SGER: Deccan Volcanism Implicated in K-T Mass Extinction

德干火山活动的生物效应及其对K-T大灭绝的潜在影响可能是目前K-T研究中尚未解决的主要问题。最近的研究表明，德干圈闭喷发的大部分（80%）发生在磁极C29r小于0.8 m.y.的范围内，跨越了白垩纪-第三纪（K-T）边界，最后一次喷发发生在大旦纪早期的C29n。这两个德干圈闭形成了最长的熔岩流，绵延1000公里，穿过印度，流入孟加拉海。然而，确定在C29r主要喷发阶段K-T大灭绝发生的位置仍然存在问题，因为圈闭间沉积物通常沉积在河流或河口环境中，这提供了较差的年龄控制。因此，估计德干火山活动的生物和环境后果的模型通常低估了德干气体排放的速度和数量，从而得出火山活动不可能导致K-T大灭绝的结论。PIs对印度东南部Krishna-Godavari盆地浅海层序的圈闭间沉积物的初步研究表明，德干C29r火山大爆发结束于K-T大灭绝，这表明火山作用和撞击可能是造成这次大灾难的原因。本项目拟研究C29n期德干火山活动主要阶段的开始、持续时间和结束及其对海洋生物的影响，以及恐龙灭绝和C29n期火山活动及其与大年纪早期生物恢复的关系。具体来说，他们将测试两个假设：(1)德干火山作用在K-T大灭绝中发挥了关键作用；(2)德干火山作用对大灭绝后延迟已久的生物恢复负有责任。他们最初发现德干火山的主要阶段结束于K-T大灭绝（Rajahmundry和Meghalaya），并通过分析新的岩心，恢复了两个最长的德干圈闭熔岩流的表间和表下沉积物，计划通过这些发现来实现这一目标。这个项目的结果可能会通过直接将大灭绝与大火成岩省联系起来，为有争议的大灭绝辩论打开潜在的变革性研究思路。这项研究是与美国国家科学基金会国际科学与工程办公室共同资助的。

The biotic effects of Deccan volcanism and its potential impact on the K-T mass extinction are perhaps the major unsolved problems in K-T studies today. Recent studies indicate that the bulk (80%) of the Deccan trap eruptions occurred over less than 0.8 m.y. in magnetic polarity C29r spanning the Cretaceous-Tertiary (K-T) boundary and that the last Deccan eruption occurred in the early Danian C29n. These two Deccan Traps form the longest lava flows extending 1000 km across India and out to the Sea of Bengal. However, determining just where within the C29r major eruptive phase the K-T mass extinction occurred has remained problematic because intertrappean sediments were generally deposited in fluvial or estuarine environments, which provide poor age control. As a result, models estimating the biotic and environmental consequences of Deccan volcanism have generally underestimated the rate and quantity of Deccan gas emissions by orders of magnitude leading to conclusions that volcanism could not have caused the K-T mass extinction. PIs preliminary investigations of the intertrappean sediments in shallow marine sequences of the Krishna-Godavari Basin in SE India revealed that the major Deccan C29r volcanic eruptions ended at the K-T mass extinction, which suggests that volcanism and impact(s) may have caused this catastrophe.In this project PIs propose to investigate the onset, duration and end of the main phase of C29r Deccan volcanism and its biotic consequences in the marine realm as well as the dinosaur extinction and C29n volcanism and its relationship to the long delayed early Danian biotic recovery. Specifically, they will test two hypotheses: (1) Deccan volcanism played a crucial role in the K-T mass extinction, and (2) Deccan volcanism is responsible for the long-delayed biotic recovery after the mass extinction. PIs plan to accomplish this by building on their initial discovery that the main Deccan volcanic phase ended at the K-T mass extinction (Rajahmundry and Meghalaya) and by analyzing new drill cores that recover intertrappean and infratrappean sediments of the two longest Deccan Trap lava flows. The results of this project may open the contentious mass extinction debate to potentially transformative research ideas by directly linking mass extinctions to large igneous provinces.This research is jointly funded with NSF's Office of International Science and Engineering.