Journal ArticleDOI
Atmospheric Influence of Earth's Earliest Sulfur Cycle
TLDR
Mass-independent isotopic signatures in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal.Abstract:
Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.read more
Citations
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The Microbial Engines That Drive Earth's Biogeochemical Cycles
TL;DR: Virtually all nonequilibrium electron transfers on Earth are driven by a set of nanobiological machines composed largely of multimeric protein complexes associated with a small number of prosthetic groups.
Book
Molecular mechanisms of photosynthesis
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Journal ArticleDOI
The evolution and future of earth's nitrogen cycle
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Journal ArticleDOI
The rise of oxygen in Earth’s early ocean and atmosphere
TL;DR: The initial increase of O2 in the atmosphere, its delayed build-up in the ocean, its increase to near-modern levels in the sea and air two billion years later, and its cause-and-effect relationship with life are among the most compelling stories in Earth’s history.
Journal ArticleDOI
The snowball Earth hypothesis: testing the limits of global change
Paul Hoffman,Daniel P. Schrag +1 more
TL;DR: The recent discovery that late Neoproterozoic ice sheets extended to sea level near the equator poses a palaeoenvironmental conundrum as discussed by the authors, which does not account for major features such as abrupt onsets and terminations of discrete glacial events, their close association with large (> 10&) negative d 13 C shifts in seawater proxies, the deposition of strange carbonate layers (cap carbonates) globally during postglacial sea-level rise, and the return of large sedimentary iron formations.
References
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Journal ArticleDOI
Least squares fitting of a straight line with correlated errors
TL;DR: In this paper, the fitting of a straight line when both variables are subject to crrors is generalized to allow for correlation of the z and y errors, illustrated by reference to lead isochron fitting.
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Geochim. cosmochim. acta
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Burial of organic carbon and pyrite sulfur in sediments over phanerozoic time: a new theory
Robert A. Berner,Robert Raiswell +1 more
TL;DR: In this article, it was shown that the locus of major organic carbon burial has shifted over time from normal marine environments, as at present, to non-marine freshwater, or to euxinic environments, in the geologic past.
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The Proterozoic biosphere : a multidisciplinary study
J. William Schopf,Cornelis Klein +1 more
TL;DR: In this article, the Proterozoic and early Cambrian microfossils: prokaryotes and protists, trace and body fossils are described and compared to the modern mat-building microbial communities.