Geometric Analysis Of Geological Structures In Hancheng Mining Area

Hancheng mining area has characteristic of complex geological structures,which has exerted an increasing influence on mine safety production.Therefore,it is of great significance to investigate the regularities of structural distribution.Based on the geometric analysis of the structure,structural evolution pattern in Hancheng mining area is generally analyzed,the main conclusions and results are as follows:(1)The general structural framework shows a monoclinal structure,northeast trend and southwest tendency,which is remaining wing of inverted anticline in the Hancheng mining area.Faults and folds are more developed,but there are obvious differences in space.Their features are subdivision of belts in east-west direction,subdivision of areas in north-south direction,the complex structure in southeastern area and the simple structure in northwestern area.They are different in the growth instensity,which is characterized as strong in eastern and southern area and weak in western and northern area.From the development of fault structural pattern,the cutting-layer fault is mostly developed in southern area,the layer-slipings is mostly developed in northern area,which is characterized by the layer-sliping structures developing in northern area and faults developing in southern area.(2)Regional shear joints are generally developed in mining area,which developed a group of early conjugate shear joints in north-east and north-west,and a group of late conjugate shear joints in east-west and south-north.The shear joints in east-west and south-north are mostly developed.Then the directions of shear joints are identified with the direction of minor fault dense belts.(3)The layer-slipings and its closely related tectonic coal are widely developed,which has obvious division.In northern area,the fold layer-sliping is mostly developed and the distribution of tectonic coal is wide and the rank is high.In southern area,the fault layer-sliping is mostly developed and the distribution of tectonic coal is less,with the primary structure coal and low rank coal.(4)the main group pattern of folds is parallel type.In the plane,the main group patterns of faults are parallel,,and en echelon type.In the profile,the main group patterns of faults are stepped,graben and horst type,imbricate type only developes in the shallow margin in southeastern mining area.(5)Geological structures of the mining area are formed in three phases:Buckle folds and reverse faults in east-west and failure planes in north-east and north-west formed during Indosinian period.Buckle folds and reverse faults in north-east and failure planes in east-west and south-north formed during Yanshan period.A great number of normal faults formed during Himalayan period.The three phase structures are mutually restricted,superimposed and transformed,which makes the geological structure of the mining area complex.(6)The structural characteristics in Hancheng mining area:The structural strength is strong in eastern and southern area and weak in western and northern area,the layer-sliping develops in northern area and the fault develops in southern area.According to those characteristics,the mining area was divided into three primary structural units in the east-west direction,four second-oder structural units and four third-oder structural units in the south-north direction.