山西中条山铜矿峪铜矿矿床地质特征及成因探讨

发布时间：2018-05-11 05:29

本文选题：斑岩型铜矿床 + 围岩蚀变　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：铜矿峪铜矿床位于中条山铜多金属成矿带,是目前中国最古老的斑岩型铜(钼)矿床之一。本文通过详尽的野外地质调查,查明矿床的围岩蚀变和蚀变分带特征,运用显微镜、电子探针等研究蚀变矿物,对花岗闪长斑岩体进行锆石LA-ICP-MS U-Pb定年、Lu-Hf同位素和地球化学分析,根据流体包裹体岩相学、显微测温、群包裹体成分和C、H、O、S同位素分析等研究,揭示成矿流体来源、性质、演化以及成矿物质的来源,进而探讨矿床成因。矿床早期的蚀变有钠硅酸盐化、钾硅酸盐化、青磐岩化,晚期的蚀变为长石分解蚀变。在空间分布上,钠硅酸盐化位于岩体内部,钾硅酸盐化位于岩体和周围围岩中,青磐岩化位于钾硅酸岩化外侧,长石分解蚀变叠加在早期钾硅酸盐化蚀变,位于钾硅酸盐化与青磐岩化之间;铜矿化应开始于钾硅酸盐阶段的晚期,石英硫化物阶段是最主要的矿化阶段,石英碳酸盐阶段次之,另外碳酸盐阶段也贡献了部分铜。通过锆石U-Pb测年,得到铜矿峪矿床斑岩的的上交点年龄,分别为2159±19Ma和2148±39Ma。而变花岗斑岩中辉钼矿的Re-Os模式年龄为2129Ma,表明成岩成矿在时代上具有一致性。εHf(t)值大部分为负值,还有少量的正值,二阶段模式年龄落于2706~3007Ma之间。表明铜矿峪铜矿斑岩体的岩浆源区的初始物质主要来源于壳幔同熔的产物。成矿流体系统由早期的中高温、高氧逸度、富CO2的岩浆热液,经过中阶段的流体沸腾、温度降低、氧逸度降低、CO2逸失等过程演化为还原性流体,导致大量金属硫化物的沉淀,然后经过大气降水的不断加入、温度降低等过程,形成晚期的低温、中低氧逸度、低盐度、贫CO2的大气降水热液。氢氧同位素特征显示,在成矿的早期阶段,成矿流体主要为原生岩浆水,随着成矿阶段过程的进行,大气降水混入的比例则越来越多。碳氧同位素特征显示成矿流体与花岗斑岩的关系比较密切,并受到后期的蚀变和混染作用影响,具有多源性的特征。硫同位素特征则显示成矿物质具有深源的特征。
[Abstract]:The copper ore deposit, located in the copper polymetallic metallogenic belt in the middle mountain, is one of the oldest porphyry copper (molybdenum) deposits in China. In this paper, a detailed field geological survey has been made to find out the alteration of the surrounding rock and the characteristics of alteration zoning. Using microscopes, electron probe and other altered minerals, the zircon LA-ICP-MS U- of the granodiorite rock mass was carried out. Pb dating, Lu-Hf isotopes and geochemical analysis, according to the study of fluid inclusion petrography, microthermometry, composition of group inclusions and C, H, O, S isotopes, reveals the origin, properties, evolution and origin of ore-forming fluids, and then discusses the genesis of ore deposits. The early alteration of the ore deposits was sodium silicate, potassium silicate and green rock. In space distribution, the sodium silicate salinization is located inside the rock mass, and the potassium silicate is located in the rock mass and surrounding rock. The rock rock is located in the lateral of the potassium silicate rock, and the decomposition alteration of the feldspar is superimposed on the early potash silicate alteration, which lies between the potassium silicates and the rock rock. In the late stage of the potassium silicate phase, the phase of the quartz sulfide is the most important phase, the quartz carbonate stage is the second stage and the carbonate phase contributes to some copper. Through the zircon U-Pb dating, the upper intersection age of the porphyry of the copper mine valley is obtained, which are 2159 + 19Ma and 2148 + 39Ma. respectively, and the Re-Os model of the molybdenite in the granite porphyry. The age is 2129Ma, indicating that the diagenesis and mineralization are consistent in the age. Most of the value of epsilon Hf (T) is negative, there is a small amount of positive value, and the two stage pattern age falls between 2706~3007Ma. Oxygen fugacity, the CO2 rich magmatic hydrothermal fluid, through the boiling of fluid in the middle stage, the decrease of temperature, the decrease of oxygen fugacity, the evolution of the CO2 fugacity, and the precipitation of a large number of metallic sulphides, and then the continuous addition of atmospheric precipitation and the reduction of temperature, form a late low temperature, medium and low oxygen fugacity, low salinity, and the poor CO2 atmosphere. The characteristics of hydrogen and oxygen isotopes show that in the early stage of the mineralization, the ore-forming fluid was mainly primary rock water. With the progress of the metallogenic stage, the proportion of atmospheric precipitation was more and more. The carbon and oxygen isotope characteristics showed that the relationship between the ore-forming fluid and the granite porphyry was closer, and was influenced by later alteration and contamination. The characteristics of sulfur isotope indicate that the ore-forming material has the characteristics of deep source.

【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.41

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