| Xiada-Jinjing gold ore field is a representative and typical distribution area of quartz vein type gold deposit in southeast Guizhou.It is obviously controlled by structures,and mainly distributed within 500 m of the both sides along the east-west Gaoniang fault zone.The farther from the fault,the less the gold ore distribution.There is a long history of gold mining in the study area,but the exploration and research remain stagnant and there is still a huge ore prospecting space in the deep part of the mining area.Many experts and scholars have carried out a lot of research on the geochemical characteristics of the field,the source of metallogenic material and the genesis of the deposit,however,there is less research on the structural characteristics of the study area and its relationship with gold deposits.This paper takes Gaoniang fault as the research object,based on previous research,through the field investigation to Gaoniang fault in different directions along the fault location of structural feature detailed observation and indoor synthetic analysis,from the characteristics of the Gaoniang fault and the tectonic stress field,and discusses the relationship between the Gaoniang fault and the gold mine,aims to provide guidance for prospecting predictions from a tectonic perspective in the study area.The Xiada-Jinjing gold mine is located in the south of Tianzhu county and in the southwest section of jiangnan orogenic belt.In geohistory,it has experienced many stages of tectonic movements such as Wuling movement,Xuefeng movement,Caledonian movement and Yanshan movement.From ocean-land transition to intracontinental orogenic evolution,a series of northeast,northwest and east-west directions structural tracks were formed in the study area to jointly control the formation and distribution of gold deposits in the Jinjing gold field..The Gaoniang fault zone is mainly characterized by brittle deformation,rock deformation and metamorphism is stronger,and joints developed,where the stress concentration area is in the Gaoniang town and Jinjing village.The northeast direction ore-containing fold structures were sheared aleft by Gaoniang fault,Indicated that the Gaoniang fault zone has a compressive stress near the EW direction.A series of fault triangles with high angles tending to the north are developed on the south of the western section of the fault,it shows that the western section of the fault is a normal fault,east of the Jinjing is a high Angle fault which tends to the south.Indicating that the fault has transtensional nature.Based on the detailed observation and analysis of the internal structure of the Gaoniang fault zone,joints,conjugate shear joints,and regional tectonic analysis methods were used and through the method of stereographic projection to determine the principal stress direction of the tectonic stress field in the Gaoniang fault zone,and the time and evolution of the tectonic stress field were discussed,thus,the direction of the principal stress of the tectonic stress field in the Gaoniang zone of the study area is divided into four directions: NW-direction principal stress,NE-direction principal compressive stress,near-EW principal compressive stress,and NWW-direction compressive stress.Determined the age and evolution characteristics of tectonic stress field of Gaoniang fault,that is,the first phase is NW direction→the second phase NW direction is converted to NWW direction→the third phase is near EW direction to NE direction→the fourth phase is NE direction generally corresponds to Xuefeng period→Caledonian period→Yanshan period→Xima period;the first period is pre-mineralization principal stresses,the second and third periods are principal stress during mineralization period.and the fourth period is the principal stress in the late period of mineralization.the four phase stress is mutual restriction of the isotropic structure in the study area.Further on the basis of the characteristics of Gaoniang faults and the characteristics of gold deposits in the study area,the control effect of Gaoniang faults on gold ore is discussed,and a map of structural ore-controlling models was established;Gaoniang faults were used as ore-forming structures to provide ore-forming materials and ore-forming fluids,migration pathways and oreforming materials provide the driving force for the active migration.In the area of coupling with the structure of the Gaoniang fault,it is a favorable space for finding a large ore body. |
