Geochemistry

@misc{popova1965organic6,
    author = "Popova, Z. P. and Glazunova, N. N",
    title = "Organic residues in the oil from Markovskii oil field",
    year = "1965",
    howpublished = "Academy of Sciences of the USSR Reports, v. 161, no. 3, p. 673-675; English translation by American Geological Institute, 1965, Academy of Science, USSR Reports, v.161, p. 67-69",
    note = "talkorigins\_source = {true}; raw\_reference = {Popova, Z. P., and Glazunova, N. N., 1965, Organic residues in the oil from Markovskii oil field: Academy of Sciences of the USSR Reports, v. 161, no. 3, p. 673-675; English translation by American Geological Institute, 1965, Academy of Science, USSR Reports, v.161, p. 67-69.}"
}

@misc{zharkova1965carnallite8,
    author = "Zharkova, T. M",
    title = "Carnallite in Cambrian salt deposits of the Siberian Platform",
    year = "1965",
    howpublished = "Academy of Sciences of the USSR Reports, v. 164, no. 1, p. 177- 178; English translation by American Geological Institute, 1966, Academy of Science, USSR Reports, v.164, p. 144-145",
    note = "talkorigins\_source = {true}; raw\_reference = {Zharkova, T. M., 1965, Carnallite in Cambrian salt deposits of the Siberian Platform: Academy of Sciences of the USSR Reports, v. 164, no. 1, p. 177- 178; English translation by American Geological Institute, 1966, Academy of Science, USSR Reports, v.164, p. 144-145.}"
}

@misc{kolosov1968complex2,
    author = "Kolosov, A. S. and Pustyl'nikov, A. M. and Kharkova, T. M",
    title = "Complex ferrum and manganese chlorides in Cambrian salt deposits of Kansko-Tassyevskoi basin",
    year = "1968",
    howpublished = "Academy of Sciences of the USSR Reports, v. 181, no. 6, p. 213-216",
    note = "talkorigins\_source = {true}; raw\_reference = {Kolosov, A. S., Pustyl'nikov, A. M., and Kharkova, T. M., 1968, Complex ferrum and manganese chlorides in Cambrian salt deposits of Kansko-Tassyevskoi basin: Academy of Sciences of the USSR Reports, v. 181, no. 6, p. 213-216.}"
}

@misc{noble1968deepocean5,
    author = "Noble, C. S. and Naughton, J. J",
    title = "Deep-ocean basalts",
    year = "1968",
    howpublished = "Inert gas and uncertainties in age dating: Science, v. 162, p. 265-267",
    note = "talkorigins\_source = {true}; raw\_reference = {Noble, C. S., and Naughton, J. J., 1968, Deep-ocean basalts: Inert gas and uncertainties in age dating: Science, v. 162, p. 265-267.}"
}

@misc{macintyre1970why3,
    author = "MacIntyre, F",
    title = "Why the Sea is Salt",
    year = "1970",
    howpublished = "Scientific American, v. 223, no. 5",
    note = "talkorigins\_source = {true}; raw\_reference = {MacIntyre, F., 1970, Why the Sea is Salt: Scientific American, v. 223, no. 5.}"
}

@article{doi1010160009254171900404,
    author = "Meinschein, W. G.",
    title = "Advances in organic geochemistry, 1966",
    year = "1971",
    journal = "Chemical Geology",
    url = "https://doi.org/10.1016/0009-2541(71)90040-4",
    doi = "10.1016/0009-2541(71)90040-4",
    openalex = "W2321478890"
}

@misc{mckirdy1974organic4,
    author = "McKirdy, D. M",
    title = "Organic geochemistry in Precambrian research",
    year = "1974",
    howpublished = "Precambrian Research, v. 1, p. 75-137",
    note = "talkorigins\_source = {true}; raw\_reference = {McKirdy, D. M., 1974, Organic geochemistry in Precambrian research: Precambrian Research, v. 1, p. 75-137.}"
}

@article{doi1010160016703775901246,
    author = "Meinschein, W. G.",
    title = "Advances in organic geochemistry 1973",
    year = "1975",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(75)90124-6",
    doi = "10.1016/0016-7037(75)90124-6",
    openalex = "W2320773461"
}

A description is given of the geology, mineralogy, and geochemistry of the Rabbit Lake deposit, located in the immediate vicinity of the unconformity between an Aphebian/Archean metamorphosed basement and overlying unmetamorphosed sandstones of the Helikian Athabasca Formation. In the deposit several stages of alteration, mineralization, remobilization, and redeposition, separated by intermittent brecciation, are recognized. The alterations, predominantly chloritization with some tourmalinization, silicification, and dolomitization, are accompanied by introduction of H 2 O, MgO, probably also B, and by leaching of SiO 2, Na 2 O, K 2 O, CaO, and Sigma Fe 2 O 3. The deposit is of complex mineralogy and typified by a broad suite of elements including U, Ni, Co, Cu, Pb, Zn, Fe, Mn, As, S, and Se.In the history of the deposit conditions have repeatedly oscillated between oxidizing and reducing, and the temporal relationships between oxidizing, reducing, and mineralizing episodes indicate the importance of redox reactions in shaping the deposit.After comparison with other unconformity-type deposits in the Athabasca Basin, a diagenetic-hydrothermal metallogenetic model is presented. The model invokes percolation of oxidizing diagenetic solutions in the Athabasca Formation, which, being heated under the influence of the geothermal gradient, eventually attained temperatures of around 200 degrees C at the floor of the basin. Reaction of the heated diagenetic solutions with graphitic basement rocks generated methane, which acted as a mobile reductant. Mineralization resulted from interaction of flows of the methane-bearing reducing solutions and the oxidizing diagenetic solutions. The latter have carried the ore constituents to the site of reduction and, hence, of deposition.The ore constituents may have been derived from the Athabasca Formation by leaching during a process of intrastratal weathering and oxidation. Thus, in a broad sense, processes governing the formation of the Saskatchewan unconformity-type deposits may have been similar to those that give rise to sandstone-type roll-front deposits.

@article{doi102113gsecongeo7381450,
    author = "van Hoeve, J. P. and Sibbald, T.I.I.",
    title = "On the genesis of Rabbit Lake and other unconformity-type uranium deposits in northern Saskatchewan, Canada",
    year = "1978",
    journal = "Economic Geology",
    abstract = "A description is given of the geology, mineralogy, and geochemistry of the Rabbit Lake deposit, located in the immediate vicinity of the unconformity between an Aphebian/Archean metamorphosed basement and overlying unmetamorphosed sandstones of the Helikian Athabasca Formation. In the deposit several stages of alteration, mineralization, remobilization, and redeposition, separated by intermittent brecciation, are recognized. The alterations, predominantly chloritization with some tourmalinization, silicification, and dolomitization, are accompanied by introduction of H 2 O, MgO, probably also B, and by leaching of SiO 2, Na 2 O, K 2 O, CaO, and Sigma Fe 2 O 3. The deposit is of complex mineralogy and typified by a broad suite of elements including U, Ni, Co, Cu, Pb, Zn, Fe, Mn, As, S, and Se.In the history of the deposit conditions have repeatedly oscillated between oxidizing and reducing, and the temporal relationships between oxidizing, reducing, and mineralizing episodes indicate the importance of redox reactions in shaping the deposit.After comparison with other unconformity-type deposits in the Athabasca Basin, a diagenetic-hydrothermal metallogenetic model is presented. The model invokes percolation of oxidizing diagenetic solutions in the Athabasca Formation, which, being heated under the influence of the geothermal gradient, eventually attained temperatures of around 200 degrees C at the floor of the basin. Reaction of the heated diagenetic solutions with graphitic basement rocks generated methane, which acted as a mobile reductant. Mineralization resulted from interaction of flows of the methane-bearing reducing solutions and the oxidizing diagenetic solutions. The latter have carried the ore constituents to the site of reduction and, hence, of deposition.The ore constituents may have been derived from the Athabasca Formation by leaching during a process of intrastratal weathering and oxidation. Thus, in a broad sense, processes governing the formation of the Saskatchewan unconformity-type deposits may have been similar to those that give rise to sandstone-type roll-front deposits.",
    url = "https://doi.org/10.2113/gsecongeo.73.8.1450",
    doi = "10.2113/gsecongeo.73.8.1450",
    openalex = "W1964327963"
}

@article{crossref1979geochemistry,
    title = "Geochemistry of organic matter in ore deposits",
    year = "1979",
    journal = "Organic Geochemistry",
    url = "https://doi.org/10.1016/0146-6380(79)90020-2",
    doi = "10.1016/0146-6380(79)90020-2",
    number = "3",
    openalex = "W4240402265",
    pages = "188",
    volume = "1"
}

ABSTRACT A new pyrolysis instrument, developed by the Institut Francais du Petrole, and called "Rock-Eval" (see Espitalie, etal., OTC Paper 2935, 1977), has been successfully operated on the BenOceanLancer drill ship. As an integral part of a computer assisted mud logging unit, the device was used to rapidly identify and evaluate petroleum source beds during offshore drilling operations. The data allowed determination of the petroleum generating potential and the degree of maturation of the source rocks at the well site. It also provided a useful stratigraphic correlation tool. Advantages of applying this technique on the well site are:better and more representative samples, leading to more accurate geochemical profiling,instant access of the data to the well site geologist and exploration management, andintegration of geochemical data with conventional mud logging data during drilling operations. This report describes the well site implementation and evaluation of the pyrolysis device. Because this instrument was designed for laboratory research, several significant problems had to be solved prior to use at the well site. Among these were: electrical problems specific to this device, weighing small samples (100 mg) at sea, and partial automation of the system to improve efficiency and precision. Extensive intercalibration checks with a land-based instrument were also conducted. Examples of data and applications to offshore exploration are given. The economics of operating the device offshore are favorable. INTRODUCTION Organic geochemistry has become increasingly important to offshore oil exploration. As previously pointed out by Dow1, "Attention must be focused not only on traps and reservoirs, but on whether there is a reasonable expectation that they contain oil and gas before committing to expensive ventures in the largely unknown realm of continental slopes and rises." Source beds must be identified and an estimate made of their oil and gas potential and degree of maturation. When integrated with geophysical and geological data, this organic geochemical information can lead to identification of those segments of sedimentary basins where oil and/or gas have been generated in the subsurface. Conventional geochemical profiling of wells requires carefully selected samples from drill cutings, sidewall cores, and conventional cores which are shipped to land-based laboratories for detailed analysis. Final delivery of data to users commonly follows weeks, if not months, later. This report describes a joint project by Chevron Oil Field Research Company, Chevron Overseas Petroleum, Inc., and Exploration Logging, Inc., to evaluate the use of a new analytical device to rapidly screen large numbers of samples for geochemical data at the well site. Valuable information regarding the presence of source beds, the stratigraphy of organic matter, and the significance of hydrocarbon shows was made available at the same time as mud logs and electric logs.

@article{doi1040433410ms,
    author = "Clementz, David M. and Demaison, Gerard and Daly, A.R.",
    title = "Well Site Geochemistry By Programmed Pyrolysis",
    year = "1979",
    journal = "Offshore Technology Conference",
    abstract = {ABSTRACT A new pyrolysis instrument, developed by the Institut Francais du Petrole, and called "Rock-Eval" (see Espitalie, etal., OTC Paper 2935, 1977), has been successfully operated on the BenOceanLancer drill ship. As an integral part of a computer assisted mud logging unit, the device was used to rapidly identify and evaluate petroleum source beds during offshore drilling operations. The data allowed determination of the petroleum generating potential and the degree of maturation of the source rocks at the well site. It also provided a useful stratigraphic correlation tool. Advantages of applying this technique on the well site are:better and more representative samples, leading to more accurate geochemical profiling,instant access of the data to the well site geologist and exploration management, andintegration of geochemical data with conventional mud logging data during drilling operations. This report describes the well site implementation and evaluation of the pyrolysis device. Because this instrument was designed for laboratory research, several significant problems had to be solved prior to use at the well site. Among these were: electrical problems specific to this device, weighing small samples (100 mg) at sea, and partial automation of the system to improve efficiency and precision. Extensive intercalibration checks with a land-based instrument were also conducted. Examples of data and applications to offshore exploration are given. The economics of operating the device offshore are favorable. INTRODUCTION Organic geochemistry has become increasingly important to offshore oil exploration. As previously pointed out by Dow1, "Attention must be focused not only on traps and reservoirs, but on whether there is a reasonable expectation that they contain oil and gas before committing to expensive ventures in the largely unknown realm of continental slopes and rises." Source beds must be identified and an estimate made of their oil and gas potential and degree of maturation. When integrated with geophysical and geological data, this organic geochemical information can lead to identification of those segments of sedimentary basins where oil and/or gas have been generated in the subsurface. Conventional geochemical profiling of wells requires carefully selected samples from drill cutings, sidewall cores, and conventional cores which are shipped to land-based laboratories for detailed analysis. Final delivery of data to users commonly follows weeks, if not months, later. This report describes a joint project by Chevron Oil Field Research Company, Chevron Overseas Petroleum, Inc., and Exploration Logging, Inc., to evaluate the use of a new analytical device to rapidly screen large numbers of samples for geochemical data at the well site. Valuable information regarding the presence of source beds, the stratigraphy of organic matter, and the significance of hydrocarbon shows was made available at the same time as mud logs and electric logs.},
    url = "https://doi.org/10.4043/3410-ms",
    doi = "10.4043/3410-ms",
    openalex = "W2026709713"
}

@misc{hunt1979petroleum1,
    author = "Hunt, J. M",
    title = "Petroleum Geochemistry and Geology",
    year = "1979",
    howpublished = "San Francisco, W.H. Freeman \& Co., 617 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Hunt, J. M., 1979, Petroleum Geochemistry and Geology: San Francisco, W.H. Freeman \& Co., 617 p.}"
}

@article{doi1010160165237082800235,
    author = "Larter, Steve and Douglas, A.G.",
    title = "Pyrolysis methods in organic geochemistry: An overview",
    year = "1982",
    journal = "Journal of Analytical and Applied Pyrolysis",
    url = "https://doi.org/10.1016/0165-2370(82)80023-5",
    doi = "10.1016/0165-2370(82)80023-5",
    openalex = "W2005392285"
}

@article{doi1010160009254183900827,
    author = "Hodgson, G. W.",
    title = "Advances in organic geochemistry 1979",
    year = "1983",
    journal = "Chemical Geology",
    url = "https://doi.org/10.1016/0009-2541(83)90082-7",
    doi = "10.1016/0009-2541(83)90082-7",
    openalex = "W2321419236"
}

Middle Devonian barrier complex within the Pine Point lead-zinc ore field located within the immature to marginally mature zone with respect to petroleum generation. Certain of the host rocks of the ore field were deposited in highly reducing conditions such that organic matter of algal or microbial origin has been preserved to a remarkable degree. Yields of extractable (soluble) material relative to organic carbon are extremely high, which has resulted in the local migration of immature bitumens and heavy oil within the shallow regime. Polymerization of nitrogen, sulfur, and oxygen compounds, and asphaltenes. Biodegradation of bitumens is a relatively late process. The question of a genetic relationship between lead-zinc sulfide and organic matter remains open.--Modified journal abstract.

@article{doi102113gsecongeo7811,
    author = "Macqueen, R. W. and Powell, T.G.",
    title = "Organic geochemistry of the Pine Point lead-zinc ore field and region, Northwest Territories, Canada",
    year = "1983",
    journal = "Economic Geology",
    abstract = "Middle Devonian barrier complex within the Pine Point lead-zinc ore field located within the immature to marginally mature zone with respect to petroleum generation. Certain of the host rocks of the ore field were deposited in highly reducing conditions such that organic matter of algal or microbial origin has been preserved to a remarkable degree. Yields of extractable (soluble) material relative to organic carbon are extremely high, which has resulted in the local migration of immature bitumens and heavy oil within the shallow regime. Polymerization of nitrogen, sulfur, and oxygen compounds, and asphaltenes. Biodegradation of bitumens is a relatively late process. The question of a genetic relationship between lead-zinc sulfide and organic matter remains open.--Modified journal abstract.",
    url = "https://doi.org/10.2113/gsecongeo.78.1.1",
    doi = "10.2113/gsecongeo.78.1.1",
    openalex = "W2039503452"
}

@article{doi1010160016703784903673,
    author = "Hedges, John I.",
    title = "Advances in organic geochemistry 1981",
    year = "1984",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(84)90367-3",
    doi = "10.1016/0016-7037(84)90367-3",
    openalex = "W3080398110"
}

@misc{saller1984petrologic7,
    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.}"
}

@article{doi1010160301926885900841,
    author = "Mossman, David J. and Dyer, Betsey Dexter",
    title = "The geochemistry of Witwatersrand-type gold deposits and the possible influence of ancient prokaryotic communities on gold dissolution and precipitation",
    year = "1985",
    journal = "Precambrian Research",
    url = "https://doi.org/10.1016/0301-9268(85)90084-1",
    doi = "10.1016/0301-9268(85)90084-1",
    openalex = "W2011720734",
    references = "crossref1979geochemistry"
}

@article{doi101016001670378690205x,
    author = "Ott, A Schmidt",
    title = "Advances in Organic Geochemistry 1983",
    year = "1986",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(86)90205-x",
    doi = "10.1016/0016-7037(86)90205-x",
    openalex = "W2921067423"
}

Ninety samples from cores of Cambra-Proterozoic sediments at eight locations were analyzed by Rock-Eval pyrolysis to determine both kerogen type and thermal maturation levels as a means of assessing source beds and petroleum potential relative to known gas accumulations in the Old Fort Island sandstones in the Colville Hills. Organic-rich partings in dolostones within the Mount Cap Old Fort Island section contain Type II kerogen which has been thermally matured high into, and possibly in part beyond, the oil generation window in the Colville area. Dark grey shales of the Mount Cap Formation are also potential source beds. Those shales exhibiting a greenish cast contain too little organic carbon to have source potential. Total organic carbon in Proterozoic beds is low and their source potential is questionable. To the west in the Ontaratue area, Cambra-Proterozoic strata are all low in organic carbon and are interpreted to be thermally overmature. Greenish Mount Cap beds in the Mackenzie Depocentre are too low in kerogen to be source beds or to define a level of thermal maturity.

@misc{macauley1987organic,
    author = "Macauley, G",
    title = "Organic Geochemistry of Some Cambrian-Proterozoic Sediments, Colville Hills, Northwest Territories",
    year = "1987",
    abstract = "Ninety samples from cores of Cambra-Proterozoic sediments at eight locations were analyzed by Rock-Eval pyrolysis to determine both kerogen type and thermal maturation levels as a means of assessing source beds and petroleum potential relative to known gas accumulations in the Old Fort Island sandstones in the Colville Hills. Organic-rich partings in dolostones within the Mount Cap Old Fort Island section contain Type II kerogen which has been thermally matured high into, and possibly in part beyond, the oil generation window in the Colville area. Dark grey shales of the Mount Cap Formation are also potential source beds. Those shales exhibiting a greenish cast contain too little organic carbon to have source potential. Total organic carbon in Proterozoic beds is low and their source potential is questionable. To the west in the Ontaratue area, Cambra-Proterozoic strata are all low in organic carbon and are interpreted to be thermally overmature. Greenish Mount Cap beds in the Mackenzie Depocentre are too low in kerogen to be source beds or to define a level of thermal maturity.",
    url = "https://doi.org/10.4095/130272",
    doi = "10.4095/130272",
    openalex = "W2982163602"
}

@article{doi1010160016703788903705,
    author = "Murphy, Sister M.E",
    title = "Advances in organic geochemistry, 1985",
    year = "1988",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(88)90370-5",
    doi = "10.1016/0016-7037(88)90370-5",
    openalex = "W1530289586"
}

ABSTRACT The prevailing explanation for the origin of organic-rich sediments and rocks invokes deposition under conditions of anoxia. However, recent research suggests that high primary production and not water-column anoxia provides the first-order control on the accumulation of organic-rich facies in the modern oceans. Oxygen minima do not appear to have any direct effect on carbon accumulation in continental margin or marginal sea environments. Sediments accumulating in the modern Black Sea, the type euxinic basin, are not particularly enriched in organic matter despite the presence of an anoxic water column, although a sapropel containing extremely high carbon concentrations was deposited during the Holocene at a time when the basin was oxic. Results of a recently published coupled ocean-atmosphere model indicate that during the Cretaceous, thermohaline and surface circulation in the oceans was similar to or more intense than modern conditions, despite the overall equable climate. Such conditions confound the idea that circulation in the Cretaceous Atlantic, for example, was punctuated by oceanic anoxic events brought about by more sluggish circulation. Sporadic temporal and spatial increases in primary production, reflecting changes in the behavior and/or state of the ocean-atmosphere system, constitute a more tenable explanation for the occurrence of modern and Quaternary carbon-rich sediments and Cretaceous black shales. Consequently, the fundamental control on the accumulation of carbon-rich facies in the oceans and marginal seas is not the presence or absence of anoxia.

@article{doi1013060c9b232b171011d78645000102c1865d,
    author = "Pedersen, T. F. and Calvert, S. E.",
    title = "Anoxia vs. Productivity: What Controls the Formation of Organic-Carbon-Rich Sediments and Sedimentary Rocks?",
    year = "1990",
    journal = "AAPG Bulletin",
    abstract = "ABSTRACT The prevailing explanation for the origin of organic-rich sediments and rocks invokes deposition under conditions of anoxia. However, recent research suggests that high primary production and not water-column anoxia provides the first-order control on the accumulation of organic-rich facies in the modern oceans. Oxygen minima do not appear to have any direct effect on carbon accumulation in continental margin or marginal sea environments. Sediments accumulating in the modern Black Sea, the type euxinic basin, are not particularly enriched in organic matter despite the presence of an anoxic water column, although a sapropel containing extremely high carbon concentrations was deposited during the Holocene at a time when the basin was oxic. Results of a recently published coupled ocean-atmosphere model indicate that during the Cretaceous, thermohaline and surface circulation in the oceans was similar to or more intense than modern conditions, despite the overall equable climate. Such conditions confound the idea that circulation in the Cretaceous Atlantic, for example, was punctuated by oceanic anoxic events brought about by more sluggish circulation. Sporadic temporal and spatial increases in primary production, reflecting changes in the behavior and/or state of the ocean-atmosphere system, constitute a more tenable explanation for the occurrence of modern and Quaternary carbon-rich sediments and Cretaceous black shales. Consequently, the fundamental control on the accumulation of carbon-rich facies in the oceans and marginal seas is not the presence or absence of anoxia.",
    url = "https://doi.org/10.1306/0c9b232b-1710-11d7-8645000102c1865d",
    doi = "10.1306/0c9b232b-1710-11d7-8645000102c1865d",
    openalex = "W2124452658",
    references = "doi1010160012825283900016, doi1010160146638080900170, doi101144gsjgs13720171, doi101146annurevea05050177001535, doi1015159780691209401, doi102110pec77250019, doi102475ajs2837641, openalexw2106559152"
}

@article{landais1996organic,
    author = "Landais, P.",
    title = "Organic geochemistry of sedimentary uranium ore deposits",
    year = "1996",
    journal = "Ore Geology Reviews",
    url = "https://doi.org/10.1016/0169-1368(95)00014-3",
    doi = "10.1016/0169-1368(95)00014-3",
    number = "1-3",
    openalex = "W1966177718",
    pages = "33-51",
    volume = "11",
    references = "doi101007978364285806213, doi1010079783642964466, doi101007bf01988374, doi1010160009254183900827, doi1010160016703764900092, doi101016001670378690205x, doi1010160016703788903705, doi101029eo066i037p00643, doi10106311674108, doi102113gsecongeo7381450, doi102516ogst1986003, meyer1989thermal, openalexw2727055235"
}

@article{doi101016s0146638097000569,
    author = "Hedges, John I. and Oades, JM",
    title = "Comparative organic geochemistries of soils and marine sediments",
    year = "1997",
    journal = "Organic Geochemistry",
    url = "https://doi.org/10.1016/s0146-6380(97)00056-9",
    doi = "10.1016/s0146-6380(97)00056-9",
    openalex = "W2042895971",
    references = "doi10100797814615289062, doi1010160009254194900620, doi1010160016703789901919, doi1010160016703795000739, doi1010160146638086900896, doi105860choice314371"
}

@article{li1997organic,
    author = "Li, Zhaolin and Guo, Hongzhong and Lie, Lihong",
    title = "Organic geochemistry of lead-zinc polymetallic deposits, northern Guangdong",
    year = "1997",
    journal = "Chinese Journal of Geochemistry",
    url = "https://doi.org/10.1007/bf02870917",
    doi = "10.1007/bf02870917",
    number = "4",
    openalex = "W2042354793",
    pages = "330-335",
    volume = "16",
    references = "doi1010079781349170395, doi1010079783642878138, doi1010079783642964466, doi10130683d91f0616c711d78645000102c1865d, doi102113gsecongeo7811"
}

@article{doi101007bf03052904,
    author = "Hu, Kai and Xiao, Zhenyu and Zhai, Jianping and Yu, Chensheng and Huang, Zhen and Liu, Qing",
    title = "Minerogenetic mechanism of the Songxi silver-antimony deposit of northeastern Guangdong—Ore-controlling role of organic matter",
    year = "1999",
    journal = "Geochemistry",
    url = "https://doi.org/10.1007/bf03052904",
    doi = "10.1007/bf03052904",
    openalex = "W2030551699",
    references = "li1997organic"
}

@article{doi101016s0375674299000850,
    author = "Min, M.-Z. and Meng, Zhanpeng and Sheng, Guoying and Min, Yi-Seo and Liu, X.",
    title = "Organic geochemistry of paleokarst-hosted uranium deposits, South China",
    year = "2000",
    journal = "Journal of Geochemical Exploration",
    url = "https://doi.org/10.1016/s0375-6742(99)00085-0",
    doi = "10.1016/s0375-6742(99)00085-0",
    openalex = "W1964957410",
    references = "crossref1979geochemistry"
}

Abstract We conducted organic geochemical analyses on the largest suite of oils and source-rock extracts from the Tarim basin, northwest China, currently available. Statistical cluster analysis of the entire suite of Tarim oils distinguishes at least seven genetic groups of oils. The largest group of oils was collected from the Tazhong and Tabei uplifts and originated from marine Middle-Upper Ordovician anoxic marls that mark slope facies at the margins of structural uplifts. Two other genetic groups most likely originated from marine Middle-Upper Ordovician source rocks, but of distinct facies, with one an oxic shale-rich source west of the Bachu uplift and the other an anoxic shale source at Tazhong. Other genetic oil groups originated from various nonmarine source rocks. The largest of these groups consists of oils from the Luntai uplift, which best correlate with Jurassic lacustrine mudstones in the Kuqa depression, although Triassic lacustrine mudstones cannot be eliminated as a source for these oils. Two oils from southwest Tarim are highly mature. Despite uncertainty due to low biomarker concentrations, these oils probably originated from nonmarine shaly source rocks. The two remaining genetic groups consist of single oil samples: Yi603 (an oil likely derived from coal in the Kuqa depression) and Qu1 (derived from Carboniferous or Jurassic shaly source rock from the west flank of the Bachu uplift). Sample 63KLT (a seep sample from west of Kashi) has attributes of a lacustrine source rock and clusters with oils from Luntai. These results suggest that numerous source rocks occur in the basin, but they likely are areally restricted. Our results do not support previous published work that suggests that hypothesized euxinic source rocks might account for reserves of up to 350 billion bbl of oil.

@article{doi101306a9673c52173811d78645000102c1865d,
    author = "Hanson, Andrew D. and Zhang, S. C. and Moldowan, J. Michael and Liang, D. G. and Zhang, B. M.",
    title = "Molecular Organic Geochemistry of the Tarim Basin, Northwest China",
    year = "2000",
    journal = "AAPG Bulletin",
    abstract = "Abstract We conducted organic geochemical analyses on the largest suite of oils and source-rock extracts from the Tarim basin, northwest China, currently available. Statistical cluster analysis of the entire suite of Tarim oils distinguishes at least seven genetic groups of oils. The largest group of oils was collected from the Tazhong and Tabei uplifts and originated from marine Middle-Upper Ordovician anoxic marls that mark slope facies at the margins of structural uplifts. Two other genetic groups most likely originated from marine Middle-Upper Ordovician source rocks, but of distinct facies, with one an oxic shale-rich source west of the Bachu uplift and the other an anoxic shale source at Tazhong. Other genetic oil groups originated from various nonmarine source rocks. The largest of these groups consists of oils from the Luntai uplift, which best correlate with Jurassic lacustrine mudstones in the Kuqa depression, although Triassic lacustrine mudstones cannot be eliminated as a source for these oils. Two oils from southwest Tarim are highly mature. Despite uncertainty due to low biomarker concentrations, these oils probably originated from nonmarine shaly source rocks. The two remaining genetic groups consist of single oil samples: Yi603 (an oil likely derived from coal in the Kuqa depression) and Qu1 (derived from Carboniferous or Jurassic shaly source rock from the west flank of the Bachu uplift). Sample 63KLT (a seep sample from west of Kashi) has attributes of a lacustrine source rock and clusters with oils from Luntai. These results suggest that numerous source rocks occur in the basin, but they likely are areally restricted. Our results do not support previous published work that suggests that hypothesized euxinic source rocks might account for reserves of up to 350 billion bbl of oil.",
    url = "https://doi.org/10.1306/a9673c52-1738-11d7-8645000102c1865d",
    doi = "10.1306/a9673c52-1738-11d7-8645000102c1865d",
    openalex = "W2144998196",
    references = "doi101306ad462bc816f711d78645000102c1865d, doi101306bdff8b0a171811d78645000102c1865d"
}

@article{doi101016s0146638002001687,
    author = "Meyers, Philip A.",
    title = "Applications of organic geochemistry to paleolimnological reconstructions: a summary of examples from the Laurentian Great Lakes",
    year = "2003",
    journal = "Organic Geochemistry",
    url = "https://doi.org/10.1016/s0146-6380(02)00168-7",
    doi = "10.1016/s0146-6380(02)00168-7",
    openalex = "W2100866593",
    references = "doi1010160009254185900117, doi1010160016703779902576, doi1010160146638086900896, doi1010160146638096000411, doi101016s0146638097000491, doi101130dnaggnak3, doi10130694885688170411d78645000102c1865d, doi105860choice314371"
}

Abstract Detailed biomarker and light hydrocarbon geochemistry confirm that the marine Mississippian Barnett Shale is the primary source rock for petroleum in the Fort Worth Basin, north-central Texas, although contributions from other sources are possible. Biomarker data indicate that the main oil-generating Barnett Shale facies is marine and was deposited under dysoxic, strong upwelling, normal salinity conditions. The analysis of two outcrop samples and cuttings from seven wells indicates variability in the Barnett Shale organic facies and a possibility of other oil subfamilies being present. Light hydrocarbon analyses reveal significant terrigenous-sourced condensate input to some reservoirs, resulting in terrigenous and mixed marine-terrigenous light hydrocarbon signatures for many oils. The light hydrocarbon data suggest a secondary, condensate-generating source facies containing terrigenous or mixed terrigenous-marine organic matter. This indication of a secondary source rock that is not revealed by biomarker analysis emphasizes the importance of integrating biomarker and light hydrocarbon data to define petroleum source rocks. Gases in the Fort Worth Basin are thermogenic in origin and appear to be cogenerated with oil from the Barnett Shale, although some gas may also originate by oil cracking. Isotope data indicate minor contribution of biogenic gas. Except for reservoirs in the Pennsylvanian Bend Group, which contain gases spanning the complete range of observed maturities, the gases appear to be stratigraphically segregated, younger reservoirs contain less mature gas, and older reservoirs contain more mature gas. We cannot rule out the possibility that other source units within the Fort Worth Basin, such as the Smithwick Shale, are locally important petroleum sources.

@article{doi10130611030606014,
    author = "Hill, Ronald J. and Jarvie, Daniel M. and Zumberge, John E. and Henry, Mitchell E. and Pollastro, Richard M.",
    title = "Oil and gas geochemistry and petroleum systems of the Fort Worth Basin",
    year = "2007",
    journal = "AAPG Bulletin",
    abstract = "Abstract Detailed biomarker and light hydrocarbon geochemistry confirm that the marine Mississippian Barnett Shale is the primary source rock for petroleum in the Fort Worth Basin, north-central Texas, although contributions from other sources are possible. Biomarker data indicate that the main oil-generating Barnett Shale facies is marine and was deposited under dysoxic, strong upwelling, normal salinity conditions. The analysis of two outcrop samples and cuttings from seven wells indicates variability in the Barnett Shale organic facies and a possibility of other oil subfamilies being present. Light hydrocarbon analyses reveal significant terrigenous-sourced condensate input to some reservoirs, resulting in terrigenous and mixed marine-terrigenous light hydrocarbon signatures for many oils. The light hydrocarbon data suggest a secondary, condensate-generating source facies containing terrigenous or mixed terrigenous-marine organic matter. This indication of a secondary source rock that is not revealed by biomarker analysis emphasizes the importance of integrating biomarker and light hydrocarbon data to define petroleum source rocks. Gases in the Fort Worth Basin are thermogenic in origin and appear to be cogenerated with oil from the Barnett Shale, although some gas may also originate by oil cracking. Isotope data indicate minor contribution of biogenic gas. Except for reservoirs in the Pennsylvanian Bend Group, which contain gases spanning the complete range of observed maturities, the gases appear to be stratigraphically segregated, younger reservoirs contain less mature gas, and older reservoirs contain more mature gas. We cannot rule out the possibility that other source units within the Fort Worth Basin, such as the Smithwick Shale, are locally important petroleum sources.",
    url = "https://doi.org/10.1306/11030606014",
    doi = "10.1306/11030606014",
    openalex = "W2156007437",
    references = "doi101016014663809190039m"
}

@article{doi101016jorggeochem200809011,
    author = "Grosjean, Emmanuelle and Love, Gordon D. and Stalvies, Charlotte and Fike, David A. and Summons, Roger E.",
    title = "Origin of petroleum in the Neoproterozoic–Cambrian South Oman Salt Basin",
    year = "2008",
    journal = "Organic Geochemistry",
    url = "https://doi.org/10.1016/j.orggeochem.2008.09.011",
    doi = "10.1016/j.orggeochem.2008.09.011",
    openalex = "W1989860834",
    references = "doi1010160146638088901155, doi101016014663809190039m, doi101016b0080437516081275"
}

@article{doi101016joregeorev201210004,
    author = "Greenwood, Paul F. and Brocks, Jochen J. and Grice, Kliti and Schwark, Lorenz and Jaraula, Caroline Marie B. and Dick, Jeffrey M. and Evans, Katy",
    title = "Organic geochemistry and mineralogy. I. Characterisation of organic matter associated with metal deposits",
    year = "2012",
    journal = "Ore Geology Reviews",
    url = "https://doi.org/10.1016/j.oregeorev.2012.10.004",
    doi = "10.1016/j.oregeorev.2012.10.004",
    openalex = "W2035877353",
    references = "doi101007978364285806213, doi101016001670379500005k, landais1996organic"
}

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100-200 m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time-equivalent shallow-water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent-extractable bitumen, and measured whole-rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient-rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment-starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans.

@article{doi101111gbi12236,
    author = "Stolper, Daniel A. and Love, Gordon D. and Bates, Steven M and Lyons, Timothy W. and Young, Edward and Sessions, Alex L. and Grotzinger, J. P.",
    title = "Paleoecology and paleoceanography of the Athel silicilyte, Ediacaran–Cambrian boundary, Sultanate of Oman",
    year = "2017",
    journal = "Geobiology",
    abstract = "The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>\textasciitilde 100-200 m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time-equivalent shallow-water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent-extractable bitumen, and measured whole-rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient-rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment-starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans.",
    url = "https://doi.org/10.1111/gbi.12236",
    doi = "10.1111/gbi.12236",
    openalex = "W2604641676",
    references = "doi1010160016703778902193, doi1010160016703794903816, doi101016030442039500008f, doi101016jchemgeo200409003, doi101126science28153811342, doi101126science28554301033, doi10130694885688170411d78645000102c1865d, doi101306ad462bc816f711d78645000102c1865d, doi102113gselements72107, doi102516ogst1998036"
}

The Xiamaling Formation in the North China Block contains a well-preserved 1400 Ma sedimentary sequence with a low degree of thermal maturity. Previous studies have confirmed the dynamic and complex nature of this evolving marine setting, including the existence of an oxygen-minimum zone, using multi-proxy approaches, including iron speciation, trace metal dynamics, and organic geochemistry. Here, we investigate the prevailing redox conditions during diagenesis via the biomarkers of rearranged hopanes from the finely laminated sediments of the organic-rich black shales in Units 2 and 3 of the Xiamaling Formation. We find that rearranged hopanes are prominent in the biomarker composition of the oxygen-minimum zone sediment, which is completely different from that of the sediment in the overlying anoxic strata. Since the transition process from hopanes to rearranged hopanes requires oxygen via oxidation at the C-l6 alkyl position of 17α(H)-hopanes, we infer that dissolved oxygen led to the transformation of hopane precursors into rearranged hopanes during the early stages of diagenesis. The use of hopanoid hydrocarbons as biomarkers of marine redox conditions has rarely been previously reported, and the hydrocarbon signatures point towards oxic bottom waters during the deposition of Unit 3 of the Xiamaling Formation, which is consistent with the earlier oxygen-minimum zone environmental interpretation of this Unit.

@article{doi101038s41598018313786,
    author = "Wang, Xiaomei and Zhao, Wenzhi and Zhang, Shuichang and Wang, Huajian and Su, Jin and Canfield, Donald E. and Hammarlund, Emma U.",
    title = "The aerobic diagenesis of Mesoproterozoic organic matter",
    year = "2018",
    journal = "Scientific Reports",
    abstract = "The Xiamaling Formation in the North China Block contains a well-preserved 1400 Ma sedimentary sequence with a low degree of thermal maturity. Previous studies have confirmed the dynamic and complex nature of this evolving marine setting, including the existence of an oxygen-minimum zone, using multi-proxy approaches, including iron speciation, trace metal dynamics, and organic geochemistry. Here, we investigate the prevailing redox conditions during diagenesis via the biomarkers of rearranged hopanes from the finely laminated sediments of the organic-rich black shales in Units 2 and 3 of the Xiamaling Formation. We find that rearranged hopanes are prominent in the biomarker composition of the oxygen-minimum zone sediment, which is completely different from that of the sediment in the overlying anoxic strata. Since the transition process from hopanes to rearranged hopanes requires oxygen via oxidation at the C-l6 alkyl position of 17α(H)-hopanes, we infer that dissolved oxygen led to the transformation of hopane precursors into rearranged hopanes during the early stages of diagenesis. The use of hopanoid hydrocarbons as biomarkers of marine redox conditions has rarely been previously reported, and the hydrocarbon signatures point towards oxic bottom waters during the deposition of Unit 3 of the Xiamaling Formation, which is consistent with the earlier oxygen-minimum zone environmental interpretation of this Unit.",
    url = "https://doi.org/10.1038/s41598-018-31378-6",
    doi = "10.1038/s41598-018-31378-6",
    openalex = "W2888926155",
    references = "doi1010160146638086900100, doi101016014663809190039m, doi101017cbo9780511524868, doi101126science1258410, doi107185geochempersp11"
}

The South Oman Salt Basin (SOSB) has been studied extensively for knowledge concerning the habitat of the enigmatic Ediacaran-Cambrian oils that are produced from that region. Geological, geochemical, geophysical, and geochronological investigations have all contributed to improved understanding of the range of late Neoproterozoic depositional environments recorded there. Of particular interest has been the deep Athel depocenter within the SOSB that features a silica-rich interval known as the Al Shomou Member or Athel Silicilyte and the co-eval A4 carbonate-evaporite sequence that straddles the Ediacaran-Cambrian boundary. The deep basin has been suggested to be anoxic and euxinic based on studies of sulfur isotopes, trace metal distributions and other proxies. Organic geochemistry has provided some clues concerning aspects of the depositional environments and microbial communities prevailing during this interval. However, ambiguities remain including a paucity of convincing molecular evidence for euxinia in the photic zone of the basin. Here, we present a comprehensive study of biomarker hydrocarbons, including steroids, triterpenoids, and carotenoids. Among the compounds detected is a distinctive array of aromatic carotenoids. Relatively low abundances of monoaromatic carotenoids, such as chlorobactane, okenane, and β-isorenieratane, suggest the possibility of transient photic zone euxinia with a shallow chemocline or, perhaps, exogenous inputs from microbial mats. However, it is the dominance of renieratane and renierapurpurane over isorenieratane in diaromatic carotenoids and their association with abundant C38 and C39 carotenoids that identifies cyanobacteria as major contributors to the inventory of carotenoids. Our results, based on multiple lines of molecular evidence and statistical analysis, also suggest that the Athel Silicilyte was biogeochemically distinct from the other units of the Ara Group. Overall, our study has important implications for understanding other late Neoproterozoic depositional environments.

@article{doi101111gbi12407,
    author = "Roussel, Anaïs and Cui, Xingqian and Summons, Roger E",
    title = "Biomarker stratigraphy in the Athel Trough of the South Oman Salt Basin at the Ediacaran-Cambrian Boundary.",
    year = "2020",
    journal = "Geobiology",
    abstract = "The South Oman Salt Basin (SOSB) has been studied extensively for knowledge concerning the habitat of the enigmatic Ediacaran-Cambrian oils that are produced from that region. Geological, geochemical, geophysical, and geochronological investigations have all contributed to improved understanding of the range of late Neoproterozoic depositional environments recorded there. Of particular interest has been the deep Athel depocenter within the SOSB that features a silica-rich interval known as the Al Shomou Member or Athel Silicilyte and the co-eval A4 carbonate-evaporite sequence that straddles the Ediacaran-Cambrian boundary. The deep basin has been suggested to be anoxic and euxinic based on studies of sulfur isotopes, trace metal distributions and other proxies. Organic geochemistry has provided some clues concerning aspects of the depositional environments and microbial communities prevailing during this interval. However, ambiguities remain including a paucity of convincing molecular evidence for euxinia in the photic zone of the basin. Here, we present a comprehensive study of biomarker hydrocarbons, including steroids, triterpenoids, and carotenoids. Among the compounds detected is a distinctive array of aromatic carotenoids. Relatively low abundances of monoaromatic carotenoids, such as chlorobactane, okenane, and β-isorenieratane, suggest the possibility of transient photic zone euxinia with a shallow chemocline or, perhaps, exogenous inputs from microbial mats. However, it is the dominance of renieratane and renierapurpurane over isorenieratane in diaromatic carotenoids and their association with abundant C38 and C39 carotenoids that identifies cyanobacteria as major contributors to the inventory of carotenoids. Our results, based on multiple lines of molecular evidence and statistical analysis, also suggest that the Athel Silicilyte was biogeochemically distinct from the other units of the Ara Group. Overall, our study has important implications for understanding other late Neoproterozoic depositional environments.",
    url = "https://pubmed.ncbi.nlm.nih.gov/32643313/",
    doi = "10.1111/gbi.12407",
    openalex = "W3041216472",
    pmid = "32643313",
    references = "doi1010070306479540, doi1010160016703795000739, doi101016014663809190039m, doi101017cbo9780511524868, doi10103823005, doi101038272216a0, doi101038nature05345, doi101111j157469762001tb00576x, doi101306ad462bc816f711d78645000102c1865d"
}

@article{vtorushina2020geochemistry,
    author = "Vtorushina, Ella and Bulatov, Timur and Kul’kov, Mikhail and Povzhik, Petr and Eroshenko, Anna and Tsigankov, Andrey",
    title = "Geochemistry of organic matter in between-the-salt deposits: northern block of Pripyatsky Petroleum Basin",
    year = "2020",
    journal = "Oil and gas geology = Geologiya nefti i gaza",
    url = "https://doi.org/10.31087/0016-7894-2020-5-83-94",
    doi = "10.31087/0016-7894-2020-5-83-94",
    number = "5",
    openalex = "W3100258524",
    pages = "83-94"
}

@article{doi101016jmarpetgeo2021105098,
    author = "Xie, Xiaomin and Zhu, Guangyou and Wang, Ye",
    title = "The influence of syngenetic hydrothermal silica fluid on organic matter preservation in lower Cambrian Niutitang Formation, South China",
    year = "2021",
    journal = "Marine and Petroleum Geology",
    url = "https://doi.org/10.1016/j.marpetgeo.2021.105098",
    doi = "10.1016/j.marpetgeo.2021.105098",
    openalex = "W3158352038",
    references = "doi101016jprecamres2019105438"
}

@article{doi101016jmarpetgeo2021105126,
    author = "Gao, Ping and He, Zhiliang and Lash, Gary G. and Zhou, Qin and Xiao, Xianming",
    title = "Controls on silica enrichment of lower cambrian organic-rich shale deposits",
    year = "2021",
    journal = "Marine and Petroleum Geology",
    url = "https://doi.org/10.1016/j.marpetgeo.2021.105126",
    doi = "10.1016/j.marpetgeo.2021.105126",
    openalex = "W3163293157",
    references = "doi101016jprecamres2019105438"
}

Abstract The effects and timing of the evolution of siliceous sponge and radiolarians on the mode of silica burial and oceanic silica cycling in the early Cambrian are still controversial. Bedded cherts of the lower Cambrian Yurtus Formation deposited in a subtidal shelf environment. They display diagnostic sedimentary features, including intraclastic chert grains, edgewise chert breccias, weakly compacted grains and rip‐up clasts, and rapid silica cementation, collectively indicating primary and very early silicification at and near the sediment–water interface. This depositional mode contrasts with Phanerozoic biogenic cherts but is comparable with that of Precambrian cherts precipitated from silica‐rich seawater. The Yurtus cherts therefore provide direct and compelling sedimentological evidence of the continuation of silica‐rich seawater into the early Cambrian, consistent with the extensive coeval chert depositions elsewhere. These results contrast with the long‐held view of rapid decline in seawater silica concentrations in the earliest Phanerozoic, and elucidate coeval Si‐coupled geochemical cycling, silica‐biomineralization and fossil preservation.

@article{doi101111ter12541,
    author = "Zhou, Xiqiang and Chen, Daizhao and Zhang, Liyu and Tang, Dongjie and Guo, Chuan",
    title = "Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts",
    year = "2021",
    journal = "Terra Nova",
    abstract = "Abstract The effects and timing of the evolution of siliceous sponge and radiolarians on the mode of silica burial and oceanic silica cycling in the early Cambrian are still controversial. Bedded cherts of the lower Cambrian Yurtus Formation deposited in a subtidal shelf environment. They display diagnostic sedimentary features, including intraclastic chert grains, edgewise chert breccias, weakly compacted grains and rip‐up clasts, and rapid silica cementation, collectively indicating primary and very early silicification at and near the sediment–water interface. This depositional mode contrasts with Phanerozoic biogenic cherts but is comparable with that of Precambrian cherts precipitated from silica‐rich seawater. The Yurtus cherts therefore provide direct and compelling sedimentological evidence of the continuation of silica‐rich seawater into the early Cambrian, consistent with the extensive coeval chert depositions elsewhere. These results contrast with the long‐held view of rapid decline in seawater silica concentrations in the earliest Phanerozoic, and elucidate coeval Si‐coupled geochemical cycling, silica‐biomineralization and fossil preservation.",
    url = "https://doi.org/10.1111/ter.12541",
    doi = "10.1111/ter.12541",
    openalex = "W3160008276",
    references = "doi101016001670379290303z, doi101016jchemgeo200810016, doi101016jpalaeo200703016, doi101038nature10969, doi101111gbi12236, doi101126scienceaad5787, doi101130b255551, doi101130b263281, doi101130b303461, doi101146annurevmarine121211172346, doi1023073514743"
}

@article{doi101016jcoal2022103972,
    author = "Zhang, Kun and Liu, Rong and Ding, Wenjing and Li, Li and Liu, Zhaojun",
    title = "The influence of Early Cretaceous paleoclimate warming event on sedimentary environment evolution and organic matter sources in Yin'e Basin: Evidence from petrology and molecular geochemistry",
    year = "2022",
    journal = "International Journal of Coal Geology",
    url = "https://doi.org/10.1016/j.coal.2022.103972",
    doi = "10.1016/j.coal.2022.103972",
    openalex = "W4220711258",
    references = "doi101016jearscirev2020103499"
}

Accumulated records of organic microfossils span billions of years of Earth history. The majority of this record consists of prokaryotes plus eukaryotes of a protistan grade, yet this type of fossilisation is also capable of capturing the organically preserved remains of animals. Recently, it has become apparent that non-biomineralizing animal groups, otherwise known only from rare instances of exceptional fossilisation, can preserve in this fashion. Given this high taphonomic fidelity combined with the temporal continuity of organic microfossil preservation, it is clear this style of fossilisation has the potential to circumvent some of the major biases that afflict the current early animal fossil record. Despite this, there have been no attempts to survey recorded instances of animal-derived organic microfossils. We constructed a global database comprising 394 studies of organic microfossils covering 399 sedimentary rock formations spanning the Tonian–Cambrian Stage 5/Wuliuan Stage (1 Ga to 505 Ma). The database consolidates scattered reports and provides a first appraisal for how a record of metazoans emerges within the broader archives of organic microfossils. Scrutiny of the current record reveals that organic microfossils contain the oldest body fossil evidence for a number of key metazoan clades, including the Chaetognatha, Annelida, Priapulida, ‘lobopods’ and Panarthropoda, Crustacea, Pterobranchia, and potentially even the Bilateria. Also detected among this record are the fossilised remains of poriferans, chancelloriids, palaeoscolecids, loriciferans, bradoriids, trilobites, wiwaxiids, molluscs, hyoliths, brachiopods and chordates. Our data shows that metazoan-derived remains are relatively common constituents of palynological preparations from sediments of a Cambrian age or younger. Such metazoan remains are also detected in organic microfossil assemblages from several formations of late Ediacaran age, but are entirely absent from the large number of equivalent preparations from older sediments, throughout the Proterozoic. In this view, signs of animal diversification emerge as a unidirectional signal embedded within a deeper record of organic microfossils. We argue here that the absence of animal remains among the large number of equivalent studies from Tonian, Cryogenian and early Ediacaran strata weakens the case for the existence of a cryptic animal biosphere during the Tonian and Cryogenian.

@article{doi101016jearscirev2022104107,
    author = "Slater, Ben J. and Bohlin, Madeleine S.",
    title = "Animal origins: The record from organic microfossils",
    year = "2022",
    journal = "Earth-Science Reviews",
    abstract = "Accumulated records of organic microfossils span billions of years of Earth history. The majority of this record consists of prokaryotes plus eukaryotes of a protistan grade, yet this type of fossilisation is also capable of capturing the organically preserved remains of animals. Recently, it has become apparent that non-biomineralizing animal groups, otherwise known only from rare instances of exceptional fossilisation, can preserve in this fashion. Given this high taphonomic fidelity combined with the temporal continuity of organic microfossil preservation, it is clear this style of fossilisation has the potential to circumvent some of the major biases that afflict the current early animal fossil record. Despite this, there have been no attempts to survey recorded instances of animal-derived organic microfossils. We constructed a global database comprising 394 studies of organic microfossils covering 399 sedimentary rock formations spanning the Tonian–Cambrian Stage 5/Wuliuan Stage (1 Ga to 505 Ma). The database consolidates scattered reports and provides a first appraisal for how a record of metazoans emerges within the broader archives of organic microfossils. Scrutiny of the current record reveals that organic microfossils contain the oldest body fossil evidence for a number of key metazoan clades, including the Chaetognatha, Annelida, Priapulida, ‘lobopods’ and Panarthropoda, Crustacea, Pterobranchia, and potentially even the Bilateria. Also detected among this record are the fossilised remains of poriferans, chancelloriids, palaeoscolecids, loriciferans, bradoriids, trilobites, wiwaxiids, molluscs, hyoliths, brachiopods and chordates. Our data shows that metazoan-derived remains are relatively common constituents of palynological preparations from sediments of a Cambrian age or younger. Such metazoan remains are also detected in organic microfossil assemblages from several formations of late Ediacaran age, but are entirely absent from the large number of equivalent preparations from older sediments, throughout the Proterozoic. In this view, signs of animal diversification emerge as a unidirectional signal embedded within a deeper record of organic microfossils. We argue here that the absence of animal remains among the large number of equivalent studies from Tonian, Cryogenian and early Ediacaran strata weakens the case for the existence of a cryptic animal biosphere during the Tonian and Cryogenian.",
    url = "https://doi.org/10.1016/j.earscirev.2022.104107",
    doi = "10.1016/j.earscirev.2022.104107",
    openalex = "W4284883919",
    references = "doi101002spp21347, doi101016jcub201509066, doi101016jgr200706007, doi101016jpalaeo200703046, doi101016jpalwor201707001, doi101017s0094837300003778, doi101038s415590160022, doi101038s41559020013347, doi101038s4158602103773z, doi101038srep04682, doi101098rspb20182505, doi101098rstb20061843, doi101111brv12614, doi101111brv12864, doi101111j150239311971tb01864x, doi101111j1525142x201200562x, doi101111pala12168, doi101111pala12200, doi101111pala12273, doi101111pala12307, doi101111pala12325, doi101111pala12350, doi101126science1189910, doi101126science1206375, doi101126scienceaau8800, doi101130g397881, doi101130g479071, doi10166609102r1, doi105860choice304422, doi105962bhltitle68064"
}

@article{doi101016jmarpetgeo2022105991,
    author = "Zhao, Guanyu and Deng, Qian and Zhang, Haizu and Wang, Haozhe and Cheng, Bin and Liao, Zewen",
    title = "Trace elements and stable isotopic geochemistry of two sedimentary sections in the lower Cambrian strata from the Tarim Basin, northwest China: Implications for silicification and biological evolution",
    year = "2022",
    journal = "Marine and Petroleum Geology",
    url = "https://doi.org/10.1016/j.marpetgeo.2022.105991",
    doi = "10.1016/j.marpetgeo.2022.105991",
    openalex = "W4307142284",
    references = "doi101111ter12541"
}

The fault-bounded, NS-oriented Wajid Graben is imaged by seismic profiles below the reflection from the lower Cambrian pre-Siq unconformity (Angudan unconformity, ca. 525 Ma) in southern Saudi Arabia. It is ca. 350 km long, 60–150 km wide, and the graben-infill rocks (3–5 km thick) are buried at a depth of 7–8 km below sea level, and have not been penetrated by a borehole. A clue to the graben’s origin consists of the outline of a seismically transparent, domal feature (ca. 20 km basal width, ca. 2 km crestal height) below the Angudan reflection. The feature is interpreted as a salt dome and assigned to the Ara Group in the South Oman salt basins (ca. 555–538 Ma). Based on the salt-dome interpretation and regional tectonics, the region spanning Oman and the Wajid Graben shared a common tectono-stratigraphy in the East Arabia Terrane from ca. 580 or before. The collision between West and East Gondwana along the Mozambique Ocean Suture occurred much earlier to the west of the Wajid Graben during the Amar Orogeny (ca. 640–600 Ma). The Mozambique Suture zone is either the Amar Suture if the Mozambique down-going slab was east-dipping below the island arc in the Ar Rayn Terrane; or (2) along the eastern flank of the Ar Rayn Terrane if the slab was west-dipping. In northern Saudi Arabia, where the Ar Rayn Terrane is covered by Phanerozoic sediments, its signature is expressed by the NS-oriented Central Arabia Magnetic Anomaly. In southern Saudi Arabia, the suture zone also passes beneath the Phanerozoic cover rocks to the east of the Arabian Shield, and probably emerges along one of flanks of the island arc in the Al Mukalla Terrane in Yemen.

@article{doi1010800020681420232177891,
    author = "Al-Husseini, Moujahed",
    title = "Infra-Cambrian Wajid Graben and the Mozambique Suture, Saudi Arabia",
    year = "2023",
    journal = "International Geology Review",
    abstract = "The fault-bounded, NS-oriented Wajid Graben is imaged by seismic profiles below the reflection from the lower Cambrian pre-Siq unconformity (Angudan unconformity, ca. 525 Ma) in southern Saudi Arabia. It is ca. 350 km long, 60–150 km wide, and the graben-infill rocks (3–5 km thick) are buried at a depth of 7–8 km below sea level, and have not been penetrated by a borehole. A clue to the graben’s origin consists of the outline of a seismically transparent, domal feature (ca. 20 km basal width, ca. 2 km crestal height) below the Angudan reflection. The feature is interpreted as a salt dome and assigned to the Ara Group in the South Oman salt basins (ca. 555–538 Ma). Based on the salt-dome interpretation and regional tectonics, the region spanning Oman and the Wajid Graben shared a common tectono-stratigraphy in the East Arabia Terrane from ca. 580 or before. The collision between West and East Gondwana along the Mozambique Ocean Suture occurred much earlier to the west of the Wajid Graben during the Amar Orogeny (ca. 640–600 Ma). The Mozambique Suture zone is either the Amar Suture if the Mozambique down-going slab was east-dipping below the island arc in the Ar Rayn Terrane; or (2) along the eastern flank of the Ar Rayn Terrane if the slab was west-dipping. In northern Saudi Arabia, where the Ar Rayn Terrane is covered by Phanerozoic sediments, its signature is expressed by the NS-oriented Central Arabia Magnetic Anomaly. In southern Saudi Arabia, the suture zone also passes beneath the Phanerozoic cover rocks to the east of the Arabian Shield, and probably emerges along one of flanks of the island arc in the Al Mukalla Terrane in Yemen.",
    url = "https://doi.org/10.1080/00206814.2023.2177891",
    doi = "10.1080/00206814.2023.2177891",
    openalex = "W4321791042",
    references = "doi101016jprecamres2020105954"
}

China is endowed with mineral resources due to its prolonged and dynamic geological evolutionary history. Marine carbonate-hosted Pb-Zn deposits are mostly concentrated in the southern part of China, represented by the world-class metallogenic belt in the Sichuan-Yunnan-Guizhou (“SYG”) triangle in the Yangtze Block, and those Pb-Zn deposits hosted in the Himalayan-Tibetan Orogenic Belt and in the Cathaysia Block. This paper presents a preliminary review of the geological characteristics of the major Pb-Zn mineral deposits in these regions, including the Huize, Maozu and Daliangzi deposits in the SYG triangle, the Jinding, Huoshaoyun and Chapupacha deposits in the Himalayan-Tibetan Orogenic Belt, and the Fankou and Panlong deposits in the Cathaysia Block. The aim is to gain an improved understanding of the geological controls on the carbonate-hosted Pb-Zn deposits in China. In general, the carbonate-hosted Zn-Pb deposits in the Yangtze and Cathaysia Blocks display many similarities, including the mineralization being mainly controlled by stratigraphy (i.e., coarse dolomite layers in certain stratigraphic units) and structure (i.e. well-developed fault systems). The deposits are distinctively high in Pb+Zn grades and enriched in dispersive elements including Ga, Ge, Ag, Cd, and Tl, and are spatially associated with the Permian Emeishan flood basalts. The most distinct geological features of the Zn-Pb deposits in the Himalayan-Tibetan Orogenic Belt is the occurrence of pervasive evaporites and the development of breccias and oxide ores. Overall, deep regional structures, including crustal faults and suture zones and the combined existence of organic matter and evaporites are among those crucial factors to form the large carbonate-hosted Pb-Zn deposits in China.

@misc{doi1061153eyly2924,
    author = "Zhou, Lingli and Zheng, Yi and Duan, Xlaoxia and Meng, Yumlao and Yu, Pengpeng and Li, Zhan-Ke and Xiong, Suo‐Fei and Xiao, Fan and Wang, Yongbin and Zhou, Jia‐Xi",
    title = "Carbonate-hosted Pb-Zn deposits in China: a review of the geological characteristics and genesis",
    year = "2023",
    abstract = "China is endowed with mineral resources due to its prolonged and dynamic geological evolutionary history. Marine carbonate-hosted Pb-Zn deposits are mostly concentrated in the southern part of China, represented by the world-class metallogenic belt in the Sichuan-Yunnan-Guizhou (“SYG”) triangle in the Yangtze Block, and those Pb-Zn deposits hosted in the Himalayan-Tibetan Orogenic Belt and in the Cathaysia Block. This paper presents a preliminary review of the geological characteristics of the major Pb-Zn mineral deposits in these regions, including the Huize, Maozu and Daliangzi deposits in the SYG triangle, the Jinding, Huoshaoyun and Chapupacha deposits in the Himalayan-Tibetan Orogenic Belt, and the Fankou and Panlong deposits in the Cathaysia Block. The aim is to gain an improved understanding of the geological controls on the carbonate-hosted Pb-Zn deposits in China. In general, the carbonate-hosted Zn-Pb deposits in the Yangtze and Cathaysia Blocks display many similarities, including the mineralization being mainly controlled by stratigraphy (i.e., coarse dolomite layers in certain stratigraphic units) and structure (i.e. well-developed fault systems). The deposits are distinctively high in Pb+Zn grades and enriched in dispersive elements including Ga, Ge, Ag, Cd, and Tl, and are spatially associated with the Permian Emeishan flood basalts. The most distinct geological features of the Zn-Pb deposits in the Himalayan-Tibetan Orogenic Belt is the occurrence of pervasive evaporites and the development of breccias and oxide ores. Overall, deep regional structures, including crustal faults and suture zones and the combined existence of organic matter and evaporites are among those crucial factors to form the large carbonate-hosted Pb-Zn deposits in China.",
    url = "https://doi.org/10.61153/eyly2924",
    doi = "10.61153/eyly2924",
    openalex = "W4386747591",
    references = "li1997organic"
}

The extensive bedded cherts deposited during the Ediacaran–Cambrian (E–C) transition period play a crucial role in understanding the geological evolution of this period, yet the origin of these cherts remains disputed. Here, we present new geochemical data for cherts of the Piyuancun (PYC) Formation deposited during the Late Ediacaran and the Hetang (HT) Formation deposited during the Early Cambrian in northern Jiangxi region, Lower Yangtze region, South China. The PYC cherts contain a small amount of monaxons sponge spicules and radiolarian fragments, while the HT cherts lack siliceous organism evidence. Major and trace element analysis, coupled with discriminant diagrams, indicate a possible shift in redox conditions of seawater during the E–C transition in the northern Jiangxi region. The shift suggests a change from weakly–moderately restricted euxinic conditions to strongly restricted euxinic conditions. Furthermore, the location of both cherts are distant from the source area of siliceous organisms. Fossil evidence, as well as the values of Fe/Ti and Fe/(Mn+Ti), Eu anomalies, Post-Archean Australian Shale (PAAS) normalized REE+Y patterns, and various discriminant diagrams, support the conclusion that the PYC and HT cherts originated primarily from direct seawater precipitation, with the PYC cherts exhibiting weak hydrothermal evidence. Upwelling contributes to the formation of HT cherts and organic matter (OM) accumulation. Ocean acidification, triggered by OM degradation and biodegradation processes during the E–C transition period, leads to the extensive silica precipitation and preservation. These results enhance our understanding of the geological processes during the E–C transition.

@article{doi101016jjop202407002,
    author = "Xie, Guoliang and Zhou, Gao-Jie and Sun, Yu-Yong and Hu, Yan-Ran and Hao, Weiduo",
    title = "Geochemistry of cherts from the northern Jiangxi region, South China: Implication for paleoenvironment",
    year = "2024",
    journal = "Journal of Palaeogeography",
    abstract = "The extensive bedded cherts deposited during the Ediacaran–Cambrian (E–C) transition period play a crucial role in understanding the geological evolution of this period, yet the origin of these cherts remains disputed. Here, we present new geochemical data for cherts of the Piyuancun (PYC) Formation deposited during the Late Ediacaran and the Hetang (HT) Formation deposited during the Early Cambrian in northern Jiangxi region, Lower Yangtze region, South China. The PYC cherts contain a small amount of monaxons sponge spicules and radiolarian fragments, while the HT cherts lack siliceous organism evidence. Major and trace element analysis, coupled with discriminant diagrams, indicate a possible shift in redox conditions of seawater during the E–C transition in the northern Jiangxi region. The shift suggests a change from weakly–moderately restricted euxinic conditions to strongly restricted euxinic conditions. Furthermore, the location of both cherts are distant from the source area of siliceous organisms. Fossil evidence, as well as the values of Fe/Ti and Fe/(Mn+Ti), Eu anomalies, Post-Archean Australian Shale (PAAS) normalized REE+Y patterns, and various discriminant diagrams, support the conclusion that the PYC and HT cherts originated primarily from direct seawater precipitation, with the PYC cherts exhibiting weak hydrothermal evidence. Upwelling contributes to the formation of HT cherts and organic matter (OM) accumulation. Ocean acidification, triggered by OM degradation and biodegradation processes during the E–C transition period, leads to the extensive silica precipitation and preservation. These results enhance our understanding of the geological processes during the E–C transition.",
    url = "https://doi.org/10.1016/j.jop.2024.07.002",
    doi = "10.1016/j.jop.2024.07.002",
    openalex = "W4400379335",
    references = "doi101111ter12541"
}

The Tano Basin in Ghana, situated within the South Atlantic margin, is a significant area for petroleum exploration. Previous studies have recognized the presence of source rocks rich in organic matter from the Cretaceous period in this basin. However, the specific origins of this organic matter, as well as the thermal maturity and depositional environment of the Cretaceous source strata, are not well characterized in existing literature. Here, geochemical data are reported on the bulk geochemical composition of 45 Maastrichtian to Albian-aged rock cuttings via pyrolysis and total organic carbon (TOC) analysis. Out of these samples, 29 were selected for further biomarker and stable carbon isotope (δ13C) analysis. The biomarker and isotopic signatures of the 29 rock extracts and 6 crude oils from the basin's productive Jubilee and TEN oil fields were compared to establish oil-oil and oil-source correlations. The Cenomanian and Turonian source rocks showed the greatest oil generation potential based on current bulk geochemical analysis. These rocks are dominated by oil-prone organic matter and are at a more favorable maturity stage compared to the Maastrichtian, Santonian, and Coniacian (M-S-C) rock suites. In contrast, the Albian rock samples, characterized by mixed Type II/III and Type III kerogen, and their high thermal maturity, indicate a high potential for the generation of gaseous hydrocarbons. The biomarker and isotope data from the Cenomanian, Turonian, and Albian (T-C-A) source rocks suggest that they were deposited in a Transitional Marine-Lacustrine environment characterized by reducing redox conditions. This environment effectively preserved organic matter from diverse sources such as bacteria, algae, and higher plants. Furthermore, biomarker ratios indicated that the T-C-A source rocks are in the early-peak mature window. On the other hand, the M-S-C source rocks appear to have been deposited under suboxic conditions in a Coastal Marine environment. Lower aquatic organisms dominate these rocks, which have an immature to marginally mature level. The analysis of lower molecular weight hydrocarbons (≤C20), characterized by an unresolved complex mixture, did not reveal any obvious correlation between the oils and the Cretaceous source rocks. However, the analysis of higher molecular weight hydrocarbons (≥C20) and isotopic ratios indicated that the commercial discoveries in the Jubilee and TEN fields share a genetic similarity and are primarily sourced from the T-C-A source rocks. Furthermore, the molecular and isotopic characteristics suggest that the M-S-C source rocks do not appear to have contributed to the oils found in the Jubilee and TEN fields. These new geochemical findings shed light on the paleoenvironmental conditions and source rock characteristics of the region, significantly contributing to our understanding of the petroleum evolution and potential of the Tano Basin.

@article{doi101016jmarpetgeo2024106697,
    author = "Amoako, Kojo and Zhong, Ningning and Shi, Shengbao and Konan, N’Guessan Francois De Sales and Osei-Boakye, Nancy Pearl and Foli, Gordon and Appau, Prince Opoku and Fenyi, Clifford and Apesegah, Ebenezer",
    title = "Organic geochemical heterogeneity of cretaceous mudrocks and reassessment of oil sources in the Tano Basin, Ghana",
    year = "2024",
    journal = "Marine and Petroleum Geology",
    abstract = "The Tano Basin in Ghana, situated within the South Atlantic margin, is a significant area for petroleum exploration. Previous studies have recognized the presence of source rocks rich in organic matter from the Cretaceous period in this basin. However, the specific origins of this organic matter, as well as the thermal maturity and depositional environment of the Cretaceous source strata, are not well characterized in existing literature. Here, geochemical data are reported on the bulk geochemical composition of 45 Maastrichtian to Albian-aged rock cuttings via pyrolysis and total organic carbon (TOC) analysis. Out of these samples, 29 were selected for further biomarker and stable carbon isotope (δ13C) analysis. The biomarker and isotopic signatures of the 29 rock extracts and 6 crude oils from the basin's productive Jubilee and TEN oil fields were compared to establish oil-oil and oil-source correlations. The Cenomanian and Turonian source rocks showed the greatest oil generation potential based on current bulk geochemical analysis. These rocks are dominated by oil-prone organic matter and are at a more favorable maturity stage compared to the Maastrichtian, Santonian, and Coniacian (M-S-C) rock suites. In contrast, the Albian rock samples, characterized by mixed Type II/III and Type III kerogen, and their high thermal maturity, indicate a high potential for the generation of gaseous hydrocarbons. The biomarker and isotope data from the Cenomanian, Turonian, and Albian (T-C-A) source rocks suggest that they were deposited in a Transitional Marine-Lacustrine environment characterized by reducing redox conditions. This environment effectively preserved organic matter from diverse sources such as bacteria, algae, and higher plants. Furthermore, biomarker ratios indicated that the T-C-A source rocks are in the early-peak mature window. On the other hand, the M-S-C source rocks appear to have been deposited under suboxic conditions in a Coastal Marine environment. Lower aquatic organisms dominate these rocks, which have an immature to marginally mature level. The analysis of lower molecular weight hydrocarbons (≤C20), characterized by an unresolved complex mixture, did not reveal any obvious correlation between the oils and the Cretaceous source rocks. However, the analysis of higher molecular weight hydrocarbons (≥C20) and isotopic ratios indicated that the commercial discoveries in the Jubilee and TEN fields share a genetic similarity and are primarily sourced from the T-C-A source rocks. Furthermore, the molecular and isotopic characteristics suggest that the M-S-C source rocks do not appear to have contributed to the oils found in the Jubilee and TEN fields. These new geochemical findings shed light on the paleoenvironmental conditions and source rock characteristics of the region, significantly contributing to our understanding of the petroleum evolution and potential of the Tano Basin.",
    url = "https://doi.org/10.1016/j.marpetgeo.2024.106697",
    doi = "10.1016/j.marpetgeo.2024.106697",
    openalex = "W4391115515",
    references = "doi101038s43247022006683"
}

Ancient epicratonic formations, which represent the bulk of pre-Jurassic sedimentary rocks, have been widely interpreted as marine deposits, but recently developed bulk-shale elemental proxies for palaeo-watermass salinity (i.e. B/Ga, Sr/Ba and S/TOC, where TOC is total organic carbon) have shown this inference to be frequently incorrect. Here, we use these proxies to test the salinity conditions of 22 representative shale and marl formations of early Cambrian to early Silurian age from five cratons (Laurentia, Avalonia, Baltica, Iran and South China) in the context of formation-specific palaeogeographical and palaeoclimatic reconstructions. Our dataset shows that around half of these formations were probably deposited under brackish or mixed brackish–marine conditions rather than fully marine conditions (as previously inferred), and that one of them represents a freshwater facies (previously interpreted as marine mainly on the basis of Cruziana traces). In most cases, the development of reduced-salinity conditions can be related to the coastal and/or humid climate belt setting in which the formation of interest was deposited. Our dataset also reveals systematically low Sr/Ba values (i.e. relative to modern brackish and marine facies), suggesting that seawater Sr concentrations were lower during the Early Paleozoic than at present. Our findings suggest that re-evaluation of the salinity characteristics of many ancient epicratonic shale and marl formations is necessary. Supplementary material: A supplementary figure and tables are available at https://doi.org/10.6084/m9.figshare.c.7063365 Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system

@article{doi101144jgs2023217,
    author = "Liu, Zhanhong and Algeo, Thomas J. and Arefifard, Sakineh and Wei, Wei and Brett, Carlton E. and Landing, Ed and Lev, Steven",
    title = "Testing the salinity of Cambrian to Silurian epicratonic seas",
    year = "2024",
    journal = "Journal of the Geological Society",
    abstract = "Ancient epicratonic formations, which represent the bulk of pre-Jurassic sedimentary rocks, have been widely interpreted as marine deposits, but recently developed bulk-shale elemental proxies for palaeo-watermass salinity (i.e. B/Ga, Sr/Ba and S/TOC, where TOC is total organic carbon) have shown this inference to be frequently incorrect. Here, we use these proxies to test the salinity conditions of 22 representative shale and marl formations of early Cambrian to early Silurian age from five cratons (Laurentia, Avalonia, Baltica, Iran and South China) in the context of formation-specific palaeogeographical and palaeoclimatic reconstructions. Our dataset shows that around half of these formations were probably deposited under brackish or mixed brackish–marine conditions rather than fully marine conditions (as previously inferred), and that one of them represents a freshwater facies (previously interpreted as marine mainly on the basis of Cruziana traces). In most cases, the development of reduced-salinity conditions can be related to the coastal and/or humid climate belt setting in which the formation of interest was deposited. Our dataset also reveals systematically low Sr/Ba values (i.e. relative to modern brackish and marine facies), suggesting that seawater Sr concentrations were lower during the Early Paleozoic than at present. Our findings suggest that re-evaluation of the salinity characteristics of many ancient epicratonic shale and marl formations is necessary. Supplementary material: A supplementary figure and tables are available at https://doi.org/10.6084/m9.figshare.c.7063365 Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system",
    url = "https://doi.org/10.1144/jgs2023-217",
    doi = "10.1144/jgs2023-217",
    openalex = "W4391947476",
    references = "doi101002spp21391, doi10100797894009324188, doi101016b978012824360200019x, doi101016b9780444538130000046, doi101016jprecamres2019105438, openalexw2296057071"
}

In the Middle East, significant evaporite units formed in the latest Precambrian–Cambrian, Triassic, Jurassic, Cretaceous and Cenozoic. The Precambrian–Cambrian period gave rise to the Ara Salt carbonate stringer plays, southern Oman and the giant Zagros anticline traps (Hormuz Formation). While outcrops of salt diapirs are common, basal detachment exposures are extremely rare. The Lakar Kuh area of Central Iran reveals the Precambrian–Cambrian basal salt detachment, on satellite images, in natural cross-section view through the entire Phanerozoic sedimentary section east of Ravar. This view illustrates how older diapiric structures (pillows and normal faults) were the focus of later contractional folds, particularly in the Jurassic and Cenozoic. The salt detachment zone contains many floating blocks (stringers) of clastic, carbonate and igneous rocks. Some blocks were stoped from the overlying beds, while most were layers originally interbedded with the evaporites. Block size, distribution and orientation is highly variable, and folding is infrequent. Lakar Kuh encompasses several key themes generally pertinent to structural geology and salt system research: the presence of sedimentary stringers within evaporites, multiple detachment levels within a thick (>5 km) stratigraphic section, detachment folding, multiphase salt activity, reactivation of older structures by newer ones and multi-stage development of salt bodies.

@article{doi101144sp55020246,
    author = "Morley, C.K. and Back, Stefan",
    title = "The Proterozoic–Cambrian salt detachment zone at Lakhar Kuh, Iran: a seismic-scale analogue for salt stringers, detachment folding and multiphase structural development",
    year = "2024",
    journal = "Geological Society London Special Publications",
    abstract = "In the Middle East, significant evaporite units formed in the latest Precambrian–Cambrian, Triassic, Jurassic, Cretaceous and Cenozoic. The Precambrian–Cambrian period gave rise to the Ara Salt carbonate stringer plays, southern Oman and the giant Zagros anticline traps (Hormuz Formation). While outcrops of salt diapirs are common, basal detachment exposures are extremely rare. The Lakar Kuh area of Central Iran reveals the Precambrian–Cambrian basal salt detachment, on satellite images, in natural cross-section view through the entire Phanerozoic sedimentary section east of Ravar. This view illustrates how older diapiric structures (pillows and normal faults) were the focus of later contractional folds, particularly in the Jurassic and Cenozoic. The salt detachment zone contains many floating blocks (stringers) of clastic, carbonate and igneous rocks. Some blocks were stoped from the overlying beds, while most were layers originally interbedded with the evaporites. Block size, distribution and orientation is highly variable, and folding is infrequent. Lakar Kuh encompasses several key themes generally pertinent to structural geology and salt system research: the presence of sedimentary stringers within evaporites, multiple detachment levels within a thick (>5 km) stratigraphic section, detachment folding, multiphase salt activity, reactivation of older structures by newer ones and multi-stage development of salt bodies.",
    url = "https://doi.org/10.1144/sp550-2024-6",
    doi = "10.1144/sp550-2024-6",
    openalex = "W4396578095",
    references = "doi101016jprecamres2020105954"
}

ABSTRACT The lower Cambrian and lower Silurian shale reservoirs of southern China display significant differences in pore characteristics that may reflect the varying effects of silica diagenesis. The lower Cambrian and lower Silurian mudstone samples from the middle–upper Yangtze platform were analyzed to elucidate silica diagenetic modifications, including their influences on pore evolution. Quartz of the studied mudstone samples includes detrital quartz, overgrowths, siliceous skeletal fragments, microquartz aggregates, silica nanospheres, and matrix-dispersed microquartz. Much of the authigenic silica precipitated in association with diagenetic alteration of the studied deposits appears to have been derived from dissolution of siliceous skeletal fragments and the smectite–illite reaction. A paucity of siliceous organisms populating the early Cambrian ocean gave rise to more complicated silica diagenetic pathways during alteration. Silica precipitation from silica-rich seawater/pore water and silica replacement by carbonate/carbonate-fluorapatite may have supplemented diagenetic modification of lower Cambrian mudstone. The species types of organisms that contributed skeletal grains to the sediments and the amount of precipitated authigenic quartz appear to have impacted organic pore evolution. The abundance of early Cambrian benthic siliceous sponge spicules appears to have muted formation of rigid microquartz aggregates and silica nanospheres that would have shielded organic pores. In contrast, the early Silurian bloom of planktonic radiolarians was associated with accumulation of organic-rich siliceous mudstone and the formation of abundant microquartz aggregates and silica nanospheres that shielded organic pores during burial. In summary, the amount and type of diagenetic quartz influenced pore characteristics of lower Cambrian and lower Silurian shale reservoir rocks of southern China.

@article{doi10130601242422096,
    author = "Gao, Ping and Xiao, Xianming and Hu, Dongfeng and Lash, Gary G. and Liu, Ruobing and Zhang, Baoyue and Zhao, Yanming",
    title = "Comparison of silica diagenesis between the lower Cambrian and lower Silurian shale reservoirs in the middle–upper Yangtze platform (southern China)",
    year = "2024",
    journal = "AAPG Bulletin",
    abstract = "ABSTRACT The lower Cambrian and lower Silurian shale reservoirs of southern China display significant differences in pore characteristics that may reflect the varying effects of silica diagenesis. The lower Cambrian and lower Silurian mudstone samples from the middle–upper Yangtze platform were analyzed to elucidate silica diagenetic modifications, including their influences on pore evolution. Quartz of the studied mudstone samples includes detrital quartz, overgrowths, siliceous skeletal fragments, microquartz aggregates, silica nanospheres, and matrix-dispersed microquartz. Much of the authigenic silica precipitated in association with diagenetic alteration of the studied deposits appears to have been derived from dissolution of siliceous skeletal fragments and the smectite–illite reaction. A paucity of siliceous organisms populating the early Cambrian ocean gave rise to more complicated silica diagenetic pathways during alteration. Silica precipitation from silica-rich seawater/pore water and silica replacement by carbonate/carbonate-fluorapatite may have supplemented diagenetic modification of lower Cambrian mudstone. The species types of organisms that contributed skeletal grains to the sediments and the amount of precipitated authigenic quartz appear to have impacted organic pore evolution. The abundance of early Cambrian benthic siliceous sponge spicules appears to have muted formation of rigid microquartz aggregates and silica nanospheres that would have shielded organic pores. In contrast, the early Silurian bloom of planktonic radiolarians was associated with accumulation of organic-rich siliceous mudstone and the formation of abundant microquartz aggregates and silica nanospheres that shielded organic pores during burial. In summary, the amount and type of diagenetic quartz influenced pore characteristics of lower Cambrian and lower Silurian shale reservoir rocks of southern China.",
    url = "https://doi.org/10.1306/01242422096",
    doi = "10.1306/01242422096",
    openalex = "W4399735356",
    references = "doi101111ter12541"
}

@article{doi101016jearscirev2025105294,
    author = "Liu, Wei and Gao, Ping and Lash, Gary G. and Xiao, Xianming",
    title = "Co-evolution of life and environment during the early Cambrian of South China: Implications for organic matter enrichment",
    year = "2025",
    journal = "Earth-Science Reviews",
    url = "https://doi.org/10.1016/j.earscirev.2025.105294",
    doi = "10.1016/j.earscirev.2025.105294",
    openalex = "W4414816726",
    references = "doi101016jepsl2021116959"
}

@article{doi101016jpalaeo2025113304,
    author = "Tang, Baiqiang and Meng, Qingtao and Hu, Fei and Jiang, Nan and Yang, Liang and Xing, Jilin and Liu, Zhaojun and Zhang, Yunbai",
    title = "Effect of Late Cretaceous marine incursions on lacustrine organic carbon burial in East Asia: Perspectives from machine learning and geochemistry",
    year = "2025",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2025.113304",
    doi = "10.1016/j.palaeo.2025.113304",
    openalex = "W4414484412",
    references = "doi101038s43247022006683"
}

Abstract The United Arab Emirates government is assessing the potential of Hormuz Salt domes for subsurface storage, aligning with the transition toward clean energy systems and carbon reduction goals. However, the geometry, kinematics, and halokinetic evolution of these salt structures remain poorly constrained. This study focuses on Jebel Al Dhanna salt dome, the only onshore exposure of Hormuz Salt in Abu Dhabi Emirate. It utilizes 3D seismic reflection data, wireline logs and sequential kinematic restoration modeling to analyze its morphology and tectonic evolution. The dome displays an elliptical geometry elongated north–south, measuring 1.2–3.2 km east–west and 2.5–4.5 km north–south, with irregular crests, steep flanks, and topographic highs. It is interpreted as a plug‐shaped salt stock with a complex bulb‐and‐neck morphology formed by multiple phases of salt mobilization. Restoration modeling indicates salt movement began shortly after the precipitation of the Hormuz Salt in the Late Ediacaran–Early Cambrian and continued to the present. An initial phase of passive rise through downbuilding occurred between the Cambrian and Carboniferous, followed by four reactivation episodes associated with regional tectonics: Permian and Late Jurassic rifting, and Late Cretaceous and Late Oligocene–Miocene compression. Tilted Upper Miocene and Quaternary strata within and around the dome indicate ongoing salt evacuation. Several wedge‐ and hook‐shaped halokinetic sequences further constrain the timing and intensity of salt movement. Our findings provide valuable insights into salt tectonics and have broader implications for subsurface storage potential and energy‐transition strategies in salt‐bearing basins.

@article{doi1010292025tc009086,
    author = "Ali, Moamen and Alshehhi, Hamda and Ali, Mohammed Y.",
    title = "Geometry and Kinematics of the Hormuz Salt at Jebel Al Dhanna, United Arab Emirates: Implications for Salt Tectonics and Subsurface Storage",
    year = "2025",
    journal = "Tectonics",
    abstract = "Abstract The United Arab Emirates government is assessing the potential of Hormuz Salt domes for subsurface storage, aligning with the transition toward clean energy systems and carbon reduction goals. However, the geometry, kinematics, and halokinetic evolution of these salt structures remain poorly constrained. This study focuses on Jebel Al Dhanna salt dome, the only onshore exposure of Hormuz Salt in Abu Dhabi Emirate. It utilizes 3D seismic reflection data, wireline logs and sequential kinematic restoration modeling to analyze its morphology and tectonic evolution. The dome displays an elliptical geometry elongated north–south, measuring 1.2–3.2 km east–west and 2.5–4.5 km north–south, with irregular crests, steep flanks, and topographic highs. It is interpreted as a plug‐shaped salt stock with a complex bulb‐and‐neck morphology formed by multiple phases of salt mobilization. Restoration modeling indicates salt movement began shortly after the precipitation of the Hormuz Salt in the Late Ediacaran–Early Cambrian and continued to the present. An initial phase of passive rise through downbuilding occurred between the Cambrian and Carboniferous, followed by four reactivation episodes associated with regional tectonics: Permian and Late Jurassic rifting, and Late Cretaceous and Late Oligocene–Miocene compression. Tilted Upper Miocene and Quaternary strata within and around the dome indicate ongoing salt evacuation. Several wedge‐ and hook‐shaped halokinetic sequences further constrain the timing and intensity of salt movement. Our findings provide valuable insights into salt tectonics and have broader implications for subsurface storage potential and energy‐transition strategies in salt‐bearing basins.",
    url = "https://doi.org/10.1029/2025tc009086",
    doi = "10.1029/2025tc009086",
    openalex = "W4416607923",
    references = "doi101016jprecamres2020105954"
}

Abstract The terminal Ediacaran to Lower Cambrian (538–521 Ma) documents the disappearance of Ediacaran soft-bodied biota and the diversification of early animals, including the emergence of small shelly fauna, archaeocyath sponges, and trilobites. Despite extensive study, the role of oceanic oxygenation in macroevolutionary events across this interval remains unclear, with understanding hindered by limited constraints on temporal and spatial variability in geochemical conditions, both regionally and globally. Here, we report multi-proxy geochemical data (including organic carbon concentrations, carbonate and organic carbon isotopes, Fe speciation, and redox sensitive trace elements) from three sections documenting different water-depths through the Early Cambrian (Terreneuvian) Yurtus Formation of the Tarim Basin, Northwest China. Our data reveal a highly dynamic oxygen minimum zone (OMZ), distinguished by a core of unstable ferruginous to dysoxic conditions, with peripheral dysoxic to oxic conditions that developed on the inner-outer shelf at different stages. The temporal and spatial extent of the OMZ appears to have been controlled by changes in productivity, driven by sea-level and climatic influences on upwelling. We expand on regional observations by considering published geochemical data from globally distributed successions across this interval, in addition to the lowest global occurrence of key fossil taxa. Our integration of regional and global geochemical data sets, alongside mechanistic insight from regional and global stratal stacking patterns, suggest that marine redox fluctuations responded dynamically to changes in upwelling driven by major sea level transgression and climate. These connected processes and palaeoenvironmental conditions formed the backdrop for the main phase of the Cambrian explosion.

@article{doi101130b378691,
    author = "Wei, Tianyuan and Cai, Chunfang and Xiong, Yijun and Bowyer, Fred and Poulton, Simon W.",
    title = "Environmental controls on Early Cambrian macroevolution: Insights from the Tarim Basin, Northwest China",
    year = "2025",
    journal = "Geological Society of America Bulletin",
    abstract = "Abstract The terminal Ediacaran to Lower Cambrian (538–521 Ma) documents the disappearance of Ediacaran soft-bodied biota and the diversification of early animals, including the emergence of small shelly fauna, archaeocyath sponges, and trilobites. Despite extensive study, the role of oceanic oxygenation in macroevolutionary events across this interval remains unclear, with understanding hindered by limited constraints on temporal and spatial variability in geochemical conditions, both regionally and globally. Here, we report multi-proxy geochemical data (including organic carbon concentrations, carbonate and organic carbon isotopes, Fe speciation, and redox sensitive trace elements) from three sections documenting different water-depths through the Early Cambrian (Terreneuvian) Yurtus Formation of the Tarim Basin, Northwest China. Our data reveal a highly dynamic oxygen minimum zone (OMZ), distinguished by a core of unstable ferruginous to dysoxic conditions, with peripheral dysoxic to oxic conditions that developed on the inner-outer shelf at different stages. The temporal and spatial extent of the OMZ appears to have been controlled by changes in productivity, driven by sea-level and climatic influences on upwelling. We expand on regional observations by considering published geochemical data from globally distributed successions across this interval, in addition to the lowest global occurrence of key fossil taxa. Our integration of regional and global geochemical data sets, alongside mechanistic insight from regional and global stratal stacking patterns, suggest that marine redox fluctuations responded dynamically to changes in upwelling driven by major sea level transgression and climate. These connected processes and palaeoenvironmental conditions formed the backdrop for the main phase of the Cambrian explosion.",
    url = "https://doi.org/10.1130/b37869.1",
    doi = "10.1130/b37869.1",
    openalex = "W4408282035",
    references = "doi101111ter12541"
}