Mechanisms and Effects of the Toarcian Oceanwide Anoxic Event

地质事件有助于了解地球生物圈的演化，有助于预测未来的发展。陶拉纪的第一个中生代关键地质事件（T-OAE）以大规模物种灭绝、全海洋缺氧和c同位素漂移为特征，表明大气和海洋生物化学循环受到扰动。触发机制存在很大争议，T-OAE的空间范围，无论是仅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引起的缺氧。只有在约克郡盆地，与三次灭绝事件有关的三方同位素偏移还有待证实。在此，揭示生物变化、氧化还原环境和同位素变化之间关系的分子生物标志物研究受到热成熟度超前的限制。在西南-德国盆地，详细的分子地球化学是可行的，但由于甲烷生成影响c同位素循环，高分辨率的c同位素方法被排除在外。在巴黎盆地的边缘，卢森堡有一段可用于高分辨率分子生物标志物和c -同位素双重研究。在这里，生物或氧化还原位移与同位素响应之间的滞后时间或反之亦然，可以以前所未有的分辨率进行研究。在T-OAE上大量CO2排放引起的海洋酸化似乎造成了岩芯腐蚀。分子地球化学将通过太平洋夏洛特女王岛剖面研究T-OAE的整体特征，揭示出明显的c同位素偏移。这种双重方法和地理空间方法提供了揭示T-OAE本质的最终潜力。

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.