地理学报 ›› 2011, Vol. 66 ›› Issue (11): 1540-1550.doi: 10.11821/xb201111010

• 水文地貌与第四纪 • 上一篇    下一篇

末次冰盛期后格尔木河下切的时空变化及其构造意义

陈艺鑫1, 张梅1, 李川川1, 李英奎2, 刘耕年1   

  1. 1. 北京大学城市与环境学院,北京 100871;
    2. Department of Geography, University of Tennessee, Knoxville, TN 37996, USA
  • 收稿日期:2011-06-20 修回日期:2011-08-31 出版日期:2011-11-20 发布日期:2011-11-20
  • 作者简介:陈艺鑫(1982-), 男, 辽宁辽阳人, 博士生, 主要从事地貌学与第四纪地质学研究。E-mail: chenyixin@pku.edu.cn
  • 基金资助:

    国家自然科学基金项目(40571014; 40971002); 国家重点基础研究发展规划项目(973 项目) (2005CB422001)资助

Fluvial Incision Process and Its Tectonic Implications of Golmud River since Last Glaciation Maximum

CHEN Yixin1, ZHANG Mei1, LI Chuanchuan1, LI Yingkui2, LIU Gengnian1   

  1. 1. College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;
    2. Department of Geography, University of Tennessee, Knoxville, TN 37996, USA
  • Received:2011-06-20 Revised:2011-08-31 Published:2011-11-20 Online:2011-11-20
  • Supported by:

    National Natural Science Foundation of China, No.40571014; No.40971002; National BasicResearch Program of China (973 Program), No.2005CB422001

摘要: 格尔木河河谷中发育有四级河流阶地,均形成于末次冰盛期之后。阶地的形成由构造抬升驱动,四级阶地代表的河流下切过程反映了四次阶段性构造抬升。以三岔河和纳赤台为代表的中游河段,四次河流阶段性下切速率分别为16~13 ka BP (T4-T3),3.33~9.33 mm/a;13~11 ka BP (T3-T2),5.5~12 mm/a;11~5 ka BP (T2-T1),0.33~1 mm/a;5 ka BP (T1 至今),0.6~0.8 mm/a,下切速率自T4 至T1 先增快后减慢。上游小南川河段5 ka BP以来的平均下切速率为4 mm/a,显著大于三岔河和纳赤台河段,同期河流溯源侵蚀速率也较快,表明小南川局部地区全新世中期抬升强烈,应为西大滩断裂强烈活动所致。受区域性构造活动差异影响,格尔木河河流阶地在局部地区出现变形,其中在三岔河和最老冲积扇扇顶存在两个下切幅度和速度高峰值,而纳赤台河段下切和缓。表明控制昆仑河和野牛沟发育的昆仑河—野牛沟断裂、山前的红石沟断裂自末次冰盛期以来持续活动。其中,昆仑河—野牛沟断裂16~13 ka BP活动速率较快,到13~11 ka BP达到最快,11 ka BP后减慢,与河流中下游整体构造活动趋势一致。

关键词: 格尔木河, 河流阶地, 下切速率, 构造抬升

Abstract: The Golmud River originates from the Kunlun Mountains and drains into the Qaidam Basin on northern Tibetan Plateau. The Golmud River valley has experienced intensive tectonic movements since the Last Glacial Maximum, which deeply influenced the geomorphologic evolution of the river. In addition, well-developed fluvial terraces and sediments are preserved in the river valley and provide vital information for studying the environmental evolution in detail. Four terraces developed in the river valley since the Last Glacial Maximum, which may be responses to four tectonic uplift events. In Nachitai and Sanchahe sections, the incision rates of the four terraces are 9.33-3.33 mm/a (T4-T3, 16-13 ka BP), 12-5.5 mm/a (T3-T2, 13-11 ka BP), 1.0-0.33 mm/a (T2-T1, 11-5 ka BP) and 0.8-0.6 mm/a (T1, since 5 ka BP), respectively. The incision rate increased from 16-11 ka BP, and then it has been decreasing since 11 ka, which implies the tectonic uplift processes. The average incision rate of Xiaonanchuan since 5 ka BP is 4 mm/a. The rate is larger than that of Sanchahe and Nachitai, indicating that the tectonic uplift is more intensive in this region. The longitudinal section of the terraces indicates that the rates and depths of incision were the largest in Sanchahe section (62 m, 3.88 mm/a) and on the piedmont (46 m, 2.88 mm/a), while it was mild in Nachitai section (26 m, 1.61 mm/a). The deformation of the terraces suggests that the Yeniugou fault at Sanchahe and the Hongshigou fault on the piedmont have been active since the Last Glacial. The Kunlun river fault is a thrust fault, and its uplift rates started to rise at 16-13 ka BP, and peaked during 13-11 ka BP, and decreased after 11 ka BP.

Key words: Golmud River, fluvial terrace, incision rate, tectonic uplift