LGM以来巽他陆坡区海洋环境对高纬气候演化事件和全球海平面变化的响应

发布时间：2018-05-03 00:18

  本文选题：快速气候变化 + 南海西南海区　； 参考：《中国科学院研究生院（海洋研究所）》2014年硕士论文

【摘要】：详细研究低纬海区古水文环境的演化模式及其与高纬地区的联系，对于千百年尺度快速气候变化机制的认识具有重要意义。以南海西南巽他陆坡CG2岩芯为材料，通过浮游有孔虫Globigerinoides ruber壳体的δ18O和Mg/Ca重建了近24ka以来的表层海水温度（SST）和盐度（SSS），结合沉积物粒度和浮游有孔虫定量统计数据重建了末次盛冰期（LGM）以来南海西南海区上部水体环境的演化历史。 结果显示，在YD、H1、8.2ka冷事件期间，巽他陆坡区盐度变高，浮游有孔虫暖水种丰度减少，温跃层变浅，沉积物砂和粉砂含量增加，粘土含量减少，平均粒径增大，而B/A暖期以及YD事件后期的响应特征正好相反。相比开放大洋末次冰消期的缓慢变暖，南海西南海区B lling早期以及YD事件后期升温迅速，且H1期间具有明显的降温，幅度达1.5℃，是典型的“格陵兰式”升温。快速气候变化期间，ITCZ南北的纬向移动，造成东亚冬季风和夏季风的反向突变，使得东亚季风影响下的南海南部海区在冷事件的变冷以及末次冰消期的快速转暖在时间相位上几乎与格陵兰冰芯的记录一致。LGM期间海平面降低，水系发育，表层海水盐度比现今低1.15‰。冰消期，海平面变化和东亚夏季风的强弱变化造成了海水盐度频繁的波动，通过对盐度变化做频谱分析，发现了全新世以来南海南部海区660年的夏季风演变周期。在H1、YD期间，东亚夏季风突然减弱，，盐度变高，B/A暖期夏季风增强，盐度变低，比较发现在这些气候事件期间东、西太平洋站位的盐度变化特征几乎是一致的。LGM以来热带西太平洋海区的上层海水环境变化与热带辐合带（ITCZ）的纬向移动及其相关的东亚季风异常有密切联系。
[Abstract]:A detailed study of the evolution model of paleohydrological environment in low-latitude sea area and its relationship with high-latitude area is of great significance to the understanding of the mechanism of rapid climate change in thousands of years. Taking the CG2 core on the Sunda continental slope in the southwest of the South China Sea as the material, By means of 未 18O and Mg/Ca of planktonic foraminifera Globigerinoides ruber shell, the surface water temperature and salinity since 24ka have been reconstructed. Combined with sediment granularity and quantitative statistical data of planktonic foraminifera, we have reconstructed the southwestern South China Sea area since the last sub-glacial age. The evolution history of the upper water environment. The results show that the salinity of Sunda continental slope becomes higher, the warm water abundance of planktonic foraminifera decreases, the thermocline becomes shallower, the sediment sand and silt content increase, the clay content decreases and the average particle size increases during the YDU H1 + 8.2ka cold event. The response characteristics of B / A warm period and late YD event are opposite. Compared with the slow warming of the last stage of the open ocean ice, the early stage of B lling and the late stage of the YD event in the south-west South China Sea are rising rapidly, and the temperature of the H1 period is obviously decreased by 1.5 鈩

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