南海北部MD12-3432站MIS 11期以来底栖有孔虫反映的古环境变化

南海具有典型边缘海特征，其北部陆坡由于具有高沉积速率的地层剖面，可以用于研究亚轨道尺度气候变化。本研究以南海北部陆坡下部MD12 3432柱状样(19°16.88′N，116°14.52′E，水深2 125 m)为主要研究材料，分析其粗组分百分含量、底栖有孔虫丰度和特定环境指示属种的百分含量与丰度，并结合相关研究结果，运用多指标综合分析，重建了南海北部陆坡MIS 11期(距今约40万年)以来的表层初级生产力和底层水溶解氧含量的演化情况。与之前研究不同，本研究发现MIS11期以来南海北部的古生产力在温暖的间冰期高、在寒冷的冰期低，且主要受控于东亚夏季风影响下低纬地区降水强度的变化。在MIS 7期和MIS 9期可能有较高溶解氧含量的底层水进入南海北部，导致在高生产力的暖期中，喜氧的低生产力指示种Cibicidoides wuellerstorfi丰度增加。

Benthic foraminifera's implications on paleo-environment variability in MD12-3432 in the northern South China Sea since MIS 11

The South China Sea (SCS) is a typical marginal sea whose northern continental slope has a high sedimentation rate, which provides ideal material for research on sub orbital scale climate variability. In this study, samples from sediment core MD12-3432 (19°16.88′N，116°14.52′E, water depth 2125 m) retrieved from the lower northern continental slope, northern South China Sea, are selected as the major research material. By applying multiple paleo environmental poxies analysis, including benthic foraminifera abundance, coarse fraction percentage, specific environment indicators percentage and abundance as well as relevant results from previous studies, the paleoceanographic history of the northern South China Sea is reconstructed, with emphasis on the variability of surface primary productivity and bottom water dissolved oxygen content. Different from previous studies, the results indicate that from Marine Isotope Stage 11(MIS 11, approximately 400 ka B.P.) the primary productivity in the northern SCS is high in warm interglacial period and low in cold glacial period, and it is mainly influenced by the intensity of precipitation controlled by the East Asian Summer Monsoon. During MIS 7 and MIS 9, the rise in the abundance of a low productivity and high dissolved oxygen indicator, the epifaunal Cibicidoides wuellerstorfi, coincides with high productivity indicators records. This inconsistency implies a possible intrusion of oxygen enriched bottom water in both warm time periods.