白垩纪中期发生过多次大洋缺氧事件（OAE1a、OAE1b、OAE1c、OAE1d、OAE2和OAE3）。这些大洋缺氧事件与火山活动、全球碳循环扰动、极端温室气候密切相关，而且还导致了海洋生物的灭绝和更替，因此受到学术界的广泛关注。然而到目前为止，海水缺氧扩张的具体机制和过程还有很大争议。由于研究区域主要集中在北大西洋和西特提斯，而来自东特提斯和太平洋的报道较少，导致这些大洋缺氧事件的具体影响范围还不确定。海洋硫循环与海水的氧化还原状态、全球碳循环以及气候环境变化息息相关。因此，本项目计划以藏南岗巴和定日地区白垩纪中期的连续沉积地层为研究对象，通过碳酸盐中的微量硫酸盐和沉积黄铁矿的多硫同位素测试分析来重建白垩纪中期东特提斯区域海洋硫循环的演变历程，结合碳、氮同位素数据和生物地层资料进一步深入探索白垩纪中期海水氧化还原状态的变化机制和过程及其与碳循环扰动、极端温室气候、海洋生物演化之间的关系。

The mid-Cretaceous (Aptian-Santonian) witnessed several Oceanic Anoxic Events (OAEs), including OAE1a, OAE1b, OAE1c, OAE1d, OAE2 and OAE3. These OAEs have received widespread attention due to their strong association with volcanic activity, global carbon cycle perturbation, super greenhouse climate, and the extinction and turnover of marine organisms. However, until now, there are still lots of controversy on the mechanism and processes of the expansion of marine anoxia. In recent years, research of mid-Cretaceous OAEs mainly focused on the proto-North Atlantic and western Tethys areas. The spatial extent of anoxia during these OAEs is still unclear due to absence of researches from eastern Tethys and Pacific Ocean. The marine sulfur cycle was closely related to the redox state of the ocean, global carbon cycle, and climate and environment change. Therefore, we plan to measure the multiple sulfur isotopic compositions of the carbonate associated sulfate and sedimentary pyrite of the continuous mid-Cretaceous deposits in Gamba and Tingri area of southern Tibet to reconstruct the mid-Cretaceous marine sulfur cycle in eastern Tethys. By integrating the S-isotopic data with carbon and nitrogen isotopic compositions and the detailed biostratigraphic data, we aim to explore the causes and process of redox changes during mid-Cretaceous and its relation with carbon cycle perturbation, climate change, and evolution of marine organisms.