基于ALOS-PALSAR卫星数据对青藏高原东缘龙日坝断裂带地表构造伸展的研究及其大地构造指示意义

龙日坝断裂带位于青藏高原最东缘,呈北东-南西向延伸,平行于其东侧的龙门山断裂带,二者大约相距150 km。与龙门山断裂带不同的是,龙日坝断裂带在青藏高原东缘相关GPS测量中表现为一明显的速度梯度带,说明龙日坝断裂带可能具有很重要的构造属性。然而有关龙日坝断裂带的地表结构构造延伸问题一直悬而未决,目前还存在许多的争议,这在一定程度上也阻碍了我们对青藏高原东缘相对于印度-欧亚板块碰撞地球动力学响应的了解。在本次研究中,我们将首次采用ALOS-PALSAR卫星数据,并结合地表地质和前人的地球物理学研究成果,来监测与龙日坝断裂带的构造活动相关的细微地表形变,并由此控制龙日坝断裂带的延伸范围。研究结果表明,龙日坝断裂带与其西南侧的抚边河断裂带相交且近乎垂直,而非前人研究所认为的龙日坝断裂带延伸至其西缘的鲜水河断裂带。综合研究结果也为了解龙日坝断裂带的大地构造属性提供了数据支持。

Recognition of the surface extent of the Longriba fault zone and its tectonic implications based on the documentation of the ALOS-PALSAR data

The Longriba fault zone is located in the easternmost of the Tibetan Plateau, extending NE-SW. It is parallel to the Longmen Shan fault zone that is about 150 km away from the Longriba fault zone to the east. Unlike the Longmen Shan fault zone, the Longriba fault zone shows as a sharp GPS gradient, indicating the Longriba fault zone would contain important tectonic features. However, how the Longriba fault zone extends at the surface has not yet been fully addressed and controversies remained, which has retarded our understanding on the tectonic response of the eastern Tibetan Plateau to the ongoing India-Eurasia collision. In this paper, integrated with surface geology and previous studies of geophysical data, we firstly employed ALOS-PALSAR satellite data to document the surface tectonic response, and therefore, to control the surface extent of the Longriba fault zone. Results show that the Longriba fault zone terminates to the west before approaching the Xianshuihe fault zone and shows perpendicular to the Fubianhe fualt zone. Results of this paper would provide important data support for us to better understand the tectonic feature of the Longriba fault zone.