SEISMOLOGY AND GEOLOGY ›› 2004, Vol. 26 ›› Issue (4): 716-726.

• Brief Report • Previous Articles     Next Articles

OPTICAL STIMULATED LUMINESCENCE (OSL) DATING OF LATE PLEISTOCENE TERRACE DEPOSITS IN THE EASTERN SEGMENT OF THE ALTYN TAGH FAULT AND ITS TECTONIC IMPLICATION

WANG Ping1, LU Yan-chou1,2, CHEN Jie1   

  1. 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2. State Key Laboratory of Loess and Quaternary Geology & Institute of Earth Environment, Chinese Academy of Science, Xi'an 710075, China
  • Received:2003-08-10 Revised:2004-07-04 Online:2004-12-02 Published:2009-11-27

阿尔金断裂带东段晚更新世阶地沉积物红外释光测年及其构造意义

王萍1, 卢演俦1,2, 陈杰1   

  1. 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;
    2. 中国科学院地球环境研究所, 黄土与第四纪地质国家重点实验室, 西安, 710075
  • 作者简介:王萍,女,1964年出生,1983年毕业于武汉地质学院地震地质专业,2003年在中国地震局地质研究所获构造地质专业博士学位,副研究员,目前主要从事活动构造与年代学研究,电话:010-62009099,E-mail:wangP901@yahoo.com.cn.
  • 基金资助:
    国家自然科学基金(40072058);地震科学联合重点基金(201018)共同资助。中国地震局地质研究所论著2004B0056。

Abstract: The ages of terrace deposits along the Shulehe River system are determined by the use of Optical Stimulated Luminescence (OSL) dating technique. The possible tectonic implications of the obtained age data are discussed as follows: (1) The Duanjiagou,Shulehe,and Tashihe Rivers are three rivers of different characters from the Shulehe River system. Several levels of terraces of different altitudes and corrosion rates were developed in the intermont basin and mountain front on the eastern segment of the Altyn Tagh fault. These terraces are the result of differential uplift of the fault blocks. (2) On the southern margin of the Changma basin,7 levels of terraces were developed along the Shulehe River. OSL dating results show that those over 100m high terraces were formed mainly about 40000 years ago,and this may indicate the intensive uplift of the Daxueshan-Xiangmaoshan Mountains and the new activity of the Changma seismic belt. The rate of tilted uplift of the southern part of the Changma basin is inferred to be 2.5mm/a. (3) At Zhaobishan gorge,five levels of terraces of the Shulehe River are still well preserved. Among them,the T3 terrace of 40~60m elevation above the stream level might be related to the new tectonic activity of the region. The T5 terrace of over 150m elevation above the stream level observed at the boca has an ESR age of approximately 200ka and an uplift rate of 0.7mm/a. (4) On the Hongliuxia fault block uplift,4 levels of terraces were developed along the Duanjiasha River. Dating results of the T1,T2 and T3 terraces show that a linear relation exists between the heights and the ages of the terraces,from which an uplift rate of 0.6mm/a can be deduced. The Hongliuxia and the Zhaobishan fault block uplifts are the fault blocks controlled by the strike-slip movement of the Altyn Tagh Fault. They have approximately the same rate of uplift that is quite different from that of the range-front uplift of the Daxueshan-Xiangmaoshan Mountains,indicating that the uplift deformation of the Tibetan Plateau in the late stage of late Pleistocene occurred mainly along the Changma active fault zone. (5) Four levels of terraces were developed at the fan apex of the Tashihe River,and the age of the T3 terrace is dated to be 78.8±5.5ka. It is postulated,therefore,that the terraces at the apex of the Tashihe River alluvial fan were formed in the middle to late stages of late Pleistocene. On the basis of OSL dating results of terrace deposits and the investigation of tectonic landforms,it is concluded that periodic uplift has occurred in the Nanjieshan fault block at 300 ka BP or during the middle to late stage of late Pleistocene.

Key words: eastern Altyn Tagh Fault, Optical Stimulated Luminescence (OSL) dating, terrace, rate of uplift

摘要: 对流经阿尔金断裂带东段的段家沙河、疏勒河和踏实河的阶地沉积物进行了细颗粒多测片红外释光(IRSL)测年,初步确定了晚第四纪各级阶地的形成年代和构造抬升速率。疏勒河在昌马盆地南缘发育7级阶地,光释光测年结果显示这些总高度超过100m的阶地可能主要形成于数万年以内,抬升速率约为2.5mm/a;照壁山峡谷疏勒河保留有5级阶地,大致形成于20万年前,阶地的抬升速率约为0.7mm/a;段家沙河在红柳峡上形成4级阶地,形成于距今7万年以来,其抬升速率约为0.6mm/a。

关键词: 阿尔金断裂带东段, 红外释光测年, 阶地, 抬升速率

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