南海北部末次冰期以来深水沉积物组成及其堆积速率的时空变化特征

发布时间：2018-05-16 06:47

本文选题：沉积物成分 + 堆积速率　；参考：《中国科学:地球科学》2017年08期

【摘要】：通过对南海北部深水断面上MD12-3428(水深903m)、MD12-3433(水深2125m)和MD12-3434(水深2995m)三个岩芯的沉积物成分及其堆积速率分析,研究末次冰期以来南海深水沉积物组成和堆积速率的时空变化特征及其控制因素.研究结果显示,南海北部末次冰期以来的深水沉积物主要由陆源碎屑(59~89%)和碳酸盐(6~38%)组成,并含有少量蛋白石(1.6~9.4%)和有机质(0.7~1.9%).陆源碎屑和碳酸盐的堆积速率分别达到2.4~21.8和0.4~6.5g cm~( 2) ka~( 1)范围,比蛋白石和有机质堆积速率高出1~2个数量级.在末次冰期以来的时间序列变化上,沉积物各成分含量及其堆积速率都具有冰期-间冰期的旋回变化,陆源碎屑、蛋白石和有机质的含量及其堆积速率在氧同位素2期显著增加,而碳酸盐的含量及其堆积速率则呈反向变化或增幅不明显,表明南海深水碳酸盐含量在低海平面时期受到陆源碎屑稀释的影响.在从陆坡向深海盆的空间变化上,陆源碎屑的含量在同时期随水深的增加而增加,但其堆积速率锐减;碳酸盐含量及其堆积速率则随水深的增加而递减;而有机质和蛋白石的含量及其堆积速率随水深增加呈现复杂的变化特征.本文研究认为,南海北部末次冰期以来深水沉积物的组成及其堆积速率受到海平面变化的强烈控制,季风降雨引起的陆源物质供给、海洋初级生产力、以及陆源碎屑和海洋生源物质的相互稀释作用,共同影响了南海深水沉积物的堆积过程.
[Abstract]:The sediment composition and accumulation rate of three cores, MD12-3428 (water depth 903m) and MD12-3434 (water depth 2995m), are analyzed in the deep water section of the northern South China Sea. The temporal and spatial variation characteristics and controlling factors of the composition and accumulation rate of deep-water sediments in the South China Sea since the last glacial period were studied. The results show that the deep-water sediments in the northern part of the South China Sea since the last glacial period are mainly composed of continental clastic rocks (59.89) and carbonates (638) and contains a small amount of opal (1.69.4g) and organic matter (0.71.9g). The accumulation rates of continental clastic and carbonate are within the range of 2.4 ~ 21.8 and 0.4 ~ 6.5g / cm ~ (-1), respectively, which are 1 ~ 2 orders of magnitude higher than those of opal and organic matter. In the time series changes since the last glacial period, the contents and accumulation rates of each component of the sediment have the cycle variation of glacial to interglacial period, and the continental clastic, The content and accumulation rate of opal and organic matter increased significantly in the second phase of oxygen isotope, while the content and accumulation rate of carbonate changed inversely or did not increase obviously. The results show that the carbonate content in the deep water of the South China Sea is affected by continental clastic dilution at low sea level. In the spatial variation from the continental slope to the deep-sea basin, the content of continental clastic increases with the increase of water depth, but its accumulation rate decreases sharply, while the carbonate content and accumulation rate decrease with the increase of water depth. However, the content of organic matter and opal and its accumulation rate show complex characteristics with the increase of water depth. In this paper, it is concluded that the composition and accumulation rate of deep-water sediments in the northern South China Sea since the last glacial period are strongly controlled by sea level changes, the supply of land-based materials caused by monsoon rainfall, and the marine primary productivity. The mutual dilution of terrestrial clasts and marine biogenic materials affects the accumulation of deep-water sediments in the South China Sea.
【作者单位】：同济大学海洋地质国家重点实验室;
【基金】：国家自然科学基金项目(批准号:91528304,41530964,91428310,41525020)资助
【分类号】：P736.21

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