郯庐断裂带南段沙溪含铜斑岩体的^(40)Ar/^(39)Ar年代学研究及意义  

^(40)Ar/^(39)Ar DATING AND GEOLOGICAL SIGNIFICANCE ON THE Cu-BEARING PORPYRITE OF SHAXI FROM SOUTHERN TAN-LU FAULT BELT

作　　者：杨晓勇[1] 

机构地区：[1]中国科学院壳幔物质与环境重点实验室中国科学技术大学地球和空间科学学院,安徽合肥230026

出　　处：《矿物岩石》2006年第2期52-56,共5页Mineralogy and Petrology

基　　金：国家自然科学基金项目(40473021);科技部973项目(2003CB214606)

摘　　要：对郯庐断裂南段沙溪含铜斑岩体中黑云母和斜长石单矿物的高精度40A r/39A r同位素测定,获得40A r/39A r平均坪年龄为132.62 M a±0.28 M a,40A r/39A r等时线平均年龄为132.59 M a±0.46 M a,而最小平均视年龄86 M a左右可能表示后期的一次热事件,可能对应于斑岩体与Cu-A u矿化有关的热液活动。这些年龄值比前人在该区及邻区获得的K-A r和R b-S r年龄更精确地代表沙溪含铜斑岩体的侵入时代。132.6M a左右的年龄代表着该区含铜(金)斑岩体的侵入时代,可以证实铜(金)斑岩型矿床是在稍后的大规模热液蚀变条件下所形成。The Shaxi porphyrites are composed of diorite-quartz diorite series,forming a medium scale copper deposit near south Tancheng-Lujiang （Tan-Lu） fault belt,central Anhui,east China. Shaxi porphyry Cu-Au deposit occurs in a complex intrusive body composed of quartz diorite porphyry,biotite-quartz diorite porphyry and fine to medium-grained porphyry diorite along the lower part of Yangtze metallogenic belt. Each biotite and plagioclase samples were analyzed for age determination by the ^40Ar/^39Ar method. The sample yield reproducible ages with a high level of confidence of both average plateau and average isoehron ages of 132, 62 Ma±0.28 Ma and 132.59 Ma±0.46 Ma respectively,which is more precise than K-Ar and Rb-Sr dating ages made previously and better constrains the times of the main event of porphyry formation of Yanshanian period of igneous intrusive in the Shaxi Cu-Au porphyry deposit. The average minimum apparent age of 86 Ma may represent the thermal event related to Cu Au mineralizaton in this region. It is believed that the age of around 132.6 Ma can represent the intrusive time in Shaxi region,and the Cu-Au mineralization should occur later by strong thermal event of magmatism.

关 键 词：斑岩体 铜(金)斑岩型矿化 ^40AR/^39AR年代学 沙溪 郯庐断裂南段 

分 类 号：P597.3[天文地球—地球化学]