【作者】 石海岗；

【导师】 薛春纪；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2011， 硕士

【摘要】 喇嘛苏铜矿位于西天山成矿带西北部的赛里木微陆块内,自发现以来备受关注、不断被认知,已取得大量研究成果,但是对矿床成因类型仍存在分歧,成矿流体研究很少。本文在研究矿床地质的基础上,通过研究矿石组构特征、主要成矿阶段矿物共生组合,利用冷热台和激光拉曼分析技术开展流体包裹体研究,结合同位素、微量元素和稀土元素研究结果,试图对矿床成因特点提供约束。喇嘛苏铜矿床与成矿相关的斑岩组合以花岗闪长斑岩和斜长花岗斑岩为主,花岗闪长斑岩可能属于同源岩浆演化晚期侵位产物;斑岩体属于典型钙碱性火山弧花岗岩,形成于大陆弧环境,是洋壳俯冲作用下发生部分熔融,交代原先的地幔楔,并混合了部分下地壳的物质,经历分离结晶作用的产物。石英硫化物成矿期是形成有用金属矿物的最重要的时期,又被划分为早期石英硫化物阶段(I)和晚期石英硫化物阶段(II)两个阶段。早期石英硫化物阶段(I)主要发育块状的磁黄铁矿-黄铁矿-黄铜矿矿石和黄铁矿-黄铜矿矿石;晚期石英硫化物阶段(II)主要发育浸染状、脉状以及团斑状的黄铁矿-黄铜矿矿石。流体包裹体和激光拉曼探针分析显示,I阶段成矿流体为H2O-NaCl-CaCl2体系,含少量的CH4,II阶段成矿流体逐渐向H2O-NaCl体系转变,含有大量的CH4。I阶段和II阶段成矿温度分别为271.2℃~ 330.7℃和130.5℃~ 249.7℃,盐度主要范围为6.01 ~ 13.94%(NaCl)和3.2 ~ 13.94%(NaCl),流体密度小于1.00 g/cm3,属于中-低温,中-低盐度、低密度还原性流体。C、H、O、S、Pb同位素结果显示成矿流体在I阶段以岩浆水为主,II阶段有大气降水的混入;II阶段含矿方解石中的C来自溶解的围岩库松木切克群灰岩;硫主要来源于岩浆,有部分的地层硫加入;金属成矿物质为地壳和地幔的混合来源,主要是由俯冲带的岩浆作用导致了上地壳源铅与深部来源铅混合;硫化物电子探针和稀土元素地球化学研究表明,成矿温度与流体包裹体的温度一致,成矿过程处于不同强度的还原环境下。结合矿床产出背景、矿床地质、控矿构造等因素,喇嘛苏铜矿床是与中酸性岩体密切相关的以斑岩-矽卡岩矿床。更多还原

【Abstract】 Lamasu copper deposit, located in the micro-continental block of Sailimu,northwest of Tianshan ore-forming belt, has receive much concerned and been studied deeply since discovered. However, considerable differences still exist between genetic type and ore-forming mechanism, apart from which, the ore-forming fluids are rarely studied. In this paper, after fabric and assemblage of the ores were studied based on the geology of the deposit, microthermometry and Laser Raman spectroscopy were used to conduct the study of fluid inclusions, which are the representative samples of ore-forming fluid, as well as the signal of determining the genetic type. Combined with the study of isotope, sulfide-EPM analysis and REE geochemistry, the genetic characteristics of the deposit were tried to be restricted.Mineralization-related porphyries are mainly plagioclase porphyry and granodiorite porphyry, and the latter may be the product of the emplacement of the consanguineous igneous magma in the late stage. The porphyries belong to typical calc-alkaline volcanic arc granite, forming in the continental arc environment and are the product of fractional crystallization, which experienced following process: partial melting after ocean crust subduction to the continental crust and replaced the original mantle wedge and mixed some lower crust.Quartz-sulfide mineralization stage is the most important stage for metal mineral formation, and divided into two sub-stages, early(I) and late(II) stages. The early stage of quartz sulfide (I) mainly develops massive pyrrhotite-pyrite- chalcopyrite ore and pyrite-chalcopyrite ores while the latter mainly disseminated, vein and patchy pyrite-chalcopyrite ores. Based on the observation and microthermometry, the system of the ore-forming fluids in I phase is H2O-NaCl-CaCl2 with a little CH4 while the latter changes into H2O-NaCl system, containing much CH4. The homogenization temperature in I-stage and II-stage is 271.2℃~ 330.7℃and 130.5℃~ 249.7℃, respectively while corresponding salinity is 6.01 ~ 13.94%(NaCl)and 3.2 ~ 13.94%(NaCl), respectively, with the density less than 1.00 g/cm3. Therefore, the ore-forming fluids in quartz-sulfide stage are low-dense, relatively reduced, medium to low temperature and salinity fluids. The study of C, H, O, S and Pb isotope shows that the ore-forming fluids in the I phase are mainly magmatic water while in the II phase were mixed with quantity of precipitation, C in in the II phase deprived from the solution of the limestone, S mainly originated from magma with part of strata mixed, and the ore-forming sources are derived from the mixture of the mantle and crust, resulting from the magmatism in the subduction belt. The EPM of the sulfide and REE geochemistry illustrate that the homogenization temperature is correct, and the reduce condition of ore-forming process is different.The factors of geologic background, ore-forming sources and ore-controlling structure lead to the conclusion that Lamasu copper deposit is a skarn-dominated porphyry - skarn deposit,closely related to the intermediate to acidic rocks.更多还原