东海西北部陆架表层沉积物重矿物组合及其沉积环境指示  

The heavy mineral assemblages of the surface sediments on the northeast shelf of the East China Sea and their environmental implication

作　　者：王中波[1,2] 杨守业[2] 张志珣[1] 何起祥[1] 蓝先洪[1] 

机构地区：[1]国土资源部青岛海洋地质研究所海洋油气资源与环境地质国土资源部重点实验室,山东青岛266071 [2]同济大学海洋地质国家重点实验室,上海200092

出　　处：《海洋学报》2012年第6期114-125,共12页

基　　金：国家自然科学基金(41040041;41206053);中国地质调查局"国土资源大调查"项目(1212010611301);中国地质调查局海洋地质调查专项工作项目(GHZ201100203);国土资源部青岛海洋地质研究所海洋油气资源与环境地质国土资源部重点实验室开放基金(MRE201228)

摘　　要：研究了东海陆架360个表层沉积物的碎屑矿物和粒度组成,利用R型聚类方法提取稳定重矿物和重矿物分异指数作为矿物分布规律的指示因子;根据快速聚类结果将重矿物组成分为3个区:东海陆架海侵体系域晚期残留砂体区、高位体系域晚期长江水下前三角洲和浙闽沿岸流泥质沉积区、高位体系域扬子浅滩沉积区。结合粒度参数和特征矿物分布、沉积物14 C年龄对各区沉积环境进行讨论,确定陆架残留沉积和改造沉积的成因、长江水下三角洲和浙闽沿岸流泥质区的范围,以及对应不同海侵层序的矿物分异特征和物质"源-汇"关系。聚类分析虽能够指示同一物源碎屑矿物分布与沉积动力关系,但物源不同,聚类结果可能误导沉积环境分析。扬子浅滩表层砂体是在距今6～4和3～2ka的两个潮流沉积发育期形成的多期改造沙波沉积。The heavy mineral assemblages and grain-size compositions of 360 surface sediment samples on the northeast shelf of the East China Sea are analyzed for the study of depositional environments. An R- type cluster analysis suggests that stable minerals or opaque minerals and a heavy mineral differentiation index can discriminate the distribution patterns of detrital minerals on the shelf. Meanwhile, a K-means cluster analysis can identify three groups： relict sandy area, subaqueous prodelta of the Changjiang River and muddy belt on the inner shelf off Zhejiang and Fujiang Provinces, and the Changjiang sand sheet area. The combination of grain size, heavy minerals,^14C age and sedimentation environment primarily deter- mines the formation of relict/reworked sediments on the mid-outer shelf and the mud distribution in the Fuiian-Zhefiang coast, and sediment source to sink transport during the postglacial transgression. The re- sults of cluster analysis clearly reveal the relation between detrital mineral compositions and hydrodynamic sorting of single--provenance sediment. However, it may cause some misleading results when complex sources exist. The surface sediments of the Changjiang tidal sand sheet are reworked tidal sand ridges with formation ages of 6- 4 and 3- 2 ka B. P.

关 键 词：重矿物 东海陆架 表层沉积物 粒度 沉积环境 聚类分析 

分 类 号：P736.211[天文地球—海洋地质]