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dc.contributor.authorLi, Chao  Concept link
dc.contributor.authorHardisty, Dalton S.  Concept link
dc.contributor.authorLuo, Genming  Concept link
dc.contributor.authorHuang, Junhua  Concept link
dc.contributor.authorAlgeo, Thomas J.  Concept link
dc.contributor.authorCheng, Meng  Concept link
dc.contributor.authorShi, Wei  Concept link
dc.contributor.authorAn, Zhihui  Concept link
dc.contributor.authorTong, Jinnan  Concept link
dc.contributor.authorXie, Shucheng  Concept link
dc.contributor.authorJiao, Nianzhi  Concept link
dc.contributor.authorLyons, Timothy W.  Concept link
dc.date.accessioned2017-04-13T14:11:35Z
dc.date.issued2016-12
dc.identifier.urihttps://hdl.handle.net/1912/8899
dc.descriptionAuthor Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geobiology 15 (2017): 211–224, doi:10.1111/gbi.12222.en_US
dc.description.abstractRecords of the Ediacaran carbon cycle (635 to 541 million years ago) include the Shuram excursion (SE), the largest negative carbonate-carbon isotope excursion in Earth history (down to -12 ‰). The nature of this excursion remains enigmatic given the difficulties of interpreting a perceived extreme global decrease in the δ13C of seawater dissolved inorganic carbon (DIC). Here, we present carbonate and organic carbon isotope (δ13Ccarb and δ13Corg) records from the Ediacaran Doushantuo Formation along a proximal-to-distal transect across the Yangtze Platform of South China as a test of the spatial variation of the SE. Contrary to expectations, our results show that the magnitude and morphology of this excursion and its relationship with coexisting δ13Corg are highly heterogeneous across the platform. Integrated geochemical, mineralogical, petrographic, and stratigraphic evidence indicates that the SE is a primary marine signature. Data compilations demonstrate that the SE was also accompanied globally by parallel negative shifts of δ34S of carbonate-associated sulfate (CAS) and increased 87Sr/86Sr ratio and coastal CAS concentration, suggesting elevated continental weathering and coastal marine sulfate concentration during the SE. In light of these observations, we propose a heterogeneous oxidation model to explain the high spatial heterogeneity of the SE and coexisting δ13Corg records of the Doushantuo, with likely relevance to the SE in other regions. In this model, we infer continued marine redox stratification through the SE but with increased availability of oxidants (e.g., O2 and sulfate) limited to marginal near-surface marine environments. Oxidation of limited spatiotemporal extent provides a mechanism to drive heterogeneous oxidation of subsurface reduced carbon mostly in shelf areas. Regardless of the mechanism driving the SE, future models must consider the evidence for spatial heterogeneity in δ13C presented in this study.en_US
dc.description.sponsorshipWe thank the National Key Basic Research Program of China (Grant 2013CB955704) and the State Key R&D project of China (Grant 2016YFA060104) as well as the NSF-ELT program and the NASA Astrobiology Institute (TWL) for funding.en_US
dc.language.isoen_USen_US
dc.relation.urihttps://doi.org/10.1111/gbi.12222
dc.subjectEdiacaran carbon cycleen_US
dc.subjectDoushantuo Formationen_US
dc.subjectShuram excursionen_US
dc.subjectSpatial heterogeneity,en_US
dc.subjectSurface-ocean oxygenationen_US
dc.titleUncovering the spatial heterogeneity of Ediacaran carbon cyclingen_US
dc.typePreprinten_US


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