西昆仑依格孜也尔河阶地沉积特征及其对河流演化的指示  

Sedimentary characteristics of Yigeziyer River terraces of West Kunlun,China and its implications for river evolution

作　　者：许应石[1] 欧健[1] 郭刚[1] 贺新星[1] XU Ying-shi;OU Jian;GUO Gang;HE Xin-xing(Geological Survey of Jiangsu Province,Nanjing 210018,China)

机构地区：[1]江苏省地质调查研究院,南京210018

出　　处：《华东地质》2020年第3期237-245,共9页East China Geology

基　　金：中国地质调查局“新疆西昆仑1∶5万J43E009017、J43E010017、J43E010018、J43E011017、J43E011018等5幅区域地质矿产调查(编号:1212011220631)”项目资助。

摘　　要：对西昆仑山前依格孜也尔河阶地进行野外地质调查,获得阶地河拔、分布、发育及沉积特征等资料。在此基础上,分析阶地沉积相及沉积环境,进一步研究西昆仑山前河流阶地发育成因及河流演化过程。依格孜也尔河发育基座阶地T4和T3,堆积阶地T2和T1,阶地T1、T2、T3和T4时代依次为5~8 ka B.P.、18~30 ka B.P.、40~50 ka B.P.和80~100 ka B.P.。阶地形成主要受控于间歇性构造抬升,受气候变化影响较小,阶地类型差异主要受河流演化影响。阶地沉积相分析表明,T4和T3阶地分别为泥石流相和冲洪积扇相,河流侵蚀作用强,间歇性堆积;T2阶地沉积期河流系统出现重大转变,呈多旋回辫状河沉积,堆积作用增强;T1阶地为主河道-漫滩相沉积,侵蚀-堆积作用趋于平衡。This study obtained heights,distribution,development and sedimentary characteristics of terraces through field geological investigation on Yigeziyer River terraces in the piedmont of West Kunlun.On this basis,authors further investigated development genesis of terraces and evolution process of river by analyzing sedimentary facies and paleo environments of different river terraces.The results show that the Yigeziyer River developed two pedestal terraces(T4 and T3)and two accumulation terraces(T2 and T1),which formed at about 80~100 ka B.P.,40~50 ka B.P.,18~30 ka B.P.,5~8ka B.P.respectively.The terraces resulted mainly from periodic tectonic uplifting,with limited effect from climate change,and the difference of terrace types was mainly influenced by river evolution.Terrace sedimentary facies analysis shows that the main sedimentary facies of T4 and T3 are debris flow sedimentary and alluvial-proluvial fan sedimentary respectively,with strong river erosion and intermittent accumulation.During the T2 sedimentary period,the river system changed greatly,the sediment shows multi-cycle braided river deposit,with enhanced accumulation.The sedimentary facies of T1 terrace was mainly channel-floodplain deposits,with the erosion-accumulation process towards to balance.

关 键 词：西昆仑 依格孜也尔河 河流阶地 沉积特征 河流演化 

分 类 号：P588.1[天文地球—岩石学]