南海北部MD12-3429站位海水古生产力和溶解氧含量特征

CHANGES OF THE PALAEO-SEA SURFACE PRODUCTIVITY AND BOTTOM WATER DISSOLVED OXYGEN CONTENT AT MD12-3429,NORTHERN SOUTH CHINA SEA

南海北部陆坡较高的沉积速率,为研究亚轨道尺度的气候变化提供了绝佳的材料。本次研究对南海北部MD12-3429站位(20°08.52′N,115°49.84′E,水深903m)0—35.21m沉积物中的底栖有孔虫属种进行统计,运用沉积物粗组分、底栖有孔虫丰度、特定环境下的底栖有孔虫属种含量(Cibicidoides wuellerstorfi,Uvigernia,Bulimina,Chilostomella oolina和Globobulimina pacifica)及底栖有孔虫堆积速率(BFAR)等指标综合研究MIS7期(约24.3万年)以来的南海北部初级生产力和中层水海水溶解氧含量的变化,并对其影响因素进行探讨分析。结果表明,该站位自MIS7期以来表层海水的营养总体呈现间冰期高、冰期低的特点,而底层水的溶解氧含量在间冰期低、冰期高,这可能受到东亚季风冬季风带来营养元素的影响。该站位水深903m,处于南海中层过渡带,本次研究的结果反映了南海北部中层水MIS7期以来营养与溶解氧含量特征。

The high sedimentation rate in the northern slope of the South China Sea （SCS）, provides excellent materials for the study of suborbital climate changes. In this paper, we study benthic foraminifera from Core MD12-3429 （20°08. 52′N, 115°49. 84′ E）, which is located in the upper northern slope of the South China Sea. Using the coarse fraction, abundance of benthic foraminifera （ Cibicidoides wuellerstorfi, Uvigernia, Bulimina, Chilostomella oolina and Globobulimina paci fica ）, and benthic foraminifera accumulation rate （BFAR）, surface primary productivity and the seawater dissolved oxygen content are reconstructed since the Marine Isotope Stages 7 （MIS 7, about 243 ka BP） in the northern South China Sea. The primary productivity was higher during the interglacial and lower during the glacial corresponding to a poor oxygen during the interglacial and enriched oxygen during the glacial, which is mainly influenced by the East Asian monsoon and the surface ocean currents. The water depth of MD12-3429 is 903 m, within the intermediate transition zone of the South China Sea. So the bottom water at Site MD12-3429 reflects the property of the intermediate water of the northern South China Sea since the MIST.