南海北部MD12-3432站深海氧同位素MIS6期到MIS5期陆源沉积物元素比值反映的古气候变化

海洋沉积物中的某些主微量元素与沉积物源区有着密切的联系，它们之间的比值变化受到源区化学风化强度的影响，因此这些元素的比值变化可以反映出海洋沉积物源区古气候的变化。本文研究了南海北部陆坡MD12-3432站位深海氧同位素6期和5期(MIS6/5) 沉积物的主微量元素，发现其表现出良好的气候控制变化特征，K/Ti、Mg/Ti、Al/Ti、Fe/Ti、Co/Ti、Zn/Ti和V/Ti等比值在MIS 5期时较高，而在MIS6期时较低。南海北部的碎屑物质主要来自中国华南地区，沉积物中元素比值的变化表明间冰期时(MIS5)华南地区陆壳化学风化增强，说明该时期华南陆地气候环境温暖湿润，这可能是间冰期时东亚夏季风加强的结果；而冰期时南海北部沉积物源区化学风化减弱，则与此时东亚冬季风较强，华南地区气候干燥寒冷相关。同时，与表层海水生产力相关的Ba/Ti比值在间冰期较高而冰期较低，反映出南海北部在间冰期时表层生产力较高而冰期时相对较低，这可能是由于东亚夏季风增强带来更多降雨，陆地化学风化作用加强，大量营养成分随河流进入南海，导致南海北部表层海水生产力增加。

Paleoclimate change reflected by element ratios of terrigenous sediments from deep-sea oxygen isotope MIS6 to MIS5 at MD12-3432 station in northern South China Sea

Some of the major and trace elements in marine sediments are closely related to the source area of sediments. The change of major and trace elemental ratio is affected by chemical weathering intensity in the source area. Therefore, the ratios can reflect paleoclimate change in the source area of marine sediments. In this work, we studied the major and trace elements of the sediments between Marine Isotope Stage (MIS) 6 and 5 in the core of MD12-3432 on the northern slope of the South China Sea. The elemental contents showed good climate control characteristics, with K/Ti, Mg/Ti, Al/Ti, Fe/Ti, Co/Ti, Zn/Ti and V/Ti ratios higher in MIS5 but lower in MIS6. The detrital materials in the northern South China Sea mainly came from southern China. The changes of elemental ratios in sediments showed increased chemical weathering of continental crusts in southern China during the interglacial period (MIS5), indicating warm and humid climate in the South China continent during this period, possibly a result of enhanced East Asian summer monsoon during the interglacial period. The chemical weathering of the source area in northern South China Sea weakened during the glacial period, in contrast to the strong East Asian winter monsoon and cold and dry climate in southern China. At the same time, the Ba/Ti ratio related to surface seawater productivity is higher in the interglacial and lower in the glacial periods, reflecting higher surface productivity during the interglacial period and relatively lower surface productivity during the glacial period in the northern part of the South China Sea. This may be due to increased surface productivity in the northern South China Sea, as increasing East Asian summer monsoon can bring more rainfall which may lead to enhanced chemical weathering on land and large amount of nutrients entering the South China Sea through river channels.