Late Quaternary Slip-rates and Slip Partitioning on the Southeastern Xianshuihe Fault System, Eastern Tibetan Plateau  

作　　者：CHEN Guihua XU Xiwei WEN Xueze CHEN Yue-Gau 

机构地区：[1]Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China [2]Earthquake Administration of Sichuan Province, Chengdu 610041, Sichuan, China [3]Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan, China

出　　处：《Acta Geologica Sinica(English Edition)》2016年第2期537-554,共18页地质学报（英文版）

基　　金：funded by National Natural Science Foundation of China(No.40802052);the National Basic Research Program of China(2004CB418401)

摘　　要：Quantitative analysis of the kinematics of the active faults distributed around the QinghaiTibetan Plateau is critical to understand current tectonic processes of the plateau. Chronological analysis, based on the comparison among regional climate and geomorphology, digital photogrammetry, offset landforms, and the tectonics were adopted in this study on the Xianshuihe fault in the eastern Tibetan plateau. Two or more offset-age data were obtained for each segment of the Xianshuihe and theYunongxi faults. The offset landforms, including river terrace, alluvial fan and glacial moraine, provide constraints for the late Quaternary slip rate of the Xianshuihe fault. The left-lateral strike slip rate of the Xianshuihe fault decreases from 17 mm/a on the northwest segment to 9.3 mm/a on the southeast segment. Regarding the Xianshuihe fault zone and its adjacent blocks as a regional tectonic system, vector analysis was used to quantitatively analyze the longitudinal kinematical transformation and transversal slip partitioning on the fault zone in terms of the kinematical parameters of the main faults within the zone. The results show that there is a distributed vertical uplift at a rate of 6.1 mm/yr caused by shortening across the Gongga Mountains region. Based on these results, we established a model of the slip partitioning for the southeastern segment of the Xianshuihe fault zone.Quantitative analysis of the kinematics of the active faults distributed around the QinghaiTibetan Plateau is critical to understand current tectonic processes of the plateau. Chronological analysis, based on the comparison among regional climate and geomorphology, digital photogrammetry, offset landforms, and the tectonics were adopted in this study on the Xianshuihe fault in the eastern Tibetan plateau. Two or more offset-age data were obtained for each segment of the Xianshuihe and theYunongxi faults. The offset landforms, including river terrace, alluvial fan and glacial moraine, provide constraints for the late Quaternary slip rate of the Xianshuihe fault. The left-lateral strike slip rate of the Xianshuihe fault decreases from 17 mm/a on the northwest segment to 9.3 mm/a on the southeast segment. Regarding the Xianshuihe fault zone and its adjacent blocks as a regional tectonic system, vector analysis was used to quantitatively analyze the longitudinal kinematical transformation and transversal slip partitioning on the fault zone in terms of the kinematical parameters of the main faults within the zone. The results show that there is a distributed vertical uplift at a rate of 6.1 mm/yr caused by shortening across the Gongga Mountains region. Based on these results, we established a model of the slip partitioning for the southeastern segment of the Xianshuihe fault zone.

关 键 词：slip partitioning kinematical transformation tectonic morphology Xianshuihe fault Gongga Mountains 

分 类 号：P315.2[天文地球—地震学] S714.7[天文地球—固体地球物理学]