Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

摘要

Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite (＞68%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea (SCS). Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe (Yellow) River. The relatively high abundant kaolinite is likely derived from the Changjiang (Yangtze) River via the Taiwan Warm Current. In contrast,large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River's submerged delta have much lower 87Sr/86Sr ratios (0.7162-0.7180) than those of the Shandong Peninsular mud wedge (0.7216-0.7249),which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang River sediments, suggesting multiple sources of the sediment in the area.

机译：通过X射线衍射分析确定了从东海西北大陆架收集的34种沉积物的粘土矿物。黏土矿物分布主要受沉积物来源和主要循环模式控制。在我们研究的地区，主要的粘土矿物是伊利石，占整个粘土组分的67％以上。伊利石的最高浓度（＞ 68％）位于济州岛的陆源性输入物无法达到的东南沿海地区。这意味着这些伊利石主要是由黑潮从南中国海（SCS）运走的。蒙脱石高度集中在西北中部和架子上的泥块中。这似乎归因于从中国运来的绿土的大量供应，那里的细粒沉积物从现代和古代的黄河（黄河）中排出。较高含量的高岭石很可能是通过台湾暖流从长江（长江）中提取的。相比之下，西北地区大量的绿泥石和高的绿泥石/高岭石比率发生，这反映了黄海沿岸流从黄海南部的运输。判别图清楚地表明，东海西北部的沉积物最终来自中国河流，特别是黄河，而东北部的沉积物可能来自济州岛。长江淹没三角洲的泥质沉积物的87Sr / 86Sr比（0.7162-0.7180）远低于山东半岛泥质楔子（0.7216-0.7249），这可能是由黄河引起的，表明了其分布模式。 87Sr / 86Sr比值作为一种新的示踪剂，以区分研究区域内陆架沉积物的来源。外层泥质沉积物的87Sr / 86Sr比值范围在0.7169至0.7216之间，介于黄河和长江沉积物之间，表明该地区的沉积物来源多种多样。

Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

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