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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.
Based on the analysis of the sediment composition and its accumulation rate of three cores MD12-3428 (water depth 903m), MD12-3433 (water depth 2125m) and MD12-3434 (water depth 2995m) on the deep-water section of the northern South China Sea, Sediment composition and accumulation rate and its controlling factors.The results show that the sediments in the deep South China Sea since the last glacial period mainly consist of terrigenous debris (59-89%) and carbonate (6 ~ 38%) , With a small amount of opal (1.6-9.4%) and organic matter (0.7-1.9%). The accumulation rates of terrigenous debris and carbonate reached 2.4-21.8 and 0.4-6.5g cm -2 ka ~ (- 1), which is 1 ~ 2 orders of magnitude higher than that of the opal and organic matter.According to the time series changes since the last ice age, the content of each component of sediments and its accumulation rate have the cycle change of glacial-interglacial period, , The content of opal and organic matter and its accumulation rate increased significantly in the second stage of oxygen isotope, but the content of carbonate and its accumulation rate changed inversely or not obviously, indicating that the carbonate content in deep-sea waters of the South China Sea was in the low sea level Impacted by terrigenous debris dilution In the spatial variation of deep basins, the content of terrigenous debris increased with the increase of water depth at the same time, but its accumulation rate dropped sharply; the carbonate content and its accumulation rate decreased with the increase of water depth; while the contents of organic matter and opal And its accumulation rate show a complex changing trend with the increase of water depth.In this paper, the composition and accumulation rate of deep-water sediments in the northern South China Sea are strongly controlled by sea level changes since the last glacial period in the northern South China Sea, and the supply of terrestrial supplies due to monsoon rainfall, Primary productivity, as well as the mutual dilution of terrigenous debris and marine biota, have combined to affect the accumulation of deepwater sediments in the South China Sea.