中文摘要：

断裂带的区域构造应力特征是研究其活动性的重要依据。在应变指示计较少的弱应变地区,磁组构是有效可选的手段。在韩城断裂带1/5万活动断层填图工作的基础上,对断裂带NE段的上峪口、渚北庄与邵家岭剖面进行了系统的岩石磁组构研究。结果表明,该区域三叠纪岩石样品磁化率椭球体以＂扁球型＂为主,表现出弱变形组构的典型特征。磁化率椭球体最大轴Kmax沿NWSE向与最小轴Kmin沿NE-SW向的分布趋势,以及断层两盘明显的差异性垂直运动、断层划痕与河流扭曲等野外证据,反映出韩城断裂带NE段受控于NW-SE向的拉张应力,兼有相对较弱的NESW向的水平挤压应力作用。断裂带不同地方的应力状态也存在一定的差异,研究区的上峪口与渚北庄剖面受到的水平挤压应力相对较弱;邵家岭则表现出较强的挤压应力作用。但邵家岭剖面大多数样品仍然落于＂扁球型＂区域内,可能说明在拉张应力控制的构造单元,即使挤压应力较为明显,沉积岩中的＂拉长型＂磁组构仍难以形成。

英文摘要：

Knowledge about regional stress field is a significant basis for better understanding the tectonic activity of faults. This study reports the magnetic fabric investigation performed at sites along the northeastern section of the Hancheng Fault zone after we finished the 1 ： 50,000 field mapping of active fualts in this region. Samples were collected at selected sites at Shaojialing, Zhubeizhuang and Shangyukoa. Our results show that magnetic fabric, derived from anisotropy of magnetic susceptibility, reveals oblate susceptibility ellipsoids that are slightly modified compared to the inferred original depositional fabric. A dominant distribution of Kmox along the NW-SE direction indicates that the northeastern section of the Hancheng Fault zone is subjected to horizontal extensional stress along this direction. A weakly NW-SE directional distribution of Kmin is interpreted to reflect the action of horizontal compressive stress. This NW-SE compressive stress at the Shaojialing site appears to be somewhat stronger than that at the Shangyukou and Zhubeizhuang sites. Nevertheless, magnetic fabric properties are located in the oblate area in the Pj- T and Flinn diagrams. This may reflect inhomogeneous distributions of tectonic stresses along the Hancheng Fault zone, indicating that even within a strongly extensional stress-field, prolate magnetic fabric may be difficult to develop. This work may provide basic evidence for further studies on the activity of the Hancheng Fault zone.