台湾海峡表层沉积物中黏土矿物特征及物质来源
摘要: 利用X射线衍射仪，对比分析台湾海峡及周边表层沉积物的黏土矿物特征，讨论长江、福建和台湾河流对海峡黏土矿物的贡献程度。福建河流（闽江）的黏土矿物以高岭石为主（>40％），其次是伊利石（30％）和绿泥石，不含蒙脱石；长江和浙闽泥质区的黏土矿物特征是伊利石含量最高（61％～66％），其次是绿泥石（16％～17％）和高岭石（10％～13％），少量蒙脱石（6％～9％）。台湾河流（浊水溪）黏土矿物组合为伊利石（>70％）和绿泥石，不含高岭石和蒙脱石为特征。台湾海峡高岭石含量由西向东明显减少，说明高岭石主要来自福建的河流。〖JP2〗台湾海峡50 m等深线以东区域的黏土矿物具有高的伊利石和绿泥石含量，低的蒙脱石和高岭石含量，且伊利石的化学指数和结晶度值都明显低于长江和福建的河流，反映台湾河流的物质来源。在台湾暖流作用下，台湾河流为台湾海峡中北部提供了大量的伊利石和绿泥石。福建近海的黏土矿物主要是由福建河流提供的，但在平潭岛周边海域的黏土矿物可能有长江物质的混合。〖JP〗
Clay Minerals in Surface Sediments of the Taiwan Strait and Their Provenance
Abstract: The Taiwan Strait connects the East China Sea and the South China Sea, which are two major marginal seas of west Pacific Ocean. This region serves as a canonical area for investigating the terrigenous detrital materials that are transported into the sea, including the provenance and flux, as well as the modelling of the distribution, transport and dispersion in continental shelf areas. Under the combined influence of the southbound Zhemin Coastal Current (ZCC) and northbound Taiwan Warm Current, the sediments in the Taiwan Strait exhibit the characteristics of multiple origins.Clay minerals in surface sediments from the Taiwan Strait and adjacent area were analyzed by XRay Diffraction (XRD) method to constrain the possible provenances including the Yangtze, Fujian and Taiwanese rivers. Clay mineral assemblage in the Min River (one of the largest Fujian rivers) consists dominantly of kaolinite (>40%) with minor amounts of illite and chlorite but without smectite, indicating that clay minerals in Min River drainage basin is originated from upriver granites by weathering under warm and humid conditions. Yangtzedominated clays have relatively high illite (61%～66%), with small amounts of chlorite (16%～17%) and kaolinite (10%～13%), low smectite (6%～9%) and poor illite crystallinity. Taiwandominated clays (Zhoshui River), in contrast, have the highest illite contents (>70%), and no smectite. The clay mineral assemblages from both sides of the Taiwan Strait are different, because of the source rocks and weathering condition factors. In the Taiwan Strait, kaolinite contents of the sediments decrease gradually from west to east, indicating that they are mostly originated from Fujian rivers. In the east region of the 50 m isobath in the Taiwan Strait, the clay mineral assemblage is dominated by illite and chorite with scarce smectite and kaolinite (both generally<5%), different from those of the Yangtze and Fujian rivers. Moreover, both chemistry index and crystallinity of illite are lower than those of the Yangtze and Fujian rivers, but similar to those of the Taiwanese rivers. Our data suggest that most of illite and chlorite in the northern Taiwan Strait were provided by Taiwanese rivers through the Taiwan Warm Current. However, clay minerals in offshore areas of Fujian Province were mainly provided by Fujian rivers, and locally possible mixed by the Yangtze river, such as the neighbor oceanic area of Pingtan island.
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