作　　者： ; ; ; ;

机构地区： 中国地质大学北京地球科学与资源学院

出　　处： 《矿床地质》 2011年第2期266-278,共13页

摘　　要： 文章对邦铺钼(铜)矿区产出的中新世二长花岗斑岩〔(16.23±0.19)Ma〕及古新世黑云二长花岗岩〔(62.1±1.9)Ma〕的锆石进行了微量元素和Hf同位素组成的研究。锆石Hf原位分析表明,邦铺钼(铜)矿区含矿二长花岗斑岩、成矿前黑云二长花岗岩的176Hf/177Hf比值分别为0.282818～0.282904和0.282748～0.282969,εHf(t)平均值分别为+3.0和+3.1,地壳Hf模式年龄平均值分别为878Ma和816Ma。表明岩浆源区主要来源于年轻地幔的组分,但在岩浆演化中遭受了古老地壳物质的混染。通过理论计算,获得二长花岗斑岩、黑云二长花岗岩锆石Ce4+/Ce3+比值分别为557.53和239.5,说明含矿岩体的氧逸度大于不含矿岩体的氧逸度。通过区域对比研究,从拉萨到工布江达,从雅鲁藏布江至念青唐古拉,冈底斯成矿带岩浆源区可能混染了越来越多的古老地壳物质,岩浆氧逸度逐渐增大。 This paper reports trace element compositions and Hf isotope compositions of zircons from Miocene monzogranite porphyry（16.23±0.19 Ma）and Paleocene biotite monzonitic granite（62.1±1.9 Ma）in the Bangpu Mo（Cu）deposit,Tibet.LA-MC-ICP-MS in-situ Lu-Hf isotope analysis of zircon grains from the ore-bearing monzogranite porphyry and the pre-mineralization biotite monzonitic granite gave 176Hf/177Hf ratios ranging from 0.282 818 to 0.282 904 and from 0.282 748 to 0.282 969,the average εHf（t）of 3.0 and 3.1 and the average TDM2 of 878 and 816 Ma,respectively,suggesting that their parental magmas were mainly derived from a young mantle and partly mixed with old continental crust rock during the evolution.The Ce4＋/Ce3＋ ratios of the same zircons were 557.53 and 239.5,indicating that ore-bearing rocks were in higher oxygen fugacity than barren ones.From Lhasa to Gongbo＇gyamds and from Yarlung Zangbo suture to Nyainqentanqlha,the magmas in Gangdese metallogenic belt were increasingly contaminated by old crust material,accompanied by the increase of their oxygen fugacity.

关 键 词： 地球化学 同位素 比值 二长花岗斑岩 黑云二长花岗岩 邦铺钼 铜 矿 冈底斯 西藏

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]