| 摘要: |
| 依照 Stokes 定律, 由 256 个东海陆架表层沉积物样品中提取了<2μm 粒级组分、制成定向片, 通过 X-射线衍射(XRD)分析以及 Biscaye(1965)方法计算了蒙皂石、伊利石、高岭石和绿泥石四种矿物的相对含量。结果显示, 东海陆架区表层沉积物粘土矿物相对含量由高到低组成为伊利石(平均 65.4%)、绿泥石(平均 14.4%)、蒙皂石(平均 13.3%)和高岭石(平均 6.9%); 东海陆架表层沉积物中高岭石含量有向海减小的趋势; 陆架区东北部和中南部的伊利石含量较低、蒙皂石含量较高, 东南部的伊利石和蒙皂石含量分布与其相反; 绿泥石在研究区东部和东北部含量较低。聚类分析显示, 东海陆架<2 μm 粒级沉积物可分为“类长江”与“类黄河”两种类型。类长江细颗粒沉积物主要分布在东海陆架中西部地区; 类黄河沉积物在研究区东北部、东部和南部的部分区域分布。东北部的类黄河沉积物可能来自黄河或废黄河口, 而南部和东部的细颗粒沉积物可能是晚更新世冰期干冷气候下形成的产物与现代河流入海细颗粒的混合物。
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| 关键词: 东海陆架, 粘土矿物, 长江, 黄河, 细颗粒物质来源 |
| DOI：10.11693/hyhz201005002002 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目, 40776030 号和 0576032 号。 |
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| CLAY MINERALS IN SURFACIAL SEDIMENTS OF THE EAST CHINA SEA SHELF：DISTRIBUTION AND PROVENANCE |
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ZHOU Xiao-Jing1,2, LI An-Chun1, WAN Shi-Ming1, MENG Qing-Yong1
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1.Key Lab of Marine Geology & Environment, Institute of Oceanology, Chinese Academy of Sciences;2.The First Institute of Oceanography, State Oceanic Administration
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| Abstract: |
| Terrigenous clay minerals are mainly the downstream product of weathering of detrital minerals, and they are sensitive to the weather characters of source areas. According to previous studies, the fine-grained sediment on the East China Sea Shelf (ECSS) mainly comes from Changjiang River, Huanghe River or the old Huanghe River subaqueous delta. The relative contents of clay minerals from Changjiang and Huanghe Rivers are different. Therefore, the clay mineral composition can be used as an indicator of sediment provenance. The <2 μm size fractions of 256 surficial sediments in the ECSS were isolated by from sand-free sediment according to Stokes settling velocity and by centrifugation. Oriented clay slides were prepared by pipetting about 1 ml clay solution on to glass slides and allowing them to dry in air. The air-dried, heated (490℃ for 2 h) and glycolated clay slides (glycolated at 60℃ for 12 h) were scanned from 3° to 35° 2θ, at 2.4° 2θ/min on a D8 Advance X-Ray Diffractometer using Cu-Kα radiation. The relative abundance of chlorite (14?), illite (10?), kaolinite (3.57 ?) and smectite (17?) were evaluated by the Biscaye (1965) semi-quantitatively method. It showed that the ECSS surficial sediment composed of 65.4% illite, 14.4% chlorite, 13.3% smectite, and 6.9% kaolinite. The contents of kaolinite decreased from land to sea; the relative abundance was lower for illite and higher for smectite in the north-east and south-central of study areas; but the chlorite content was lower in the east and north-east. According to the clustering analysis of the four main clay minerals, the East China Sea shelf <2 μm sediment can be divided into Changjiang-like and Huanghe-like sediments, and there is absent Taiwan-like sediment. The type of Changjiang-like sediment mainly distribute in the central and western regions of the ECSS, and they come from modern Changjiang River; the <2 μm sediments in southeastern part of the ECSS might originate from the Yellow River, or from the relict sediments formed in dry and cold climates such as Pleistocene Ice Age and then mixed with fine modern riverine sediments under marine hydrodynamic processes.
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| Key words: st China Sea Shelf, Clay minerals, Changjiang River, Huanghe River, Fine-grained sediment provenance |
