| 西藏斑岩-矽卡岩-浅成低温热液铜多金属矿成矿作用、勘查方向与资源潜力 |
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| 关键词:porphyry-epithermal type porphyry-skarn type Gangdise metallogenic belt Bangong Co–Nujiang metallogenic belt metallogenic potential continental volcanic rock Tibet |
| 基金项目:国土资源部公益性行业科研专项(编号: 201511017)；中国地质调查局二级项目(编号: DD20160026) |
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| Mineralization, Exploration and Resource Potential of Porphyry-skarn-epithermal Copper Polymetallic Deposits in Tibet |
| Main metallogenic belts in Tibet have become the important part of the Eastern Tethyan metallogenic domain. Since 1999, with the full implementation of the geological survey by China Geological Survey and the deepening of the basic research on national public welfare and the timely follow-up of commercial exploration, the real breakthrough in prospecting has been realized. Based on the review of the previous data and research results in combination of the recent progress in research by the authors’ research group, this paper summarizes the geological characteristics and metallogenic regularity of the main deposits in the metallogenic belts, Tibet, arranges some major problems affecting the exploration and evaluation as well as prospecting breakthrough, builds an exploration model of the main ore district, and puts forward the further prospecting direction and resource potential. Four main metallogenic belts in Tibet are distinctive. The Eastern Tethyan metallogenic domain concentrates a variety of deposit types from Neo-Tethys subduction to collision, with the complicated ore-controlling factors. The main ore deposits are porphyry-skarn-epithermal copper polymetallic deposits and magmatic hydrothermal vein deposits, and their metallogenic ages are from 170 to 12 Ma. Tibet has become the most important resource reserve base in China with large span of metallogenic ages, various types of deposits, complex metallogenic elements and good ore quality. In the Yulong metallogenic belt of east Tibet, besides porphyry copper (molybdenum) deposits, skarn deposits in the external contact zone of porphyry, such as Yulong No. II and No. V orebodies and Angqing silver-lead-zinc (copper) orebody, also have important industrial values. The diagenetic and metallogenic epoch is 40~38 Ma, and the ore-forming rock and orebody are controlled by the anticline of the NW-striking slip structure. The identification of the existence of low sulfidation epithermal deposits in the Dianzhong Formation of Linzizong Group in the Gangdise metallogenic belt shows the important significance of exploration of the porphyry-epithermal copper polymetallic (silver, gold, lead and zinc) deposits in the distribution area of Linzizong Group in the West of Xietongmen-Angren County. Research results of mineral deposits can be one of the pointers for the determination of the tectonic setting. The collision event of Indian and the Asian continents occurred at 52~50 Ma. At least the Dianzhong volcanic rock is the product of the continental margin arc, and the typical epithermal deposits, even porphyry-epithermal deposits, were formed. If ore-bearing porphyry contact has carbonate rocks, it is necessary to evaluate the skarn type copper polymetallic orebodies or lead-zinc silver orebodies along the contact zone and in the depth. Granite porphyry and granodiorite porphyry which intruded in 90~13 Ma might form larger skarn deposits, such as Jiama, Zhibula in the Qulong periphery, Bangpu, Dongzhongla-Mengya’a ore concentration area, Nuri, Gaerqiong and Galale deposits with similar characteristics. Orebodies of this type have more industrial values than porphyry copper (molybdenum) orebodies. The porphyry-high sulfidation epithermal-cryptoexplosive breccia type deposits were formed by the porphyry-epithermal metallogenic system in 120~116 Ma in the Duolong ore concentration area of the Bangong Co-Nujiang metallogenic belt. The continental andesitic volcanic rock-Meiriqiecuo Formation (K1m) (110 Ma) serves as the good post-mineralization cover, which constitutes one of the necessary conditions for the preservation of this kind of deposits. Strong alterations in the andesitic, dacitic and rhyolitic volcanic rocks of Zenong Group, Anni Formation, Qushenla Formation, Meiriqiecuo Formation (140~110 Ma) on both sides of the Bangong Co-Nujiang junction zone and the rich volcanic apparatuses are the products of the Neo-Tethys subduction. The metallogenic geological background is similar to that of the Andean metallogenic belt in South America, showing good metallogenic potential. Tibet has initially identified copper resources of >60 million tons, molybdenum resources of >3 million tons, a total of associated gold > 1 000 tons, associated silver of > 25 000 tons, and lead and zinc resources of >10 million tons. Tibet has become China's most important nonferrous metal reserve base, and this study concludes that the copper resource potential in Tibet will exceed 150 million tons. |
| TANG Ju-xing,WANG Qin,YANG Huan-huan,GAO Xin,ZHANG Ze-bin,ZOU Bing.2017.Mineralization, Exploration and Resource Potential of Porphyry-skarn-epithermal Copper Polymetallic Deposits in Tibet[J].Acta Geoscientica Sinica,38(5):571-613. |
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