Secular changes in environmental stresses and eukaryotes during the Early Triassic to the early Middle Triassic
Secular changes in environmental stresses and eukaryotes during the Early Triassic to the early Middle Triassic
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DOI：
10.1016/j.palaeo.2016.03.006
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Ryosuke Saito;K. Kaiho;M. Oba;J. Tong;Zhong‐Qiang Chen;S. Takahashi;J. Chen;L. Tian;R. Biswas
中科院分区：
文献类型：
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作者：
Ryosuke Saito;K. Kaiho;M. Oba;J. Tong;Zhong‐Qiang Chen;S. Takahashi;J. Chen;L. Tian;R. Biswas
早三叠纪，在二叠纪末大灭绝之后，是一个生物多样性严重低下的时期。越来越多的证据表明，在二叠纪末大灭绝之后，变化的环境压力是广泛而强烈的。本文报道了华南地区下三叠统至中三叠统地层（青岩剖面和巢湖剖面）的生物标志物，包括环境胁迫生物标志物（2-甲基藿烷指数）和真核藻类生物标志物（甾烷和c21n -烷基苯比值）。利用2-甲基藿烷指数，我们检测了早三叠世大部分时间环境胁迫的持久性。利用甾烷和c21n -烷基苯比值，我们发现真核藻类的生物量在中三叠世早期至早期逐渐增加。中三叠世早期青岩剖面（雷达坡段）环境压力的减小与青岩生物群的“爆发”同步，具有丰富多样的无脊椎海洋动物的特征。由于2-甲基藿烷指数揭示的环境胁迫包含多种因素（如pH和温度），因此我们无法确定当时的确切胁迫；然而，我们的结果反映了在生物完全恢复期间恶劣环境的改善。
The Early Triassic, following the end-Permian mass extinction, was an interval of severe low diversity. Increasing amounts of evidence demonstrate that variable environmental stresses were widespread and intense after the end-Permian mass extinction. Here we report biomarkers from lowest Triassic to lower Middle Triassic strata in South China (Qingyan and Chaohu sections), including biomarkers for environmental stress (2-methyl hopane index) and eukaryotic algae (steranes and C21n-alkylbenzene ratio). Using the 2-methyl hopane index, we detected the persistence of environmental stress during most of the Early Triassic. Using steranes and the C21n-alkylbenzene ratio, we found a gradual increase in the biomass of eukaryotic algae during the Early to early Middle Triassic. A decrease in environmental stress in the Qingyan section (Leidapo Member) during the early Middle Triassic was synchronous with the “explosion” of the Qingyan Biota, which is characterized by a high abundance and diversity of invertebrate marine animals. Because the environmental stresses revealed by the 2-methyl hopane index encompass various factors (e.g., pH and temperature), we cannot identify the exact stresses at that time; however, our results reflect the amelioration of harsh environments for life during the interval of complete biotic recovery.