Collaborative Research: Flood volcanism and environmental impacts--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：瓜达卢普世末期、二叠纪末期、三叠纪-侏罗纪界线、白垩纪-古近纪界线(KPB)--在时间上与大陆溢流玄武岩(CFB)火山作用密切相关。矛盾的是，KPB与德干陷阱CFB和墨西哥尤卡坦的希克苏鲁布撞击有关，引发了一场长达30年的关于因果关系的激烈辩论。德干火山在KPB/CHICXULUB时间之前很久就开始了，并在KPB/CHICXULUB时间之后很久才继续，但最大的德干火山喷发(WAI亚群)似乎是在KPB和CHICXULUB撞击后约5万年内开始的，这表明这一喷发子集可能是由撞击引发的。目前尚不清楚是德干火山的大规模洪灾玄武岩喷发还是希克苏鲁伯撞击(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从地幔羽流到地壳岩浆活动再到喷发和大气/生物圈效应的地球系统相互作用，提高我们对德干火山活动的起源、时间和环境影响的理解。这项研究将包括以下方面：(1)根据物理火山学和地球化学特征，结合对挥发性物质含量的分析，确定德干岩浆作用的成因和地球动力学背景；(2)研究德干圈闭的放射性同位素年代学，以严格限制其喷发速度及其与其他KPB事件的关系；(3)建立地幔和地壳岩浆作用的地球物理模型；(3)德干火山喷发释放挥发物和气溶胶，以及因地震和影响而产生的动态(地震)应力触发火山活动的机制；(4)分析以前未纳入陆地主要地层学的印度西部近海的地球物理勘探数据。这些研究的结果将与其他显生界CFB事件进行比较，其中一些事件是，重要的是，一些事件与大灭绝无关。

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.