西藏多龙斑岩-浅成低温热液型铜(金)矿集区地质特征及找矿潜力分析

    Geological characteristics and prospecting potential analysis of Duolong porphyry-epithermal copper (gold) ore district in Tibet

    • 摘要: 本文在总结多龙矿集区地质特征的基础上,开展了矿山深边部的潜力分析,以期为下一步的找矿预测提供勘查思路。多龙斑岩-浅成低温热液型铜(金)矿集区位于西藏班公湖-怒江成矿带的北西侧,主要由铁格隆南超大型斑岩-浅成低温热液型铜(金)矿床,拿若大型斑岩-隐爆角砾岩筒型铜(金)矿床,多不杂、波龙、多不杂西大型斑岩型铜(金)矿床,尕尔勤、地堡那木岗高硫化浅成低温热液型铜(金)矿点组成,共探获铜资源量超过1 500万t,伴生金超250 t,伴生银3 900 t。多龙矿集区形成于早白垩世(120 Ma)班公湖-怒江洋盆北向俯冲的陆缘弧环境,物质源区为壳幔混合源,成矿岩浆岩主要为中酸性的闪长玢岩-花岗闪长斑岩-花岗斑岩系列,具有弧岩浆特征。俯冲板片的折返是多龙矿集区深部岩浆形成和侵位的主要动力学机制,成矿后安山质火山岩(110 Ma)的覆盖对矿床起到重要的保存作用。多不杂矿区F2逆断层将矿体分割成上、下两部分,下部分矿体是找矿的重点方向。铁格隆南矿区深钻揭露了由南向北的逆冲断层,该逆冲断层将矿体错断并推覆到“红层”沉积之上,其下盘是寻找另一半隐伏矿体的方向。尕尔勤矿区大面积发育指示浅成低温热液成矿系统的“硅帽”,明显富集Au、Ag、As、Sb、Bi、Cu等元素,Au、As、Sb、Hg等呈现较好的元素组合异常,具有寻找浅成低温热液型矿床的潜力。地堡那木岗矿区发育高硫化浅成低温热液型蚀变(高岭石化、地开石化、明矾石化等)和矿物组合(铜蓝、蓝辉铜矿、斑铜矿等),且物探、化探、遥感异常套合良好,是未来矿产勘查的重点。区内逆冲断层对矿床的改造作用是未来研究的重点,对进一步的勘查评价具有重要的指导意义。

       

      Abstract: On the basis of summarizing the geological characteristics of the Duolong ore district, this paper conducts a potential analysis of the depth and margin areas of the mine, in order to provide ideas for ore exploration prediction. Duolong porphyry-epithermal copper (gold) ore district is located in the northwest of the Bangongco-Nujiang Metallogenic Belt in Tibet. It is mainly composed of Tiegelongnan giant porphyry-epithermal copper (gold) deposit; Naruo large porphyry-cryptoexplosive breccia copper (gold) deposit; Duobuza, Bolong, and Duobuzaxi large porphyry copper (gold) deposits, and Gaerqin, Dibaonamugang high sulfidation-epithermal copper (gold) ore occurrences. A total of over 15 million tons of copper have been discovered in the Duolong ore district, with over 250 tons of associated gold and 3 900 tons of associated silver. Duolong ore district was formed in a continental margin arc environment of the northward subducting of Bangongco-Nujiang Ocean Basin in the early Cretaceous (120 Ma). The material source is a mixed of crust and mantle, and the ore-forming magmatic rocks are mainly the moderately acidic diorite porphyry-granodiorite porphyry-granite porphyry series, with arc magmatic characteristics. The rollback of subducting plates is the main dynamic mechanism for the formation and emplacement of deep magma in the Duolong ore district. The coverage of andesitic volcanic rocks (110 Ma) after mineralization plays an important role in the preservation of the deposit. The F2 reverse fault in Duobuza ore area divides the ore body into upper and lower parts, and the lower part of the ore body is the key direction for prospecting. The deep drilling in the Tiegelongnan ore area exposes a reverse fault, the ore body on the hanging wall overlies the “red layer”, the foot wall is the direction for the missing half of ore body. The extensive development of “lithocaps” indicating epithermal mineralization system, the enrichment of elements such as Au, Ag, As, Sb, Bi, Cu, etc. and the good combined anomalies of Au, As, Sb, Hg, etc. in the Gaerqin ore area show the potential for epithermal deposits. The development of high sulfidation epithermal alteration (kaolinite, dickite, alunite, etc.) and mineral assemblages (covlite, digenite, bornite, etc.) in Dibaonamugang ore area and well intergrated geophysical, geochemical, and remote sensing anomalies make it a focus of future mineral exploration. The transformation effect of thrust faults on deposits in the area is a key focus of future research and has important guiding significance for further exploration and evaluation.

       

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