ORCID Profile
0000-0002-2808-1821
Current Organisations
Larner College of Medicine, University of Vermont
,
University of Tasmania
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Publisher: Elsevier BV
Date: 04-2018
Publisher: Geological Society of America
Date: 09-06-2020
Abstract: Additional information on seawater-pyrite link and method. br
Publisher: Springer Science and Business Media LLC
Date: 13-03-2018
DOI: 10.1038/S41598-018-22695-X
Abstract: The period 1800 to 800 Ma (“Boring Billion”) is believed to mark a delay in the evolution of complex life, primarily due to low levels of oxygen in the atmosphere. Earlier studies highlight the remarkably flat C, Cr isotopes and low trace element trends during the so-called stasis, caused by prolonged nutrient, climatic, atmospheric and tectonic stability. In contrast, we suggest a first-order variability of bio-essential trace element availability in the oceans by combining systematic s ling of the Proterozoic rock record with sensitive geochemical analyses of marine pyrite by LA-ICP-MS technique. We also recall that several critical biological evolutionary events, such as the appearance of eukaryotes, origin of multicellularity & sexual reproduction, and the first major ersification of eukaryotes (crown group) occurred during this period. Therefore, it appears possible that the period of low nutrient trace elements (1800–1400 Ma) caused evolutionary pressures which became an essential trigger for promoting biological innovations in the eukaryotic domain. Later periods of stress-free conditions, with relatively high nutrient trace element concentration, facilitated ersification. We propose that the “Boring Billion” was a period of sequential stepwise evolution and ersification of complex eukaryotes, triggering evolutionary pathways that made possible the later rise of micro-metazoans and their macroscopic counterparts.
Publisher: Elsevier BV
Date: 10-2015
Publisher: MDPI AG
Date: 29-06-2020
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 (~1800–900 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.
Publisher: Geological Society of America
Date: 09-06-2020
DOI: 10.1130/GEOL.S.12456332.V1
Abstract: Additional information on seawater-pyrite link and method. br
Publisher: Springer Science and Business Media LLC
Date: 12-03-2019
Publisher: Informa UK Limited
Date: 04-2012
DOI: 10.4161/AUTO.19496
Publisher: Elsevier BV
Date: 03-2017
Publisher: Society of Economic Geologists
Date: 07-02-2017
Publisher: Elsevier BV
Date: 08-2016
Location: United States of America
Location: United States of America
No related grants have been discovered for Indrani Mukherjee.