冲绳海槽南部沉积层序的粒度特征  

Grain-size Variations of Terrigenous Sediment Sequences in the South Okinawa Trough

作　　者：李军[1] 高抒[2] 孙有斌[1] 曾志刚[1] 

机构地区：[1]中国科学院海洋研究所 [2]南京大学海岸与海岛开发教育部重点实验室,南京210093

出　　处：《沉积学报》2003年第3期461-466,共6页Acta Sedimentologica Sinica

基　　金：国家重点基础研究规划项目 (973) (编号G2 0 0 0 0 4 670 2 );国家自然科学基金 (批准号 :40 1 0 60 0 6和 40 1 760 2 0 );中国科学字知识创新工程项目 (KZCX2 - 2 0 7)联合资助

摘　　要：对取自冲绳海槽南部的A2 3孔经前处理后的沉积物样品进行了粒度测试 ,探讨了陆源沉积层序的粒度特征。沉积物平均粒径、分选系数、偏态、峰态等粒度参数的变化显示出A2 3孔的沉积层序以 4 0 0cm为界可分为上、下两段 ,下段各参数稳定 ,代表了比较稳定的水动力条件的沉积环境 ;上段则波动较大 ,小规模浊流沉积频繁发育 ,暗示了不稳定的沉积环境。浊流层内粗粒与细粒组分含量及粒度分布的变化具有明显的规律性。通过分析A2 3孔陆源沉积层序的各沉积参数特征 ,认为冲绳海槽南部的沉积环境和动力在时间尺度上有较大的变化 ,东海陆架物质向南部海槽的输运可能是以峡谷为通道的重力作用引起的床底沉积作用为主。另外 ,对陆源碎屑和全样粒度结果的对比 。Terrigenous detritus samples extracted from a piston core A23, located in the so uthern Okinawa Trough, were analyzed in terms of the grain-size characteristics . The results show that the terrigenous sequences in the core can be divided int o two parts on the basis of the variations in the grain-size parameters. The l ower sequence is characterized by constant grain-size parameters; whilst the up per part is controlled by turbidite layers with a thickness of about 2～20 cm, which caused very large variations of the parameters. The large variation of gra in-size composition and distribution of the turbidite sequences significantly disturbed the normal formation of the sediment sequences. The gain-size distri bution modes and parameters of a turbidite bed were analyzed in detail, which sh ow very regular variation in the bed. According to all grain-size character istics of the core, the depositional environment and sediment dynamics is very c omplex and the main mechanism of the transportation of the terrigenous material from East China Sea Shelf to the trough is in the form of bedload through canyo ns. Furthermore, pretreatment to the marine sediments is important, which enable s us to compare the grain-size characteristics between terrigenous detritus and the bulk grain-size.

关 键 词：冲绳海槽 沉积层序 粒度特征 粒度参数 粒度分布 浊流沉积 

分 类 号：P736.2[天文地球—海洋地质]