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.

中文翻译：

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利用th同位素限制华南舒兰姆游览期间的海洋氧合作用。

Ediacaran沉积物记录了一个异常的全球碳循环扰动，该扰动与广泛的海洋氧合作用，即Shuram负C同位素偏移（NCIE）有关。但是，由于代理人的特殊性（例如，Mo和U同位素的富余沉积物），在此事件期间基于代理人的全球海洋氧化还原条件的估算受到很大限制。现代全球海水文档均匀铊同位素组成（ε ²⁰⁵被记录在现代euxinic沉积物TL = -6.0）由于显著氧化锰埋葬。在这里，我们提供了新的数据，说明该沉积物沉积减少，但距离圣巴巴拉盆地非硫化物水柱下（ε ²⁰⁵Tl = -5.6±0.1）还忠实地捕获了全球海水T1同位素值。因此，T1同位素的替代利用可以扩展到严格的多氧环境之外。其次，为了更好地约束Shuram NCIE期间的全球氧化还原条件，我们测量了华南上图山托组上部局部富油和铁质页岩的Tl同位素。的ε ²⁰⁵这些页岩的T1值表现出从≈-3有减少的趋势，以≈-8，与Shuram NCIE的发作大致重合。有ε ²⁰⁵在Shuram NCIE主间隔期间的Tl值（-5.1至-7.8）比现代全球海水更接近负值。这些结果表明，氧化锰的埋藏量接近或什至大于现代埋葬量，这可能与有氧条件的扩大有关。海洋氧合可能是Shuram NCIE和Ediacaran型生物群进化的重要诱因。随后，铊同位素示出了增加从现代海洋值值附近的现代全局输入或更重的趋势（ε ²⁰⁵铊≈-2.5〜0.4）之前，从所述NCIE恢复发生。这些记录可能表明，在Shuram NCIE后期，全球海洋中的含氧条件有所减少。