THE CHARACTERISTICS OF UPPER PALEOZOIC ADULARIA-SERICITE TYPE OF AXI GOLD DEPOSIT,XINJIANG

Axi gold deposit, located in the north part of western Tianshan, Xinjiang, belongs to Yili-center Tianshan continental crust of Kazakhstan plate. It occurs in Upper Paleozoic Tulasu volcanic basin in Yili area. The volcanic rocks of the fifth lithologic member in Dahalajunshan formation are distributed dominantly in the mining area, including andesite, dacite, volcanic breccia, volcanic agglomerate, bomb-bearing volcanic breecia, rhyodacite, tuff, crystal tuff, crystal-lithic tuff and trachyandesite.A little amount of the first lithologic member of Aqialehe formation including conglomerate and grey green tuff feldspathic litharenite,and diorite-porphyrite, quartz andesite-porphyrite and feldsporphyre also appears in the mining district. Aqialehe formation which is a suit of continental-marine sedimentary rock overlays on the Dahalajunshan formation. In the mining district, the fault structure with strikes of NW and E-W are dominant, the secondary ones are the arcuate and radial faults controlled by volcanic apparatus. Many volcanic vents develop in the mining district. The orebody, which is the kind of auriferous quartz vein, is located near one of the caldera and controlled by the fault striking S-N. The mineral assemblage is pyrite, marcasit, arsenopyrite, sphaleyite, chalcopyrite, galena,pyrrhotite, polybasite,naumannite, clausthalite, electrum, gold, zinc, tetrahedrite, bornite, specularite, limonite, quartz, sericite, muscovite, illite, hydromuscovite, calcite, adularia, chlorite, chalcedony, montmorrillonite etc.The alterations of wallrock include silication, sericitization, chloritization, carbonation, adularization, albitization etc. The metallogenic epoch is Lower Carboniferous.The mineralizing temperature ranges between 81~260℃. The salinity of metallogenic of fluid is between 0.35%~9.6%. lgƒo₂ is between -37~-39. So Axi gold deposit belongs to the type of epithermal hydrothermal adularia-sericite.