西藏班公湖—怒江成矿带南侧矽卡岩型铜多金属矿床S、Pb同位素组成及成矿物质来源

班公湖—怒江成矿带南侧分布着多个与班公湖—怒江洋南向俯冲、碰撞、后碰撞伸展各阶段有关的矽卡岩型铜多金属矿床，目前对单个矿床的研究较多，而对形成于不同环境下的矿床之间的对比研究较少。本文通过对该成矿带南侧典型矽卡岩型铜多金属矿床的S、Pb同位素特征进行较为系统的总结，并结合前人对辉钼矿Re同位素、成矿岩体地球化学特征、成岩成矿时代及区域构造演化等研究的成果，对不同构造背景下所形成的4个矿床的成矿物质来源进行对比研究。研究表明：舍索矿床的S同位素具有明显的双峰式分布，为壳幔混合来源，而区内典型矿床的S同位素显示从班公湖—怒江洋南向俯冲（舍索）→碰撞（嘎拉勒、尕尔穷）→后碰撞（班戈日阿）逐渐富集重硫的特征；Pb同位素显示舍索较其他矿床更富集放射成因Pb，舍索、班戈日阿矿床成矿物质主要来源于念青唐古拉群结晶基底，而同碰撞期形成的嘎拉勒、尕尔穷矿床则显示了明显的壳幔混合来源的特征，念青唐古拉群结晶基底对尕尔穷矿床的成矿物质有少量贡献。此外，斑岩-矽卡岩复合型矿床的成矿物质来源具有壳幔混源的特征，而单一的矽卡岩型矿床以上地壳来源为主。

Sulfur and Lead Isotopic Composition and Their Ore-Forming Material Source of Skarn Copper Polymetallic Deposits in Southern Tibet Bangonghu-Nujiang Metallogenic Belt

Numerous skarn Cu polymetallic deposits are discovered in the southern Bangonghu-Nujiang suture zone (BNSZ),which are related to the Bangonghu-Nujiang Middle Tethys Ocean southward subduction,collision,and post-collision.There are a lot of researches on a single deposit,but not on the contrast between two deposits.The authors systematically summarized the characteristics of S and Pb isotope of these deposits in combination with the previous researches on the Re isotope,the geochemical characteristics of metallogenic rock body,rock-forming and ore-forming age,and regional tectonic evolution,and took the contrasts between deposits into the study on the ore-forming materials of these deposits formed under different tectonic backgrounds.The results show that the δ34S values of Shesuo deposit present a notable bimodel distribution,which can be explained by the mixing of stratum and mantle.In summary,the 34S values were gradually enriched from the oceanic crust subduction stage (Shesuo),through the plate collision stage (Galale and Gaerqiong),to the post-collisional stage (Bangeria).The composition of Pb isotope indicates that the Shesuo deposit is enriched in radiogenic lead than the other deposits,and the ore forming material of Shesuo and Bangeria deposits were mainly sourced from the Nyainqentanglha group crystalline basement,while Galale and Gaerqiong deposits were from a mixture of crust-mantle materials,and the basement has a small contribution to the Gaerqiong deposit.In addition,the ore forming material of porphyry-skarn deposits has the characteristics of the mixture of crust-mantle materials,while the material of a skarn deposit mainly came from the upper crust.