Mesozoic Structural Characteristics Of The Jizhou Range In The North Of Taihang Mountains

Taihang mountains has long been known as a tectonic-magmatic belt.And,it was considered to be an intraplate orogenic belt by scholars in recent years.Therefore,the mechanism of the formation of Taihang mountains is still a controversial subject.Most of the literature,which involves the structural study of the Taihang mountains,focused on the extensional structural deformation in early Cretaceous,especially the Zijinguan fault and piedmont fault zone of Taihang mountains.However,there was an intensive contraction structural deformation in Taihang mountains during Mesozoic.The reserved contraction structure in Mesozoic was fragmentary and incomplete,and confined by small to medium scale syncline structure separated by massive basement rocks and Cenozoic basins,after being destroyed by late extensional faults,as well as massive loss of cap rock caused by tectonic uplift.The study area located in the southeastern Xinding basin and the west of Taihang Mountain belt.The Jizhou Range thrust nappe tectonic belt and tilted syncline constituted Jizhou Range fault-fold belt.To Probe the underlying cause of fonnation of Jizhou Range thrust nappe tectonic belt,this paper distributes the geologic observation spot along the NW limb of Jizhou Range syncline and south limb of Jingle basin to analyze the forced direction and the formation mechanism of thrust fault.Based on the field observation and profile analysis from southward to northward in Yuwangdong,Baijiashan,Nanwangxiang,Lijiazhuang and Wutai County,and microscope observation combined with lithology and deformed characters,there were detachment layers in Mesoproterozoic and Cambrian strata and lots of lack of rock stratum in Jizhou Range.Because of intensive tectonic deformation in thrust nappe belt and slender deformation in the core and the southeastern wing of Jizhou Range syncline,there was no NW-SE compression forces featured by structure characteristics of Jingle basin in the west of Jizhou Range.Therefore,it could be concluded that the formation of Jizhou Range thrust nappe tectonic belt is not caused by the NW-SE compression forces,but the SE-NW compression forces of "bulldozer model" without a long distance transport.