Geological-geochemical Characteristics And Genesis Of Haoyaoerhudong Gold Deposit In Inner Mongolia

The Haoyaoerhudong gold deposit, which is attached to Xinhure town in Urad MiddleBanner of Inner Mongolia, locates in the west of the Mesoproterozoic Bayan Obo rift on thewest section of the northern margin of the North China plate. As a gold ore of big reservesand low grade, the Haoyaoerhudong ore deposit reach to213t in proved reserve, while itsgrade only is0.82g/t. The orebody occurs in the greyish metamorphic fine sandstone andsiltstone of the Bayan Obo flock, the shape of orebody is stratiform,and is controlled bystratum and fracture zones, The orebody is primarily occurrenced in greyish blackmetamorphic fine sandstone and siltstone and phyllite of the first and second segment of BiLute petrofabric. The types of ore are auriferous quartz vein type and metamorphismclasolite type.The types of rock mass of diggings are biotite granite、granite、dioritic porphyrite andgabbro. The U-Pb ages of zircon of granite porphyry、monzonitic granite porphyry and biotitegranite are290.9±2.8Ma、287.5±1.9�'�267.9²74.0Ma,showing rock mass formed in Earlyearly Permian.The Ar-Ar age of biotite in pegmatite quartz vein is267.4±2Ma,showing therelationship of orebody and rock mass is compact. The heat of magmatism and concomitantore-forming fluid made the gold of the stratum enrichment,and deposited in theadvantageous section， and magmation simultaneously supplied partial metallogenicmaterial.The homogenization temperature of fluid inclusion in different stage of mineralizationtrempers:（1）early quartz vein stage245.2℃～323.3℃， average values295.8℃;（2）quartz-pyrite stage236.9℃～317.5℃，average values287.3℃；（3） quartz-polymetallicsulfide stage231.7℃～322.9℃，average values275.3℃；（4） carbonate stage187.6℃～312.9℃，average values231.8℃。The range of salinity of fluid inclusion is7.04%²1.26%，average values13.26%，salinity is medium.The analysis of laser Raman reveals the basis ofgas-liquid two-phase fluid inclusion is H₂O、 CO₂、 N₂and CH₄， pertaining toH₂O-CO₂-N₂-CH₄system.The region of ore-forming pressure is2.65⁶.27km, average values3.91km, pertaining toSub-bottom.According to research of Mineral Deposits’s characteristic、stratum、ore、geochemistry characteristic of magmatite and fluid inclusion，considering the Haoyaoerhudong golddeposit is black rock series gold deposit, the mineralization of Haoyaoerhudong golddeposit、Zhulazhaga gold deposit and Saiyinwusu gold deposit in central and westernregions of Inner Mongolia happened in hercynian period,and belong to Pal-Asiametallogenic domain,are similar to Dakoushan gold deposit in South Tianshan、Sarwar jasgold deposit in South Tianshan、Muluntau gold deposit in Uzbekistan and Kumtor Gold minein Kyrghyzstan. The characteristic makes it possible to search large and ultra-large type golddeposit in Inner Mongolia.