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通过对东经90°海岭ODP758钻孔岩心3.5Ma以来的浮游有孔虫远洋记录的研究,结合岩性地层、稳定同位素地层、碳酸盐地层等资料,探讨了喜马拉雅山加速隆升、“中更新世气候转型”、“中布容溶解”事件等重大构造、环境事件在研究区的表现及相关机制。通过对各项指标的分析和对比,根据ODP758岩心的有孔虫组合面貌、古温度、古盐度和古温跃层的变化情况,推断研究区在1.4～0.7Ma期间的气候变化可能是在“中更新世气候转型”条件下发生的。碳酸钙、碳酸钙沉积通量和非碳酸钙沉积通量曲线在1.7Ma时快速增长,与现有资料显示的青藏高原的隆升历史相符,分别与青藏高原隆升过程中的青藏运动A幕、B幕、C幕(1.7Ma)和昆仑-黄河运动(1.2～0.6Ma)相当。碳酸钙含量、大于150μm的粗组分含量、浮游有孔虫沉积通量和浮游有孔虫生物地层揭示出在0.5～0.4Ma期间研究区深海碳酸盐遭受了强烈溶解。此事件与大西洋、太平洋、印度洋及南沙海区沉积记录中的“中布容溶解”事件一致。
Based on the oceanic records of planktonic foraminifera recorded since the core of ODP758 drilled at 90 ° ridge in the east of the sea for 3.5Ma and the data of lithologic strata, stable isotope strata and carbonate strata, we discussed the accelerated uplift of the Himalayas, Pleistocene climatic transformation “, ” in the cloth dissolve “event and other major structures, environmental events in the study area performance and related mechanisms. According to the analysis and comparison of each index, according to the foraminiferal assemblage, palaeoclimatic temperature, paleosalinity and paleoclimate change of ODP758 core, it is concluded that the climate change during the period of 1.4 ~ 0.7Ma in the study area may be at ”In the Pleistocene climatic transition “ under the conditions. Calcium carbonate, calcium carbonate deposition flux and non-calcium carbonate deposition flux curve increased rapidly at 1.7Ma, which is consistent with the existing data showing the uplift history of the Qinghai-Tibet Plateau, respectively, and the A scene of the Qinghai- , B curtain, C curtain (1.7Ma) and Kunlun - Yellow River Movement (1.2 ~ 0.6Ma) equivalent. Calcium carbonate content, coarse fraction above 150 μm, planktonic foraminiferal sediment flux, and planktonic foraminifera biota reveal that deep sea carbonate was strongly dissolved during the 0.5-0.4 Ma period. This event is consistent with the ”Cloth Dissolution" event in the sedimentary records of the Atlantic Ocean, Pacific Ocean, Indian Ocean and Nansha Sea.