摘要
利用 1 994年 85- 90 4航次获取的冲绳海槽中段表层沉积物样品 ,测定其硅酸盐相的 87Sr/86Sr和 1 4 3 Nd/1 4 4 Nd比值 ,以定量研究冲绳海槽中段表层沉积物硅酸盐物质的来源。结果表明 ,冲绳海槽中段陆坡区表层沉积物硅酸盐相的 87Sr/86Sr、1 4 3 Nd/1 4 4 Nd与东海陆架沉积物硅酸盐相的 87Sr/86Sr和 1 4 3 Nd/1 4 4 Nd相当 ;槽底和东坡沉积物硅酸盐相的 87Sr/86Sr和 1 4 3 Nd/1 4 4 Nd值介于中国大陆硅酸盐物质和海槽火山碎屑的 87Sr/86Sr、1 4 3 Nd/1 4 4 Nd比值之间 ,并大致具有两端员混合特征。利用以Sr同位素为参数的二端员混合方程进行物源定量分析的结果表明 ,冲绳海槽中段的西坡和槽底表层沉积物硅酸盐相以陆源物质为主 ,最大值为 91 0 7% ;由西向东 ,陆源物逐渐减少 ,在海槽东坡含量最小 ,最小值为 9 93% ;火山源物质在东坡含量最高 ,最大值为 64 92 % ,由东向西、由北向南 ,火山源物质逐渐减少为零。
Provenance of sediments from the meddle Okinawa Trough has always been a focused problem, for which, many researches have conducted in terms of the mineralogy and geochemistry. However, none of them is not concerned with quantitative partition of mixed sediments according their endmembers. In the present paper, the provenance of mixed surface sediments from the middle Okinawa Trough is discussed using Sr and Nd isotopes, on the basis of which the sediments are partitioned into endmembers using strontium isotope. It is shown that the 87 Sr?/ 86 Sr and 143 Nd?/ 144 Nd ratios of silicate facies in mixed sediments of the western slope from the middle Okinawa Trough are equal to those of silicate facies in the sediments from the East China Sea shelf. 87 Sr?/ 86 Sr and 143 Nd?/ 144 Nd ratios of silicate detritus in the sediments from the bottom and eastern slope of the middle Okinawa Trough are between those from China's land and those of volcanoclastic materials of the Okinawa Trough, demonstrating the nature of two end member mixture. Quantitative partition illustrates that sediments from the bottom and eastern slope of the middle Okinawa Trough are dominated by terrigenous detritus, maximum content accounting for 91 07%. Terrigenous detritus gradually decreased from the west to the east, and minimium content is located on the eastern slope, accounting for 14%. Oppositely, volcanic detritus has a maximium on the eastern slope, accounting for 64.92%; it gradually decreases to zero to wards the west.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
2001年第3期319-326,共8页
Oceanologia Et Limnologia Sinica
基金
国家自然科学基金!资助项目
4 970 60 68号
国家自然科学重点基金!资助项目
4 973 62 1 0号
