摘要
白土金铅矿床位于康山—上宫断裂与马超营断裂交会部位,大地构造位于华北陆块南缘,金矿体、银矿体与铅矿体异体共生,主要呈脉状、似层状产于碳酸盐岩中的次级断裂中。通过对白土金铅矿床主要岩矿石进行稀土元素、微量元素测试,稀土元素特征说明热液交代和变质交代作用普遍发育,具体特征为:①w(REE_(大理岩))>w(REE_(石英正长岩))>w(REE_(安山岩))>w(REE_(构造岩))>w(REE_(矿化白云岩))>w(REE_(矿化石英脉)),呈现出蚀变矿化程度越强稀土元素总量越低的特征;②稀土元素球粒陨石标准化配分曲线表现出随矿化增强呈斜率增大、轻稀土元素富集程度降低、重稀土元素富集程度增加的趋势;③蚀变对安山岩、构造岩、大理岩等岩石的Eu异常影响不明显,矿化则使Eu呈现出明显负异常,且蚀变对安山岩、构造岩、大理岩等岩石的Ce异常影响明显,使Ce由正异常逐渐演变成负异常,矿化则使Ce负异常程度进一步加大。将主要岩矿石微量元素与华北陆块壳微量元素含量对比,发现安山岩、大理岩作为主要赋矿围岩,成矿元素Ag、Sb、Pb、W、Zn呈富集状态,为铅成矿提供了高背景值,蚀变后安山岩中Pb、W呈现出明显富集现象,暗示热液流体本身携带Pb、W成矿元素或对围岩成矿元素有热液交代富集作用;异常强度上,构造岩、石英脉、石英正长岩、(大理)白云岩与安山岩类相比,富集或亏损强度较大,且异常强度依次加强,说明成矿物质来源与龙家园组碳酸盐岩关系密切。综上所述,白土金铅矿床的成因总体上以岩浆热液充填交代为主,但叠加了后期陆相火山沉积改造。
Baitu Au-Pb Deposit is located at the intersection of the Kangshan-Shanggong Fault and Machaoying Fault on the southern margin of the North China Craton.The Au,Ag,and Pb ore bodies are in heterogeneous coexistence.They mainly occur in secondary fault zones in carbonate rocks in a vein-like and layered manner.This paper conducted rare earth and microelement tests on the main rocks.The characteristics of rare earth elements indicate widespread development of hydrothermal and metamorphic metasomatism.The specific characteristics are:①w(REE_(marble))>w(REE_(quartz syenite))>w(REE_(andesite))>w(REE_(tectonic rock))>w(REE_(mineralized dolomite))>w(REE_(mineralized quartz vein)),showing a feature of the greater the degree of alteration mineralization,the lower the total rare earth content;②The rare earth distribution curve shows that with mineralization,slope increases,enrichment degree of light rare earth decreases,and enrichment degree of heavy rare earth increases;③The influence of alteration on Eu element anomalies in rocks such as andesite tectonic rock and marble is not significant,while mineralization results in a significant negative anomaly of Eu element.Additionally,the alteration has a significant impact on Ce element anomalies in andesite,tectonic rock,and marble,causing the Ce element to evolve gradually from positive anomalies to negative anomalies.Mineralization further increases the degree of negative anomalies in Ce elements.Comparing the microelements of the main rocks and ores with that of the North China continental crust,it was found that andesite and marble are the main host rocks,and the ore-forming elements Ag,Sb,Pb,W,and Zn are enriched,providing high background value for lead mineralization.After alteration,Pb and W elements in andesite show obvious enrichment,suggesting that the hydrothermal fluid itself carries Pb and W ore-forming elements or has a hydrothermal metasomatic enrichment effect on the ore-forming elements in the wall rocks;In terms of anomalous intensity,tectonic rocks,quartz veins,quartz syenites,and(marble)dolomite have higher enrichment or depletion intensity compared to andesite rocks,and the anomalous intensity is sequentially strengthened,indicating a close relationship between the source of ore-forming matters and the carbonate rocks of Longjiayuan Formation.In summary,the genesis of Baitu Au-Pb Deposit is generally dominated by magmatic hydrothermal filling and metasomatism,but it is superimposed with later continental volcanic sedimentary transformation.
作者
蔡焕花
张苏坤
刘玉刚
姚小东
王俊德
王小涛
程蓓雷
Cai Huanhua;Zhang Sukun;Liu Yugang;Yao Xiaodong;Wang Junde;Wang Xiaotao;Cheng Beilei(No.1 Institute of Geological&Mineral Resources Survey of Henan;Key Laboratory of Au-Ag-Polymetallic Deposit Series and Deep-seated Metallogenic Prognosis of Henan Province;College of Earth and Planetary Sciences,Chengdu University of Technology)
出处
《黄金》
CAS
2024年第8期99-111,共13页
Gold
基金
河南省重点研发与推广专项科技攻关项目(232102320316)
河南省地矿局自筹科研项目(豫地矿科研〔2021〕Z-1号)
河南省自然资源科研项目(2023-610-11)
河南省地勘基金项目(豫国土资发〔2015〕70号,〔2017〕22号)。
关键词
豫西
白土金铅矿床
稀土元素
微量元素
矿床成因
蚀变
Western Henan
Baitu Au-Pb Deposit
rare earth elements
microelements
deposit genesis
alteration
