Deposition or diagenesis? Probing the Ediacaran Shuram excursion in South China by SIMS

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dc.contributor.authorCui, Huanen
dc.contributor.authorKitajima, Koukien
dc.contributor.authorOrland, Ian J.en
dc.contributor.authorXiao, Shuhaien
dc.contributor.authorBaele, Jean-Marcen
dc.contributor.authorKaufman, Alan J.en
dc.contributor.authorDenny, Adamen
dc.contributor.authorZhou, Chuanmingen
dc.contributor.authorSpicuzza, Michael J.en
dc.contributor.authorFournelle, John H.en
dc.contributor.authorValley, John W.en
dc.date.accessioned2024-02-13T14:06:29Zen
dc.date.available2024-02-13T14:06:29Zen
dc.date.issued2021-11en
dc.description.abstractThe Ediacaran Period (ca. 635–541 Ma) witnessed the earliest paleontological evidence for macroscopic animals (i.e., Ediacara biota) and geochemical observations of the largest carbon cycle anomaly in Earth history (i.e., Shuram Excursion, SE). Numerous hypotheses have been proposed for the origins of the SE, ranging from primary seawater anomaly to syn- or post-depositional diagenesis. Despite intensive geochemical and theoretical work published in the past decade, empirical evidence that is strictly based on fundamental petrographic results at the micrometer scale is still limited. To evaluate depositional compositions and diagenetic effects on samples from the SE, we investigated the EN3 interval in the Doushantuo Formation of South China via integrated cathodoluminescence (CL), secondary ion mass spectrometry (SIMS), and scanning electron microscope (SEM). Detailed petrographic observations reveal that the EN3 limestone is dominated by calcite microspar, with minor but variable amounts of disseminated zoned dolomite crystals. The former likely formed via neomorphism of depositional micrite, while the latter was the result of progressive post-depositional dolomitization. The mean values of paired SIMS δ13Ccalcite and δ13Cdolomite compositions are indistinguishable in each sample and consistent with published micro-drilled bulk-powder δ13C values, which we interpret to represent depositional “background” signals of seawater dissolved inorganic carbon (DIC). We also observed μm-scale variability of SIMS δ13C data that may reflect a variable diagenetic overprint after deposition. Our integrated petrographic and geochemical results are consistent with a depositional origin of the SE and provide little evidence for the hypothesized isotope alteration by meteoric and mixing-zone diagenesis or late burial diagenesis. In light of this study, we propose that the SE indeed represents a marine carbon cycle anomaly that bears a close temporal link to the Ediacaran surface environment.en
dc.description.versionPublished versionen
dc.format.extent36 page(s)en
dc.format.mimetypeapplication/pdfen
dc.identifierARTN 103591 (Article number)en
dc.identifier.doihttps://doi.org/10.1016/j.gloplacha.2021.103591en
dc.identifier.eissn1872-6364en
dc.identifier.issn0921-8181en
dc.identifier.orcidXiao, Shuhai [0000-0003-4655-2663]en
dc.identifier.urihttps://hdl.handle.net/10919/117971en
dc.identifier.volume206en
dc.language.isoenen
dc.publisherElsevieren
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectShuram excursionen
dc.subjectDoushantuo formationen
dc.subjectMethaneen
dc.subjectDiagenesisen
dc.subjectCarbonatesen
dc.subjectEdiacaranen
dc.titleDeposition or diagenesis? Probing the Ediacaran Shuram excursion in South China by SIMSen
dc.title.serialGlobal And Planetary Changeen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.otherArticleen
dc.type.otherJournalen
pubs.organisational-group/Virginia Techen
pubs.organisational-group/Virginia Tech/Scienceen
pubs.organisational-group/Virginia Tech/Science/Geosciencesen
pubs.organisational-group/Virginia Tech/All T&R Facultyen
pubs.organisational-group/Virginia Tech/Science/COS T&R Facultyen

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