【作者】 程彦博；

【导师】 毛景文；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 本次工作在前人研究工作的基础上，以个旧超大型锡多金属矿床及与成矿有关的岩浆岩为重点研究对象，通过系统的野外地质研究和岩石地球化学、矿床地球化学研究，对研究区内中生代大规模岩浆作用与成矿作用的地质与地球动力学背景、金属矿床成因和成矿作用过程进行了系统的研究，取得了部分新认识与成果，并分别建立了岩浆作用和成矿作用模型。对个旧地区与成矿有关的岩浆岩进行了微量元素、稀土元素以及Sr-Nd-Hf同位素地球化学研究。结果表明，个旧地区中生代岩浆岩的结晶时代基本一致，集中在78-85 Ma之间，可以视为同期岩浆作用的产物。地球化学研究表明，个旧地区的花岗岩类在形成过程中发生了不同程度的分异结晶作用，其原岩主要为地壳物质发生部分熔融而形成，但是有少量的地幔物质组分加入；辉长岩和暗色微粒包体代表了地幔端元的组分及与壳源岩浆发生化学混合的产物，辉长岩的母岩为来自岩石圈地幔的物质发生部分熔融，在经过少量的地壳混染而形成，暗色微粒包体则代表的是这种玄武质岩浆与花岗质岩浆发生化学成分交换后的结果；碱性岩和镁铁质岩墙的地球化学特征暗示其均直接源于岩石圈地幔，碱性岩为幔源岩浆经历强烈的分异结晶作用形成，而镁铁质岩墙则为同一幔源岩浆在上升至地表的过程中受到大量地壳物质的混染的结果。上述研究表明，在晚白垩世时期，个旧地区的地壳物质与地幔物质之间存在强烈的相互作用。以整个矿集区为研究对象开展了系统的野外地质现象观察和矿床地球化学及成矿年代学研究。研究表明，在个旧锡多金属矿集区，成矿金属元素分带围绕花岗岩体的垂直方向和水平方向都有分布；同时，在个旧地区不同类型的成矿体系中，在不同阶段，成矿流体的温度和盐度等相关特征性参数均展现出连续的演化规律，是典型的与花岗岩有关的热液矿床。H-O同位素数据也佐证了这一认识，因为不同阶段的成矿流体存在明显的差异，暗示在成矿过程的早期阶段以花岗岩出溶的岩浆水为主要成矿流体，而在晚阶段则与天水或者地表水发生了流体混合作用。系统的S同位素研究也从另一个角度为这一认识提供了有力的支持。此外，云母Ar-Ar、辉钼矿Re-Os及锡石U-Pb测年方法均表明，与矿区内不同类型的岩浆岩时代类似，个旧矿集区的矿化作用均发生于晚白垩世。上述研究一致表明，个旧锡多金属矿集区的矿化为岩浆热液成因，而非同生成因。更多还原

【Abstract】 This study targets at the magmatic rocks and Sn polymetallic ores in the Gejiudistrict, Yunnan Province, aiming to resolve the problems correlate with geodynamicsetting, ore-forming process and ore deposit model of the mineralization in the studyarea.Systematic new SHRIMP/LAICP-MS U-Pb zircon dating results indicate that allthe intrusive rocks in the Gejiu district are coeval, ranging from 78 Ma to 85 Ma.Elemental- and isotopic geochemistry of these rocks revealed that the granites in theGejiu district experienced different degrees of fractionation, and they mainly sourcedfrom crust-derived materials with minor input of mantle-derived magma. The Jiashagabbro derived from the partial melting of the lithospheric mantle with somecontamination of crustal materials, and the mafic microgranular enclaves represent theresults of magma mingling and mixing between the crustal- and mantle-derivedmagmas. Both alkaline rocks and mafic dykes sourced from lithospheric mantle butexperienced different evolution process. Based all these ideas, we concluded that anextensive interaction between mantle and crust happened in Gejiu district during LateCretaceous.Metal zonation, both in horizontal and vertical direction are clearly developed inthe Gejiu Sn polymetallic ore district, commonly from W-Be-Bi±Mo±Sn zone, toCu-Sn zone and to Pb-Zn zone. New data indicates that the homogenizationtemperature and salinity of the ore-forming fluid display continuous varations indifferent mineralization stages, which is a typical characteristics of the granite-relatedhydrothermal deposit. Sulfur isotope of various sulfide, Hydrogen and Oxygenisotopic compositions of different stage’s quartz exhibit obvious difference, whichsupport the above idea from another points. Moreover, by applying of differentanalytical methods on different minerals, which include mica Ar-Ar, molybdenumRe-Os and LA-ICP-MS cassiterite U-Pb dating, new data revealed that all the orestyles in the Gejiu district formed in a short time, and all the mineralization andmagmatism ages are very similar. This means all the mineralization formed in LateCaretaceous rather than Triassic. Above all, the large scale metallic accumulation andmineralization in Gejiu district are hydrothermal origin, not syngentic.更多还原