新疆叶尔羌河上游全新世阶地的释光年代与河流下切速率  

OPTICAL DATING OF THE HOLOCENE TERRACE SEDIMENTS AND THE INCISION RATE IN THE UPPER REACH OF THE YARKANT RIVER IN XINJIANG

作　　者：刘进峰[1] 陈杰[1] 王昌盛[1] 

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029

出　　处：《地震地质》2011年第2期421-429,共9页Seismology and Geology

基　　金：地震动力学国家重点实验室自主研究课题(LED2010A04);科技部国际科技合作计划项目(2008DFA20860);地震行业科研专项(200808015)共同资助

摘　　要：采用细颗粒石英简单多片再生法对新疆叶尔羌河上游阶地进行了光释光测年,并在不同实验室进行了等效剂量对比测试,结果基本一致。测年结果显示,该阶地沉积形成于距今4.3～7.3ka,自阶地形成以来,河流下切(27±5)m,下切速率(6.3±1.2)mm/a。塔什库尔干河中上游河流的快速下切可能与慕士塔格山穹窿的快速隆升或第四纪冰川作用有关。The Tashkurgan-Yarkant River,which is the upper reach of the Tarim River,originates from the Karakoram Mountains in the west syntaxis of the Tibetan Plateau.Thick terrace sediments are widespread along the Tashkurgan-Yarkant River.These deposits contain geologic fingerprints that allow identification of the environmental changes and geologic hazards.However,few geochronological data was available on these sedimentations to allow us to build an irreproachable age model.4 samples of fine grains from one terrace profile were dated by optically stimulated luminescence（OSL）dating method.In darkroom,fractions of fine grains（4～11μm）were extracted from the bulk samples.OSL signal measurements were performed on an automated Daybreak system.Identical De plateau in the thermal treat was observed in preheat plateau test.Tests of luminescence characteristics confirm the suitability of the material for OSL dating.Our results indicate the deposition age for these sediments is between 4.3～7.3ka.After the river terrace deposited,the river has deeply incised for 27±5m,with the incision rate 6.3±1.2mm/a.The thermochronologic data show that the magnitude of exhumation decreases from upstream（west）to downstream（east）along the Tashkurgan-Yarkand River.These data may reflect the the active uplift process of Mustagh Ata antiform.

关 键 词：河流阶地 光释光测年 叶尔羌河 下切速率 

分 类 号：P315.2[天文地球—地震学]