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

摘要： 基于TM遥感影像的构造地貌解译和野外活动断层滑动矢量的测量和分析,阐述了太行山南缘断裂带第四纪左旋走滑活动的构造和地貌标志,反演了断裂变形的构造应力场,探讨了太行山南缘断裂带左旋走滑活动的区域运动学意义。研究表明,第四纪时期太行山南缘断裂带是一条斜张左旋走滑断裂。断层滑动矢量观测显示新近纪以来有2期引张应力作用:早期为NE-SW向引张,晚期为NNW-SSE向引张,这个观测结果与渭河地堑盆地的新近纪—第四纪2期引张构造应力场一致。根据华北盆地构造资料推断,太行山南缘断裂带向东延伸与盆地内的泌阳-开封-商丘断陷带相接,共同构成了南华北和北华北2个断陷区的构造边界。指出该断裂带作为南华北块体北缘,其新构造时期的斜张左旋走滑活动与南部秦岭断裂系左旋走滑活动一致,它们组成了一个宽阔的、向东撒开的、弥散型分布的左旋走滑形变带,调节着华南地块相对于华北地块向SEE方向的构造挤出。

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