柴达木盆地三湖地区第四系沉积相研究

Study on Sedimentary Facies of the Quaternary in Sanhu Area of Qaidam Basin

柴达木盆地三湖地区第四系自下而上划分为5个层序。对野外露头、岩心、测井、地震和地化等资料的综合研究表明,本区主要发育冲积扇、扇三角洲、三角洲、湖泊等沉积相类型,以湖泊相为主。冲积扇相可划分为扇根、扇中和扇端3个亚相;扇三角洲相、三角洲相均以前缘亚相为主;湖泊相则可分为滨湖、浅湖和半深湖3个亚相。不同层序发育时期内各种沉积相的发育规模不同。各种沉积相在空间上有规律分布:在南部斜坡和北部的哑叭尔、全吉地区主要发育冲积扇和扇三角洲沉积,在盐湖和察尔汗地区主要发育河流三角洲沉积,其他地区发育湖泊沉积。各个层序的沉积相平面展布表明半深湖沉积位置和沉积中心有由西向东不断迁移的趋势。在综合分析各种成果的基础上,建立了研究区的沉积模式,并指出研究区的有利勘探带大致位于涩南—金达一带以及驼西鼻隆、台东鼻隆、涩东鼻隆等北斜坡构造发育带。

The Quaternary of the Sanhu area in Qaidam Basin is subdivided into 5 sequences from bottom to top.The comprehensive analysis of outcrop,core,drilling,logging,seismic and analysis testing data indicates that in the area are developed the facies types such as alluvial fan,fan delta,delta and lake facies,with the lake facies being predominant.The alluvial fan can be subdivided into three subfacies as root,middle part and extremity.The front is predominant in the fan delta and the delta.The lake facies can be subdivided into three subfacies as the shore lake,shallow lake and half-deep lake.In different sequence periods there are different scales of facies.Various facies distribute regularly in space.The alluvial fan and the fan delta facies develop in the southern slope and northern Yaba＇er and Quanji areas.The delta facies develop in Yanhu and Qarhan areas.And other areas are all occupied by the lake facies.Each plane distribution of sedimentary facies in each sequence indicates that the depositional places of the half-deep lake and the depositional center have the migration trend from west to east.Finally,on the basis of the comprehensive analysis on various results,the sedimentary model in the studied area is built.And it is pointed that the favorable exploration regions in the studied area are located in Senan-Jinda area and the structure development zones in the northern slope such as Tuoxi,Taidong and Sedong uplifts.