东北印度洋气候和表层洋流受印度季风控制，其海洋初级生产力是生态系统的基础，连接着大气和海洋碳库，是古海洋和碳循环研究的热点。本研究通过对东北印度洋东经90°海岭I105A孔柱状沉积物中的颗石进行定量分析，获得了末次冰期以来颗石绝对丰度与主要属种相对百分含量记录，重建东北印度洋海洋初级生产力的变化规律。/t/nka以来该区海洋初级生产力经历3个阶段：末次冰期较高、冰消期显著降低、全新世保持较低水平，与孟加拉湾其他古生产力指标变化趋势基本一致。与印度洋古环境资料对比发现，当印度夏季风增强时，东北印度洋淡水输入增多，海洋初级生产力降低，揭示末次冰期以来印度夏季风降水及其导致的海水分层很可能是东北印度洋海洋初级生产力变化的主要驱动力，并且受地球轨道岁差周期的调控。

The climate and surface currents of the northeastern Indian Ocean are controlled by the Indian Monsoon, and its marine primary productivity is the foundation of the ecosystem, which connects the atmosphere and ocean carbon cycle. In this study, coccolith quantitative analysis has been carried out from the marine sediments in Core I105A on the 90°E Ridge of the northeastern Indian Ocean to obtain the records of the coccolith absolute abundance and the relative percentages of dominated coccolithophore species, which are used to reconstruct the variation of marine primary productivity in thenortheastern Indian Ocean since last glaciation. The results show that the marine primary productivity in this area has experienced through three stages since last 54 ka: (1) high productivity during the last glaciation; (2) a significantly decrease in productivity during the deglaciation; and (3) the lowest productivity during the Holocene. This kind of pattern is basically consistent with the variations of other paleo-productivity proxies in the Bay of Bengal. Comparison with the paleoenvironmental data of the Indian Ocean indicates that the marine primary productivity decreases when the freshwater input to the northeastern Indian Ocean increases due to intensified Indian Summer Monsoon. It reveals that the evolution of marine primary productivity in the northeastern Indian Ocean since the last glaciation has most probably been driven by seawater stratification associated with the precipitation of the Indian Summer Monsoon, a process regulated by the Earth orbital precession cycles.