MINEROGENIC CHARACTERISTICS OF GOLD MINERALIZATIONIN IN XIKOUZI-BADAOKA AREA,INNER MONGOLIA

Xikouzi-Badaoka area is rectonically located in the north of Ergun massif,where the Proterozoic metamorphic rocks are outcropped, with intense Jurassic magmatic activities.The E-W trending basement structures are superposed by a series of Jurassic left handed compresso shearing NE-trending faults and tensile N-S trending faults.The Au mineralization bodies occur as veins and lenses in altered fracture zones within metamorphic rocks and biotite admellite,or in the contacts between the metamorphic rocks and quartz diorite.The gold ores are altered rocks and quartz veins.The associated wall-rock alterations include silicification,pyritization and beresitization.The REE patterns of porphyroid biotite-admellite and quartz-diorite are similar to those of gold orebodies.The S-isotopic values of pyrites in ores are between-1.4 and-8.5.The vapor phase compositions of minerogenic fluid are mainly H₂O,CO₂ and N₂,with minor CH₄,C₂H₆ and O₂;while the liquid phase,mainly Cl^-,F^-,SO₄^2-,Na+ and K+ with minor Ca²⁺ and Mg²⁺.Geochemistry studies indicate that the Au-mineralization is closely related to biotite-admellite and quartz-diorite.The minerogenic materials are mainly derived from lower crust and/or mantle.The minerogenic fluid is alkali-riched weakly reducible magmatic hydrothermal solution.