Collaborative Research: Flood volcanism and environmental impacts -- A multidisciplinary investigation of the Deccan Traps and events at the Cretaceous-Paleogene boundary

越来越多的证据表明，最近的四次大灭绝事件：瓜德鲁普末期；二叠纪;三叠纪-侏罗纪大边界;白垩纪-古近纪界线（KPB）在时间上与陆相洪水玄武岩（CFB）火山作用密切相关。矛盾的是，KPB与德干地堡CFB和墨西哥尤卡坦的希克苏鲁伯撞击有关，这引发了一场持续了30年的关于因果关系的激烈争论。德干火山活动早在KPB/希克苏鲁伯时期之前就开始了，并在之后持续了很长时间，但最大的德干火山喷发（Wai亚群）似乎是在KPB和希克苏鲁伯撞击后约5万年开始的，这表明这一亚群的喷发可能是由撞击引发的。目前尚不清楚大的德干洪水玄武岩喷发或希克苏鲁伯撞击（或两者兼而有之）是KPB灭绝的原因，因为两者都可能向大气中注入了大量的挥发物、气溶胶和微粒。该项目的研究将通过考虑地幔柱对流、地壳岩浆活动、火山喷发和大气/生物圈效应等地球系统相互作用，提高我们对德干圈层火山活动的成因、时间和环境影响的理解。研究内容包括：(1)基于物理火山学和地球化学特征，结合挥发物含量分析，研究德干岩浆活动的成因和地球动力学背景；(2)德干圈闭的放射性同位素年代学，以严格约束其喷发速度及其与其他KPB事件的关系；(3)地幔和地壳岩浆过程的地球物理模拟，德干火山喷发释放的挥发物和气溶胶，以及地震和冲击引起的动力（地震）应力触发火山的机制；(4)分析印度西部近海的地球物理勘探资料，这些资料以前没有被整合到德干陆地主要地层中。这些研究结果将与其他显生宙CFB事件进行比较，其中一些与大灭绝有关，更重要的是，有些与大灭绝无关。

Increasing evidence suggests that the four most recent mass extinction events: end-Guadalupian; end-Permian; Triassic-Jurassic boundary; Cretaceous-Paleogene boundary (KPB)- are closely associated in time with continental flood basalt (CFB) volcanism. Paradoxically, the KPB is associated with both the Deccan Traps CFB and the Chicxulub impact in Yucatan, Mexico, engendering an intense three-decades-old debate over causal relationships. Deccan volcanism began well before and continued well after KPB/Chicxulub time, but the largest Deccan eruptions (Wai Sub-group) appear to have been initiated within ~50,000 years of both the KPB and the Chicxulub impact, suggesting that this subset of eruptions may have been triggered by the impact. It remains unclear whether large Deccan flood basalt eruptions or the Chicxulub impact (or both) were the cause of the KPB extinction, because both may have injected massive amounts of volatiles, aerosols, and particulates into the atmosphere. This project's research will improve our understanding of the genesis, timing, and environmental effects of Deccan Traps volcanism by considering Earth systems interactions from mantle plume convection to crustal magmatism to eruption and to atmosphere/biosphere effects. The research will include studies of: (1) The genesis and geodynamic context of Deccan magmatism based on physical volcanology and geochemical signatures, coupled with analysis of volatile contents; (2) Radioisotopic geochronology of the Deccan Traps to tightly constrain their eruptive tempo and relation to other KPB events; (3) Geophysical modeling of mantle and crustal magmatic processes, launching of volatiles and aerosols by the Deccan eruptions, and mechanisms of volcanic triggering by dynamic (seismic) stresses due to earthquakes and impacts; (4) Analysis of geophysical exploration data from offshore western India that has not previously been integrated into the main on-land Deccan stratigraphy. Results of these studies will be compared with other Phanerozoic CFB events, some of which are and, importantly, some of which are not associated with mass extinction.