| Taihang Mountains tectonic-magmatic belt has been a hot-point of geological researches for a long time because of its various minerals, complex structures, predominant geological location and other factors. One of the main structures in the Taihang Mountains is Zijingguan fault zone with a NNE trending and a SE-dipping direction on a macro-scale. It is meaningful for the research of granitic intrusions and ore deposits, the source of magma and metallogenic material, as well the mechanism for the formation of the Mesozoic tectonic framework of North China. On the basis of the previous studies and structural phenomena, this thesis has made a systematic study on the structural features of the Zijingguan fault zone. Through some field investigations and laboratory analysis, the geometric, kinematic and dynamic characteristics of the fault have been discussed, and the main features are as follows:(1) The Zijingguan fault zone is NNE trending as a whole, dipping SE,the north part is steep, while the south is flat.(2) The Zijingguan fault zone has experienced three-stage of tectonic activities with different intensity: the first and second stages are strong compressional activities; the third one is extensional faulting, which is weaker compared to the previous two activities.(3) Since the Zijingguan fault zone distributes discontinuously in the plane, each segment of the fault is arranged by the left oblique steps and the fault is segmented in the plane.(4) The Zijingguan fault zone is shown a zonation in different mechanical properties of strata.(5) The Zijingguan fault zone has experienced three times of tectonic activities with different nature. The first stage: the NNE strong compression in Late Jurassic; the second stage: the compressive stress zones and the left-granite thrusts were formed by the NW to SN extrusion from Late Jurassic to Early Cretaceous; the last stage: the NW-SE tensional and dextral strike-slip motion in Late Cretaceous... |
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