关键词: 太行山南缘断裂带, 新构造活动, 斜张左旋走滑, 弥散型变形

Abstract: Basing on TM imagery interpretation and field analysis of striated fault planes, we present in this paper morphological and structural evidence for Quaternary left-lateral strike-slip motion along the southern marginal fault zone of the Taihangshan Mountains and discuss their implication for regional kinematics. It is shown that the southern marginal fault zone of the Taihangshan Mountains behaves as a transtensional left-lateral strike-slip fault during Quaternary. Morphological evidence for left lateral strike-slip motion includes offsets of stream channels across the fault trace and offsets of late Quaternary alluvial fans developed on the hanging wall of the range front fault zone. Field analysis of striated fault planes shows two families of striations. The older one resulted from NE-SW to NNE-SSW extension, probably Miocene in age, and the younger one from NW-SE to NNW-SSE extension, possibly Pliocene Quaternary in age. These observations are consistent with those established in the Weihe graben, where these two extensional stresses have been well dated. Structural data from the basins indicate that the southern marginal fault zone of the Taihangshan Mountains extends eastward along the Miyang Kaifeng Shangqiu fault depression zone, making up a tectonic boundary that separates the northern Bohaiwan rhombic basin from the southern North China triangular basin. Neotectonic deformation is dominated by right slip faulting on NNE-striking faults in the northern domain and left slip faulting on E-W-striking faults. It is postulated that the southern marginal fault zone of the Taihangshan Mountains and its eastward continuation into the North China basin forms the northern boundary of a broad distributed deformation zone bounded to the south by the Qinling fault system. Left-lateral strike-slip faulting along this distributed deformation zone during the Pliocene-Quaternary accommodated the SEE-ward extrusion of the South China block with respect to North China.

Key words: Southern marginal fault zone of Taihangshan Mountains, Neotectonic activity, left-lateral strike-slip faulting, distributed deformation