50 Myr recovery from the largest negative δ13C excursion in the Ediacaran ocean
50 Myr recovery from the largest negative δ13C excursion in the Ediacaran ocean
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DOI：
10.1111/j.1365-3121.2006.00674.x
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发表时间：
2006-04
期刊：
影响因子：
2.4
通讯作者：
E. Guerroué;P. Allen;A. Cozzi;J. Etienne;M. Fanning
中科院分区：
文献类型：
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作者：
E. Guerroué;P. Allen;A. Cozzi;J. Etienne;M. Fanning
埃迪卡拉纪(∼630-542Ma)沉积的沉积岩中含有碳酸盐，其碳同位素比值表现出明显的负漂移，从+5‰急剧下降到−12‰，然后次线性恢复到正δ13C值。同位素年龄(U/Pb)和热沉陷模拟相结合，以限制时间上的漂移，并表明开始于∼600 Ma，恢复持续时间约为50Myr。这种漂移在阿曼得到了广泛的认可，并在其他地方的埃迪卡拉纪地层中具有潜在的相关性，因此可能代表了埃迪卡拉期的一个特征。这种碳同位素漂移的幅度远远超过其他新元古代异常。负漂移和长期恢复的同位素趋势至少跨越了一次短暂的冰期(580 Ma)，但似乎与冰川作用无关，这表明新元古代海洋碳同位素记录中的负异常与冰期没有直接或唯一的联系。
Sedimentary rocks deposited during the Ediacaran period (∼630–542 Ma) contain carbonates whose carbon isotopic ratios show a marked negative excursion consisting of a precipitous drop from +5‰ to −12‰, followed by a sub‐linear recovery to positive δ13C values. Isotopic ages (U/Pb) and thermal subsidence modelling are combined to constrain the excursion in time and indicate an onset at ∼600 Ma, and duration of recovery of approximately 50 Myr. The excursion is widely recognized in Oman and has potential correlatives in Ediacaran strata elsewhere, and may thus represent a characteristic feature of the Ediacaran period. The amplitude of this carbon isotope excursion far exceeds those of other Neoproterozoic anomalies. The isotopic trend of negative excursion and long‐term recovery spanned at least one short‐lived glacial episode (at 580 Ma), but appears unrelated to glaciation, which indicates that negative anomalies in the Neoproterozoic marine carbon isotope record are not directly or uniquely linked to ice ages.