锡铁山SEDEX型铅锌矿床成矿物质来源综述

Review of the ore-forming matters' sources of the Xitieshan SEDEX type Pb-Zn deposit

锡铁山矿床是我国大型铅锌矿床之一,Zn+Pb金属量超过2000X10(4)t,矿石品位在10%～25%之间.为全面了解矿床成矿流体和成矿金属元素的来源,笔者在野外调研的基础上,系统研究了该矿床不同类型矿体中铅、硫、碳、氧、氩、锶等同位素组成特征.铅同位素组成特征显示矿床中的原始铅主要来源于地壳深部或上地幔,在造山带期受到改造;矿石中方铅矿δ(34)S为0.19‰～3.89‰,反映出含矿热液具深源流体的特征;(87)Sr/(86)Sr集中在0.70875～0.72240之间,表明成矿物质来源应以壳源为主,有部分幔源物质的混入.从而判定锡铁山铅锌矿床成矿物质可能最初来源于晚奥陶世地层,晚泥盆世至晚石炭世(317Ma)受到第一次变质改造;200～279Ma是主要的变质改造成矿期.

The Xitieshan deposit,one of the large scale Pb-Zn deposits in China, has reserved more than 20,000,000 ton Pb and Zn resources with the grade between 10% and 25%.In order to get a complete knowledge of sources of the ore-forming fluid and metallic elements,the author has systemtically researched the isotope composition of Pb,S,C,O,H,Sr etc in orebodies of different types in this deposit based on the field work.Pb isotope composition has shown that the original Pb mainly comes from deep crust or upper mantle with its alteration happening in orogenic belt period;δ34S of the galenite in ores is 0.19‰～3.89‰,and showes that the ore-bearing hydrotherm ownes the charcteristics of deep-source fluid;87Sr/86Sr is concentrating at 0.70875～0.72240,which has infered that the ore-forming matters mainly come from crust with part of them from mantle.It has concluded that the ore-forming matters may primarily come from Late Ordovician strata,and be altered in Late Devonian till Late Carboniferous at first time;most metamorphic alteration happened in 200～279 Ma.