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对“国际大洋发现计划”(IODP)351航次U1438A孔晚更新世以来沉积物中黏土矿物的组成、含量及矿物学特征进行了分析。结果表明,U1438A孔中黏土矿物以伊利石为主,平均含量为57%;其次是蒙皂石,平均含量为26%;绿泥石的平均含量为14%;高岭石的含量最少,平均仅为3%。伊利石的结晶度较好(<0.4°Δ2θ),而且化学指数较低(<0.43),表明伊利石主要形成于干冷的气候环境。通过将U1438A孔黏土矿物组合特征与周边可能源区对比,并结合黏土矿物的结晶参数特征,认为蒙皂石主要来源于奄美三角盆地周边岛弧火山物质;伊利石、绿泥石和高岭石主要来自于亚洲大陆风尘。(伊利石+绿泥石)/蒙皂石比值阶段性增加与亚洲大陆晚更新世以来变干冷的趋势是一致的。(伊利石+绿泥石)/蒙皂石和(伊利石+绿泥石)/高岭石比值在冰期的高值,指示了冰期亚洲风尘物质输入的增加,这是对亚洲大陆冰期干旱化和东亚季风增强的响应。
The composition, contents and mineralogical characteristics of clay minerals in sediments since the Late Pleistocene of U1438A Hole in “IODP” 351 were analyzed. The results show that the clay minerals in U1438A are mainly illite with the average content of 57%, followed by smectite, with an average content of 26%, chlorite with an average content of 14%, kaolinite with the least average content Only 3%. The illite has a good crystallinity (<0.4 ° Δ2θ) and a low chemical index (<0.43), indicating that the illite is predominantly formed in a dry and cold climate. By comparing the characteristics of U1438A clay mineral assemblages with the surrounding probable source areas and combining with the crystalline parameters of clay minerals, smectite is believed to originate mainly from the island arc volcanic material around the Amami-Triangle basin; illite, chlorite and kaolinite Dust from the Asian continent. (Illite + chlorite) / smectite ratio increased in stages consistent with the tendency of the Asian continent to become drier since late Pleistocene. (Illite + chlorite) / smectite and (illite + chlorite) / kaolinite ratios during glacial periods, indicating an increase in the input of dust and dust material in Asia in the glacial period. This is an indication of the glacial aridification of the continental shelf in Asia East Asian monsoon enhanced response.