天山开都河流域河流阶地形成年代与新构造运动意义

Age of Kaidu River Terraces and Significance of Neotectonic Movement,Tianshan

天山开都河流域河流阶地序列及形成时代研究对揭示天山山脉新生代构造隆升意义重大。据野外工作确定开都河流域发育7级河流阶地,类型以堆积阶地为主,对具代表性的河流阶地采集10个ESR样品,测试成果表明,阶地形成时代为(3.6±0.3)ka^(653.7±65)ka。开都河流域河流阶地与天山北麓玛纳斯河流域河流阶地形成具可对比性,表明天山地区中更新世至全新世普遍存在河流下蚀作用。结合河流阶地高程,用线性回归定量计算出河流下切速度为0.101 m/ka,能约束天山山脉新构造时期的隆升速率。研究表明开都河流域河流阶地受构造隆升和气候变化共同控制,河流下蚀作用的地质营力来源于地壳的整体隆升。

The research of sequence and age aboat Kaidu River terrace has always been in a low degree,which is of great significance to revel the tectonic uplift of the Tianshan mountains.According to the detailed field work,Kaidu River Basin developed 7 river terrace that mainly of accumulational terrace.The test results from 10 typical ESR samples which are collected in Kaidu River basin show that the formation time of river terraces is between(3.6±0.3)^(653.7±65)ka.The comparison of Manasi River terraces in the northern piedmont Tianshan Mountains indicate that the erosion of both two rivers is widespread during the Middle Pleistocene to Holocene epoch.The results which calculated by linear regression combine with the altitude of river terraces shows that the incision rate of Kaidu River is averaged as 0.101 m/ka.This results could constrain the uplifting rate of the Tianshan Mountains during the neotectonic period.A lot of studies indicate that Kaidu River terraces are controlled by tectonic uplift and climate change.The geologic agent of the erosion of the river originates from the overall uplift of the crust.