中全新世以来琼东南陆架粘土矿物特征及物质来源

以往针对南海北部陆架沉积物物质来源的诸多研究, 在一定程度上忽略了海南岛物质的影响.基于柱状沉积物样品的岩性、粒度、粘土矿物和AMS14C年代分析, 探讨了琼东南陆架沉积区X2站沉积物的物质来源.结果表明, X2站沉积物可划分为上、下两段, 下段(Ⅰ, 240~120 cm)主要为粘土质粉砂, 上段(Ⅱ, 120~0 cm)主要为粉砂质砂.粘土矿物主要由伊利石和高岭石组成, 含有少量绿泥石和蒙脱石.对比分析显示, 伊利石和绿泥石可能主要来自于珠江和台湾岛; 高岭石可能主要来源于海南岛和珠江, 蒙脱石主要来自于近源的雷琼地区, 即海南岛物源对南海北部陆架西段具有一定的影响.近4 ka以来, X2站沉积物的明显变粗和高岭石含量逐渐增高, 说明海南物质的输入增强, 这可能是由于近4 ka以来的气候变化或者人类活动增强所致. 

Clay Mineral Characteristics and Provenance of Continental Shelf Sediments in Eastern Hainan Island since Middle Holocene

The influence of Hainan Island has been ignored in the previous researches of sediment provenance in the continental shelf of the northern South China Sea. Therefore, the sediment provenances on the basis of lithology, grain-size, AMS14C dating, clay mineral analysis that were carried out for Core X2 located in the continental shelf of the Hainan Island in the South China Sea are discussed in the paper. The results show that Core X2 is separated into two stages, namely the upper one and the lower one. The lower one(Ⅰ, 240-120 cm) is mainly composed of clay silt while the upper one (Ⅱ, 120-0 cm) consists mainly of silty sand. Clay minerals in Core X2 mainly consist of illite and kaolinite, with associated chlorite and smectite. The comparison of clay mineral assemblages between sediments at Core X2 and other potential provenances indicates that predominant illite and chlorite may have been originated from Taiwan and the Pearl River, whereas kaolinite may has been provided mainly by Hainan Island and the Pearl River; smectite was derived mainly from Leiqiong area. It shows that materials on Hainan Island have certain influence on the continental shelf in the northern South China Sea. The coarsening of the sediment and the higher content of the kaolinite mean that Hainan Island provides more materials than other provenances in stage Ⅰ, which may have been resulted from climatic variation and enhancement from human activities since 4 ka.