GEOCHEMISTRY AND METALLOGENESIS OF HUOSHI BULAK ALKALI-FELDSPAR GRANITE, XINJIANG

The Huoshi Bulak alkali-feldspar granite, located in the south of Huoshi Bulak of Artux City, Xinjiang,intruded into Early Permian Bieliangjin group and Late Permian Kutiereke group. The isotopic age of the alkali-feldspar granite intrusion is 261.5±2.7 Ma. A detailed study on geology, petrology, mineralogy and geochemistry of the alkali-feldspar granite shows that the granite is composed mainly of perthite(70%-75%),quartz(23%-27%),plagioclase(1%-2%),biotite(<1%) and muscovite(<1%). The accessory minerals in these rocks include magnetite, anatase, zircon, rutile, titanite, tourmaline, fluorite etc. The chemical composition is characterized by rich SiO 2(73.20%-76.86%),total alkaline-rich(Na²O+K²O=7.91%-10.54%),high total REE(ΣREE=515.90×10^-6),σ=1.98-3.70,A/NKC=0.87-1.04,LREE/HREE=2.41, (La/Yb)_N=6.34,(La/Sm)_N=5.12,and intensive europium deletion (δEu=0.12). Of the trace elements, Huoshi Bulak alkali-feldspar granite is with high Li, Rb, Nb, Zr, Th, Ni and Sc, enriched in F and B,poor in Cr, Co, Ni, V, Sr and Ba. Metallogenetically, the granite is obviously rich in Cu, Au, W, Sn, Pb and Zn, showing characters of Sn-polymetallic rock body, which is favorable for Sn-polymetallic mineralization. The metallogenesis of Haoshi Bulak orefield, which is related to the magmatic activity, is produced by the magmatic differentiation. The magmatic activity provided ore-forming materials and hydrothermal fluid. The emplacement of the rock body formed skarn and hornfels in the surrounding rocks, accompanied by Sn,Mo, Fe, Nb, Ta, REE, Cu, Pb and Au mineralization that is regularly distributed in the contact belt and outside of the rock body.