西藏谷露盆地西缘断裂新活动特征研究

Study on the New Active Characters of Western Margin Fault of Gulu Basin,Tibet

摘要:

谷露盆地位于亚东-当雄构造带的最北端,全长约50 km。通过遥感解译和实地野外考察,将盆地内的堆积扇分为中更新世、晚更新世末期-全新世和全新世晚期三期,并认为其西缘断裂带是一条既有垂直运动又兼具右旋走滑的正断层。通过测定错断地质体位移和沉积物年龄样品,得到断裂带在1952年当雄北7.5级地震的同震水平位移为5.5 m,同震垂直位移为2~5 m;4 ka以来的水平滑动速率为3.75 mm/a,垂直滑动速率为0.5~1.5 mm/a;大约10 ka以来的水平滑动速率为1.0~5.0 mm/a,垂直滑动速率为0.5~0.85 mm/a。

Abstract:

Gulu Basin which extends over 50 km is situated in the middle of Tibet,and belongs to the north segment of Yadong-Dangxiong fault zone.Based on interpretation of remote sensing and geological tracing result,the ages of sedimentary fans are divided into three stages： Mid-Pleistocene,late time of Late-Pleistocene to Holocene and late time of Holocene.The western margin fault of Gulu Basin is a normal fault which has both vertical and right-lateral movement.Through researching the displacements and the sediments dates, it is obtained that the coseismic displacement is about 5.5 m, and the coseismic vertical displacement is 2-5 m in Ms at north of Dangxiong in 1952; the horizontal slip speed is 3. 75 mm/a, and theis 0. 5-1.5 mm/a since 4 ka; the horizontal slip speed is 1.0-5.0 mm/a,and the vertical slip speed is 0. 5-0.85 mm/a since about 10 ka.