Geological Characteristics And Genesis Of Guyang Chengshengqu Gold Deposit,Inner Mongolia

Changshengqu gold deposit is located in the Xiashihao town of Guyang county,in central Inner Mongolia.The geotectonics are located in the southern edge of the Guyang fault basin in the Inner Mongolia axis of the north China platform.The amount of gold metal is 23.5 tons,reaching the level of large gold deposits.In this paper,the regional geological characteristics are studied,the geological characteristics of the deposit and fluid are studied in detail,the ore-controlling factors of the deposit are analyzed in depth,finally,the genesis of the deposit is summarized.The main understanding is as follows:1.The outlying strata in the mining area is mainly composed of various rock formations of the Wulashan group in the middle Paleozoic.The gold ore body is not selective to the occurrence rock stratum.In addition,mineralization is also possible in granite and mixed rocks.Fold structure and fault structure are developed in this area.The main ore-bearing structures are the east-west and south-north fault structures.Magmatic activities are frequently distributed widely in the mining area.2.The degree of gold mineralization is closely related to pyritization and silicification.The closer the gold ore,the stronger the alteration of pyritization and silicification in the surrounding rocks will be;otherwise,it will be weak.The alteration of surrounding rocks mainly includes silicification,pyritization,sericitization,kaolinization,chloritization,epidotization,carbonate and potassium.The hydrothermal gold mineralization of changshengqu gold deposit is divided into three stages: white quartz vein stage,quartz-pyrite stage and quartz-polymetallic sulfide stage.3.The high gold background value of the Wulashan formation is the main "source layer" of gold deposits in this region,and granite is another "source layer" of gold deposits in this region.The development of mining area structure and the frequent magmatic activity promoted the formation of gold deposits.According to the typical shallow-level deformation characteristics of ore-bearing fault and ore-forming period and the relationship between ore body and rock body space cutting,it is concluded that the ore-forming period of changshengqu gold deposit is Yanshan epoch.4.According to the temperature data of fluid,longtime canal gold uniform temperature ranges from 144.1? to 273.5?,the main metallogenic stage of gas liquid two phase inclusions homogenization temperature from 185.7? to 273.1?,the peak of 210~240?,can be on behalf of the gold deposits metallogenic peak temperature,which belongs to lower temperature.Metallogenic late stages of gas liquid two phase inclusions homogenization temperature from 144.1? to 246.6?,the peak at 140?~160?,belong to the category of low temperature;Through the petrographic characteristics of fluid inclusion,the ore-forming pressure in the main ore-forming stage is estimated to be about 55~80 MPa,the relationship between depth and pressure is fitted,and then the formation depth of this deposit is 5.93~7.30 km,belonging to the medium-forming depth.5.The spatial distribution,occurrence and scale of gold ore in the changshengqu gold deposit are strictly controlled by fracture tectonics.The ore are completely in fault tectonics,and there is no selectivity for the occurrence rock strata.The genesis of the deposit is hydrothermal gold deposit.Many times of migmatization,at the same time,with magmatism and metamorphism,making the hydrothermal gold high background values in the district of Wulashan rock group formation reached the activation,migration and concentration of gold element,Finally,under the strong hydrothermal function of Yanshan epoch,the deposit was precipitated and enriched in favorable tectonic positions,forming a gold deposit dominated by quartz vein type on the surface and near surface of this mining area,and dominated by hydrothermal alteration type in the deep part.