中文摘要：

龙日坝断裂带位于松潘-甘孜地块的东北部,距离其东侧龙门山断裂带大约200km.龙日坝断裂带具有右旋逆冲活动特征,呈北东向展布,与龙门山断裂带基本平行.这条新发现的陆内走滑断裂带由于其特殊的地理位置,目前已引起了广泛的关注.本文利用重力数据的处理和解释,并结合SinoProbe-02深反射地震剖面数据进行由段到面的综合研究,揭示了扬子板块西部边界的伸展和龙日坝断裂带的构造属性.结果显示扬子板块西边界呈不规则分布,而龙日坝断裂带的形成与扬子板块的不规则分布有关.扬子西边界的北段已越过龙门山断裂带延伸至龙日坝断裂带附近,南段则逐渐沿龙门山断裂带分布.龙日坝断裂带代表了扬子板块结晶基底延伸的最西端.印度-欧亚板块碰撞造成了青藏高原物质北东-东向运移.至松潘地块东缘,由于受扬子板块结晶基底的阻挡,在龙日坝断裂带附近产生了应力差而形成了龙日坝断裂带.本文的研究结果将有助于我们更好的了解青藏高原东缘对印度板块与欧亚板块陆陆碰撞所产生的构造响应,以及揭示青藏高原东缘地震灾害发生机制.

英文摘要：

The Longriba fault zone is located in the eastern Tibetan Plateau（eastern Songpan-Ganzi terrane）.It is-200 km northwest of and subparallel to the Longmen Shan fault zone of the eastern edge of the Tibetan Plateau.The NE-SW striking Longriba fault zone is featured with dextral transpressive shearing.It has raised wide interests due to it specific geographic location.In this paper,we first aim at integrating a variety of gravity data and SinoProbe-02 deep seismic reflection data to extract new geological information of the deep-seated sources beneath the eastern Tibet.Results indicate that the Yangtze block possesses heterogeneous special distribution along its western margin,which has extended beyond the Longmen Shan fault zone to the Longriba fault zone. Thus, the Longriba fault zone represents the westernmost extension of the Yangtze block.Its formation and evolution is attributed to the resistance and absorbance of the existing highly thrusted Yangtze block to the ongoing eastward block motion of the Tibetan Plateau.Results of this paper will help us better understand the tectonic response of the eastern Tibetan Plateau to the ongoing India-Eurasia collision and the regional earthquake mechanism as well.