| The structure location of the study area is at the intersection of the Songpan-Ganzi fold system and the structural unit of the Yangtze quasi-station.Which is the central area ofthe Kangding-Daofu fork rift and the intersection of deep fault of the north and south of the Anning River,the deep fault of the Xianshui River in the northwest,the MaoxianWenchuandeep fault in the northeast and the deep fault junction in the BeichuanYingxiu area.The Kangding complex,the oldest crystal matrix in Sichuan Province,has been exposed in the deposit.The regional location of this area is unique and its oreforming conditions and geological background are relatively good.The stratum of the study area is a two-layer structure,and the stratum is centered on the “Kangding Complex”.The specific distribution includes the Zanli Formation and the Lengzhuguan Formation(Upper Pacific – Upper Proterozoic).Both form the base.On the east and north sides of the "Kangding Complex",there are the Yanjing Group of the Pre-Sinian Strata,the Dengying group in Upper-Sinian Strata,the Ordovician Strata,the Silurian Strata,the Devonian Strata,the Carboniferous Strata,the Permian Strata and the Upper Triassic Strata.On the west side of the "Kangding Complex" are metastable strata including Silurian,Devonian,Carboniferous,Permian,etc.,which form the cover layer.After several strong structure actives,especially in the Indosinian-Yanshan-Xishan period,the geological structure in the study area has changed due to the repeated tension of the two large troughs and the nappe-slip structure caused by the collision.Especially in different structure periods and strikes,the fault structure develops better.The fold structure includes the Jixinliangzi anticline,Changchang syncline,Kuiyonggou syncline,Dongmagou syncline,Jiangdagou compound anticline and Zhalanghaizi anticline.The faults include the Yalagou thrust fault,the Jiangdagou fault,the Lianghekou thrust fault,the Hongfeng thrust fault,the E'ri fault,and the Daxueshan-Nongeshan fault.Affected by the large nappe sliding structure,the northeast,northwest,east-west faults and shear zones are large in scale and characterized.It constitutes the most important orecontrolling and ore-bearing structure in the study area.The structure setting in the study area is a nappe structure belt composed of F1 thrust faults.The main structure line is the early NE-SW reverse fault,and the fault planes tend to be almost NW;the fault zone has strong shear zones and fracture zones.As a feature,mineralization and alteration phenomena are distributed along the fault,which are the result of intense compression stress in the mining area.In the middle and late mining areas,nw-se and nee-sww faults are developed.These faults are relatively small in size,but the right line is misdirected by the ne-sw to fault.In general,the mining area is the thrust belt nature of the thrust nappe structure and is a good metallogenic structure environment.The F1 fault in the mining area is the main fault that runs through the entire structure zone.It is northwest-south-eastward,with a general tendency to northwest,and a dip angle of 35° to 40°.It is a compression-torsional fault,which is affected by regional structure and is located in the northwest of the fault.The disc produces a large number of interlaminar sliding structures,fractures(such as F7,F8,F9)and fractured fracture zones,interbedded exfoliation structures,fissures,etc.,which provide favorable conditions for later mineralization.According to the preliminary analysis of the oreforming process of each ore section of the mining area,the F1 fault can be judged as the ore-conducting structure,and the F7,F9,F10,F11,F12,F13,F14,F15 faults can be judged as the ore-bearing structure.F8 and F9 faults is identified as destructive structure.According to the research and analysis,the metallogenic model of the gold deposit is: the deep fault formed in the Jinning-Chengjiang period,the magmatic hydrothermal fluid and the deep thermal brine connecting the deep crust and the upper mantle to form the early Kangding complex.The ore belt provides a mineral source for the Changyanwo gold deposit;the orogenic structure and the main ore-controlling and orebearing structures in the Caledonian-Hercynian orogeny;under the combined influence of high-energy heat flow and structure dynamics,The ore-forming material is activated and extracted.Underground ore-bearing hydrothermal fluids and deep magmatic hydrothermal fluids move upward along the ore-conducting structure under structure dynamics,and then accumulate in the vicinity of the fault-fracture zone.Ore bodies eventually form along ore-bearing structures such as shear fracture zones,where two sets of faults meet.Therefore,it can be concluded that the gold deposit in researching area is the result of deep structural superposition and regional structure evolution.It belongs to orogenic gold deposit from metallogenic geological background,and structural altered gold deposit from genetic point of view. |
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