南海晚第四纪陆源沉积:粒度组成、动力控制及反映的东亚季风演化  

GRAIN SIZE DISTRIBUTION AND DYNAMIC CONTROL OF LATE QUATERNARY TERRIGENOUS SEDIMENTS IN THE SOUTH CHINA SEA AND THEIR IMPLICATION FOR EAST ASIAN MONSOON EVOLUTION

作　　者：郑洪波[1] 陈国成[1] 谢昕[1] 梅西[1] 李建如[1] 葛黄敏[1] 黄恩清[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《第四纪研究》2008年第3期414-424,共11页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:40676033);国家重点基础研究发展规划项目(批准号:2007CB815906);国家自然科学基金创新研究群体科学基金项目(批准号:40621063)联合资助

摘　　要：对南海北部MD05—2904孔、西部ND05—2901孔、南部MD05—2897孔的有孔虫氧同位素进行测定，建立了高分辨率的年代地层。对3个孔的陆源碎屑组分的粒度分布进行了测定和主成分因子分析，结果发现，南海北部陆坡（南部陆坡）的陆源碎屑沉积特征主要受单一的因子Fn（Fs）控制，它可以控制62％（59％）的粒度变化特征。与Fn密切相关的粒度组分为1．52～2．92μm和11．8～27．4μm，与Fs相关的粒度组分为〈2．42μm和6．76—14．30μm。南海西部陆坡获得两个主控因子Fwl和Fw2，分别控制46％和32％的粒度变化特征，与Fwl相关的粒度组分为1．26～2．66μm和10．8～14．3μm，与Fw2相关的粒度组分为4．24～7．42μm和30．1～43．7μm。对敏感粒级的变化序列进行分析发现，北部的Fn与海平面升降作用紧密相关，呈现冰期／间冰期旋回尺度的周期性。而南部的Fs呈现高频的岁差周期波动，可能与夏季风演化引起的源区风化、河流搬运等的变化有关。南海西部的陆源沉积物主要来自南海的西南和北部两个地区，分别由东亚夏季风和冬季风驱动的洋流搬运，Fwl和Fw2恰恰代表了这两种动力控制。因此，Fwl和Fw2控制的粒度组成变化间接指示了东亚夏季风和冬季风的演化。研究认为，晚第四纪以来东亚夏季风受控于低纬区的夏季日射量的变化，呈现典型的岁差周期性，而冬季风主要受高纬冰盖变化驱动，呈冰期／间冰期旋回尺度的波动，这反映了东亚季风演化的双重驱动机制。Based on high-resolution oxygen isotope stratigraphy of Core MD05 - 2904, Core MD05 - 2901, and Core MD05 -2897, which are located at the northern, western, and southern slopes of South China Sea （SCS） respectively,the grain size distribution of terrigenous sediments of the three cores was measured and analyzed through principle component analysis. For the northern SCS （ southern SCS）, only one main control factor Fn （ Fs） was recognized,which is responsible for about 62% （59%） variance of granularity of the sediments. Whereas for the western SCS,two main control factors （ Fwl and Fw2） were recognized, which are responsible for about 46% and 32% variance of granularity, respectively. Each principal factor controls its own grain size distribution. Fo is responsible for 1.52 - 2.92μm% and 11. 8 -27.4μm% ,the variations of which are linked to sea level change. F8 is responsible for 〈 2.42μm% and 6.76- 14. 30μm%, the variations of which are linked to high frequency summer monsoon activity. Fwl is responsible for 1.26 -2.66μm% and 10. 8 - 14. 3μm% ,while Fw2 for 4.24 -7.42μm% and 30.1 -43.7μm%. Fwl and Fw2 are linked to the input flux from the southwest and north areas of SCS respectively, which were transported by the opposite surface currents driven by East Asian summer monsoon and winter monsoon. It is observed that the East Asian summer monsoon has fluctuated at precession band, and therefore has been forced by changes of solar insolation in low latitude, whereas ice-volume forcing is probably the factor in determining the strength and timing of the East Asian winter monsoon.

关 键 词：南海 第四纪 陆源碎屑 粒度 东亚季风演化 

分 类 号：P534.63[天文地球—第四纪地质学] P736[天文地球—古生物学与地层学]