气候变化领域集成服务门户(CCPortal): Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes

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DOI	10.1111/gbi.12379
	Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes
	Fan H.; Nielsen S.G.; Owens J.D.; Auro M.; Shu Y.; Hardisty D.S.; Horner T.J.; Bowman C.N.; Young S.A.; Wen H.
发表日期	2020
ISSN	14724677
起始页码	348
结束页码	365
卷号	18 期号:3
英文摘要	Ediacaran sediments record an unusual global carbon cycle perturbation that has been linked to widespread oceanic oxygenation, the Shuram negative C isotope excursion (NCIE). However, proxy-based estimates of global ocean redox conditions during this event have been limited largely due to proxy specificity (e.g., euxinic sediments for Mo and U isotopes). Modern global seawater documents a homogenous Tl isotope composition (ε205Tl = −6.0) due to significant manganese oxide burial, which is recorded in modern euxinic sediments. Here, we provide new data documenting that sediments deposited beneath reducing but a non-sulfidic water column from the Santa Barbara Basin (ε205Tl = −5.6 ± 0.1) also faithfully capture global seawater Tl isotope values. Thus, the proxy utilization of Tl isotopes can extend beyond strictly euxinic settings. Second, to better constrain the global redox conditions during the Shuram NCIE, we measured Tl isotopes of locally euxinic and ferruginous shales of the upper Doushantuo Formation, South China. The ε205Tl values of these shales exhibit a decreasing trend from ≈−3 to ≈−8, broadly coinciding with the onset of Shuram NCIE. There are ε205Tl values (−5.1 to −7.8) during the main Shuram NCIE interval that approach values more negative than modern global seawater. These results suggest that manganese oxide burial was near or even greater than modern burial fluxes, which is likely linked to an expansion of oxic conditions. This ocean oxygenation may have been an important trigger for the Shuram NCIE and evolution of Ediacaran-type biota. Subsequently, Tl isotopes show an increasing trend from the modern ocean value to values near the modern global inputs or even heavier (ε205Tl ≈ −2.5 ~ 0.4), occurring prior to recovery from the NCIE. These records may suggest that there was a decrease in the extent of oxygenated conditions in the global oceans during the late stage of the Shuram NCIE. © 2020 John Wiley & Sons Ltd
关键词	carbon cycle Ediacaran global ocean isotopic analysis isotopic composition oxygenation perturbation proxy climate record redox conditions thallium water column California China Pacific Ocean Santa Barbara Basin
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/133188
推荐引用方式 GB/T 7714	Fan H.,Nielsen S.G.,Owens J.D.,et al. Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes[J]. Geobiology,2020,18(3).
APA	Fan H..,Nielsen S.G..,Owens J.D..,Auro M..,Shu Y..,...&Wen H..(2020).Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes.,18(3).
MLA	Fan H.,et al."Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes".18.3(2020).