Global and local drivers of the Ediacaran Shuram carbon isotope excursion
Global and local drivers of the Ediacaran Shuram carbon isotope excursion
复制标题
DOI：
10.1016/j.epsl.2022.117368
复制
发表时间：
2022-01-21
影响因子：
5.3
通讯作者：
Strauss, Justin V.
中科院分区：
文献类型：
--
作者：
Busch, James F.;Hodgin, Eben B.;Strauss, Justin V.
Ediacaran Shuram碳同位素漂移（CIE）发生在Gaskiers冰川作用之后，并且发生在宏观动物化石出现之前。以前对Shuram CIE的解释提出了地球碳循环的全球扰动，伴随着重大的气候和环境变化。这些研究假设碳酸盐碳同位素通过Shuram CIE记录海水中溶解的无机碳的组成。通过对来自四个不同古大陆五个地点的新的地球化学、沉积学和地层学数据的汇编，我们发现所有分析的Shuram CIE序列具有普遍的相似性，包括一个共同的海侵-海退序列，该序列与大量地球化学代理（三角洲C-13、三角洲O-18、三角洲（44）/Ca-40、Sr/Ca、Mn/Sr、U/Ca）的类似变化相一致。尽管这些广泛的相似之处部分之间，有重要的差异，可能与碳酸盐岩成岩作用的变化之间的代理水深。具体来说，我们发现偏移的幅度是最大的斜坡环境中的成岩作用是沉积物缓冲和较小的浅水环境中的流体缓冲成岩作用为主。伴随Shuram CIE的海侵在幅度（类似于10- 100 s m）和持续时间（> 1 My）上与板块重组驱动的海平面波动一致。这些耦合的地球化学和地层观测反对流星和埋藏成岩作用的驱动程序的偏移，相反，他们最好的解释是全球变化的地点和强度的光合初级生产力在浅水环境中，并不一定需要在全球气候或海洋氧化还原的大变化。(C)2022 Elsevier B. V.保留所有权利。
The Ediacaran Shuram carbon isotope excursion (CIE) follows the regional Gaskiers glaciation and occurs before the appearance of macroscopic animal fossils. Previous interpretations for the Shuram CIE have proposed global perturbations to Earth's carbon cycle accompanied by significant climatic and environmental change. These studies assume that carbonate carbon isotopes through the Shuram CIE record the composition of dissolved inorganic carbon in seawater. Through a compilation of new geochemical, sedimentological, and stratigraphic data from five localities on four separate paleocontinents, we find that all of the analyzed Shuram CIE successions share general similarities including a common transgressive-regressive sequence that is coincident with similar shifts in a host of geochemical proxies (delta C-13, delta O-18, delta(44)/Ca-40, Sr/Ca, Mn/Sr, U/Ca). Despite these broad similarities between sections, there are important differences in the proxies between water depths that may be linked to changes in carbonate diagenesis. Specifically, we find the excursion's magnitude is largest in slope environments where diagenesis is sediment-buffered and smaller in shallow-water settings dominated by fluid-buffered diagenesis. The transgression that accompanied the Shuram CIE is consistent in amplitude (similar to 10-100s m) and duration (> 1 My) with eustatic fluctuations driven by plate reorganization. These coupled geochemical and stratigraphic observations argue against meteoric and burial diagenesis as drivers for the excursion; instead, they are best explained by global changes to the locus and intensity of photosynthetic primary productivity in shallow-water environments and do not necessarily require large changes in global climate or marine redox.(C) 2022 Elsevier B.V. All rights reserved.