【作者】 刘江涛；

【导师】 杨立强；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2014， 博士

【摘要】 滇西北地区位于西南三江成矿带中段,是我国斑岩—矽卡岩型铜多金属矿产的重要基地。论文以区内最具代表性的普朗铜矿床、羊拉铜矿床为研究对象,通过资料分析、野外考察、室内鉴定、地球化学测试等方法,讨论了晚三叠世古特提斯洋闭合过程中成矿斑岩体的起源、演化、流体出溶以及Cu元素的在容矿裂隙—脉系统中的运移、富集过程。获得如下主要成果：1.根据手标本、镜下斑晶的蚀变残余结构,首次将羊拉铜矿床中平硐3725中2号、9号矿体下盘发育的灰白色蚀变岩的原岩恢复为石英二长斑岩,并利用锆石LA-ICP-MS U-Pb方法测定其成岩年龄228.1+1.0Ma,与228Ma的辉钼矿Re-Os年龄一致,为成矿母岩的确立提供了依据。2.通过对斑岩体氧化—还原性的研究,提出Ce(IV)/Ce(III)值大于250,δEu小于0.38是区内岛弧环境中岩体斑岩型矿化地球化学指标；Ce(IV)/Ce(III)值大于150,δEu小于0.13是陆缘弧环境中矽卡岩型矿化的地球化学指标。3.MME的产状特征、地球化学及同位素特征表明,羊拉复式岩体MASH过程以长英质岩浆对围岩的同化混染为主；普朗复式岩体则以基性岩浆注入到酸性岩浆为主要方式,为铁镁质岩浆去气后与长英质岩浆双对流的产物。4.普朗铜矿床中发育大量磁黄铁矿,成矿流体含较多CO2、CO和CH4等还原性组分,氧逸度低于FMQ缓冲剂,具还原性斑岩型铜矿的特征。还原性流体中Cu的溶解度比氧化性流体中的低,但Au的溶解度不受的影响,CH4还可使SO2还原形成S2-,为辉钼矿的形成提供物质基础,使矿体中Cu品位偏低且伴生大量Au、Mo矿化。5.羊拉铜矿床为矽卡岩型矿床,成矿岩体为石英二长斑岩,但并非碳酸盐岩与岩体直接接触发生“双交代”形成的典型的矽卡岩矿床,而是以岩浆流体为主携带成矿物质在远离岩体部位与地层中的大理岩透镜体单向交代的产物。6.斜向俯冲-剪切背景下,鱼波复背斜西翼的层间滑脱及顺层剪切构造控制了羊拉铜矿床矿体“弯曲梳状”的产出形态；平行于消减带的弧平行断裂、不同成因的张性脉以及岩浆-流体相互作用的裂隙构成了普朗铜矿床流体运移的通道并为Cu提供存储场所,控制着“多节葫芦状”矿体的产出。更多还原

【Abstract】 Northwest Yunnan located at middle of Sanjiang metallogenic belt, where is a important basement of porphyry-skarn copper and multi-metal in China. The study selected Pulang and Yangla deposite as representative, through data analysis, field investigation, indoor appraisal, geochemical test methods, to discusse magmatic origin, evolution and magma-fluid dissolved in late magmatism, migration and enrichment of copper element in fissure vein system. The main results are as follows:1. According to the hand specimens, the microscopic residual structure of gray altered rock in Yangla copper deposit, the original rock of which is quartz monzonitic porphyry, and by means of LA-ICP-MS zircons U-Pb isotopic dating, gaining its diagenetic age as228.1±0.3Ma, which consistent with predecessor’s mineralization age who use molybdenite Re-Os method, which provides the basis for the ore-forming parent rock.2. The research of oxidability-reducibility of porphyry indicate that the value of Ce(IV)/Ce(III) is great than250,8Eu is less than0.38which is the geochemical indicators of porphyritic type mineralization in arc environment; the value of Ce(IV)/Ce(III) is greater than150, SEu is less than0.13which is the geochemical indicators of skarn type mineralization in continental arc environment.3. The occurrence of MME and its geochemical characteristics show that the MASH process of Yangla complex is felsic magma which come up with assimilation and contamination with surrounding rock. The in Pulang complex is mainly through massing basic magma into acid magma, and it’s the result of mafic magma degassing and convection together with felsic magma.4. Pulang copper deposit have large amount of pyrrhotite and owning lots of reducing compositions, such as CO2, CO and CH4in the ore-forming fluid, and with fO2values below the FMQ buffer, characterized by reduced porphyry copper deposits. The copper solubility in reduced fluid is lower than that in the oxidized fluid, but the gold solubility is not affected, that makes Cu grade low but with massive Au, Mo mineralization.5. Yangla copper deposit is typical skarn deposit, and ore forming rock is QMP. Although, the deposit is not a product of carbonate rocks direct contact with magmatic rocks, but a replacement of mainly magmatic fluid carrying ore-forming elements and lens marble in layer.6. Under the background of oblique subduction, the interbending fault and shear of Yubo anticlinorium made the shape of the Yangla deposit ore like as "bended comb". Arc parallel structures, tension viens and fractures made the shape of Pulang despite like as "plurality of gourd".更多还原