Yang Chuan, Rooney Alan D, Condon Daniel J, Li Xian-Hua, Grazhdankin Dmitriy V, Bowyer Fred T, Hu Chunlin, Macdonald Francis A, Zhu Maoyan
Geochronology and Tracers Facility, British Geological Survey, Keyworth NG12 5GG, UK.
Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA.
Sci Adv. 2021 Nov 5;7(45):eabi9643. doi: 10.1126/sciadv.abi9643. Epub 2021 Nov 3.
The rise of complex macroscopic life occurred during the Ediacaran Period, an interval that witnessed large-scale disturbances to biogeochemical systems. The current Ediacaran chronostratigraphic framework is of insufficient resolution to provide robust global correlation schemes or test hypotheses for the role of biogeochemical cycling in the evolution of complex life. Here, we present new radio-isotopic dates from Ediacaran strata that directly constrain key fossil assemblages and large-magnitude carbon cycle perturbations. These new dates and integrated global correlations demonstrate that late Ediacaran strata of South China are time transgressive and that the 575- to 550-Ma interval is marked by two large negative carbon isotope excursions: the Shuram and a younger one that ended ca. 550 Ma ago. These data calibrate the tempo of Ediacaran evolution characterized by intervals of tens of millions of years of increasing ecosystem complexity, interrupted by biological turnovers that coincide with large perturbations to the carbon cycle.
复杂宏观生命的崛起发生在埃迪卡拉纪时期，这一时期见证了生物地球化学系统的大规模扰动。当前的埃迪卡拉纪年代地层框架分辨率不足，无法提供可靠的全球对比方案，也无法检验生物地球化学循环在复杂生命演化中所起作用的假说。在此，我们展示了来自埃迪卡拉纪地层的新放射性同位素年代数据，这些数据直接限定了关键化石组合以及大幅度的碳循环扰动。这些新数据和整合后的全球对比表明，华南地区的埃迪卡拉纪晚期地层存在时间穿时现象，并且在5.75亿年至5.5亿年前的时间段内有两次大规模的负碳同位素偏移：舒拉姆偏移以及一次较年轻的偏移，后者大约在5.5亿年前结束。这些数据校准了埃迪卡拉纪演化的节奏，其特征是生态系统复杂性在数千万年的时间里不断增加，期间被与碳循环的大规模扰动同时发生的生物更替所打断。
