邹亮, 窦衍光, 陈晓辉, 胡邦琦, 林曦. 冲绳海槽中南部不同环境表层沉积物质来源[J]. 海洋地质与第四纪地质, 2021, 41(1): 115-124. DOI: 10.16562/j.cnki.0256-1492.2020082001
引用本文: 邹亮, 窦衍光, 陈晓辉, 胡邦琦, 林曦. 冲绳海槽中南部不同环境表层沉积物质来源[J]. 海洋地质与第四纪地质, 2021, 41(1): 115-124. DOI: 10.16562/j.cnki.0256-1492.2020082001
ZOU Liang, DOU Yanguang, CHEN Xiaohui, HU Bangqi, LIN Xi. Provenance analysis for surface sediments in different depositional environments of the middle-south Okinawa Trough[J]. Marine Geology & Quaternary Geology, 2021, 41(1): 115-124. DOI: 10.16562/j.cnki.0256-1492.2020082001
Citation: ZOU Liang, DOU Yanguang, CHEN Xiaohui, HU Bangqi, LIN Xi. Provenance analysis for surface sediments in different depositional environments of the middle-south Okinawa Trough[J]. Marine Geology & Quaternary Geology, 2021, 41(1): 115-124. DOI: 10.16562/j.cnki.0256-1492.2020082001

冲绳海槽中南部不同环境表层沉积物质来源

Provenance analysis for surface sediments in different depositional environments of the middle-south Okinawa Trough

  • 摘要: 对冲绳海槽中南部3种不同沉积环境(东海外陆架、东海陆坡和冲绳海槽)表层沉积物进行了稀土等元素地球化学分析,结果显示,冲绳海槽和陆坡表层沉积物具有与台湾物质来源类似的稀土元素配分模式,La/Sm-Gd/Yb散点图也显示海槽和陆坡沉积物主要分布在台湾物源端元区,表明冲绳海槽中南部海槽和陆坡表层沉积物主要来源于台湾,而外陆架沉积物明显的重稀土亏损与大陆河流(特别是长江、黄河)沉积物来源较为一致。为进一步判断外陆架表层沉积物来源,对外陆架沉积物重矿物进行分析鉴定,结果显示,外陆架沉积物重矿物以普通角闪石-绿帘石-石榴石-赤褐铁矿为组合特征,与长江沉积物重矿物组成特征类似,其明显缺乏台湾河流来源的典型重矿物锆石、黄河来源典型重矿物云母、浙闽沿岸来源典型重矿物磁铁矿,说明台湾、黄河和浙闽沿岸并非研究区外陆架表层沉积物主要物源。根据以往测年等研究成果,研究区外陆架沉积物年代较老,应为古长江物质经东海现代环流体系不断改造而成。

     

    Abstract: In this paper, surface sediments taken from three different depositional environments, i.e. the outer continental shelf, slope, and trough, of the middle-south Okinawa Trough were analyzed for rare earth elements (REE). The results suggest that the REE distribution patterns of the surface sediments from the continental slope and the Okinawa Trough are quite similar to those from Taiwan. The discrimination plot of La/Sm-Gd/Yb also shows that the surface sediments from continental slope and the Okinawa Trough are mainly located in the diagram close to the provenance end of Taiwan, further supporting the conclusion that the surface sediments of the continental slope and the Okinawa Trough are doubtlessly sourced from Taiwan. The obvious loss of heavy REE in the sediments of the outer continental shelf is consistent with the source of continental river sediments. In order to recognize the source of surface sediments in the outer shelf sedimentary area, the heavy mineral compositions of these sediments were analyzed. The results show that the heavy mineral assemblages of the outer continental shelf sediments are mainly composed of common hornblende, epidote, garnet, limonite, similar to the source composition of the Changjiang river. The outer continental shelf sediments are lack of zircon, mica, and magnetite, typical heavy minerals found in Taiwan, Huanghe river, and Minjiang river sediments respectively, which suggests that Taiwan, Yellow River, and the coast of Zhejiang and Fujian are not the main contributors to the outer continental shelf sediments. According to the results of previous dating data, the sediments of the outer shelf are relatively old, suggesting that the outer shelf sediments should be formed by the rework of the palaeo-Changjiang river materials by the modern circulation system of the East China Sea.

     

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