南海东北部陆坡结核成因及对冷泉活动的指示

doi:10.3969/j.issn.1001-909X.2020.02.003

摘要/Abstract

摘要： 本文对2018年利用“海龙Ⅲ”ROV在南海东北部陆坡采集到的多金属结核样品进行了矿物学和地球化学分析。结果表明研究区结核以棒状为主,具有2层结构。结核外层的矿物学和元素组成特征与水成型多金属结核较为相似。结核内层多发育孔洞,以针铁矿为主,有黄铁矿残余,Fe、As元素含量高,Mn、REE等元素含量低。NH-2结核样品内部的碳酸盐组分的全岩δ¹³C为-30.91‰。所研究结核样品的早期形成过程与冷泉活动密切相关,结核生长后期冷泉活动停止或是减弱,在等深流作用下结核黄铁矿被氧化成针铁矿,之后锰铁氧化物继续在结核外部生长。

关键词: 结核, 冷泉, 南海, 东沙, 大陆坡

Abstract: The polymetallic nodule samples were analyzed for their mineralogical and geochemical features, which were acquired on the northeastern slope of the South China Sea using the ROV named as Sea Dragon III. The results showed that the nodules in the study area were predominantly by rod-shaped with a two-layer structure. The outer layer of the polymetallic nodules was mineralogically and geochemically similar to hydrogenic nodules. While the inner layer was porously and composed of goethite with residual minor pyrite. Geochemically, the inner layer was characterized by high concentration of Fe and As but extremely low concentration of Mn, REE and other elements. The inner layer carbon isotopes ( δ¹³C ) of sample NH-2 was -30.91‰. The study presented that the early forming process of the nodules was related to the activities of cold seep, but the pyrite was oxidized following the extinction of cold seep. Under the influences of contour current in the area, the ferromanganese oxides continued to grow in the outer layer of the nodules.

Key words: cold seep, South China Sea, Dongsha, continental slopes

中图分类号:

P744

陆怡, 初凤友, 董彦辉, 朱志敏, 朱继浩, 鲁江姑. 南海东北部陆坡结核成因及对冷泉活动的指示[J]. 海洋学研究, 2020, 38(2): 16-25.

LU Yi, CHU Fengyou, DONG Yanhui, ZHU Zhimin, ZHU Jihao, LU Jianggu. Formation of nodules on continental slopes in thenortheast of the South China Sea and itsimplications for cold seep[J]. Journal of Marine Sciences, 2020, 38(2): 16-25.

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