THE GENESIS OF THE XINDIAN GOLD DEPOSIT IN LIAONING PROVINCE

The Gaixian formation of Liaohe group is composed of terrigenous clastic clayey sedimentary rocks interlayered by acid intermediate volcanic rocks and/or volcanic clastic sedimentary rocks.The siliceous veins are formed by metamorphic defferentiation in the long geologic era.In the process,Au and other mineralizing materials in the metamorphic rocks were firstly activated and then migrated and enriched in the siliceous veins.In Yanshanian epoch,the metamorphic rocks were metasomated and resoluted,and formed porphyroid biotite-granite.The Au and other mineralizing materials were mostly migrated into post-magmatic hydrothermal fluid,and not precipitated until the fluid varied to weak acid and reductive solution.The characteristics of Pb and S isotopes and chondrite-normalized REE pattern prove that the mineralizing materials are from Gaixian formation.The composition of inclusions in quartz and H and O isotopes demonstrate that the mineralizing hydrothermal fluid came from mainly the post magmatic hydrothermal solution.The shearing structures formed by magmatic activities are the migratory channels of the hydrothermal solution and space for the forming of veins or ore-bodies.Xindian gold deposit is a post-magmatic hydrothermal type of gold deposit.