Kinematics And Dynamics Analysis Of Geological Structures In Hancheng Mining Area

As an energy and basic industry,the coal industry plays an important role in supporting the national economy and soclial development of Shaanxi province.Located at the east of the"black belt coal production base " in the Shaanxi province,Hancheng mining area has a long history,which has made a significant contribute for Shaanxi province and even the country's economic.But the geological structures of Hancheng Mining Area are so complex that restrict an the exploitation of coal resources in the mining area.Therefore,to carry out the project of study on kinematics and dynamics of Hancheng mining geological structures,we could reveal the formation mechanism of geological structures and have a indepth understanding of the development of the distribution rule of geological structures,which make the efficient exploitation of mine safety.At the same time,it also has a certain theoretical significance and practical reference value for the further study of coal structure and structural coal-control.Through the research of this subject,the following main achievements are obtained.(1)By using the method of subsidence history analysis and balanced section,we calculate the amount of up-and-down movement,contraction and extension of the mining area.The calculation results show that the cumulative thickness of formation from Late Carboniferous to Middle Triassic at the mining area subsidence above 1300m,and the thickness of formation uneven uplift above 600m from Late Triassic to Middle Miocene;In the north and south direction the formation shrinkage rate is 1.4%in the Indochina period,From the southeast to the northwest the formation of compressional shrinkage is 11.52%in the Yanshanian stage,and the tensile stretch rate is above 2.7%in the Himalayan period from the northwest to the southeast.We found the kinematic characteristics that the compressional shrinkage of the southern strata is larger than and the northen in the north and south direction,the compressive shrinkage of the formation becomes smaller from the southeast to the northwest,and the shrinkage rate of the northwest is greater than that of the north-south.(2)Hancheng mining area is squeezed under the influence of near South North extrusion force during the Indosinian period,"the squeezing action of the southern region is relatively strong,and the northern region is relatively weak";Then,Hancheng Mining Area is squeezed from SE to NW extrusion stress during the Yanshan period,which make "the squeezing action of the eastern region is relatively strong,and the western region is relatively weak ",and the plane shear stress is concentrated in the north zone;Finally the regional tectonic stress field invert to tension from north west to south east during the Himalayan period,at the same time stretching extends all the way to modern times and develops toward the north and west.(3)Near east to west fold and thrust faults,the conjugate shear joints of the NE and NW shear planes formed during Indosinian epoch in Hancheng mining area with the characteristics of the tectonic deformation of the southern region is stronger than that of the northern region;the basic pattern of the study area formed in Yanshan period with NE trending folds and thrusts and conjugate shear joint of nearly east-west and North-South trending shear fracture,where the tectonic deformation of the eastern region is stronger than that of the west and more slip structures and tectonic coals are developed in the north area;General development of extensional normal faults and their combination with a law tectonic deformation around eastern is stronger than western and have the same effect on southern than northern during the Himalayan in the study area.Geological structures of the three stages are mutually restricted,superimposed and reconstructed,which makes the geological structure of the Hancheng mining area complex.