| The Xitieshanlead-zinc deposit is located in the middle section of North Qaidam,and the tectonic position is the fissure orogenic belt of the secondary tectonic unit located in the active belt of Chaidamu(rift valley).As a typical SEDEX deposit in China,it has been explored to a large scale and is of great value in both economic and scientific research.However,in terms of ore exploration breakthrough,the study on ore control structure of xitieshan lead-zinc deposit is relatively weak and controversial.Based on the predecessors' research results,on the basis of using the ore field structure theory to carry out the research work,through field geological survey and indoor analysis,find out the basic solder iron mountain pb-zn deposit of main ore-controlling tectonic geometry and kinematics,ore-controlling tectonic pattern of the ore deposit is discussed,and provides a theoretical model for further deep ore prospecting.The main understandings are as follows:(1)don't fold structure of regional development in the studied area,interlayer fold more development,according to the fold formation mechanism can be divided into type A type B fold and fold,A type of fold can be divided into two groups: A group of hub to NW plunging,another group of hub pour SE plunging,combining with the field evolutionary history,speculated that the group to SE plunging fold formed in the late caledonian,time limit of about 400 ma;B-type folds were produced in all layers of the region,and they were produced in the form of "S" or "S" type,vertical and inverted folds.The formation period was relatively broad,and all the b-type folds were produced from caledonian period to indo-chinese period.(2)the geometric and kinematic characteristics of ductile deformation and major faults in the region were identified.The kinematics of ductile deformation is left shear.F1 is a double thrust structure with a section inclination NE.F2 is a thrust fault facing NE with a steep dip,with a local sinistral strike-slip property.F3 is a sinistral strike-slip fault,with a NW?SE transition from 320°-330°to 290°-300°.F4 and F5 are thrust faults with overall trend of NE in the section,and F6 are large-size active thrust faults with overall trend of NE in the section.(3)compressive shear deformation and fractures F1,F2 and F3 are the main ore-controlling structures in the region.The extrusion and shear deformation causes the surrounding rock to undergo strong foliation.The layered ore bodies become lenticular,vein-like and layer-like,and generally lie on the SE side with the lateral Angle of 25-30°.F1 fault causes local inversion of ore body and host rock;F2 fault causes the loss of secondary ore-bearing geological body(O3tnb lithologic segment),which has no extension in the plane and deep,and is "wedge-shaped".The branching normal fault at the end of F3 fault is tangential to F2,forming the formation of the O3 tnc lithologic segment with a "large abdomen" shape and the output of the ore free zone in the mining area.(4)based on the identification of the characteristics of the jet port,the characteristics of the original mineralization,the zone characteristics of the surrounding rock alteration and the production characteristics of the ore body,new evidence is provided for the genesis of the ore deposit in the mining area,which is considered to be a typical SEDEX type deposit. |
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