Metallogenic Fluid Characteristics And Genesis Of Jinchanggouliang Gold Deposit In Inner Mongolia

Jinchanggouliang gold deposit is located in the northern margin of the North China Platform,which is rich in gold resources.It forms a metallogenic linear belt extending 1500km from east to west,with about 900 deposits.Hart?2002?considered that most deposits in the northern margin of the North China Platform have low sulfide content and NaCl-H₂O-CO₂ system,which are orogenic or intrusive-related deposits.Jinchanggouliang deposit has different types,high sulfide content,NaCl-H₂O system and lack of CO₂,which may be a porphyry deposit.This paper studies the Jinchanggouliang gold deposit by means of field investigation,inclusion micro-thermometry,Pb isotope analysis,H-O isotope analysis,quartz cathodoluminescence and geological thermometer,and draws the following conclusions:1.The mesofacies in Duimiangou is porphyry-like granodiorite with characteristics of porphyry deposit.A large number of UST,quartz veins and pegmatite-like rocks are developed,and a large number of hydrothermal solutions are exuded.Fluid inclusions in Xitaizi and Duimiangou intrusions are divided into gas-liquid two-phase inclusions and halite-bearing crystalline inclusions,which are NaCl-H₂O system and without CO₂.The homogenization temperature of these two inclusions is close,the temperature is higher,and the salinity is different.2.Fluid inclusions in gold-bearing quartz veins are gas-liquid two-phase inclusions with low salinity.The ore-forming fluid is a medium-high temperature-NaCl-H₂O system,which does not contain CO₂.Quartz H-O isotopes in gold-bearing quartz veins show that ore-forming fluids mainly come from magmatic water,and a small amount from metamorphic water and meteoric precipitation.The Pb isotope sources of ore bodies,rock bodies and metamorphic rocks are mainly from the mantle and lower crust.The original Pb isotope shows that the source of ore bodies is mainly from the Duimiangou,and a small amount is from the metamorphic rock.3.Jinchanggouliang is a vein-type gold deposit related to porphyry,which is controlled by structure and related to the mesophase of the Duimiangou intrusive body.Its metallogenic age is the same as that of the Mianggou mesophase.Its metallogenic depth is 2-5 km,and it distributes in the Pb-Zn belt of the zoning of the ore-bearing porphyry deposit.