On mineralogical and geochemical records of paleosedimentary environmental variation in the northeastern South China Sea since the late Pleistocene
On mineralogical and geochemical records of paleosedimentary environmental variation in the northeastern South China Sea since the late Pleistocene
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DOI：
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发表时间：
2004
影响因子：
1.4
通讯作者：
Yang Qun-hui
中科院分区：
文献类型：
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作者：
Yang Qun-hui
根据碎屑矿物学和地球化学特征，对南海东北部69孔长560 cm（20° 07.10 ′N，118° 49.0 ′E，水深2 971 m）的岩芯进行了分析，结果表明，该岩芯可划分为晚更新世末次冰期和全新世，界线在165 cm左右。这一结果与浮游有孔虫的氧、碳稳定同位素分析结果一致。末次冰期，沉积物中重矿物含量高，自生黄铁矿丰富，SiO_2、S含量高，CaCO_3含量低，Na/Al、Mg/Al、Na/K比值高，表明该地区处于相对封闭的缺氧环境，气候干冷，化学风化条件弱。沉积物主要由硅质沉积物组成。沉积物中CaCO_3含量较低可能是由于陆源组分的稀释作用所致。冰后期，CaCO_3和Al_2O_3含量升高，Na/Al、Mg/Al和Na/K比值降低，反映沉积环境为开放的氧化环境，气候湿热，化学风化作用增强。沉积物主要由铝硅酸盐沉积物组成。碳酸盐含量的最大值出现在冰消期。
Based on the clastic mineralogical and geochemical characteristics, it is indicated that the core 69 with a length of 560 cm (20°07 .10′N,118°49 .0′E; 2 971 m water depth) sampled by gravity-piston corer from the north-eastern South China Sea could be divided into the late Pleistocene last glacial period and the Holocene epoch with a boundary at about 165 cm. This result consists with that of the oxygen and carbon stable isotopic analyses of planktonic foraminifers. During the last glacial period, there was a relatively closed anoxic environment, dry and cold climate, weak chemical weathering conditions which were suggested by the characteristics of higher content of heavy mineral with abundant authigenic pyrite, higher SiO_2 and S contents, and lower CaCO_3 content, as well as higher ratios of Na to Al, Mg to Al and Na to K in sedimentary samples. The sediments are composed mainly of siliceous deposits. The lower CaCO_3 contents of sediments might caused by the dilution of terrigenous components. In turn, during the postglacial period, the CaCO_3 and Al_2O_3 contents became higher, and the ratios of Na to Al , Mg to Al and Na to K decreased, which reflected that the sedimentary environment became an open oxidation environment, the climate became humid and hot with a stronger condition of chemical weathering. The sediments are composed mainly of aluminosilicate deposits. Furthermore, the maximum carbonate content occurs in the deglaciation period.