Mineralogy and Mineral Chemistry of the Cretaceous Duolong Gold-Rich Porphyry Copper Deposit in the Bangongco Arc,Northern Tibet
作者单位：Key Laboratory of Mineral ResourcesInstitute of Geology and GeophysicsChinese Academy of Sciences
会议名称：《中国科学院地质与地球物理研究所2012年度（第12届）学术年会》
会议日期：2013年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：fundedbyNSFC(NaturalScienceFoundation of China)(40902027,40672068) the important research direction project of the Academy of Sciences of China(KZCX2-YW-Q04-2) China Geological Survey project(20089932)
关 键 词：Bangongco arc Duolong gold-rich porphyry copper deposit mineral chemistry mineralogy
摘 要：The Early Cretaceous Duolong gold-rich porphyry copper deposit is a newly discovered deposit with proven 5.38 Mt Cu resources of 0.72% Cu and 411 gold of 0.23 g t in northern *** porphyry and quartz diorite porphyrite are the main ore-bearing porphyries.A wide range of hydrothermal alteration associated with these porphyries is divided into potassic,argillic and propylitic zones from the ore-bearing porphyry center outward and *** the hydrothermal alteration zones,secondary albite(91.5-99.7% Ab) occurs along the rim of plagioclase phenocryst and *** K-feldspar(75.1-96.9% Or) replaces plagioclase phenocryst and matrix or occurs in *** occurs mainly as matrix and veinlet in addition to phenocryst in the potassic *** biotite are Mg-rich and formed under a highly oxidized condition at temperatures ranging from 400℃ to 430℃ .All the biotites are absent in F,and have high Cl content(0.19-0.26% ),with log(X/X) values of -2.74 to -2.88 and IV(Cl) values of—3.48 to—3.35,suggesting a significant role of chloride complexes (CuCl and AuCl) in transporting and precipitating copper and *** are present in all alteration zones and correspond mainly to *** have similar Fe/(Fe+Mg),Mn/(Mn+Mg) ratios,and a formation temperature range of 280-360℃ .However,the formation temperature of chlorite in the quartzgypsurn -carbonate-chlorite vein is between 190℃ and 220℃ ,indicating that it may have resulted from a later stage of hydrothermal ***/Fe ratios of chlorites have negative correlation with AP,suggesting oxygen fugacity of fluids increases with decreasing *** mineral inclusions in the biotite phenocrysts show high SO content(0.44-0.82% ) and high Cl content(1-1.37% ),indicating the host magma had a high oxidation state and was enriched in S and *** highest Cl content of apatite in the propylitic zone may have resulted from pressure decrease,and the lowest Cl content of apatite in t