气候变化领域集成服务门户(CCPortal): Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman

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DOI	10.1016/j.epsl.2020.116462
	Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman
	Gong Z.; Li M.
发表日期	2020
ISSN	0012821X
卷号	547
英文摘要	The Ediacaran is a highly dynamic period in terms of large perturbations in Earth's atmosphere, biosphere, and climate. Among these perturbations, a pronounced negative carbon isotope excursion, known as the Shuram excursion (SE), is characterized by the most depleted δ13C values (-12‰) that have ever been observed in the geological record. A poorly determined chronostratigraphic framework makes the SE difficult to correlate and compare globally. Therefore, it is hard to study the potential connection between the SE and coeval climate and biological variations. Here, we present a high-resolution astrochronological study of the Ediacaran Shuram and Buah Formations, Nafun Group, Oman, in which the SE is reported for the first time. Power spectral analysis of the 600-m long gamma ray log of the Miqrat-1 Well shows that a hierarchy of astronomically-forced climate cycles (eccentricity, obliquity, and precession) is accurately-preserved. Using multiple statistical tests, we constructed a sedimentation rate variation profile that covers the entire SE, which is characterized by low rates in shale-dominated layers and high rates in shale-carbonate interbedded layers. The duration of the SE in Oman is suggested to be 7.7 ± 0.2 Myr, which agrees with estimates from South Australia, South China, and the United States. An identical duration of the SE supports its global synchroneity and indicates a primary origin of the depleted δ13C values. Combined with the newly proposed termination age (562.5 ± 1.1 Ma) of the SE, our astrochronological results suggest that the onset age of the excursion is 570.2 ± 1.1 Ma. The astrochronology of the SE delineates the tempo of the excursion, with a rapid decrease (∼ 1 Myr) from the onset to its isotopic nadir followed by a more gradual recovery (∼ 6–7 Myr) towards the termination. The new chronostratigraphic framework permits further investigations of the potential causal links between the global carbon cycle and the widespread glaciation, the oceanic oxygenation, and the biological diversification in Ediacaran time. © 2020 Elsevier B.V.
关键词	astrochronology Ediacaran gamma ray Nafun Group Shuram excursion
英文关键词	Carbon; Earth atmosphere; Gamma rays; Glacial geology; Radioactivity logging; Shale; Spectrum analysis; Biological variation; Carbon isotope excursions; Global carbon cycle; Multiple statistical tests; Negative carbon isotope excursions; Power spectral analysis; Sedimentation rates; South Australia; Isotopes; astronomy; carbon isotope; chronology; chronostratigraphy; climate variation; Ediacaran; geological record; perturbation; sedimentation rate; spectral analysis; Oman
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202611
作者单位	Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, United States; Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States
推荐引用方式 GB/T 7714	Gong Z.,Li M.. Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman[J],2020,547.
APA	Gong Z.,&Li M..(2020).Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman.Earth and Planetary Science Letters,547.
MLA	Gong Z.,et al."Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman".Earth and Planetary Science Letters 547(2020).