution inferred by micro-computed tomography",
    year = "2013",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT ‘Microsaurs’ (Lepospondyli) were a group of tetrapods whose fossil record spanned the Mississippian–Early Permian, and have sometimes been implicated in the origins of lissamphibians (especially the fossorial caecilians). Although common in the well-sampled Permian deposits of Texas and Oklahoma, little is known of conservative recumbirostran ‘microsaurs’ from more northerly localities (Kansas/Nebraska). Data on a new, well-preserved recumbirostran, Huskerpeton englehorni, gen. et sp. nov., from the Eskridge Formation, Nebraska, reveal affinities to the purported gymnarthrid ‘Euryodus’ bonneri (here moved to a new genus, Proxilodon) from the Speiser Formation, Kansas. High resolution micro-computed tomography reveals important endocranial data, including an ossified ‘supraoccipital’ that is usually absent in gymnarthrids, a dorsal sinus separating the synotic tectum from the dermal skull roof as in ostodolepids, ventral flanges of the frontals articulating directly with the ascending lamina of the sphenethmoid, and tall, ossified ‘pleurosphenoids,’ thereby providing useful comparison with morphologically derived recumbirostrans. A cladistic analysis of 60 taxa and 227 characters recovered a monophyletic clade of Huskerpeton, Proxilodon, and the recently described Tambaroter within a more inclusive clade that includes gymnarthrids and ostodolepids (both nested members of the Recumbirostra and putative outgroups to caecilians). Whereas other lepospondyls (i.e., lysorophians) are abundant in the region, the records of Huskerpeton and Proxilodon reveal that only two ‘microsaur’ genera are adequately known from the lowermost Permian of Kansas/Nebraska and demonstrate similarities between the Eskridge and Speiser faunas. Moreover, these forms may represent the ground plan from which more specialized fossorial forms (gymnarthrids and ostodolepids) evolved. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP",
    url = "https://doi.org/10.1080/02724634.2013.728998",
    doi = "10.1080/02724634.2013.728998",
    openalex = "W1976294394",
    references = "doi101016s0031018203006643, openalexw2531755153"
}

@article{ernst2013lower,
    author = "Ernst, Andrej and Gorgij, Mohammad N.",
    title = "Lower Permian bryozoan faunas from Kalmard area, central Iran",
    year = "2013",
    journal = "Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen",
    url = "https://doi.org/10.1127/0077-7749/2013/0330",
    doi = "10.1127/0077-7749/2013/0330",
    number = "3",
    openalex = "W2322946695",
    pages = "275-324",
    volume = "268"
}

@article{openalexw2595382713,
    author = "Barrett, Terry R.",
    title = "Hierarchal genetic stratigraphy of the Wreford Limestone Formation (Lower Permian, Gearyan) in northeastern Kansas",
    year = "2015",
    journal = "K-State Research Exchange (Kansas State University)",
    url = "https://openalex.org/W2595382713",
    openalex = "W2595382713"
}

@inproceedings{andmiller2019paleoclimate,
    author = "Miller, Keith B. and McCahon, Thomas J.",
    title = "PALEOCLIMATE CONTRASTS BETWEEN THE LATEST PENNSYLVANIAN (VIRGILIAN) CYCLOTHEMS AND EARLIEST PERMIAN (WOLFCAMPIAN) CYCLOTHEMS OF KANSAS",
    year = "2019",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://doi.org/10.1130/abs/2019sc-325777",
    doi = "10.1130/abs/2019sc-325777",
    openalex = "W2948458865"
}

Abstract We describe aggregative microconchid (Lophophorata) tubes from the uppermost Permian (upper Changhsingian) and Lower Triassic (Olenekian) lacustrine and fluvial strata of the Tunguska and Kuznetsk basins and the southern Cis-Urals, Russia. These attach to clam shrimp carapaces, bivalve shells, terrestrial plant fragments and a horseshoe crab head shield, and also form their own monospecific agglomerations. Planispiral tubes of a wide size range (0.1–2.5 mm) create dense settlements on these firm substrates, which likely comprise multiple generations of the same species. These finds confirm that this extinct lophophorate group was inhabiting non-marine continental basins during latest Permian and earliest Triassic time, when they were major suspension feeders in such limnic ecosystems. Microconchids dispersed extensively and rapidly in the aftermath of the Permian–Triassic mass extinction into both marine and continental basins at low and moderately high latitudes, which were notably different in salinity, temperature, depth and redox conditions. This confirms that small lightly calcified microconchids were a genuine disaster eurytopic group, whose expansion may have been promoted by low predator pressure and low competition for substrate.

@article{doi101017s0016756820001375,
    author = "Щербаков, Д. E. and Vinn, Olev and Zhuravlev, Andrey Yu.",
    title = "Disaster microconchids from the uppermost Permian and Lower Triassic lacustrine strata of the Cis-Urals and the Tunguska and Kuznetsk basins (Russia)",
    year = "2021",
    journal = "Geological Magazine",
    abstract = "Abstract We describe aggregative microconchid (Lophophorata) tubes from the uppermost Permian (upper Changhsingian) and Lower Triassic (Olenekian) lacustrine and fluvial strata of the Tunguska and Kuznetsk basins and the southern Cis-Urals, Russia. These attach to clam shrimp carapaces, bivalve shells, terrestrial plant fragments and a horseshoe crab head shield, and also form their own monospecific agglomerations. Planispiral tubes of a wide size range (0.1–2.5 mm) create dense settlements on these firm substrates, which likely comprise multiple generations of the same species. These finds confirm that this extinct lophophorate group was inhabiting non-marine continental basins during latest Permian and earliest Triassic time, when they were major suspension feeders in such limnic ecosystems. Microconchids dispersed extensively and rapidly in the aftermath of the Permian–Triassic mass extinction into both marine and continental basins at low and moderately high latitudes, which were notably different in salinity, temperature, depth and redox conditions. This confirms that small lightly calcified microconchids were a genuine disaster eurytopic group, whose expansion may have been promoted by low predator pressure and low competition for substrate.",
    url = "https://doi.org/10.1017/s0016756820001375",
    doi = "10.1017/s0016756820001375",
    openalex = "W3119974076",
    references = "doi101016jpalaeo201612051, doi101017jpa2016131, doi101130001676061966771121pioepf20co2"
}

Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall.

@article{doi1017161kgsbulletinno23520441,
    author = "Miller, Keith B. and West, Ronald R.",
    title = "Reevaluation of Wolfcampian Cyclothems in Northeastern Kansas: Significance of Subaerial Exposure and Flooding Surfaces",
    year = "2024",
    journal = "Bulletin (Kansas Geological Survey)",
    abstract = "Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall.",
    url = "https://doi.org/10.17161/kgsbulletin.no.235.20441",
    doi = "10.17161/kgsbulletin.no.235.20441",
    openalex = "W4406748914"
}