淮北夹沟—桃山集地区推覆构造研究

A STUDY OF THRUST TECTONICS OF JIAGOU－ TAOSHANJI AREA, NORTHERN ANHUI

本区存在大型中生代推覆构造,所有震旦纪—古生代的沉积岩层都卷入了褶皱和断裂,构造推覆发生在较高构造部位,属脆性变形域,以台阶状逆断层和断层相关褶皱为特征。区内存在若干推覆构造,每个岩片均可分为上盘、下盘和滑动层系三部分,共查明8个滑动岩系。是一种发生在早中生代的盖层推覆,无根褶皱，也是徐宿地区最重要的控煤构造。最后对推覆构造的地球动力学机制进行了讨论。

Large scale thrust tectonics occurred in Early Mesozoic in the Xuzhou－ Suzhou region,southern margin of North China plate.The strata that were involved in this thrust tectonics are Neo－ Proterozoic－ Paleozoic sedimentary layers,characterized by strongly brittle deformation of step－ type thrusting and fault－ related folding (fault propagation fold).Thrust flakes with various scales and shapes were developed well in the Jiagou－ Taoshanji area;each flake consists of upper rock－ block,slipping fault and lower rock－ block.Eight slipping beds that are related to thrust tectonics were reported.The paper researched geometry,kinematics,timing of emplacement and shortening rate of thrust bodies.Thrust structural styles include superimposition－ type and step－ type; duplex－ type and klippe－ type also develop in the region.The Xuzhou－ Suzhou arc tectonics can be divided into three parts from east to west:(1) the Tan－ Lu thrust root zone,marked by lower－ angle thrust of Neo－ Proterozoic with weakly ductile shear deformation,(2) the Jiagou－ Taoshanji middle zone,characterized by fault－ related fold,step－ type thrust with lower－ middle dip angle of fault,(3) the northern Anhui－ Xiaoxian County front zone of superimposion thrust with high－ angle of fault.Regional detachment fault is located between the Neo－ Proterozoic rocks and Paleo－ Proterozoic metamorphic basement in the deep crust;thrust structures that occur at surface are a cover thrust of the Paleozoic sedimentary rocks.Authors described in detail the three typical structural phenoma,that is,the Lihuashan－ Zhangzhuang superimposition thrust zone,the Wuyanquan step－ type thrust zone and the Dashankou－ Changwo klippe zone.The movement of thrust is from ESE to WNW,namely from Tan－ Lu fault zone to North Anhui.Large－ scale thrust tectonics in the studied area constrained the distribution and richness of coal beds.Study results suggest that the large－ scale thrust event was caused by Early Mesozoic intracontinental subduction and took place after Late Triassic and prior to Late Jurassic,corresponding with a collision between the North China continent and Yangzi continent along the Dabieshan suture zone.