胶东半岛夏甸金矿床与大尹格庄金矿床蚀变地球化学特征对比研究  

Comparative study on the alteration geochemical characteristics of Xiadian Gold Deposit and Dayingezhuang Gold Deposit in Jiaodong Peninsula

作　　者：付政凯 李岳智 王海正 王杜涛 高学坎 辛梓豪 陈煜东 Fu Zhengkai;Li Yuezhi;Wang Haizheng;Wang Dutao;Gao Xuekan;Xin Zihao;Chen Yudong(Zhaojin Mining Co.,Ltd.;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,Central South University;School of Geosciences and Info-physics,Central South University)

机构地区：[1]招金矿业股份有限公司 [2]中南大学有色金属成矿预测与地质环境监测教育部重点实验室 [3]中南大学地球科学与信息物理学院

出　　处：《黄金》2024年第12期89-98,113,共11页Gold

基　　金：国家自然科学基金项目(42202332);招金矿业地质科研项目(ZJ-XDJK2022350)。

摘　　要：大尹格庄金矿床和夏甸金矿床是招平断裂内典型的“焦家式”破碎带蚀变岩型金矿床,从招平断裂向外依次发育黄铁绢英岩化和红化蚀变。但是,二者蚀变元素迁移特征是否存在差异,前人关注较少,对此开展了详细的岩相学、矿物学、地球化学研究。夏甸金矿床红化蚀变表现为Fe_(2)O_(3)、K_(2)O带入,指示其为钾长石替代斜长石过程中含铁矿物混入的复合蚀变,而大尹格庄金矿床的红化蚀变为钠长石化-绢云母化-钾长石化复合蚀变,出现K_(2)O带入,Na_(2)O与Fe_(2)O_(3)带出。这2个金矿床的红化蚀变岩均富集与金成矿相关的元素,但夏甸金矿床的红化蚀变表现出As亏损特征,而大尹格庄金矿床的红化蚀变则表现出Zn和Cd亏损特征。大尹格庄金矿床的黄铁绢英岩化蚀变富集K_(2)O、Fe_(2)O_(3)、MgO和LOI,而夏甸金矿床亏损K_(2)O、CaO、MgO和TiO_(2),这种差异指示了大尹格庄金矿床发育更强的绿泥石化和绢云母化,可能是该矿床发育斜长角闪岩中暗色矿物及斜长石在水岩反应中分解使流体K_(2)O、MgO含量升高所致。夏甸金矿床的黄铁绢英岩化蚀变中Au的带入程度相对低于大尹格庄金矿床,可能是由于该矿床发育的荆山群大理岩水岩反应对流体pH变化起到了缓冲作用,阻碍了金硫络合物分解沉淀。Dayingezhuang Gold Deposit and Xiadian Gold Deposit are typical"Jiaojia-type"fractured zone alteration rock gold deposits within the Zhaoping Fault.Sequential alterations from the fault outward include beresitization alteration and K-feldspar alteration.However,differences in alteration-related element migration between the_(2)deposits have received limited attention.This study conducted detailed petrographic,mineralogical,and geochemical investigations.K-feldspar alteration at Xiadian Gold Deposit is characterized by Fe_(2)O_(3)and K_(2)O enrichment,indicating a composite alteration involving potassium feldspar replacing plagioclase with iron-bearing mineral inclusions.In contrast,the K-feldspar alteration at Dayingezhuang Gold Deposit is a composite alteration of albite-sericite-potassium feldspar,showing K_(2)O enrichment alongside Na_(2)O and Fe_(2)O_(3)depletion.Both deposits'K-feldspar alteration rocks are enriched in gold-associated elements,but Xiadian Gold Deposit shows As depletion,whereas Dayingezhuang Gold Deposit exhibits Zn and Cd depletion.Beresitization alteration at Dayingezhuang Gold Deposit enriches K_(2)O,Fe_(2)O_(3),MgO,and LOI,while Xiadian Gold Deposit exhibits depletion in K_(2)O,CaO,MgO,and TiO_(2).These differences suggest stronger chloritization and sericitization at Dayingezhuang Gold Deposit,potentially caused by the breakdown of mafic minerals and plagioclase in amphibolite in water-rock reactions,increasing K_(2)O and MgO content in fluids.Gold migration during beresitization alteration is less pronounced at Xiadian Gold Deposit compared to Dayingezhuang Gold Deposit,likely due to buffering effects from marble water-rock reactions in the Jingshan Group,stabilizing fluid pH and inhibiting gold-sulfur complex breakdown and deposition.

关 键 词：围岩蚀变 蚀变地球化学特征 红化蚀变 黄铁绢英岩化 质量平衡 破碎带 蚀变岩型金矿床 胶东 

分 类 号：TD11[矿业工程—矿山地质测量] P618.51[天文地球—矿床学]