南海东沙海域冷泉渗漏区沉积物稀土元素地球化学特征

发布时间：2018-03-08 14:50

本文选题：稀土元素　切入点：冷泉渗漏　出处：《海洋地质与第四纪地质》2017年05期 　论文类型：期刊论文

【摘要】：东沙海域是我国典型的冷泉活动区,该区域表层沉积物的稀土元素地球化学特征不仅受其源区控制,同时也可能会受到冷泉渗漏活动的影响。本文选取位于南海北部陆坡973-4站位的柱状样为研究对象,该站位位于21°54.3247’N、118°49.0818’E,水深为1 666m,柱状样总长1 375cm,采用电感耦合等离子质谱(ICP-MS)、X射线荧光光谱(XRF)等分析测试方法,测得样品的稀土元素以及部分微量和主量元素数据,并结合总碳(TC)、总有机碳(TOC)以及有孔虫质量分数等数据,探讨了冷泉泄漏对周围成岩环境及沉积物稀土元素地球化学特征的影响。结果发现,973-4站位柱状样在海底以下459~619cm深度范围内稀土元素含量整体异常减少,但所有样品稀土元素分布模式及相关稀土元素参数均十分一致。结合冷泉活动研究,表明该区域沉积物元素地球化学特征的异常与物源无关,是受自生碳酸盐岩的增加所影响。此外,通过分析δCe值随深度的变化以及自生碳酸盐岩和硫酸盐-甲烷转换带(SMTZ)的分布情况发现三者相关度很高,表明自生碳酸盐岩的增加很可能是该区域发生的冷泉渗漏导致的甲烷厌氧氧化作用(AOM)所产生的。
[Abstract]:Dongsha sea area is a typical cold spring active area in China. The geochemical characteristics of rare earth elements in surface sediments of this area are not only controlled by its source area. At the same time, it may also be affected by the leakage of cold spring. In this paper, the columnar sample located at 973-4 station on the northern slope of the South China Sea is selected as the research object. The station is located at 21 掳54.3247N, 118 掳49.0818e, with a water depth of 1666 m and a total length of 1375 cm. The data of rare earth elements and some trace and principal elements of the samples are obtained by ICP-MS X-ray fluorescence spectrometry (XRFs) and other analytical methods. Combined with the data of TCX, TOC, TOC and foraminifera mass fraction, and so on, The effects of cold spring leakage on the diagenetic environment and the geochemical characteristics of REE in sediments are discussed. The results show that the REE contents of the column samples at station Hui973-4 decrease in the depth of 459 ~ 619 cm below the sea floor, and the REE contents decrease as a whole in the range of 459 ~ 619 cm below the sea floor. However, the REE distribution patterns and related REE parameters of all samples are very consistent. Combined with the study of cold spring activity, it is shown that the anomaly of geochemical characteristics of elements in the sediments in this area is independent of the provenance. In addition, by analyzing the variation of 未 ce value with depth and the distribution of authigenic carbonate rock and SMTZ, it is found that the correlation among them is very high. It is suggested that the increase of authigenic carbonate rocks is probably due to the anaerobic oxidation of methane (AOM) caused by cold spring leakage in the region.
【作者单位】：中国科学院天然气水合物重点实验室中国科学院广州能源研究所;海洋国家实验室海洋矿产资源评价与探测技术功能实验室;中国科学院大学;中国地质调查局油气资源调查中心;国土资源部天然气水合物重点实验室中国地质调查局青岛海洋地质研究所;
【基金】：国家自然科学基金项目(41273022) 中国石油-中科院科技合作项目(2015A-4813) 中国科学院青年创新促进会项目(2014321) 青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室开放基金(KC201703)
【分类号】：P736.4

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