丽江-小金河断裂第四纪以来的左旋逆推运动及其构造地质意义——陆内活动地块横向构造的屏蔽作用  

SINISTRAL THRUSTING ALONG THE LIJIANG-XIAOJINHE FAULT SINCE QUATERNARY AND ITS GEOLOGIC-TECTONIC SIGNIFICANCE--Shielding effect of transverse structure of intracontinental active block

作　　者：向宏发[1] 徐锡伟[1] 虢顺民[1] 张晚霞[1] 李洪武[1] 于贵华[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地震地质》2002年第2期188-198,共11页Seismology and Geology

基　　金：国家重点基础研究发展规划项目 (G19980 4 0 70 1)

摘　　要：通过卫、航片解释、野外活断层调查实测与年龄测试分析发现 :斜切中国西南“川滇菱块”的横向构造———丽江 -小金河断裂为一断面高角度倾向NW的逆左旋走滑型活动断裂。通过盆地复位和同沉积盆地的位错分析 ,确定了该断裂第四纪以来的水平位错量为 7 4～ 7 6km。断裂两侧差异隆升及相应堆积物的分析表明 ,中更新世以来 ,断裂垂直位错量达 5 0 0～ 70 0m以上。由此计算得到丽江 -小金河断裂第四纪和中更新世以来的水平与垂直位错速率分别为 3 7～ 3 8mm/a和 1 0～1 5mm/a。水平位错及相关年龄测试资料表明 ,该断裂晚更新世以来的平均位错速率在 2 6～4 0mm/a之间 ,中值为 3 3mm/a ;全新世以来的平均位错速率在 2 5～ 5 0mm/a之间 ,中值为3 5mm/a。第四纪各时段以来滑动速率的较好相似性表明 ,长期以来 ,该断裂的活动具相对稳定性和活动地块边界的持久性。The Lijiang Xiaojinhe Fault lies in Northwest Yunnan Plateau, striking N40°E and extending for 360km. It is an important transverse active fault, obliquely cutting the 'Sichuan Yunnan Rhombic Block' in southwest China. Interpretation of aerophotos, field investigation, and age determination of this active fault have revealed that the fault is an active reverse sinistral strike slip fault, dipping northwest at high angle. Relocation of basins and analysis of synsedimentary dislocation of the basins provide an estimate of the horizontal dislocation amount along the fault of 7.4～7.6km since Quaternary. In addition to the large scale horizontal movement, the vertical differentiation of relief and landforms on both sides of the fault is also strikingly shown. The relief along the fault strand from Lijiang northeastward to Ninglang and Muli is higher on the northwest side and lower on the southeast side, between which lie a series of steep fault scarps and a topographically steep zone. Comparison of the relief on both sides of the fault shows that the vertical throw of the fault is 500～700m or more. The horizontal and vertical dislocation rates along the Lijiang Xiaojinhe Fault since Quaternary and since middle Pleistocene are estimated preliminary to be 3 7～3 8mm/a and 1 0～1 5mm/a, respectively. In the northeast of Lijiang, especially along the Changping Muzhuda and Baerqiao area in Ninglang, a series of evidence of sinistral horizontal dislocation, such as offset ridges, gullies, proluvial fans, and terraces was found. The amount of horizontal dislocation varies from several meters to hundreds meters. All these may indicate the characteristics of obvious movement along the fault since late Quaternary. The amounts of horizontal dislocation and the related data of age determination indicate that the average dislocation rate since late Pleistocene is in the range of 2 6～ 4 0 mm/a with a mean value of 3 3mm/a; the average dislocation rate since Holocene is in the range of 2 5～5 0mm/a w

关 键 词：左旋逆推运动 陆内活动地块 横向构造 屏蔽作用 逆走滑运动 第四纪 丽江-小金河断裂 

分 类 号：P542.3[天文地球—构造地质学]