中布容期热带西太平洋深部[CO32-]变化：碳循环过程与气候效应

中布容期海洋环境以及全球气候发生重大转型，期间深海碳酸钙溶解作用显著加强，MIS 11及其之后的间冰期相比之前更加温暖。然而中布容期深海碳酸钙溶解加强幅度、大洋碳储量演化及其与间冰期转型间的关联悬而未决，重建过去海洋碳酸盐系统参数是研究上述问题的关键。本项目以热带西太平洋岩心为材料，应用浮游有孔虫Mg/Ca、δ18O以及粒径标准化壳体重量（SNW）等指标，在评估表层海水温度与盐度等环境因素对SNW的可能影响后，利用浮游有孔虫SNW恢复中布容期深海碳酸根离子浓度（[CO32-]）变化。基于深海[CO32-]演化，并结合有孔虫碎壳率等数据，确认中布容溶解事件在热带西太平洋的记录。根据中布容溶解事件中深海[CO32-]下降幅度，定量评估此次溶解事件强度，并揭示当时大洋碳酸钙生产状况。最后，对比中布容期间冰期转型前后冰消期深海[CO32-]特征，探讨大洋碳储量演化在中布容期间冰期气候转型中的作用。

The mid-Brunhes interval is a significant period in the history of Quaternary climate. It contains the mid-Brunhes dissolution event and the onset of warmer interglacials. However, there are still major uncertainties regarding this time interval, including the extent of mid-Brunhes dissolution event, the evolution of oceanic carbon storage and its significance for the mid-Brunhes climatic transition. Application of paleo-carbonate proxies is crucial for improving our understanding of these scientific issues. Here, Mg/Ca ratios and δ18O values of planktonic foraminifera are measured to investigate the potential effect of multiple environmental parameters, such as temperature and salinity, on the “size-normalized weight” (SNW) of planktonic foraminifera. After the assessment of the proxy reliability, SNW of planktonic foraminifera are used to reconstruct deep-water carbonate ion concentrations ([CO32-]) in the western tropical Pacific during the mid-Brunhes interval. Along with foraminiferal fragmentation data, the SNW-based [CO32-] record is used to recognize the mid-Brunhes dissolution event. Then, the extent of dissolution event, and the pelagic carbonate production during the mid-Brunhes, are revealed by the deep-water [CO32-] decline. Finally, based on the comparison of deglacial variabilities in deep-water [CO32-] before and after the mid-Brunhes climatic transition, this project will provide further insights into the carbon storage in the deep tropical Pacific during the mid-Brunhes and its role in contemporaneous global climate change.