【作者】 张智宇；

【导师】 杜杨松；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2011， 博士

【摘要】 安徽铜山矽卡岩铜矿床产于长江中下游成矿带中的安庆–贵池矿集区。区内赋矿地层为下二叠统栖霞组与中石炭统黄龙组,褶皱与断裂是重要的控矿构造。中生代岩浆活动强烈,形成了石英闪长玢岩、石英二长斑岩和花岗闪长斑岩等侵入岩。在花岗闪长斑岩与赋矿地层的接触带,产有一定规模的含铜矽卡岩。本文对该区矽卡岩矿床进行了详细研究,重点分析了矽卡岩演化规律和矿床成因,建立了矽卡岩空间成矿模式,取得了以下主要成果和认识。1.铜山岩体成岩年龄为145.1±1.2 Ma,与成矿年龄(147.5±2.3Ma)基本一致。该岩体是由壳幔同熔岩浆上升侵位形成的,岩浆结晶的温度为750 ~ 755℃,压力为1.16 ~ 1.64 kb。岩体形成于板块碰撞后隆起到造山晚期的构造背景。2.铜山铜矿矽卡岩具有明显的时空分带。水平方向上,近岩体的矽卡岩中石榴石含量较高,远岩体的矽卡岩中透辉石含量较高;靠近大理岩带发育钙铁辉石矽卡岩,远离大理岩带的灰岩硅化较强。垂向上,从浅部到深部依次产有角岩、钙质矽卡岩和镁质矽卡岩。铜多富集于含石英脉的岩体、距岩体较远的矽卡岩、角岩及大理岩中。在时间上,矽卡岩经历了进化交代阶段、磁铁矿阶段、石英-硫化物阶段和晚期退化蚀变阶段。其中,大规模的黄铜矿化主要发生于石英-硫化物阶段。3.成矿物质主要来源于岩浆,偶有地层硫混入;在进化交代阶段,成矿流体主要来源于岩浆水,碳源主要为海相沉积碳酸盐岩;在退化蚀变阶段,大气降水在成矿流体中的比例逐渐增大,也为流体系统提供了重要的碳源。4.流体包裹体有Ⅰ型含子晶多相包裹体、Ⅱ型气液包裹体和Ⅲ型富CO2包裹体三类。进化交代阶段的成矿流体具有高温、高盐度特征;退化蚀变阶段由于大气降水参与,流体温度与盐度均依次降低。5.铜山铜矿矽卡岩属于接触交代成因,垂向上矽卡岩类型主要受地层岩性控制,矽卡岩分带模式受控于地质体不同空间部位的成矿流体性质、围岩特征、氧化还原态及温度等条件。更多还原

【Abstract】 Tongshan skarn copper deposit is located in the Anqing-Guichi ore-clustered district of the Lower Yangtze River metallogenic belt. Ore host strata include the Qixia Formation of the Lower Permian and the Huanglong Formation of the Middle Carboniferous. Folds and faults are important ore control structures. Intrusions formed during the intense magmatism of the Mesozoic Era consist of quartz diorite porphyry, quartz monzonite porphyry and granodiorite porphyry. Copper-bearing skarns on a certain scale occur in the contact zone between the granodiorite porphyry and ore host strata. A detailed study has been carried out on the skarn deposit in this area, with a focus on an analysis of skarn evolution and ore genesis so as to set up a mode of skarn mineralization. The following are major achievements obtained in this dissertation.1.The Tongshan intrusion is dated at 145.1±1.2 Ma, close to the metallogenic age (147.5±2.3Ma). Emplacement of the crust-mantle syntactic magma is responsible for the formation of this intrusion. The crystallization conditions of minerals are estimated to be temperature of 750 to 755℃and pressure of 1.16 to 1.64 kb. The tectonic setting for the formation of the pluton is defined as post collision uplift to late orogeny.2. Skarn in the Tongshan copper deposit indicates an evident temporal and spatial Zoning. Horizontally, garnet is rich in the skarn near the intrusion, but diopside is rich in the skarn far from the intrusion. Hedenbergite skarn occurs near the marble zone, but limestone with stronger silicification exists far away from the marble zone. Vertically, hornfel, calcareous skarn and magnesian skarn occur in order from shallow to deep. Enrichment of Cu exists in the porphyries with quartz veins, skarns far from intrusion, hornfel and marble. The evolution process of skarns includes prograde metasomatic, magnetite, quartz-sulfide, and late retrograde stages. Copper mineralization mainly happened in quartz-sulfide stage.3. Ore-forming material may be mainly from magma, but sulfur occasionally from strata. During the prograde metasomatic stage, ore-forming fluids may be mainly from magmatic water, but carbon generally from marine sedimentary carbonate. In contrast, meteoric water may be gradually increased in the ore-forming fluids and provide a larger part of carbon during the retrograde stage.4. Inclusions includeⅠ-type of polyphase inclusions with daughter crystals,Ⅱ-type of fluid inclusions andⅢ-type of CO2-rich inclusions. From the prograde metasomatic stage to the retrograde stage, addition of meteoric water is responsible for the decrease of temperature and sality of ore-forming fluids.5. The skarn in the tongshan copper deposit is contact metasomatism skarn. Vertical occurrence of skarns and metamorphic rocks may be controlled by the lithologies of strata. The zoning mode of skarns may be controlled by the property of fluids and wall-rocks, redox state and temperature condition in the different locations of geological bodies.更多还原