南海湖泊沉积物中的陆源粉尘记录

RECORDS OF TERRIGENOUS DUST IN LACUSTRINE SEDIMENTS FROM DONGDAO ISLAND,SOUTH CHINA SEA

  • 摘要: 对采集于南海西沙东岛"牛塘"的湖泊沉积柱(DY6)进行元素、粒度、显微成像、扫描电镜及场发射能谱分析。元素分析结果表明,Ti、Al元素在沉积柱中的含量远高于3个主要沉积端元(珊瑚砂、鸟粪和植物),具有外源的特征,在Ti和Al的高值层位中存在较多不溶于酸的粉尘颗粒,与春季合肥地区收集到的北方风尘颗粒形貌特征相近,粒径相对较小,也与季风携带沉降于朝鲜半岛和南海北部海域的风尘形貌相似;X射线能谱分析结果显示,这些粉尘颗粒物成分以硅酸盐岩和石英为主,很可能是东亚冬季风携带下源自亚洲大陆的沉积;沉积物中Ti和Al的含量变化可以用于指示历史时期南海中北部海域陆源粉尘颗粒的沉降通量。

     

    Abstract: A lacustrine sediment core (DY6) was collected from the "Nietang Pond" on Dongdao Island,South China Sea (SCS). Geochemical,morphological,and mineralogical analyses were performed for the sediment samples. The results of major elements showed that the concentrations of Ti and Al in the sediment samples were much higher than those in three end-members (coral sand,guano and plants). Hierarchical clustering analysis of geochemical elements indicated that Al and Ti were exogenetic. Furthermore,according to the microscopic analysis,there are more acid-insoluble particles in the subsamples with high Ti (Al) contents,some of which showed similar morphological characters with the eolian dusts from Hefei,the loess-paleosol particles from Korea and the dust deposits from the north of SCS. The major elements concentrations of the acid-insoluble particles surfaces detected by X-ray energy spectrum revealed that these particles were mainly made up of silicate and quartz. Consequently,the accumulation of Ti and Al in the lacustrine sediments of Dongdao Island was quite possibly caused by the input of the terrigenous dust from the interior of Asia continent. The East Asian Winter Monsoon might be the transportation medium.

     

/

返回文章
返回