How hot was the Jurassic Greenhouse climate?

对地球历史上温暖时期的研究有助于深入了解气候系统在二氧化碳和温度升高下的行为。其中一个这样的间隔是侏罗纪，大气中的二氧化碳浓度接近目前的浓度约400 ppm或更高。这个温暖世界的一个重要特征是存在大型陆表海航道，如北美中晚侏罗世圣丹斯海（例如Danise等人，2020年）。最大的时候，圣丹斯海从犹他州一直延伸到北冰洋。这些大型的陆表海航道是我们关于古代海洋气候和生物多样性的许多信息的主要来源。然而，越来越多的证据表明，由于水体、深度、盐度和分层的变化，这些航道往往与公海条件脱钩，是缺氧的场所。因此，了解这些系统是至关重要的，以重建的作用，陆表海航道在海洋环流，碳循环和气候improvementation.This研究将调查关键站点内的圣丹斯海，在美国和加拿大。将使用从野外工作中获得的稳定同位素和聚集同位素生物碳酸盐样品进行分析，以前所未有的空间分辨率重建温度和碳循环。碳酸盐凝聚同位素温度计是重建陆缘环境温度的宝贵工具，因为它独立于碳酸盐沉淀的水的同位素组成（Price et al. 2019; Vickers et al. 2019; Bajnai et al. 2020; Paxton et al. 2020）。分析技术将用于评估地球化学特征和生物保存（例如，电感耦合等离子体原子发射光谱仪（ICP-AES）和阴极发光岩相学。

Examination of warm intervals in Earth's history help develop insight into the behavior of the climate system under elevated carbon dioxide and temperature. One such interval is the Jurassic which sees atmospheric CO2 concentrations close to current concentrations of around 400 ppm or higher. A significant feature of this warmer world was the presence of large epicontinental seaways such as the Middle-Late Jurassic Sundance Sea of North America (e.g. Danise et al. 2020). At its greatest extent the Sundance Sea stretched from Utah to the Arctic Ocean. These large epicontinental seaways are the dominant source for much of our information about ancient marine climates and biodiversity. There is, however, growing evidence that these seaways are often decoupled from open-ocean conditions because of variations in water mass, depth, salinity, and stratification and being a loci of anoxia. Hence, understanding these systems is critical to reconstruct the role epicontinental seaways play in terms of ocean circulation, carbon cycling, and climate amelioration.This research will investigate key sites within the Sundance Sea, in the USA and Canada. Using stable isotopes and clumped isotopes biogenic carbonate samples derived from fieldwork, will be analysed to reconstruct temperature and carbon cycling at unprecedented spatial resolution. The carbonate clumped isotope thermometer is a valuable tool for reconstructing temperatures in epicontinental settings due to its independence from the isotopic composition of the water from which a carbonate precipitates (Price et al. 2019; Vickers et al. 2019; Bajnai et al. 2020; Paxton et al. 2020). Analytical techniques will be used to evaluate the geochemical character and biogenic preservation (e.g., Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) and the cathodoluminescence petrography.