Fluctuations of the oceanic Ca isotopic budget and environmental changes during highly dynamic transitions of the Cenozoic.

IODP第320次和第321次探险从赤道东太平洋取回了保存完好的连续岩心材料，为重建新生代气候提供了极好的档案，这一时期以快速和极端的气候多变而闻名。除了重建温度和盐度波动之外，这次考察的一个主要目的是加强对碳循环的理解，特别是碳酸盐补偿深度(CCD)、CaCO3溶解和生产力之间的相互作用。新生代太平洋CCD值的快速变化揭示了海洋碳、钙收支的强烈变化。钙的确切作用尚不清楚；尤其是需要进一步限制(大陆输入、陆架风化、溶解钙的无补偿消耗)的大量浮游性CaCO3沉积的钙来源。基于微化石记录，我们将重建古海水δ44/40Ca的波动，模拟气候变化关键时期的海洋钙收支，更好地约束钙在大规模CCD44/40Ca变化和重要地层转变期间的输入、再分配和输出中的作用。

IODP Expeditions 320 and 321 retrieved well preserved continuous core material from the equatorial eastern Pacific that provides an excellent archive for reconstructions of Cenozoic climate, a period which is known for its times of rapid and extreme climate variability. Besides reconstruction of temperature and salinity fluctuations, a main aim of this expedition was to enhance the understanding of carbon cycling, in particular the interplay of carbonate compensation depth (CCD), CaCO3-dissolution and productivity. Major and rapid changes in the Pacific CCD during the Cenozoic reveal strong dynamics in the oceanic C and Ca budget. The exact role of Ca is yet unclear; in particular the Ca sources for the massive pelagic CaCO3 deposition during CCD deepening need to be further constrained (continental input, shelf-weathering, uncompensated consumption of dissolved Ca). Based on microfossil records, we will reconstruct the fluctuations of δ44/40Ca of the paleo seawater, model the oceanic Ca budget during key periods of climate change, and better constrain the role of Ca in terms of input, redistribution and output during times of massive CCD changes and important stratigraphic transitions.