Geochronology and Geochemical Characteristics of Intrusion in the Jinchangliang Gold Deposit,Inner Mongolia and Their Tectonic Significance

Discovered and mined in recent years, the Jinchangliang gold deposit has not yet been studied in its genetic type. In this paper, the geological features of ore deposit, S isotopic composition, metallogenic age and elements geochemical of the granite closely related to mineralization were discussed. The results of the geological features of ore deposit and S isotopic composition show that ore-bearing hydrothermal solution was closely related with the intrusion of magmatic. The granite is characteristic of high silica SiO_2=72.38%-72.98%, high aluminum and Al_2O_3=14.22%-14.35%, low calcium CaO=0.16% -0.26%, and low value of FeOT/MgO（6.86-7.73）, and rich in alkalis Na_2O＋K_2O=9.11%-9.24%, suggesting that it is high-K calc-alkaline, highly fractionated, weak aluminum A-type granite. The REE patterns are inclined to right and show intense fractionation between LREE and HREE, without obvious negative Eu anomaly（δEu=0.80-0.84）. The primitive mantle-normalized spidergrams are characterized by depletion of Ba, U, Ta, Nb, Zr, Ti and P, which implies that the granite has the characteristics of the crust-mantle mixing. S isotopes also indicate that the material source of gold deposit is closely related to the granite rocks. The LA-ICP-MS Zircon UPb age of the Damiao rock mass medium-fine grained monzogranite（belonging to the early IndoChina） is（245±1） Ma. It shows that Jinchangliang gold deposit was not formed in Yanshanian, but the early Indo-China. Specifically speaking, the deposit was formed in the collision stage of the North China plate and the Siberian plate.