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Pyrite textures, trace elements and sulfur isotope chemistry of Bijaigarh Shales, Vindhyan Basin, India and their implications

Citation

Mukherjee, I and Deb, M and Large, RR and Halpin, J and Meffre, S and Avila, J and Belousov, I, Pyrite textures, trace elements and sulfur isotope chemistry of Bijaigarh Shales, Vindhyan Basin, India and their implications, Minerals, 10, (7) Article 588. ISSN 2075-163X (2020) [Refereed Article]


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Copyright 2020 the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.3390/min10070588

Abstract

The Vindhyan Basin in central India preserves a thick (~5 km) sequence of sedimentary and lesser volcanic rocks that provide a valuable archive of a part of the Proterozoic (~1800900 Ma) in India. Here, we present an analysis of key sedimentary pyrite textures and their trace element and sulfur isotope compositions in the Bijaigarh Shale (1210 52 Ma) in the Vindhyan Supergroup, using reflected light microscopy, LA-ICP-MS and SHRIMP-SI, respectively. A variety of sedimentary pyrite textures (fine-grained disseminated to aggregates, framboids, lags, and possibly microbial pyrite textures) are observed reflecting quiet and strongly anoxic water column conditions punctuated by occasional high-energy events (storm incursions). Key redox sensitive or sensitive to oxidative weathering trace elements (Co, Ni, Zn, Mo, Se) and ratios of (Se/Co, Mo/Co, Zn/Co) measured in sedimentary pyrites from the Bijaigarh Shale are used to infer atmospheric redox conditions during its deposition. Most trace elements are depleted relative to Proterozoic mean values. Sulfur isotope compositions of pyrite, measured using SHRIMP-SI, show an increase in δ34S as we move up stratigraphy with positive δ34S values ranging from 5.9 (lower) to 26.08 (upper). We propose limited sulphate supply caused the pyrites to incorporate the heavier isotope. Overall, we interpret these low trace element signatures and heavy sulfur isotope compositions to indicate relatively suppressed oxidative weathering on land during the deposition of the Bijaigarh Shale.

Item Details

Item Type:Refereed Article
Keywords:Bijaigarh shale, pyrite, Middle Proterozoic, SHRIMP-SI, LA-ICP-MS
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Geochemistry not elsewhere classified
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Mukherjee, I (Dr Indrani Mukherjee)
UTAS Author:Large, RR (Professor Ross Large)
UTAS Author:Halpin, J (Dr Jacqueline Halpin)
UTAS Author:Meffre, S (Dr Sebastien Meffre)
UTAS Author:Belousov, I (Dr Ivan Belousov)
ID Code:139897
Year Published:2020
Funding Support:Australian Research Council (DP150102578)
Web of Science® Times Cited:1
Deposited By:CODES ARC
Deposited On:2020-07-13
Last Modified:2020-08-05
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