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

摘要： 调查研究表明,自中新世以来,红河断裂大规模右旋走滑运动及其伴生构造变形有如下一些主要特征在几何结构上,可将整个红河断裂系分为北、中、南3个变形区。北区东侧为滇西北伸展裂陷区,以轴向NNW,NNE和近SN向3组上新世以来的裂陷型断盆为特征,北段西侧为兰坪—云龙古近纪、新近纪压缩变形区;中段变形以右旋剪切走滑运动为特征,南部断裂东侧有滇东中新世以来的压缩变形,西侧为藤条河中新世拉伸断陷区。上述变形特征反映在构造地貌上为北部盆岭构造、中段线性断谷断盆构造及南部压(张)性盆地变形,其中苍山—洱海一带断裂两侧主夷平面的巨大落差是红河断裂上新世以来断陷正断作用的显著代表。在时空演化上,从古近纪经中新世至上新世,断裂主体活动部位在南段,并呈由南向北的“撕裂”格局,上新世以后至第四纪,尤其是晚第四纪以来,主体活动部位已转移至北段,表现为由N向SE的滑移伸展变形;变形区的范围大小和变形幅度表明红河断裂的东盘地块始终是作为地块相对运动的主动盘。

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