DOI: 10.1016/j.epsl.2020.116462
论文题名: Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman
作者: Gong Z. ; Li M.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 547 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164989
Appears in Collections: 气候变化与战略
There are no files associated with this item.
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
Recommended Citation:
Gong Z.,Li M.. Astrochronology of the Ediacaran Shuram carbon isotope excursion, Oman[J]. Earth and Planetary Science Letters,2020-01-01,547