Tracing continental weathering during the Permo-Triassic extinction event (WET)

大陆风化是地球气候系统中的一个重要变量，也是影响海洋-大气和地球化学循环过程的一个关键组成部分。大陆硅酸盐的化学风化消耗大气中的二氧化碳，并作为一个有效的气候控制过程。此外，风化将碳酸盐和金属离子带入世界海洋，对海洋pH值、碱度和营养供应产生影响。然而，风化随时间的演变及其对与气候变化有关的外部强迫的反应仍然缺乏制约。在大规模灭绝时期，地球经历了深刻的生物变化和极端的环境扰动，大陆化学风化往往被列为影响碳循环的主要环境因素。二叠纪-三叠纪事件是中生代最大规模物种灭绝的直接原因，人们对此存在广泛争议，但人们认为，西伯利亚火山活动中大量快速释放的二氧化碳脉冲引发了海水酸化，全球变暖，并通过增加大陆排放和营养输入的温室条件，海洋缺氧，提出了物种灭绝的机制。为了记录风化作用作为气候控制过程的作用，并调查大陆风化、缺氧和营养循环之间的联系，我们的目标是从特提斯洋沿着不同大陆边缘沉积的特征良好的海洋碳酸盐中产生高分辨率的锂、镁、钙和锶同位素剖面。每个同位素体系都可以约束不同的和离散的风化过程的同位素指纹。结合起来，这些同位素代理将允许描绘大陆风化和海洋碱度的变化，并将提供更好的见解如何二叠纪-三叠纪环境的演变和风化如何帮助推动海洋-大气化学的变化。我们的样本将由其他参与科学家同时进行评估，以获得更多的替代数据和生物后果，从而生成关于营养物质可用性、生产力和缺氧及其作为气候相关压力源对生态系统的影响的关键生物地球化学信息。

Continental weathering is a critical variable in Earth’s climate system and a key component of the processes influencing ocean-atmosphere and biogeochemical cycling. Chemical weathering of continental silicates consumes atmospheric carbon dioxide and acts as an effective climate control process. In addition, weathering delivers carbonate and metal ions into the world’s oceans with implications for ocean pH, alkalinity, and nutrient supply. The evolution of weathering through time and its response to external forcing related to changes in climate remains, however, poorly constrained. At times of mass extinction, where the Earth witnessed profound biological changes and experienced extreme environmental perturbations, continental chemical weathering is often listed as a main environmental factor influencing the carbon cycle. The direct cause of the greatest mass extinction of the Phanerozoic, the Permo-Triassic event, is widely debated, but a pulse of massive and rapid release of carbon dioxide from Siberian Trap volcanism is thought have triggered seawater acidification, global warming and, through increased greenhouse conditions with elevated continental discharge and nutrient input, marine anoxia, proposed mechanisms for species extinction. To document the role of weathering as a climate control process, and to investigate the link between continental weathering, anoxia and nutrient cycling, we aim to produce high resolution lithium, magnesium, calcium and strontium isotope profiles from well-characterized marine carbonates deposited along distinct continental margins of the Tethyan ocean. Each isotope system can constrain distinct and discrete isotopic fingerprints of weathering processes. In combination, these isotope proxies will allow delineating changes in continental weathering and ocean alkalinity and will provide improved insights into how the Permo-Triassic environment evolved and how weathering helped driving changes in ocean-atmosphere chemistries. Our samples will be concurrently evaluated by other participating scientists for additional proxy data and biological consequences to generate key biogeochemical information on nutrient availability, productivity and anoxia and their impact as climate-related stressors to ecosystems.