Global mercury cycle during the end-Permian mass extinction and subsequent Early Triassic recovery
Global mercury cycle during the end-Permian mass extinction and subsequent Early Triassic recovery
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二叠纪末大规模灭绝期间的全球汞循环以及随后的三叠纪早期恢复
DOI：
10.1016/j.epsl.2019.02.026
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发表时间：
2019
影响因子：
5.3
通讯作者：
Zhang Lei
中科院分区：
文献类型：
--
作者：
Wang Xiangdong;Cawood Peter A.;Zhao He;Zhao Laishi;Grasby Stephen E.;Chen Zhong-Qiang;Zhang Lei
二叠纪末生物大灭绝（EPME）发生在距今252 Ma，是中生代最严重的生物大灭绝。被EPME破坏的海洋生态系统有一个非常长的恢复，并没有实质性的恢复，直到下三叠统的Smithian-Spathian亚阶段边界（SSB）（5至9 Ma后的EPME）。虽然西伯利亚圈闭大火成岩省（STLIP）被认为是大灭绝的驱动力，但对于早三叠世长期恢复的原因仍然存在争议;尽管已经提出了新的STLIP火山作用。然而，这些先前的研究是根据沉积在北方纬度环境中的沉积物的地球化学记录得出结论的。为了在全球范围内研究STLIP与灭绝/恢复过程之间的关系，我们研究了南纬度高纬度地区和赤道剖面的汞化学地层学，包括汞浓度和同位素，这些剖面跨越晚二叠世长兴阶至早三叠世斯帕西阶亚阶序列;印度北方克什米尔的古尔尤尔峡谷剖面和中国南部的巢湖剖面。有机和无机碳同位素数据分别确定了巢湖剖面的EPME层位和Guryul Ravine剖面的SSB。Hg/TOC值急剧升高接近EPME地平线，并保持高值，直到较低的Isarcicella Isarcica牙形刺带，该基地被认为是大规模灭绝的结束。在地层上覆层中，Hg/TOC通常显示较低的值，在两个剖面上略有波动。这些波动可能与早三叠世强烈的化学风化作用引起的陆源汞流入量增加有关，如Hg和Al含量之间的正相关性以及早三叠世样品中较不积极的Δ 199 Hg值所示。我们的数据，提出了第一个南半球汞记录从Guryul沟，结合以前的结果，表明异常高汞沉积在EPME发生全球。此时的Δ 199 Hg值通常为正值，反映了大气汞，与我们认为表明STLIP喷发的全球影响的火山汞源一致。相比之下，没有证据表明，全球汞/TOC异常在旷日持久的早三叠世生物复苏，这表明，潜在的更新STLIP火山活动只有北方半球的全球汞循环的影响。这种有限的影响，可能仍然在延迟早三叠世恢复中发挥了作用。
The end-Permian mass extinction (EPME) at∼ 252 Ma was the most severe extinction in the Phanerozoic. Marine ecosystems devastated by the EPME had a highly prolonged recovery, and did not substantially recover until after the Smithian–Spathian substage boundary (SSB) of the Lower Triassic (5 to 9 Ma after the EPME). While the Siberian Traps large igneous province (STLIP) has been invoked as the driver of the mass extinction, there remains controversy as to the cause of the protracted Early Triassic recovery; although renewed STLIP volcanism has been suggested. These previous studies though have drawn conclusions based on geochemical records of sediments deposited in northern latitude settings. To investigate the relationship between STLIP and extinction/recovery processes on a global base, we examined mercury chemostratigraphy, including mercury concentrations and isotopes, from high southern latitude and equatorial sections that span the Late Permian Changhsingian to Early Triassic Spathian substage successions; the Guryul Ravine section, Kashmir in northern India, and the Chaohu section in southern China. Organic and inorganic carbon-isotope data define the EPME horizon in the Chaohu section and the SSB in the Guryul Ravine section, respectively. Hg/TOC values are dramatically elevated approaching the EPME horizon and maintain high values until the lower Isarcicella Isarcica conodont zone, the base of which is believed to be the end of the mass extinction. In the stratigraphically overlying beds, Hg/TOC generally displays lower values with slight fluctuations through the two sections. These fluctuations are likely related to the increased terrestrial Hg influx associated with strong chemical weathering in the Early Triassic, as shown by a positive correlation between the contents of Hg and Al, and by less positive Δ 199 Hg values in Early Triassic samples. Our data, presenting the first Southern Hemisphere Hg record from Guryul Ravine, in combination with previous results, indicates that anomalous high mercury deposition at the EPME occurred globally. The generally positive Δ 199 Hg values at this time reflects atmospheric-derived Hg, consistent with a volcanic Hg source which we suggest indicates global impact of STLIP eruption. In contrast, there is no evidence for a global Hg/TOC anomaly during the protracted Early Triassic biotic recovery, suggesting that potentially renewed STLIP volcanism had only a northern hemisphere influence on the global Hg cycle. This more limited impact, may still have played a role in the delayed Early Triassic recovery.