本文選題：大渡河金成礦帶 + 黃鐵礦　； 參考：《成都理工大學》2017年碩士論文

【摘要】：大渡河金成礦帶位于康滇地軸南北向構造帶北端,鮮水河、龍門山與攀西裂谷所構成的三叉裂谷交匯形成的特殊構造部位。近年來的地質勘探工作表明,該研究區(qū)具有“三層樓”的構造格局,與之相對應的礦床也有“三層樓”格局的分布特點,分別為基底中金礦床、蓋層中金礦床、界面中金礦床。不同層位的金礦床的載金礦物主要為黃鐵礦,這說明黃鐵礦對大渡河流域金礦床的成因有重要的指示意義。本文對大渡河金成礦帶不同賦礦層位金礦床中黃鐵礦的標型特征進行研究,通過野外地質考察、室內測試分析,并結合前人研究成果,得出以下認識:大渡河金成礦帶不同賦礦層位金礦床中的礦物成分組合基本類似,金屬礦物主要為黃鐵礦,其次有方鉛礦、黃銅礦等,主要載金礦物為黃鐵礦,脈石礦物為石英。蓋層中金礦床的圍巖主要為碳酸鹽巖,基底中金礦床的圍巖主要為花崗巖。蓋層中金礦床的黃鐵礦晶形主要為立方體,少見五角十二面體;界面中金礦床的黃鐵礦以聚形為主,少量立方體單形;基底中金礦床黃鐵礦晶形主要為五角十二面體、立方體。這說明三者的成礦溫度有區(qū)別,五角十二面體單晶在基底中出現最多,說明基底的成礦溫度最高,適宜五角十二面體形成;蓋層成礦溫度較低,適合立方體的形成。不同賦礦層位金礦床黃鐵礦的熱電性有著明顯的差別。蓋層中金礦床黃鐵礦導電類型為P型,基底中金礦床黃鐵礦導電類型為N型,界面中金礦床以N型為主,夾雜少量P型。導電類型可指示溫度,基底中黃鐵礦形成溫度最高,蓋層中黃鐵礦形成溫度最低,界面中黃鐵礦形成溫度介于兩者之間。但三者均符合中—低溫熱液礦床的形成溫度,三類金礦床應該都屬于中—低溫熱液礦床。不同賦礦層位的黃鐵礦微量元素均以U富集為主,說明三者具有相同的物質來源,即深部熱液,基底中的U富集程度最高,受到巖漿源區(qū)(深源)流體活動影響程度更高。蓋層中的Sr虧損程度更高,受到了地殼的混染作用。黃鐵礦的稀土元素特征表明,基底中黃鐵礦稀土元素總量ΣREE=8.60×10~(-6),與上地幔稀土元素總量ΣREE=7.30×10~(-6)相當;蓋層中黃鐵礦稀土元素總量ΣREE=25.29×10~(-6),與上地殼稀土元素總量類似,說明了蓋層中的成礦物質可能有地殼物質的參與。不同賦礦層位黃鐵礦均表現為Eu異常、Ce無異常,說明大渡河金成礦帶成礦流體為還原性流體。蓋層、基底、界面中黃鐵礦均呈現輕稀土相對富集的右傾型,說明三者具有相同的物質來源即深部幔源。
[Abstract]:The Daduhe gold metallogenic belt is located at the northern end of the north-south structural belt of the Kangdian axis and the special structural position formed by the intersection of the Trident rift of Xianshuihe, Longmenshan and Panxi rift. The geological exploration work in recent years shows that the study area has the structure pattern of "three stories" and the corresponding deposit has the distribution characteristic of "three stories" pattern, namely, the gold deposit in the basement, the gold deposit in the caprock and the gold deposit in the interface. Pyrite is the main gold bearing material of gold deposits in different horizons, which indicates that pyrite is of great significance to the genesis of gold deposits in the Dadu River Basin. In this paper, the typomorphic characteristics of pyrite in gold deposits of different ore-bearing strata in the Daduhe gold metallogenic belt are studied. Through field geological investigation, laboratory test and analysis, and combined with previous research results, The conclusions are as follows: the mineral composition of the gold deposits in different ore-bearing strata of the Daduhe gold metallogenic belt is basically similar, the main metal minerals are pyrite, the next are galena, chalcopyrite and so on, and the main gold bearing minerals are pyrite. The gangue mineral is quartz. The rock mass of gold deposit in caprock is mainly carbonate rock, and that of gold deposit in basement is granite. The pyrite crystal shape of the gold deposit in caprock is mainly cubic and rarely pentagonal dodecahedron; the pyrite in the interfacial gold deposit is mainly polymorphic and a few cubic simplex; the pyrite crystal shape of the gold deposit in the basement is mainly pentagonal dodecahedron and cube. This shows that the metallogenic temperature of the three is different. The pentagonal dodecahedron crystal appears most in the substrate, indicating that the metallogenic temperature of the substrate is the highest and suitable for pentagonal dodecahedron formation, while the caprock metallogenic temperature is relatively low, which is suitable for the formation of cubes. There are obvious differences in the thermoelectric properties of pyrite in different ore-hosting gold deposits. The conductivity type of pyrite in caprock gold deposit is P type, pyrite in basement gold deposit is N type, N type is dominant in interface gold deposit, and a small amount of P type is involved. The temperature of pyrite formation is the highest in the basement and the lowest in the caprock. The temperature of pyrite formation at the interface is between the two. But they all accord with the formation temperature of the intermediate-low temperature hydrothermal deposit, and the three kinds of gold deposits should all belong to the intermediate-low temperature hydrothermal deposit. The main trace elements of pyrite in different ore-bearing strata are U enrichment, which indicates that the three have the same material source, that is, deep hydrothermal solution, the highest degree of U enrichment in the basement and the higher degree of influence by the fluid activity in the magmatic source area (deep source). The Sr depletion in the caprock is higher and is affected by the crustal mixing. The characteristics of rare earth elements in pyrite indicate that the total amount of rare earth elements 危 REE=8.60 脳 10 ~ (10) ~ (6) in the basement is equivalent to that in the upper mantle (危 REE=7.30 脳 10 ~ (10) ~ (-6), and the total amount of rare earth element 危 REE=25.29 脳 10 ~ (10) ~ (-6) in the cap is similar to the total amount of rare earth elements in the upper crust. It is suggested that the ore-forming material in the caprock may involve the crustal material. Pyrite in different ore-bearing strata is characterized by EU anomaly and ce anomaly, indicating that the ore-forming fluid in the Daduhe gold metallogenic belt is a reductive fluid. Pyrite in the caprock, basement and interface all show a right-dip type of relative enrichment of LREE, indicating that the three have the same material source, that is, the deep mantle source.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P618.51

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