地质学报2017，Vol.91Issue(4)：836-848,13.
西藏斯弄多低硫化型浅成低温热液Ag-Pb-Zn矿床:Si-H-O同位素的示踪应用
Low-Sulfidation Epithermal Ag-Pb-Zn Deposit in Sinongduo,Tibet: Tracer Application of Si-H-O Stable Isotope Geochemistry
摘要
Abstract
Volcanic edifice of Linzizong Group in the Nanmulin basin of Lhasa Block host the Sinongduo cryptoexplosive breccias-type and hydrothermal vein-type Ag-Pb-Zn deposit.The deposit consists mainly of sphalerite and galena,with minor amount of chalcopyrite and argentite.Altered minerals are sericite,illite,chalcedony,montmorillonite,jasper,calcite,rhodochrosite and siderite,which are consistent to the basic feature of low-sulfidation epithermal deposit.This study carried out the Si,H and O isotopic analysis of siliceous bands and quartz veins cutting orebodies in vents of terrigenous volcanic rock.The results show that (1) the single mineral quartz in the siliceous bands has δ30 SiNBS-28 of-1.2‰～-0.4‰,which records geochemical features of hydrothermal sedimentary Si isotope,suggesting a sinter genesis of ancient hot spring.(2) Whole rock analysis of hydrothermal sedimentary siliceous bands reformed by late volcanic hydrothermal process has δ30 SiNBS-28 of-0.2‰～+0.3‰,indicating a mixing feature of volcanic rock and hydrothermal sedimentary rock.(3) Quartz veins cutting through orebodies have δ30 SiNBS-28 value of-0.8‰～-0.1‰,which is consistent to that of mineral quartz in hydrothermal sedimentary siliceous bands,showing high Δ30Si feature of low temperature origin.(4)O and H isotopic features of fluid inclusions from quartz veins and siliceous bands suggest O isotopic shifting due to water-rock reaction between meteoric water and volcanic rocks,indicating that ore-forming fluids experienced long-term recycling within volcanic rocks strata.Therefore,Si-H-O stable isotopic values indicate the existence of ancient hot spring in the mining area.This study shows that despite the low degree of denudation in this area,there are still great potential for low-sulfidation epithermal Au-Ag type deposits,with quartz veins of low δ30 SiNBS-28 and silicification being the important indicators for exploring low-sulfidation epithermal Au-Ag type deposits.关键词
林子宗群陆相火山岩/Ag-Pb-Zn矿/Si-H-O同位素/古热泉喷口/低硫化浅成低温热液型Au-Ag矿Key words
volcanic edifices of Linzizong Group/ag-Pb-Zn deposit/ancient hot spring vent/Si-H-O isotope/low sulfidation epithermal Au-Ag type deposit引用本文复制引用
付燕刚,胡古月,唐菊兴,刘秋平,王豪..西藏斯弄多低硫化型浅成低温热液Ag-Pb-Zn矿床:Si-H-O同位素的示踪应用[J].地质学报,2017,91(4):836-848,13.基金项目
本文为中国地质科学院业务基金(项目号:K1603)和中国地质调查局工作项目(DD20160026、12120114068401)资助的成果. （项目号:K1603）
