投稿时间：2018-10-08
修订日期：2019-06-01
网络发布日期：2019-11-04
中文摘要:在野外地质调查基础上，通过详细的岩相学和矿物学观察，以及矿床对比研究等手段，初步探讨了罗布真金银多金属矿床成因类型和地质意义。罗布真金银多金属矿床位于冈底斯陆缘火山-岩浆弧西段，矿体受NWW向断裂构造控制，呈似层状、脉状、透镜体状产于帕那组火山岩中，或产于火山岩与始新世闪长岩的接触部位。金银矿体由石英脉、蚀变岩和角砾岩组成。矿石具有角砾状、条带状和网脉状等热液型矿床典型构造。金属矿物主要有自然金、碲银矿、黄铁矿、方铅矿、毒砂和闪锌矿等，非金属矿物有石英、玉髓、绿泥石、方解石等。围岩蚀变属于中、低温环境下的一套蚀变矿物组合，有绢云母化、硅化、碳酸盐化、绿泥石化等；围岩蚀变具有从矿脉中心到围岩有绢英岩化到青磐岩化过渡分带，垂向上也有顶部伊利石、硅华、玉髓层，深部绿泥石、绢云母、微细粒石英-玉髓脉的分带。成矿流体显示出低温、低盐度的特点，主要来自于大气降水；而金、银等成矿物质主要来源于围岩。通过矿床对比研究，初步确定罗布真金银多金属矿床属于低硫化型浅成低温热液型矿床，该成因类型矿床在冈底斯成矿带西段尚属首次发现。
Abstract:This paper gives a detailed discussion on the genetic type of the Luobuzhen Au-Ag polymetallic deposit and its significance on the basis of regional geological setting, field geological survey, thin-section examination, and its comparison with similar deposits. The Luobuzhen Au-Ag polymetallic deposit is located in the western part of the Gangdise continental marginal volcanic-magma arc, Tibet. The orebodies, controlled by NWW-trending faults, are mainly in stratified, veinlet and lenticular forms, consist of quartz veins, altered and breccia rocks, and occur in the volcanic rock of Pana Formation or its contact zone with the Eocene acid-intermediate intrusive rocks. The ore exhibits typical characteristics of the hydrothermal deposit as shown by the brecciated vein as well as banded and net vein structures. The metallic minerals contain native gold, hessite, pyrite, galena, arsenopyrite and sphalerite, and the non-metallic minerals comprise quartz, chalcedony, chlorite and calcite. The wall rock alterations include sericitization, silication, carbonatation and chloritization, representing an intermediate-alkaline alteration combination formed in a medium-low temperature environment. The lateral distribution of the wall rock alteration displays phyllic zone, transitional zone and propylitization zone from the vein center to the wall rock, and the vertical zoning shows that illite, silicification and chalcedony occur at the top, whereas chlorite, sericite and micrograined quartz lie at the bottom. Mineralizing fluids characterized by low temperature and low salinity resulted from water-rock exchange reaction between atmospheric precipitation and wall rocks, whereas metallogenic materials such as gold were mainly derived from the host strata. Synthesizing the above geological information, the authors preliminary confirm that the Luobuzhen Au polymetallic deposit belongs to the low sulfide type epithermal deposit, and the genesis of this deposit was discovered for the first time in the western part of Gangdise metallic zone.
keywords:geology low sulfide type epithermal Au-Ag polymetallic deposit Luobuzhen Gangdise metallogenic belt Tibet
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基金项目:本文得到国家重点研发计划（编号：2016YFC0600308；SQ2018YFC060162）、中国地质调查项目（编号：DD20160015）和中国地质调查局成都地质调查中心青藏高原国际大学科计划的联合资助
引用文本：
黄瀚霄,李光明,刘洪,张洪铭,张林奎,余槐,焦彦杰,陈小平,梁维.2019.西藏冈底斯成矿带西段罗布真浅成低温热液型金银多金属矿床地质特征及发现意义[J].矿床地质,38(5):1117~1128HUANG HanXiao,LI GuangMing,LIU Hong,ZHANG HongMing,ZHANG LinKui,YU Huai,JIAO YanJie,CHEN XiaoPing,LIANG Wei.2019.Geological characteristics and significance of Luobuzhen epithermal Au-Ag polymetallic deposit in west of Gangdise metallogenic belt[J].Mineral Deposits38(5):1117~1128
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