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  

The First Discovery of the Low Sulfidation Epithermal Deposit in Linzizong Volcanics, Tibet: A Case Study of the Sinongduo Ag Polymetallic Deposit

作　　者：唐菊兴[1] 丁帅[2] 孟展[2] 胡古月[1] 高一鸣[1] 谢富伟 李壮[2] 袁梅[2] 杨宗耀[2] 陈国荣 李于海 杨洪钰 付燕刚 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037 [2]成都理工大学地球科学学院,四川成都610059 [3]西藏中瑞矿业发展有限责任公司,西藏拉萨850000 [4]中国地质大学(北京),北京100083

出　　处：《地球学报》2016年第4期461-470,共10页Acta Geoscientica Sinica

基　　金：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)联合资助~~

摘　　要：西藏冈底斯成矿带分布着大面积古近纪（70—40Ma）林子宗群火山岩。但如此强烈的火山-岩浆作用，与安第斯成矿带相比（如马力昆带（FranjadeMaricunga）、印地-帕斯瓜带（Franja El Indio—Pascua）），除了碰撞伸展阶段形成的驱龙、甲玛等斑岩-矽卡岩型铜多金属矿床外（23—13Ma），“缺位”资源规模大、经济价值高的浅成低温热液型矿床成矿亚系列。该类矿床是剥蚀了，还是没有发现？本文在前人工作基础上，通过详细的地质勘探、地质填图、地质编录、镜下鉴定、能谱和电子探针分析，在南木林盆地斯弄多地区林子宗群陆相火山岩中识别出低硫化浅成低温热液型银铅锌（铟镉金）矿床。矿体由产于流纹斑岩中的隐爆角砾岩型银铅锌矿体、火山机构旁侧的热液脉型银铅锌矿体及断裂上盘的银（铅锌）矿体组成，目前控制Pb＋Zn资源量超过30万吨（331＋332为主）@Pb＋Zn〉5％，Ag资源量超过400吨@Ag〉50g／t。主要金属矿物为方铅矿、闪锌矿、辉银矿、硫砷铜银矿、黄铁矿，微量黄铜矿，主要蚀变组合为：石英一玉髓一碧玉，重晶石．萤石，冰长石．伊利石．绢云母，菱铁矿一菱锰矿；矿石构造以脉状、角砾状、网脉状、条带状、层纹状、皮壳状、块状、浸染状等，发育结晶作用和交代作用形成的矿石结构；近地表发育古热泉喷口，堆积条带状、层纹状硅质沉积物。综合上述地质信息，确定该矿床为典型低硫化浅成低温热液型银多金属矿床。这一重要矿床类型的发现和确定在冈底斯成矿带乃至西藏特提斯成矿省尚属首例，对冈底斯成矿带广泛发育形成于70～40Ma的林子宗群火山岩地区区域找矿具有积极和重要的指导意义，其重要性不容低估。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

关 键 词：斯弄多 林子宗群火山岩 冰长石-绢云母-伊利石 低硫化型 浅成低温热液银多金属 冈底斯 

分 类 号：P317.3[天文地球—固体地球物理学] P618.4[天文地球—地球物理学]