曲仁盆地北缘凡口式铅锌硫化物矿床稀土元素特征

张术根^{1, 2}，姚翠霞^{1, 2}

(1. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
2. 中南大学 地球科学与信息物理学院，长沙 410083)

摘 要：为探究曲仁盆地北缘以凡口为代表的铅锌硫化物矿床的矿床成因，对该区矿石及与矿化有关的岩体做稀土元素地球化学特征研究。结果表明：黄铁矿矿石和铅锌黄铁矿矿石稀土元素球粒陨石标准化配分曲线均为富轻稀土右倾型，但大部分铅锌黄铁矿矿石重稀土段曲线右倾程度明显较低，说明黄铁矿矿化和铅锌矿化系具有不同的成矿过程，但存在物源继承关系；Eu在铅锌矿床矿石中呈正异常，在黄铁矿矿床矿石中呈低负异常，推测有偏酸性热液参与铅锌成矿作用；∑REE在燕山期侵入岩中最高，在区域寒武系地层中次之，在铅锌黄铁矿矿石中最低，推断铅锌成矿构造热事件或岩浆热事件引发了稀土元素活化迁移；矿石稀土元素的赋矿围岩灰岩、燕山一期花岗岩和中基性脉岩标准化配分曲线均显示不同程度的平坦化，反映铅锌成矿物质有多个来源；矿石与其他地质体的REEQ型聚类结果表明赋矿碳酸盐岩层是黄铁矿矿化的主要成矿物质来源，虽燕山一期花岗质岩浆为铅锌矿化提供成矿物质，但盆地基底碎屑岩层是主要成矿物质来源，燕山中晚期中基性岩脉则参与了晚期铅锌成矿作用。

关键词：凡口式铅锌硫化物矿床；稀土元素；配分模式；Q型聚类分析；两期热液成矿

RE element characteristics of Fankou-type lead-zinc sulfide deposit in northern margin of Quren basin

ZHANG Shu-gen^{1, 2}, YAO Cui-xia^{1, 2}

(1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geoscience and Info-Physics, Central South University, Changsha 410083, China)

Abstract:Rare earth elements (REE) characteristics of ores and other geological bodies were investigated to probe the genesis of Fankou-type lead-zinc sulfide deposit in the northern margin of Quren basin. The results show that the chondrite-normalized REE patterns of pyrite ores and lead-zinc pyrite ores both are LREE-enriched right type, but HREE segment curve rightist degree of lead-zinc pyrite ores is lower, meaning that pyrite and lead-zinc mineralization belong to different ore-forming processes and exist provenance inheritance relationship. Eu is positive anomaly in lead-zinc deposit ores and low negative anomaly in pyrite deposit ores, reflecting that the acidic hydrothermal is involved in lead-zinc mineralization. ∑REE of Yanshanian granitic intrusive rocks is the highest, that of regional cambrian strata is the next, that of lead-zinc pyrite ores is the lowest, indicating that the migration of REE are triggered by tectonic thermal events and magmatic events in the lead-zinc mineralization. The host strata limestone, early Yanshanian granite and intermediate-basic dike rock-nomalized REE patterns of pyrite which ores all show different degrees of planarization, implies that the multiple sources are concerned with lead-zinc mineralization. REE Q-mode hierarchical cluster analysis on ores and other related geological bodies show that the related substances from ore-bearing carbonate rocks are mainly offered to pyrite metallogenesis, and the ore-forming materials of lead-zinc metallogenesis are mostly provided by basal clastic rocks, only part by early Yanshanian granitic intrusive rocks. Late Yanshanian intermediate-basic intrusive rocks participate in the late stage of lead-zinc mineralization.

Key words:Fankou-type lead-zinc sulfide deposit; RE element; distribution pattern; Q-mode hierarchical cluster analysis; two hydrothermal stages