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Mechanisms and Effects of the Toarcian Oceanwide Anoxic Event

托阿尔克全洋缺氧事件的机制和影响

基本信息

批准号：
212888374
负责人：
Professor Dr. Lorenz Schwark
金额：
--
依托单位：
Department of Earth Sciences
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/212888374?language=en
关键词：
Mechanisms Effects Toarcian Oceanwide Anoxic

项目摘要

Geologic events help understanding geobiosphere evolution and serve predicting future development. The first critical Mesozoic geoevent in the Toarcian (T-OAE) is characterized by mass extinctions, oceanwide anoxia, and C-isotope excursions indicating perturbations of atmospheric and marine biochemical cycles. Trigger mechanisms are heavily disputed and the spatial extent of the T-OAE, either restricted to the NW-Tethys or of global nature is under debate. Key factors comprise release of gas hydrates, Karoo volcanism and anoxia caused by global transgression. Only in the Yorkshire Basin a tripartite isotope excursion linked to three extinction events could yet be proven. Here, molecular biomarker study, revealing relations between biotic changes, redox milieu and isotope shift, is limited by advanced thermal maturity. In the SW-German Basin, where detailed molecular geochemistry is feasible, a high-resolution C-isotope approach is excluded by methanogenesis affecting the C-isotope cycle. On the edge of the Paris Basin a section is available in Luxembourg, for high-resolution molecular biomarker and C-isotope dual study. Here, lag times between biotic or redox shifts and isotope response or vice versa can be studied at unprecedented resolution. Ocean acidification by massive CO2 emission upon the T-OAE seems to have caused coccolith corrosion. The global character of the T-OAE will be studied by molecular geochemistry via a section from the Pacific Queen Charlotte Island revealing a pronounced C-isotope excursion. This dual methodological and geospatial approach offers the ultimate potential of unraveling the nature of the T-OAE.

地质事件有助于理解地球生物圈的演化，并有助于预测未来的发展。托阿尔新世中生代第一次重大地质事件(T-OAE)以生物灭绝、全洋缺氧和碳同位素漂移为特征，表明大气和海洋生物化学循环的扰动。触发机制存在严重争议，T-OAE的空间范围，无论是局限于西北特提斯还是全球性质，都在争论中。关键因素包括天然气水合物的释放、卡鲁火山作用和全球海侵造成的缺氧。只有在约克郡盆地，才能证明与三次物种灭绝事件有关的三方同位素漂移。在这里，揭示生物变化、氧化还原环境和同位素位移之间关系的分子生物标志物研究，受到高级热成熟度的限制。在西南部-德国盆地，详细的分子地球化学是可行的，高分辨率的碳同位素方法被影响碳同位素循环的甲烷化作用排除在外。在巴黎盆地的边缘，卢森堡有一块可用来进行高分辨率分子生物标志物和碳同位素双重研究的剖面。在这里，可以以前所未有的分辨率研究生物或氧化还原位移和同位素响应之间的滞后时间。T-OAE上大量排放的二氧化碳造成的海洋酸化似乎导致了球石的腐蚀。T-OAE的全球特征将通过来自太平洋女王夏洛特岛的一部分分子地球化学进行研究，该部分揭示了显著的碳同位素漂移。这种双重方法和地理空间方法为揭示T-OAE的性质提供了最终的潜力。