Study On Metallogenesis Of The Keng Tou Altered Rock Type Gold Deposit In Southeast,Guizhou

The research area is located in the southwest end of Jiangnan orogenic belt,it is an important part of the xiang-guizhou gold belt.Gold deposits?points?are widely distributed in the region,research has a long history.However,due to the poor natural exploration conditions for gold deposits in southeast guizhou,and mining technology lags behind,the research work is more focused on single quartz vein type gold deposits.As a result,most of the gold deposits discovered and mined in the study area are small and medium-sized ones.In recent years,the government and social capital pay more attention to the study of gold deposits in southeast Guizhou.Some scholars in the study of quartz vein type gold deposits in this area,it is believed that there may be altered rock type gold deposits in the deep,but limited by drilling conditions,the research work is more than 300m,the characteristics and metallogenic conditions of altered rock type gold deposits have not been confirmed.This seriously restricted the progress of gold research in the study area.According to the latest exploration progress in the research area,the author takes core samples from deep boreholes.Accordingof petrology,petrographic observation,electron probe analysis,characteristic analysis of major elements,and characteristic analysis of trace elements were carried out based on the obtained samples,and Combined with previous research data,the regional geological background,mineralization characteristics,occurrence forms and mineralization of altered rock type gold deposits in the study area are studied.At present,the following are mainly achieved:The host strata of the altered rock type gold deposit of Kengtou are the second and first submember of qingshuijiang formation.Ore-bearing wall rock strip tuff slate,variable residual tuff,the gold grade up to 6.65g/t,the main ore minerals in the ore body are metal sulfide combinations such as natural gold,arsenopyrite and pyrite,and gangue minerals are usually quartz,a small amount of sericite,chlorite and calcite;Gold mineralization is obviously controlled by tectonics,the quartz vein type and altered rock type of gold ore bodies are mostly located in the collapse space formed by shallow fault propagation folds.The altered rock-type gold deposits are distributed in the fault fracture zone of the footer of the F10 fault near the core of Kengtou anticline.The ore body is generally located at and near the inflection point where the fracture dip Angle changes in the lower part of the quartz vein ore body.Arsenopyrite is the main gold deposit in altered rock type gold belt,Gold mainly occurs in fissure or margin of sulfide such as arsenopyrite in the form of fissure gold.It is of great significance to the mineralization of gold deposit in the types of toxic sand-mineralization and chlorite mineralization of wall rock alteration.The elemental geochemical characteristics of altered rock type gold deposits are basically consistent with quartz vein type,the two types of gold deposits are the same ore-forming fluid.The form of Au?HS?₂^-complex is the main form of gold migration in the study area,the main reasons affecting gold precipitation are the change of pH value and oxygen fugacity caused by the fluid phase separation process after entering the precipitation space and the water-rock reaction with the surrounding rock.Generally,the gold formed by the former is produced along with quartz vein,which may be one of the reasons for the formation of quartz vein type gold deposits in the study area.The water-rock reaction between fluid and surrounding rock is an important reason for gold deposition of altered rock type gold deposit in the study area.