金属矿床Re-Os同位素示踪与定年研究  

RE-OS ISOTOPE TRACER AND DATING METHODS IN ORE DEPOSITS RESEARCH

作　　者：蒋少涌[1] 杨竞红[1] 赵葵东[1] 于际民[1] 

机构地区：[1]南京大学地球科学系成矿作用国家重点实验室,江苏南京210093

出　　处：《南京大学学报（自然科学版）》2000年第6期669-677,共9页Journal of Nanjing University（Natural Science）

基　　金：国家杰出青年科学基金(49925306);国家重点基础研究项目(GI999043208)

摘　　要：Re Os同位素是近年来发展起来的一门新兴的同位素地球化学方法 ,它在金属矿床上的应用主要有示踪和定年两个方面 .原始地幔贫放射成因同位素 ,具有较低的187Os/ 188Os比值和γOs(t) 值 .相对而言 ,地壳岩石的187Os/ 188Os比值和γOs(t) 值均较高 .由于壳、幔岩石具有不同的187Os/ 188Os比值和γOs(t) 值 ,利用硫化物矿石的Re Os同位素组成可以揭示岩浆成因Cu Ni硫化物矿床、金矿床、斑岩铜矿以及现代大洋底块状硫化物矿床的成矿物质来源 .根据硫化物矿石和赋矿超基性岩石的Os同位素组成 ,可以估测不同来源物质在各矿床中所占的份额 .利用Re Os同位素还可以对金属硫化物进行直接定年 ,不仅能对十分古老的 ,而且能对十分年轻的金属矿床进行精确的成矿年龄测定 .Re Os isotope method is a recently developed innovative geochemical technique, which has already been used in the study of metallic ore deposits as a sensitive tracer and a dating method. The 187 Os/ 188 Os and γ Os(t) values are low in the primitive mantle due to low contents of radiogenic isotopes, whereas the crust rocks have higher 187 Os/ 188 Os and γ Os(t) values. Because of the distinct isotopic composition differences in the mantle and crust, the Re Os isotopic compositions of sulfide ores have been used to trace the origins of ore forming materials in magmatic Cu Ni sulfide deposits, gold deposits, porphyry copper deposits and modern sea floor massive sulfide deposits. It is possible to estimate the proportions of different sources in terms of Os isotopic compositions of sulfide ores and their host rocks. Re Os isotope system has also been used in direct dating of metallic sulfide ores, not only for very old, but also for very young metallic ore deposits.

关 键 词：RE-OS同位素 成矿物质来源 成矿年龄 

分 类 号：P597.1[天文地球—地球化学] P618.2[天文地球—地质学]