关键词: 伸展-走滑-压缩变形, 构造地貌, 中新世以来, 红河断裂, 中国西南

Abstract: Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Honghe (Red River) Fault zone have the following features. Geometrically,the whole Red River fault system can be divided into three deformation regions:the north,central and south deformation regions. On the eastern side of the north region lies the northwest Yunnan extensional taphrogenic belt,which is characterized by three sets of rift-type faulted basins striking NNW,NNE and nearly N-S since the Miocene time. From Miocene to Quaternary epoch,the faulted basins spread or migrated southwestwardly,but the large-scale and intensive rift-depression mainly occurred in the late Pliocene to Quaternary. The extension amount of the basin since Quaternary is about 5.6 km. On the western side of the north segment lies the Lanping-Yunlong Tertiary compressive deformation region. The deformation in the central segment is characterized by dextral strike slip or shearing,resulting in a dextral displacement of about 7.4km since Quaternary. The east Yunnan Miocene compressive deformation region lies on the eastern side of the fault in the south,and the extensive fault-depressed region is located on its western side. In tectonic-geomorphology,the afore-mentioned deformation features appear as basin range tectonics in the north,linear fault valley depressed basins in the central part and compressive (or extensive) basins in the south. Among them,the great variance of the planation surfaces on both sides of the fault in Cangshan to Erhai area is the prominent expression of the normal faulting along the Red River fault zone since Pliocene time. From the view-point of spatial-temporal evolution,the main active portion of the Red River fault zone from Eogene to Pliocene was the southern segment,which was characterized by tearing from south to north. The main active portion of the fault has migrated to the north segment since Pliocene,especially in late Quaternary,and was characterized by extensional slipping from north to southeast. The range of deformation region and the magnitude of deformation show that the eastern plate of the Red River Fault zone is always the active plate for the relative movement of the fault blocks.

Key words: extensive-strike slip-compressive deformation, tectonic-geomorphology, Miocene, Red River fault zone, southwest China