Correlating continental flood basalt volcanism, environmental change, and mass extinction events at high resolution using novel geochemical proxies in sediments

大陆溢流玄武岩火山作用被认为在地球历史上所有五次最大的大规模喷发中发挥了作用。然而，我们对火山活动如何导致环境变化导致大规模灭绝的理解受到难以确定这些事件的精确时间的阻碍，这些事件发生在1万到10万年的时间尺度上。富含火山气体的挥发性微量元素，在洪水玄武岩火山活动期间注入大气，后来沉积在沉积物中，可能在不到数万年的时间尺度上将这些过程联系起来，超出了放射性测年的分辨率。以前，沉积物中的汞（Hg）浓度一直被用作过去火山活动的代表。我们最近的工作表明，沉积岩中的碲（Te）和硒（Se）可能是火山活动的更敏感和可靠的指标。该项目将测量二叠纪-三叠纪和白垩纪-古近纪界线的沉积物剖面中的微量元素（包括汞、碲和硒），以便将西伯利亚和印度（德干）的溢流玄武岩火山活动分别与保存在同一沉积物中的环境变化和灭绝记录联系起来，分辨率为几万年。对于白垩纪-古近纪，我们还将能够确定德干火山脉冲相对于希克苏鲁布撞击事件的时间，并测试最近的假设，即撞击引发了最大的德干火山爆发。

Continental flood basalt volcanism is thought to have played a role in all five of the largest mass extinctions in Earth history. However, our understanding of how volcanism causes environmental change leading to mass extinction is hampered by difficulty determining the precise timing of these events, which occurred over 10 to 100 thousand-year timescales. Volatile trace elements which are enriched in volcanic gas, injected into the atmosphere during flood basalt volcanism, and later deposited in sediments can potentially link these processes at timescales of less than a few tens of thousands of years, beyond the resolution of radiometric dating. Previously, mercury (Hg) concentrations in sediments have been used as a proxy for past volcanism. Our recent work has shown that tellurium (Te) and selenium (Se), in sedimentary rocks may be more sensitive and reliable proxies for volcanism. This project will measure trace elements (including Hg, Te and Se) in sediment profiles across the Permian – Triassic and Cretaceous – Paleogene boundaries, in order to link flood basalt volcanism in Siberia and in India (Deccan) respectively, with the record of environmental change and extinction preserved in the same sediments, at a resolution of a few tens of thousands of years. For the Cretaceous – Paleogene, we will also be able to determine the timing of Deccan volcanic pulses relative to the Chicxulub impact event, and test the recent hypothesis that the impact triggered the largest Deccan eruptions.