Ocean acidification and biocalcification crisis at the Triassic-Jurassic boundary

三叠纪-侏罗纪边界大灭绝事件（Tr-J; 199.6 Ma）的成因仍知之甚少。一种流行的灭绝设想是，从大量洪水玄武岩流出的大量挥发物（CO2, SO2）的释放。洪水玄武岩火山作用在Tr-J灭绝中所起作用的证据包括：(1)植物叶片口孔记录的pCO2快速上升4倍；(2)碳酸盐和有机碳库中同时出现的大量负碳同位素漂移；(3)许多海洋和陆地生物群的灭绝和更替是渐进的，而不是灾难性的。与预测的人为CO2排放对海洋化学的影响类似，可以假设pCO2快速显著增加的一个主要后果是海洋表面酸化（pH值降低），从而导致碳酸盐饱和度降低（[co32]降低），从而导致生物钙化危机。事实上，浅海产碳酸盐生物，如两性核珊瑚、双壳类和球石类，在最近的雷蒂亚期显示出一些最高的灭绝率，在Tr-J界线之后的几百万年里，世界范围内的珊瑚礁建设被破坏了。此外，早侏罗世似乎标志着在文石海占优势时期，在浅海环境中广泛沉积方解石的短暂插曲。由于生物源碳酸盐生产的停止，碱度的增加可能是由非生物源碳酸盐沉淀介导的，其形式是广泛沉积的方解石、低镁方解石海洋胶结物和/或广泛沉积的泥晶沉淀物和微生物岩。本研究项目的目的是通过详细研究南阿尔卑斯山、莱西尼山脉和喀尔巴阡山脉的特提斯山脉南北边缘的Tr-J边界剖面，为这一假设的生物钙化危机寻找沉积学和地球化学证据。收集到的结果将作为进一步发展未来研究项目的试点研究。

Causes for the Triassic-Jurassic boundary mass-extinction event (Tr-J; 199.6 Ma) remain poorly understood. One popular extinction scenario envisions a role for the massive release of volatiles (CO2, SO2) from the outflow of voluminous amounts of flood basalt. Evidence for a role of flood basalt volcanism in Tr-J extinctions include: (1) a rapid four-fold rise in pCO2, documented by plant leaf stomata, (2) simultaneous, large negative carbon isotope excursions in carbonate and organic carbon pools and (3) gradual, rather than catastrophic, extinctions and turnover in many groups of marine and terrestrial biota. In analogy with the predicted impact of anthropogenic CO2 emissions on ocean chemistry, it can be hypothesized that a major consequence of a rapid and significant increase in pCO2 is the acidification of the surface ocean (pH decrease) and hence a decrease in carbonate saturation ([CO3 2 ] decrease), leading to a biocalcification crisis. Indeed, shallow marine carbonate-producing organisms, such as hermatypic scleractinian corals, bivalves and coccolithophorids, show some of the highest extinction rates during the latest Rhaetian, and reef building was disrupted worldwide for several million years after the Tr-J boundary. Furthermore, the Early Jurassic appears to mark a brief interlude of extensive calcite deposition in shallow marine settings during a time of predominant Aragonite Seas. In response to a halt in biogenic carbonate production, increased alkalinity may have been mediated by abiogenic carbonate precipitation in the form of widespread deposition of calcite ooids, low-magnesium calcite marine cements and/or microbially in the form of extensive micritic precipitates and microbialites. The aim of this research project is to find sedimentological and geochemical evidence for this hypothesized biocalcification crisis by studying in detail Tr-J boundary sections along the northern and southern margins of the Tethys in the Southern Alps, Lessini Mountains and Carpathian Mountains. The gathered results will serve as a pilot study for the further development of future research projects.