| 滇西北中甸普朗斑岩铜矿床地球化学与成矿机理初探 |
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| 引用本文：.2007.A tentative study of ore geochemistry and ore_forming mechanism of Pulang porphyry copper deposit in Zhongdian, northwestern Yunnan[J].Mineral Deposits,26(3):277~288 |
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| 基金项目:国家自然科学基金项目(40372049)、国家“973”项目(2002CB412605)和中国科学院知识创新工程重要方向项目（KZCX3_SW_125） |
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| 中文摘要:普朗斑岩铜矿是一个典型的与洋壳俯冲相关的大型乃至超大型矿床， 通过对矿区代表性含矿斑岩与无/弱矿化斑岩的稀土元素特征对比、硫同位素示踪等方面的 研究，表明矿石随Cu品位的增高，稀土总量(∑REE)和稀土分馏参数〔（LREE/HREE）、（ La/Yb）N及(La/Yb)N、(Gd/Yb)N〕呈连续降低趋势，负铕异常一般显示为逐渐增强的 趋势，但在发育有强烈的晚期钾长石脉的情况下，出现反弹减弱特征。硫化物（黄铜矿、黄 铁矿和辉钼矿）的δ34SCDT变化范围为-2.23‰～3.75‰， 基本呈塔式分布特征，主要为深源岩浆硫。 |
| 中文关键词:地球化学 斑岩铜矿 成矿机理 稀土元素 硫同位素 中甸普朗 |
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| A tentative study of ore geochemistry and ore_forming mechanism of Pulang porphyry copper deposit in Zhongdian, northwestern Yunnan |
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| Abstract:Located in Zhongdian volcanic arc in the southern part of the Yidun island arc, the Pulang porphyry copper deposit discovered in 1999 is a typical benioff subdu ction_related superlarge copper deposit. The porphyry bodies intruded into Trias sic strata of clastic rocks with carbonates and volcanic rocks. Copper mineraliz ation mainly occurs in quartz monzonite porphyry and quartz diorite porphyry, ch aracterized by potassic alteration, quartz_sericite _pyrite alteration and propy l ytization. Ore minerals include mainly chalcopyrite, pyrite, molybdenite, pyrrho tite, subordinately magnetite, chalcocite, bornite, and locally malachite. Based on a comparison of REE characteristics between typical mineralized porphyry and barren or weakly mineralized porphyry as well as a S isotopic study, it is show n that, with the increase of Cu contents of the porphyries, both the total REE c ontents (∑REE) and the REE fractionation parameters 〔(LREE/HREE), (La/Yb)N , (La/Yb)N, (Gd/Yb)N〕 decrease continuously, whereas the weak Eu anomalies on the REE distribution patterns of samples generally become stronger, with the ex ception of the weak Eu anomaly for the sample containing late stage K_feldspar c oarse veins. The δ34SCDT values of sulfides (pyrite, chalcopyrite a nd molybdenite) rang e from －2.23‰ to 3.75‰, and their normal distribution histogram indicates tha t sulfur was derived mainly from the magma. Combined with previous work on geolo gical prospecting, petrology, geochronology and fluid inclusions, the authors co mprehensively analyzed the geodynamic background for the metallogeny of the Zhon gdian Cu_polymetallic belt and discussed preliminarily ore_forming mechanism of the Pulang porphyry copper deposit. It is believed that the low angle oblique su bduction of the Ganzi_Litang ocean slab during the period from 235 Ma to 210 Ma st rongly affected the Zhongdian area in such aspects as the formation of NW_trendi ng fractures and folds and the subsequent island arc magmatic movement. A superc ritical fluid rich in Cu, Fe, S, Cl-, HCO-3, CO2+3, CO2, Na+, K+, Ca2+ components, which was formed through the evolution of the porph yritic magma derived from the partial melting of oceanic slab, reacted with the early emplaced porphyry and caused porphyry copper mineralization. |
| keywords:geochemistry, porphyry copper deposit, ore_forming mechanism,trace earth elements, sulfur isotope, Pulang,Zhongdian |
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