Wei Wei, Dong Lin-Hui, Xiao Shuhai, Lin Yi-Bo, Xu Lingang, Wei Guang-Yi, Wang Wenzhong, Tian Lan-Lan, Wei Hai-Zhen, Huang Fang
State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei 230026, China.
Natl Sci Rev. 2024 Jul 9;11(8):nwae237. doi: 10.1093/nsr/nwae237. eCollection 2024 Aug.
An increase in atmospheric O has been proposed as a trigger for the Cambrian Explosion at ∼539-514 Ma but the mechanistic linkage remains unclear. To gain insights into marine habitability for the Cambrian Explosion, we analysed excess Ba contents (Ba) and isotope compositions (δBa) of ∼521-Myr-old metalliferous black shales in South China. The δBa values vary within a large range and show a negative logarithmic correlation with Ba, suggesting a major (>99%) drawdown of oceanic Ba inventory via barite precipitation. Spatial variations in Ba and δBa indicate that Ba removal was driven by sulfate availability that was ultimately derived from the upwelling of deep seawaters. Global oceanic oxygenation across the Ediacaran-Cambrian transition may have increased the sulfate reservoir via oxidation of sulfide and concurrently decreased the Ba reservoir by barite precipitation. The removal of both HS and Ba that are deleterious to animals could have improved marine habitability for early animals.
大气中氧气的增加被认为是约5.39 - 5.14亿年前寒武纪大爆发的触发因素，但其中的机制联系仍不清楚。为深入了解寒武纪大爆发时期的海洋宜居性，我们分析了中国南方约5.21亿年前的含金属黑色页岩中的过剩钡含量（Ba）和同位素组成（δBa）。δBa值在很大范围内变化，并与Ba呈现负对数相关，这表明通过重晶石沉淀，海洋钡储量大幅（>99%）减少。Ba和δBa的空间变化表明，钡的去除是由硫酸盐的可用性驱动的，而硫酸盐最终来源于深层海水的上升流。埃迪卡拉纪 - 寒武纪过渡时期全球海洋的氧合作用可能通过硫化物的氧化增加了硫酸盐储库，同时通过重晶石沉淀减少了钡储库。去除对动物有害的HS和Ba可能改善了早期动物的海洋宜居性。
