【摘要】 基于AMS¹⁴C定年结果,对近千年来台湾以东黑潮主流区沉积物的粒度、黏土矿物组成及结晶学特征等进行研究,分析该区沉积特征、物质来源及近千年来环境演化的沉积记录。结果表明,台湾以东黑潮主流区沉积物主要为细粒的粉砂和黏土,沉积速率平均为34.44 cm/ka,低于东海陆架和冲绳海槽南部,高于开阔大洋,具有从陆架向大洋过渡的沉积特征。黏土矿物组成的分析结果表明,台湾以东黑潮主流区沉积物黏土矿物组成以伊利石（平均57%）和蒙脱石（平均25%）为主,含有少量绿泥石（平均16%）,几乎不含高岭石（平均2%）,其中蒙脱石主要来源于吕宋岛弧物质输送和附近海域原位的基性火山物质蚀变,伊利石和绿泥石主要来源于亚洲大陆风尘输送和台湾东部河流输入,高岭石主要来源于台湾东部河流和吕宋岛弧物质输入。黏土矿物的物源定量识别研究表明,研究站位的黏土矿物有26%～72%来源于亚洲大陆风尘输送,11%～55%来源于台湾东部河流输入,11%～26%来源于吕宋岛弧物质输送。近千年来沉积物物源的变化特征较好地反映了中世纪暖期、小冰期和现代暖期这3个百年尺度的全球性气候变化阶段。亚洲大陆风尘输送和台湾东部河流输入对研究区沉积物的相对贡献量变化反映了中世纪暖期较强的东亚冬季风特征和台湾地区较为干旱的气候环境,同时也反映了小冰期逐渐减弱的东亚冬季风强度和台湾地区较为湿润的气候环境。现代暖期和中世纪暖期在东亚热力差异和降水异常上的差别反映了人类活动对沉积物的扰动。而研究区小规模的沉积特征突变事件主要与暴雨、台风和地震活动相关。更多还原

【Abstract】 Grain size, clay mineral compositions and crystallinity in the sediments from the Kuroshio area of eastern Taiwan were analyzed to study the sedimentary characteristics, provenance and the environmental evolution during the past 1 000 years. The results indicate that the sediments mainly consist of fine-grained silty and clay compositions. The average sedimentation rate is 34.44 cm/ka, which is less than that in the East China Sea shelf and more than that in the South of Okinawa Trough, showing the transitional sedimentary characteristics from continental shelf to ocean. Clay minerals mainly consist of illite(with average of 57%), smectite(25%), with associated chlorite(16%) and kaolinite(2%). The illite of the sediments from eastern Taiwan mainly comes from Asian continental dust and rivers of eastern Taiwan, and the smectite mainly comes from the Luzon Arc and altered basic volcanic material from adjacent sea areas, and the chlorite and the kaolinite mainly come from the rivers of eastern Taiwan. According to the mathematical model on quantitative provenance identification on the clay minerals in this study, about 26%～72% of the clay minerals came from the Asian continental dust, and about 11%～55% of clay minerals came from rivers of eastern Taiwan, and about 11%～26% of clay minerals came from the Luzon Arc. Meanwhile, the vertical variations of the sediment during the last 1 000 years reflected three global climate change stages at the century scale, i.e., the Medieval Warm Period(MWP), the Little Ice Age(LIA) and the Current Warm Period(CWP). The variations of relative contribution of Asian continental dust and rivers in eastern Taiwan imply strong East Asian Winter Monsoon(EAWM) and dry climate in Taiwan during MWP, and also reflect decreased EAWM and humid climate in Taiwan during LIA. The differences of thermal contrast in East Asian and precipitation anomalies between CWP and MWP reflect the disturbance of human activities to the sedimentary environment. In addition, we suggest that some small-scale salutations of the sedimentary environment are mainly related to emergency events, e.g., rainstorm, typhoon and earthquake.更多还原