气候变化领域集成服务门户(CCPortal): Isotopically anomalous organic carbon in the aftermath of the Marinoan snowball Earth

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DOI	10.1111/gbi.12383
	Isotopically anomalous organic carbon in the aftermath of the Marinoan snowball Earth
	Liljestrand F.L.; Laakso T.A.; Macdonald F.A.; Schrag D.P.; Johnston D.T.
发表日期	2020
ISSN	14724677
起始页码	476
结束页码	485
卷号	18 期号:4
英文摘要	Throughout most of the sedimentary record, the marine carbon cycle is interpreted as being in isotopic steady state. This is most commonly inferred via isotopic reconstructions, where two export fluxes (organic carbon and carbonate) are offset by a constant isotopic fractionation of ~25 (termedE org−carb). Sedimentary deposits immediately overlying the Marinoan snowball Earth diamictites, however, stray from this prediction. In stratigraphic sections from the Ol Formation (Mongolia) and Sheepbed Formation (Canada), we observe a temporary excursion where the organic matter has anomalously heavy δ13C and is grossly decoupled from the carbonate δ13C. This signal may reflect the unique biogeochemical conditions that persisted in the aftermath of snowball Earth. For example, physical oceanographic modeling suggests that a strong density gradient caused the ocean to remain stratified for about 50,000 years after termination of the Marinoan snowball event, during which time the surface ocean and continental weathering consumed the large atmospheric CO2 reservoir. Further, we now better understand how δ13C records of carbonate can be post-depostionally altered and thus be misleading. In an attempt to explain the observed carbon isotope record, we developed a model that tracks the fluxes and isotopic values of carbon between the surface ocean, deep ocean, and atmosphere. By comparing the model output to the sedimentary data, stratification alone cannot generate the anomalous observed isotopic signal. Reproducing the heavy δ13C in organic matter requires the progressively diminishing contribution of an additional anomalous source of organic matter. The exact source of this organic matter is unclear. © 2020 John Wiley & Sons Ltd
关键词	carbon isotope glaciation isotopic analysis lithostratigraphy organic carbon Pleistocene sediment chemistry sedimentary structure
语种	英语
来源机构	Geobiology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/133176
推荐引用方式 GB/T 7714	Liljestrand F.L.,Laakso T.A.,Macdonald F.A.,et al. Isotopically anomalous organic carbon in the aftermath of the Marinoan snowball Earth[J]. Geobiology,2020,18(4).
APA	Liljestrand F.L.,Laakso T.A.,Macdonald F.A.,Schrag D.P.,&Johnston D.T..(2020).Isotopically anomalous organic carbon in the aftermath of the Marinoan snowball Earth.,18(4).
MLA	Liljestrand F.L.,et al."Isotopically anomalous organic carbon in the aftermath of the Marinoan snowball Earth".18.4(2020).