广西大福楼锡多金属矿床铅同位素地球化学

成永生^{1, 2}，胡瑞忠²

(1. 中南大学 地球科学与信息物理学院，有色金属成矿预测教育部重点实验室，湖南 长沙，410083；
2. 中国科学院 地球化学研究所 矿床地球化学国家重点实验室，贵州 贵阳，550002)

摘 要：为了探讨广西南丹大厂矿田大福楼锡多金属矿床的成矿物质来源及其源区特征，对矿石的铅同位素组成特征及其成矿构造环境进行分析与研究。研究结果表明：大福楼锡矿w(²⁰⁶Pb)/w(²⁰⁴Pb)=17.478~18.431，均值为17.991，极差为0.953；w(²⁰⁷Pb)/w(²⁰⁴Pb)=15.440~15.717，均值为15.582，极差为0.277；w(²⁰⁸Pb)/w(²⁰⁴Pb)=37.556~38.839，均值为38.233，极差为1.283；Φ介于0.592~0.638之间，μ为9.26~9.69，w(Th)/w(U)=3.74~3.97。根据Zartman构造模式图，大福楼锡矿床金属硫化物铅同位素数据聚为2个区域，即上地幔与造山带以及造山带与上地壳演化线之间，表明矿石铅既有地幔来源也包含上地壳成分或来自于上地壳，矿床的矿石铅并非全部由花岗岩浆所提供。另外，根据Doe铅同位素构造环境判别图，铅同位素投影点具有集中分布的特点，主要分布于造山带与下地壳演化线之间，即造山带演化线的上方，再次证实上地壳也为成矿提供了部分铅源，即上地壳也是成矿物质的来源之一。大福楼锡多金属矿床成矿作用与造山构造事件有关，矿床主要形成于造山带构造环境中。

关键词：Pb同位素；成矿物质来源；矿床成因；大福楼锡矿；广西

Lead isotope geochemistry of Dafulou tin-polymetallic deposit, Guangxi

CHENG Yong-sheng^{1, 2}, HU Rui-zhong²

(1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry,
Chinese Academy Science, Guiyang 550002, China)

Abstract:In order to discuss the ore-forming material source and its characteristics, lead isotope composition and its tectonic setting were analyzed. The results indicate that the w(²⁰⁶Pb)/w(²⁰⁴Pb) of sulfide ores range from 17.478 to 18.431, with an average of 17.991 and the maximum difference of 0.953, the w(²⁰⁷Pb)/w(²⁰⁴Pb) of sulfide ores range from 15.440 to 15.717, with an average of 15.582 and the maximum difference of 0.277, the w(²⁰⁸Pb)/w(²⁰⁴Pb) of sulfide ores range from 37.556 to 38.839, with an average of 38.233 and the maximum difference of 1.283. The values of Φ, μ and w(Th)/w(U) vary from 0.592 to 0.638, 9.26 to 9.69 and 3.74 to 3.97, respectively. According to Zartman tectonic pattern, the lead isotope values project in two zones, between the upper mantle and orogenic belt and between orogenic belt and upper crust, which suggests that the ore lead is supplied by both the mantle and crust, not all by granitic magma. In addition, on the basis of Doe lead isotope diagram for discriminating tectonic setting, the values of lead isotope are characterized by concentrated distribution, between orogenic belt and upper crust mainly, which indicates that the upper crust is also one of the main lead sources and supplies lead for mineralization. The Dafulou deposit is related to orogenic tectonic event and forms in the environment of orogenic belt.

Key words:Pb isotope; ore-forming material source; ore genesis; Dafulou tin deposit; Guangxi