长江中下游成矿带庐枞盆地小包庄铁矿床地质特征研究  

Geological characteristics of Xiaobaozhuang iron deposit in the Lu-Zong volcanic basin,the Middle-Lower Yangtze River Valley Metallogenic Belt

作　　者：刘一男[1] 范裕[1] 高昌生[2] 张千明[2] 张乐骏 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽省地质矿产勘查局327地质队,合肥246003 [3]Centre of Excellence in Ore Deposit( CODES) ,University of Tasmania

出　　处：《岩石学报》2016年第2期319-333,共15页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划"973"项目(2012CB416802);国家自然科学基金项目(41320104003;41172086;41172084)联合资助

摘　　要：罗河铁矿床位于长江中下游成矿带内庐枞火山岩盆地的西北部,是成矿带内已发现规模最大的铁矿床。2013年在罗河铁矿床深部又勘探新发现了小包庄大型铁矿床,这是长江中下游成矿带内近年来重大找矿突破之一,具有重要的理论研究意义和勘探应用价值。本文在前人工作基础上,基于详细的钻孔观察和系统的岩相学、矿相学工作并结合电子探针测试分析,研究了小包庄铁矿床的矿化蚀变特征,厘定了矿床的成矿阶段,分析了成矿作用过程,并初步探讨了矿床成因。研究表明,罗河铁矿床和小包庄铁矿床为同一成矿系统在不同深度成矿作用的产物。小包庄铁矿床主矿体矿呈厚大的透镜状、似层状产于砖桥组地层中,位于罗河铁矿床主矿体之下约800~1000m,主要由浸染状矿体组成。矿床中金属矿物主要为磁铁矿和黄铁矿,非金属矿物主要为硬石膏、透辉石和碳酸盐,矿石的代表性矿物组合为磁铁矿-硬石膏-透辉石。矿石的结构构造主要有浸染状构造、脉状构造、块状构造、自形-半自形粒状结构、他形粒状结构和筛状结构等。矿床围岩蚀变强烈,主要蚀变类型有碱性长石化、透辉石化、绿泥石化、绿帘石化、碳酸盐化和硬石膏化。小包庄铁矿床形成经历了热液期的四个阶段,即碱性长石阶段、透辉石-硬石膏-磁铁矿阶段、绿泥石-绿帘石-碳酸盐阶段和硬石膏-黄铁矿-碳酸盐-石英阶段,其中,铁矿化主要发育于透辉石-硬石膏-磁铁矿阶段。通过矿床地质特征的分析以及与宁芜地区铁矿床的对比研究,本文认为小包庄铁矿床成矿物质和成矿流体来源于深部的闪长质侵入岩（？）,而矿化发育在远离侵入岩或次火山岩之上的火山岩中,明显有别于宁芜地区玢岩铁矿床,类似于智利安第斯成矿带中部分产于安山质火山岩中的磁铁矿-磷灰石型矿床,是长江中下游成矿带中产�Luohe iron deposit is located in the northwest of Lu-Zong volcanic basin,which is the largest iron deposit in the MiddleLower Yangtze River Valley Metallogenic Belt. Xiaobaozhuang deposit was found in 2013,which is located 800 ~ 1000 m deep beneath the Luohe deposit. The discovery of Xiaobaozhuang deposit is one of the most significant prospecting progresses in the Middle-Lower Yangtze River Valley Metallogenic Belt. Based on the former work,we carried out detailed study on the geology characteristic of deposit through carefully field work,mineralography and EPMA analysis. Although Luohe and Xiaobaozhuang deposits are located in different depth,they belong to the same metallogenic system. Xiaobaozhuang ore body occurring as lens in the Zhuanqiao Formation,located800 ~ 1000 m below the Luohe orebody,ore structure are dominated by disseminate. The main ore minerals are magnetite and pyrite.The main gangue minerals are anhydrite,diopside and carbonate. The typical mineral assemblage is magnetite-anhydrite-diopside. The main ore structures include massive and disseminated structure. The main ore textures include euhedral-subhedral granular texture,anhedral granular texture and metasomatic pseudomor-phic texture. The main alteration mineral assemblage includes anhydritediopside,chlorite-epidote,pyrite-anhydrite and carbonate. The mineralization process of the deposit can be divided into four stages such as alkali feldspar stage,anhydrite-diopside-magnetite stage,chlorite-epidote-carbonate stage and anhydrite-pyrite-carbonate-quartz stage. Therein,anhydrite-diopside-magnetite stage is the main stage for ore forming. Based on the geological characteristics of the Xiaobaozhuang iron deposit and compared to Ningwu iron deposits,the article considers the Xiaobaozhuang deposit mineralization material source and ore-forming fluid is from dioritic magma in the deep,mineralization and alteration ares developed in the volcanic formation far from intrusive rock. It is obviously different from Ningwu iron deposits,similar to some

关 键 词：罗河-小包庄铁矿床 安山质火山岩 玢岩型铁矿床 庐枞火山岩盆地 

分 类 号：P618.31[天文地球—矿床学]