Ocean circulation and the ice-temperature conundrum: Unraveling the transition from the Cretaceous greenhouse into today's icehouse world

该提案的总体目标是重建过去100 Ma的特定时间间隔内的温度和冰量变化及其对海洋环流和海洋生态系统的影响，这对我们了解地球的古气候动力学特别重要。为了解决有争议的讨论古气候和古海洋学问题，拟议的项目将采用新的碳酸盐“聚集同位素”古温度计（CCIP），一个新的古氧代代理的基础上底栖有孔虫孔隙特征（BFPC），有孔虫组合数据。项目的总体目标将通过三个阶段的方法实现，包括（I）CCIP和BFPC的测试，（II）选定有孔虫类群的两个代理的校准，以及（III）它们在中、中生代选定时间段的研究中的应用。第三阶段将包括七个案例研究，其中CCIP和BFPC分析将与“经典”代理（例如，δ ~（18）O、Mg/Ca和组合计数）。这种综合方法将使温度从冰/盐度信号中分离出来，并破译各自对海洋环流和生态系统的影响，这将对有争议的古气候和古海洋过程产生新的见解。拟议中的研究最终可以为解决白垩纪温室到当今冰库世界的冰温难题迈出重要的一步。

The overall goal of this proposal is to reconstruct temperature and ice-volume changes and their effects on ocean circulation and marine ecosystems for specific time intervals of the past 100 Ma that are particularly critical for our understanding of the Earth’s paleoclimatic dynamics. To tackle controversially discussed paleoclimatic and paleoceanographic issues, the proposed project will employ the novel carbonate “clumped-isotope” paleothermometer (CCIP), a new paleo-oxygenation proxy based on benthic foraminiferal pore characteristics (BFPC), and foraminiferal assemblage data. The overall project goals will be achieved following a threestage approach that comprises (I) testing of CCIP and BFPC, (II) the calibration of both proxies for selected foraminiferal taxa, and (III) their employment in studies on selected time slices of the Ceno- and Mesozoic. Stage (III) will comprise seven case studies where CCIP and BFPC analyses will be combined with “classical” proxies (e.g., δ18O, Mg/Ca, and assemblage counts). This integrated approach will allow to separate temperature from ice/salinity signals and to decipher the respective effects on ocean circulation and ecosystems, which will yield new insights into controversially discussed paleoclimatic and paleoceanographic processes. The proposed research can ultimately provide a significant step forward towards resolving the icetemperature conundrum for the Cretaceous greenhouse to the present-day’s icehouse world.