Geochemical characterization of shales of the Eocene Disang Group, Kohima Syncline, India: Inferences to hydrocarbon potential and depositional environment

Gogoi, Mousumi; Mathur, Neeraj; Kumar, T. V. Vijay; Walling, Temsulemba; Phukan, Sarat

doi:10.1016/j.ptlrs.2020.09.001

Cited by 11 publications

(4 citation statements)

References 43 publications

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“…High values of V/Cr ratio (>2) reflect sediment deposition in anoxic conditions, and low values (<2) indicate oxic conditions [82]. Additionally, high ratios of Cu/Zn support a reducing environment, while low ratios indicate oxic conditions [79,87]. Furthermore, vanadium (V) and nickel (Ni) are considered crucial tools for paleo-redox conditions [88][89][90].…”

Section: Geochemistrymentioning

confidence: 99%

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

et al. 2023

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The Eocene deposits of Egypt provide a wide variety of shallow marine facies and fossil assemblages, allowing paleoenvironmental reconstructions in this warmhouse climate interval. Forty-three rock samples have been collected from two middle Eocene sections, exposed at southeast Beni-Suef area in northern Egypt. The studied outcrops are lithologicsally subdivided into two rock units named from base to top as follows: (1) the Qarara Formation (Lutetian) and (2) the El Fashn Formation (Bartonian). Most investigated rock samples showed richness in benthic foraminiferal assemblages and only rare occurrences of index planktonic foraminifera. They yielded 160 foraminifera species which belong to 4 suborders, 19 superfamilies, 34 families, and 59 genera. The stratigraphic distribution of the identified species allowed us to define four local benthic bio-ecozones: (1) Bolivina carinata Lowest Occurrence Zone (Lutetian), (2) Cibicides mabahethi/Cancris auriculus primitivus Concurrent-Range Zone, (3) Nonion scaphum Lowest Occurrence Zone, and (4) Brizalina cooki/Nonionella insecta Concurrent-Range Zone (Bartonian). These biozones are described and discussed in detail and correlated to stratigraphic equivalents in Egypt. The rareness of index planktonic foraminifera through the studied sections does not allow a precise biostratigraphic and chronostratigraphic correlation. The shale samples show low TOC values, which may be related to low productivity, high sediment influx, and/or prevailing oxic conditions. Bulk rock geochemistry, consistent with the benthic foraminifera ecological preferences, indicated that the studied sections were deposited in moderate to high oxygen levels and warm climatic conditions in a typical shelf marine setting. The identified species showed strong similarities with nearby southern Tethys areas, reflecting migration via the trans-Sahara seaway, and minor similarities with those identified from the northwestern Tethys and the North Atlantic province attributed to the change in the environmental and climatic conditions, such as cooler, latitudinal zoned climatic conditions along the northwestern Tethys, which was unsuitable for their biological demands. The warming trend identified from Lutetian to Bartonian intervals corresponds to the onset of the Middle Eocene Climatic Optimum (MECO).

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Section: Geochemistrymentioning

confidence: 99%

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

et al. 2023

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“…The elemental geochemistry index is now a reliable indicator for marine and lake ecosystems. The variation in elemental geochemical parameters reflects the lithofacies of shale and the sedimentary environment [46]. Wang et al discovered that lake-water depth fluctuates from deep to shallow in a high-frequency sequence unit, and element ratios in shales shift regularly, particularly near the highfrequency cycle interface [36].…”

Section: The Elemental Geochemistrymentioning

confidence: 99%

A Review on Elemental and Isotopic Geochemistry

Khalef¹,

Hassan²,

Saleh³

2022

Geochemistry and Mineral Resources

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Geochemistry is the study of the development, and distribution of chemical elements on Earth, which are found in rock-forming minerals and their byproducts, as well as in living beings, water, and the environment. The elemental geochemical variation of sediments is used to recognize the mechanisms controlling the estuarine environment and serves as a baseline for assessing the environmental effect in the future. Geochemistry is a unique field that deals with the study of mineral deposits. It also addresses the interconnections between the structures of rock, soil, water, and air, which vary according to different places. Furthermore, groundwater is the solely accessible water supply in many desert basins, particularly in developing nations. Geochemical indicators are proper instruments for addressing a diversity of hydrological issues, particularly in arid and semi-arid settings. Thermodynamically, the fugacity of oxygen (fO2) in solid earth varies by many orders of magnitude. Enstatite chondrites can have high levels of hydrogen abundance, hydrogen, and nitrogen isotope compositions like those of the earth’s mantle. The chapter deals with the basic concept of geochemistry and its types, as well as the development of geochemistry. It also explains elemental and isotopes geochemistry, human health, and medical geochemistry.

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“…This expands on the extent to which OM is intensely heated and transformed into petroleum. The molecular specification for the ratio and distribution of biomarkers has been modified to investigate the degree of thermal maturation (Gogoi et al 2021). To investigate the thermal maturation of the shaly sediments, a few molecular maturation determinants, such as the C 29 ββ(ββ + αα) ratio, the C 32 22S/(22S + 22R) ratio, and the M 30 /H 30 plus methylphenanthrene indices (MPI), were adapted (Table 1).…”

Section: Maturation Of Organic Mattermentioning

confidence: 99%

Biomarkers, stable carbon isotope, and trace element distribution of source rocks in the Orange Basin, South Africa: implications for paleoenvironmental reconstruction, provenance, and tectonic setting

Yelwa

Mustapha

Opuwari

et al. 2021

J Petrol Explor Prod Technol

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Aptian to Campanian sediments from the Western offshore to Central Orange Basin were studied by integrating molecular geochemistry, inorganic and isotopic studies to recognize their geochemical characteristics via the reconstruction of the Orange basin’s paleoweathering, paleosalinity, paleovegetation, paleoclimate, and tectonic records. Molecular analyses of both aliphatic and aromatic compounds reveal an input dominantly from a marine source. The source rocks accumulated in a reduced, anoxic, saline water column. Based on various biomarker proxies and vitrinite reflectance data, some samples are thermally mature to produce petroleum, while others are not. According to the V/Ni ratio, samples from the Orange Basin in South Africa are mainly anoxic, with only a few samples ranging from suboxic to anoxic. This is congruent with biomarker and isotope analyses that further indicate the presence of marine-derived source rocks with some terrestrial remains generating hydrocarbons. The investigated sediments are made up of intermediate igneous rocks that have undergone moderate chemical weathering. Geochemical figures on tectonic setting discriminant function diagrams revealed a continental rift of passive margin settings. As a result, the extrapolated crustal processes are directly analogous to the genesis and evolution of the Orange Basin, demonstrating Gondwana’s breaking up and the opening of the Atlantic Ocean Margin.

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Geochemical characterization of shales of the Eocene Disang Group, Kohima Syncline, India: Inferences to hydrocarbon potential and depositional environment

Cited by 11 publications

References 43 publications

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

A Review on Elemental and Isotopic Geochemistry

Biomarkers, stable carbon isotope, and trace element distribution of source rocks in the Orange Basin, South Africa: implications for paleoenvironmental reconstruction, provenance, and tectonic setting

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