| 西藏林子宗群火山岩中首次发现低硫化型浅成低温热液型矿床——以斯弄多银多金属矿为例 |
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| 关键词:Sinongduo Linzizong group volcanic rock valencianite-illite-sericite low sulfidation epithermal Ag polymetallic deposit Gangdise |
| 基金项目:中国地质调查局地质调查项目“西藏雄村-普桑果斑岩-矽卡岩型铜多金属矿成矿地质背景与找矿潜力调查”(编号: 12120114068401)；西藏中瑞矿业发展有限责任公司项目(编号: XZZR-2015) |
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| The First Discovery of the Low Sulfidation Epithermal Deposit in Linzizong Volcanics, Tibet: A Case Study of the Sinongduo Ag Polymetallic Deposit |
| Since the Paleogene (70–40 Ma), volcanic rocks of Linzizong Group have been distributed in a large area in Gangdise metallogenic belt, Tibet; nevertheless, there is an “absence” of mass resource and high economic value epithermal deposit except for the Qulong and Jiama porphyry-skarn copper polymetallic deposit (23–13 Ma) formed in the collision-stretch phase, in contrast with the Andean metallogenic belt (such as La Franja de Maricunga, Franja El Indio-Pascua) formed under the condition of extensive volcanic -magmatism. Are these deposits denudated or even not found yet? The authors have recognized a type of low sulfidation epithermal lead-zinc (In-Cd-Au) deposit in Linzizong continental volcanic rock group in Sinongduo of Namling basin, based on the detailed exploration, geological mapping, geological logging, microscopic examination, energy spectrometer analysis, electron microprobe analysis (EPMA) and the result of previous researchers. The orebodies consist of cryptoexplosion breccia type Ag-Pb-Zn orebody hosted in liparophyre, hydrothermal vein type Ag-Pb-Zn orebody beside volcanic edifice, and Ag (Pb-Zn) orebody on the hanging side of the fault. The amount of the controlled resource of Pb+Zn is over 0.3 million tons (331+332)@Pb+zinc>5%, and resource amount of Ag@Ag>50g/t is more than 400 tons. The major metallic minerals are galena, sphalerite, and argentite, pearceite, and pyrite together with rare chalcopyrite. Quartz-chalcedonite-jasper, siderite-rhodochrosite, barite-fluorite, and valencianite-illite-sericite are main associations of alteration. The main structures include veined sturcture, brecciated, mesh-veined, banded and laminated, crustified, massive and disseminated structures, the ore textures of this deposit are developed on the basis of crystallization and metasomatism. The authors found a vent of ancient hot spring near the surface, around which there are some banded and laminated siliceous sediments. These geological findings led the authors to believe that this is a typical low-sulfidation epithermal Ag polymetallic deposit. This is for the first time a deposit of this significant type was found and verified in Gangdise belt and even in Tethys metallogenic province. The essentiality for guiding exploration in the area where Linzizong Group volcanic rock was developed in 70–40 Ma in Gangdise belt would be very obvious. |
| TANG Ju-xing,DING Shuai,MENG Zhan,HU Gu-yue,GAO Yi-ming,XIE Fu-wei,LI Zhuang,YUAN Mei,YANG Zong-yao,CHEN Guo-rong,LI Yu-hai,YANG Hong-yu,FU Yan-gang.2016.The First Discovery of the Low Sulfidation Epithermal Deposit in Linzizong Volcanics, Tibet: A Case Study of the Sinongduo Ag Polymetallic Deposit[J].Acta Geoscientica Sinica,37(4):461-470. |
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