Abstract: Strike-slip faults and normal faults are dominant active tectonics in the interior of Tibetan plateau and control a series of basins and lakes showing extension since the Late Cenozoic, by contrast with the thrust faulting along the orogenic belts bordering the plateau. The late Neotectonic movement of those faults is key information to understand the deformation mechanism for Tibetan plateau. The Gyaring Co Fault is a major active right-lateral strike-slip fault striking~300° for a distance of~240km in central Tibet, in south of Bangong-Nujiang suture zone. The Gyaring Co Fault merges with the north-trending Xainza-Dinggye rift near the southern shore of Gyaring Co. From NW to SE, Dongguo Co, Gemang Co-Zhangnai Co, Zigui Co-Gyaring Co form the Gyaring Co fault zonal drainage basin. Some scholars have noticed that the formation of lakes and basins may be related to strike-slip faults and rift, but there is no analysis on the Gyaring Co fault zonal drainage basin and its response to regional tectonics. In recent years, a variety of quantitative geomorphic parameters have been widely used in the neotectonic systems to analyze the characteristics of the basin and its response mechanism to the tectonic movement. In this paper, we applied ASTER GDEM data on the ArcGIS platform, extracted the Gyaring Co fault zonal drainage basin based on Google Earth images (Landsat and GeoEye) and field work. We acquired basic geomorphic parameters of 153 sub-basin (such as grade, relief, average slope, area) and Hypsometric Index (HI) value and curve. Statistical results have indicated significant differences in scale(area and river network grade)in north and south sides of the fault. Southern drainage basins' relief, slope, HI value are higher than the northern basins, and the overall shape of hypsometric curve of northern basins are convex compared with southern concavity. Along the strike of the Gyaring Co Fault, average slope, and HI value are showing generally increasing trending and hypsometric curve become convex from west to east. By comparing and analyzing the lithology and rainfall conditions, we found that they have little influence on the basic parameters and HI value of drainage basins. Therefore, the changes of basin topographic differences between northern and southern side of fault and profile reveal the Gyaring Co Fault has experienced differential uplift since the late Cenozoic, southern side has greater uplift compared to the north side, and the uplift increased from NW to SE, thus indicate that normal faulting of the Gyaring Co Fault may enhanced by the Xainza-Dinggye rift. The early uplift of the Gangdise-Nyainqentanglha Mountain in late Cenozoic might provide northward inclined pre-existing geomorphic surfaces and the later further rapid uplift on the Gangdise-Nyaingentanglha Mountain and Xainza-Dinggye rift might contribute to the asymmetrical development of the Gyaring Co fault zonal drainage basin.

Key words: Gyaring Co Fault, drainage basin, geomorphology, hypsometric index, interior of Tibet

摘要： 依据谷歌地球提供的影像（Landsat和GeoEye）和野外工作，在ArcGIS平台上利用数字高程模型（ASTER GDEM数据）提取了格仁错断裂带153个亚流域盆地的基本参数，作了面积-高程积分。统计结果显示，南北2盘流域盆地的规模（面积、河网分级）差异显著，南盘流域盆地起伏、坡度、面积-高程积分（HI）值均略大于北盘，积分曲线总体呈"南凸北凹"的形态特征；在断裂走向上，盆地起伏、平均坡度、HI值皆呈"东南高、西北低"的趋势，积分曲线由西向东具有变凸的态势。通过分析流域岩性与降雨条件，发现它们对以上地貌参数的影响有限。因此，流域盆地差异地貌特征反映并验证了格仁错断裂晚新生代南盘相对于北盘抬升，并且其南侧申扎-定结裂谷可能强化了该差异抬升运动。同时，可能指示冈底斯-念青唐古拉山晚新生代早期隆升为流域盆地提供了向N掀斜的先存地貌面，后期该山体和申扎-定结裂谷的快速隆升进一步促成南北2盘流域不对称的发育。

关键词: 格仁错断裂, 流域盆地, 地貌, 面积-高程积分, 青藏高原内部