Structural Geomorphology Interpretation Of The Formation And Evolution Of The Qinshui Block Depression

The Qinshui block depression is the largest geological mass after destruction of the central part of North China Craton (NCC). An detailed interpretation of its formation and evolution is not only cucial for identifying the distribution pattern of geologic hazzards hindering mining industry and destroying the geoenvironment but also important for further understanding the mechanism of NCC destruction.Neotectonics of Yushe basin in the central part of Qinshui block depression were taken as object of study together with collapse pillars, which reflect geomorphic time. Based on extensive field investigation, geological logging, sample testing, and profile surveying, time-event sequences of neotectonics and geomorphology were established, which leads to construction of the Cenozoic structural geomorphological processes of the Qinshui block depression. Based on the present study, some new understandings are drawn as follows:(1) Lots of new tectonic phenomena in the central part of Qinshui block depression were identified and interpreted. The time-event sequence of structural geomorphology evolution in Qinshui block depression since Cenozoic was establised with geomorphology event.(2) Based on the case study on karst collapse pillar in Pingshun Laomaling in terms of structural geomorphology, it is indicated that karst water system in Xin’an springs was developed to a great extent during the time period of about42-45Ma and that lots of other karst collapse pillars were formed at the same time. Meanwhile, the altitude of ancient planation surface was back calculated with the maximum collapse distance of collapse pillar rock.(3) Seismetic structure were found in Gaozhuang Formation of Yushe Group, with indicates an earthquake (Ms=5-6) happened in Yushe basin during the geological history. Furthermore, a model for earthquake-induced liquefaction was established, which can be served as appropriate symbol for strata identification and comparison in small scale basin with fierce phase transformation.(4) Karst collapse pillars identified in Dayaotou, East Mountain, Taiyuan provide evidences for the disintegration of Niangziguan Springs8Ma years ago.(5) The formtion and evolution model of the Qinshui block depression was Established.Evidences obtained in this study by field investigation confirmed the existence of structure-geomorphology event since Cenozoic in Qinshui block depression. It enriched Cenozoic structural geomorphology evolution sequence in Qinshui block depression. Furthermore we found karst collapse pillar in special geomorphology part and new tectonic are significant breakthrough points for structural geomorphology interpretation, as they are important carrier for recording destruction process during late Cenozoic in Qinshui block depression, formation and disintegration karstic water system in North China.