铜陵地区老鸦岭层状钼矿床铅同位素组成研究  

Lead Isotope Study of Laoyaling Stratiform Mo Deposit in Tongling Area

作　　者：喻钢[1] 陈江峰[1] 钱卉[1] 陈树榆[2] 杨刚[1] 闫峻[1] 张成火[3] 

机构地区：[1]中国科学技术大学地球和空间科学学院,安徽合肥230026 [2]中国科学技术大学理化中心,安徽合肥230026 [3]安徽省地质矿产局321地质队,安徽铜陵244033

出　　处：《矿床地质》2004年第4期422-430,共9页Mineral Deposits

基　　金：国家重点基础研究发展规划项目"大规模成矿作用与大型矿集区预测(G1999043201)"的资助

摘　　要：安徽铜陵老鸦岭矿床中二叠系大隆组(P2d)顶部的含矿(钼矿化)黑色页岩以及附近(立新煤矿)同一层位不含矿黑色页岩的实测铅同位素组成分别为206Pb/204Pb20.20～22.37,207Pb/204Pb15.67～15.82,208Pb/204Pb38.47～38.60和206Pb/204Pb18.83～20.80,207Pb/204Pb15.65～15.76,208Pb/204Pb38.84～39.22。对137Ma的放射成因Pb进行校正后的铅同位素组成表明,含矿黑色页岩和不含矿黑色页岩均与燕山晚期火成岩无关,老鸦岭含矿黑色页岩可能具沉积成因。对沉积(约250Ma)以来的放射成因Pb进行校正后的铅同位素组成表明不含矿黑色页岩的Pb源自上地壳,而含矿黑色页岩的Pb(因而推测其他成矿金属)可能源于上地壳物质(与不含矿黑色页岩的Pb源相似)与下地壳物质的混合。The Pb isotopic compositions of Mo_bearing black shale of Dalong Formation (P 2 d ) from the Laoyaling deposit in the middle_lower Yangtze valley were determined. 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios vary from 20.20 to 22.37, from 15.67 to 15.82 and from 38.47 to 38.60, respectively. In contrast, the corresponding Pb isotopic ratios of the non_mineralized black shale from the Lixin coal mine near the Laoyaling deposit are in the ranges of 18.83～20.80, 15.65～15.76 and 38.84～39.22 respectively. The Pb isotopic compositions corrected for 137 Ma radiogenic Pb show that Pb isotopic compositions of the Laoyaling mineralized black shale and the Lixin non_mineralized black shale are significantly different from those of the feldspars from Late Yanshanian igneous rocks in the area. Pb isotopic compositions and ore textures suggest that Pb of the black shale from the Laoyaling deposit is not derived from the Yanshanian intrusive rocks, and that the Laoyaling Mo deposit is a typical sedimentary deposit hosted by the black shale. The Pb isotopic compositions corrected for 250 Ma (approximate age of the Dalong Formation) radiogenic Pb show that the Pb source of the non_mineralized black shale is upper crustal material and the Pb of the Mo_bearing black shale of the Laoyaling deposit is very likely a mixture of the Pb from upper crustal material shared by non_mineralized black shale and the Pb from the lower crust.

关 键 词：地球化学 铅同位素 黑色页岩 老鸦岭矿床 铜陵地区 

分 类 号：P597.1[天文地球—地球化学] P611[天文地球—地质学]