Abstract: The NE margin of Tibetan plateau outspreads northeastward in late Cenozoic. The west Qinling locates at intervening zone among Tibetan plateau, Sichuan Basin and Ordos block, and is bounded by East Kunlun Fault in the southwest, the north margin of West Qinling Fault in the northeast, and the Longmen Shan Fault in the southeast. The west Qinling has been experiencing intense tectonic deformation since late Cenozoic, accompanying by uplift of mountains, downward incision of rivers, frequent moderate-strong earthquakes, vertical and horizontal motion of secondary faults, and so on. A series of "V-shape" faults are developed in the transfer zone between East Kunlun Fault and north margin of West Qinling Fault. The NWW-NW striking faults include Tazang Fault, Bailongjiang Fault, Guanggai Shan-Die Shan Fault, and Lintan-Dangchang Fault; EW-NEE-NE striking faults include Ha'nan-Qingshanwan-Daoqizi Fault, Wudu-Kangxian Fault, Liangdang-Jiangluo Fault, and Lixian-Luojiapu Fault. Among them, the Southern Guanggai Shan-Die Shan Fault (SGDF)is one of the principle branch which accommodates strain partitioning between the East Kunlun Fault and the north margin of west Qinling Fault. Although some works have been done and published, the geometry of SGDF is still obscure due to forest cover, bad traffic, natural and manmade reworks. In this paper, we collected remote sensing images with various resolutions, categories, imaging time. The selected images include composite map of Landsat image (resolution is 28.5m among 1984-1997, and 14.5m among 1999-2003), Landsat-8 OLI image (15/30m), Gaofen-1 (2m/8m), Pleiades (0.5m/2m), DEM (~25m)and Google Earth image (submeter resolution). After that, we reinforced tectonic information of those images by Envi5.2 software, then we interpreted SGDF from those images. As indoor interpretation fulfilled, we testified indoor interpretation results through geomorphological and geological investigation. Finally, we got fault distribution of SGDF. Conclusions are as follows:First, remote sensing image selection and management is crucial to indoor interpretation, and image resolution is the only factor we commonly consider before, however, things have changed in places where there is complex weather and dense vegetation. Image categories, imaging time and bands selected for compositing in pretreatment and etc. should all be taken into consideration for better interpretation. Second, SGDF distributes from Lazikou town in the west, extending through Pingding town, Zhou County, Huama town, then terminating at Majie town of Wudu district in the east, the striking direction is mainly NWW, and it could be roughly divided into 3 segments:Lazikou-Heiyusi segment, Pingding-Huama segment, and Huama-Majie segment, with their length amounting to 47km, 32.5km, 47km, respectively. The arrangement pattern between Lazikou-Heiyusi segment and Pingding-Huama segment is right-stepping, and the arrangement pattern is left-stepping bending between Pingding-Huama segment and Huama-Majie segment. Third, SGDF controlled magnificent macro-topography, such as fault cliff, fault facet, which often constitute the boundary of intermontane basins or erosional surfaces to west of Minjiang River. Micro-geomorphic expressions were severely eroded and less preserved, including fault scarps, fault troughs, sinistral offset gullies and geomorphic surfaces. Finally, SGDF mainly expresses left-lateral dominated motion, only some short branch faults with diverting striking direction exhibit vertical dominated motion. The left-lateral dominated component with little vertical motion of SGDF is consistent with regional NWW-striking faults as Tazang Fault, Bailongjiang Fault and Lintan-Dangchang Fault, also in coincidence with regional boundary faults such as east Kunlun Fault and north margin of west Qinling Fault, illustrating regional deformation field is successive in west Qinling, and NWW striking faults show good inheritance and transitivity on differential slip rate between east Kunlun Fault and west Qinling Fault. The geometry of SGDF makes quantitative studies possible, and also provides scientific basis for keeping construction away from fault traces.

Key words: Guanggai Shan-Die Shan Fault, fault geometry, remote sensing image interpretation, West Qinling

摘要： 光盖山-迭山南麓断裂是东昆仑断裂向西秦岭北缘断裂应变转换的主干断裂之一，受森林覆盖、自然和人为改造、交通不便等多因素的影响，光盖山-迭山南麓断裂的几何特征一直不明确。文中收集多种类型、分辨率、时相的遥感图像并在Envi5.2平台下进行增强处理，然后对光盖山-迭山南麓断裂进行目视解译，在此基础上对重点段进行野外考察，通过一系列断错地貌和断层剖面等地质地貌现象验证解译结果，最后得到光盖山-迭山南麓断裂的几何展布，并得到以下4点认识：1）在地形起伏度高、植被密集覆盖的区域，选择遥感图像时不能只看遥感图像的分辨率，而应该综合考虑遥感图像的种类、时相或特殊的波段合成，尽可能突出构造要素，降低植被覆盖等客观环境的影响；2）光盖山-迭山南麓断裂总体走向为NWW，在平面上可分为3段，即腊子口—黑峪寺段、坪定—化马段和化马—马街段，长度分别为47km、32.5km和47km，各段由1～3条分支断层组成；3）断裂宏观地貌非常壮观，发育规模巨大的断层陡崖、断层三角面等，断层微地貌破坏严重，残留较少，主要有断层陡坎、断层沟槽、冲沟和地貌面的左旋位错等；4）断裂运动性质以左旋走滑为主，部分走向不同的分支段存在明显的逆冲。光盖山-迭山南麓断裂的几何展布是该活动断裂定量研究的基础，也可以为断层避让提供科学依据。

关键词: 光盖山-迭山断裂, 几何展布, 遥感影像解译, 西秦岭