Dynamic interplay of biogeochemical C, S and Ba cycles in response to the Shuram oxygenation event
Dynamic interplay of biogeochemical C, S and Ba cycles in response to the Shuram oxygenation event
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DOI：
10.1144/jgs2021-081
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发表时间：
2021-10-26
影响因子：
2.7
通讯作者：
Guan, Chengguo
中科院分区：
文献类型：
--
作者：
Cui, Huan;Kaufman, Alan J.;Guan, Chengguo
与显生宙地层相比，前寒武纪记录中硫酸盐矿物相对较少；这可能是由于主要缺氧的海洋中硫酸盐浓度较低。在此，我们介绍了与埃迪卡拉舒拉姆偏移 (SE) 地层相关的硫酸盐矿物汇编，该偏移是地球历史上最大的负三角洲 C-13 偏移。我们评估了 15 个东南剖面，所有这些剖面都揭示了硫酸盐矿物的存在和/或与碳酸盐相关的硫酸盐浓度的富集，表明硫酸盐储层的上升。值得注意的是，在有数据的情况下，SE 还揭示了相对于 SE 之前和之后的时间间隔，[Ba] 显着丰富。我们认为，SE期间海水硫酸盐浓度升高可能促进了硫酸盐矿物的自生。与此同时，陆架环境中Ba浓度的上升进一步促进了重晶石沉积。较大的硫酸盐储层将刺激微生物硫酸盐还原和有机物（包括甲烷）的厌氧氧化，从而促进SE的形成。整个东南部硫酸盐矿物的存在表明当时氧化剂池并未耗尽，这对之前的建模结果提出了挑战。我们的研究强调了生物地球化学 C、S 和 Ba 循环响应 Shuram 氧化事件的动态相互作用。
Compared with Phanerozoic strata, sulfate minerals are relatively rare in the Precambrian record; this is probably due to the lower concentrations of sulfate in dominantly anoxic oceans. Here, we present a compilation of sulfate minerals that are stratigraphically associated with the Ediacaran Shuram excursion (SE) - the largest negative delta C-13 excursion in Earth history. We evaluated 15 SE sections, all of which reveal the presence of sulfate minerals and/or enriched carbonate-associated sulfate concentrations, suggesting a rise in the sulfate reservoir. Notably, where data are available, the SE also reveals considerable enrichments in [Ba] relative to pre- and post-SE intervals. We propose that elevated seawater sulfate concentrations during the SE may have facilitated authigenesis of sulfate minerals. At the same time, the rise in Ba concentrations in shelf environments further facilitated barite deposition. A larger sulfate reservoir would stimulate microbial sulfate reduction and anaerobic oxidation of organic matter (including methane), contributing to the genesis of the SE. The existence of sulfate minerals throughout the SE suggests that oxidant pools were not depleted at that time, which challenges previous modelling results. Our study highlights the dynamic interplay of biogeochemical C, S and Ba cycles in response to the Shuram oxygenation event.