Early Cambrian basin in South China has deposited successive sedimentary rocks, which not only recorded geochemical information of the variation of palaeo-ocean environment, but also preserved fossils of most phyla of modern animals, such as the large-body Chengjiang and Qingjiang biotas. Although the relation between gradually oxic Cambrian Ocean and biotic diversity is recognized, the temporal and spatial variations of redox condition, as well as the influence of the variations on the biotic evolution during the early Cambrian, remain unclear. Here, we focus on all of the early Cambrian sedimentary rocks deposited in inner-shelf, outer-shelf, slope, and deep basin in the South China Block. According to the geochemical datasets, such as iron speciation, major- and trace element, Hg contents and Hg isotopic data, we have summarized and discussed the changing of marine redox condition, hydrothermal activity and basin restriction during the Cambrian Terreneuvian to the early Cambrian Age 3. In the early Cambrian Terreneuvian, oxic environment appeared in the inner shelf facies, accompanied by the occurrence of small shelly fossils. Then, hydrothermal activities occurred in the center South China block of the outer-shelf and slope facies with a ferruginous environment in the late Terreneuvian and early Cambrian Age 3. However, the water column in the block margin of this two facies was euxinic during this period. In the early Cambrian Age 3, oxic water column had expanded to the slope and deep basin facies. Based on the compiled data, we propose that strong hydrothermal activities had provided abundant of Fe and other nutrients, and terrigenous inputs which also provided amounts of terrigenous sulfur that led to distinct environments in the slope facies. In the early Cambrian Age 3, the expanding oxic water column and nutrients after the hydrothermal activities stimulated the evolution of the biological diversity together, such as the Qingjiang and Chengjiang biotas. These variations highlight the effects of redox condition and hydrothermal activities on the biotic flourish of the early Cambrian.

中文翻译：

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华南早寒武世沉积岩：海洋氧化与生物爆炸之间的联系

华南早寒武世盆地沉积了连续的沉积岩，不仅记录了古海洋环境变化的地球化学信息，还保存了大型澄江生物群、清江生物群等现代动物大部分门类的化石。尽管寒武纪海洋逐渐含氧与生物多样性之间的关系已被认识，但寒武纪早期氧化还原条件的时空变化，以及这种变化对生物进化的影响仍不清楚。在此，我们重点关注华南地块内陆架、外陆架、斜坡和深盆地沉积的早寒武世沉积岩。根据铁形态、主微量元素、Hg含量、Hg同位素等地球化学数据，总结讨论了寒武纪陆生期至寒武纪早期海洋氧化还原条件、热液活动和盆地限制的变化。 3、早寒武世陆地相,内陆架相出现好氧环境,并伴有小贝壳化石的产出。此后，华南地块中部的外陆架相和斜坡相在晚地热世和早寒武世3期发生了铁质环境的热液活动，而这两个相的地块边缘水柱在此期间为常生水柱。时期。寒武纪3早期，含氧水柱已向斜坡相和深盆相扩展。根据汇编的数据，我们认为强烈的热液活动提供了丰富的铁和其他营养物质，以及陆源输入，也提供了大量的陆源硫，导致斜坡相的独特环境。寒武纪第三纪早期，热液活动后不断扩大的含氧水体和营养物质共同刺激了生物多样性的演化，如清江生物群和澄江生物群。这些变化凸显了氧化还原条件和热液活动对寒武纪早期生物繁荣的影响。