小秦岭董家埝银矿床绢云母^(40)Ar-^(39)Ar同位素年龄及地质意义  

^(40)Ar/^(39)Ar ISOTOPIC DATING OF SERICITE FROM DONGJIANIAN SILVER DEPOSIT IN XIAOQINLING AREA AND ITS GEOLOGICAL SIGNIFICANCE

作　　者：董文超[1] 庞绪成[1] 杨东潮[2] Dong Wenchao;Pang Xucheng;Yang Dongchao(Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo,Henan China;No.2 Institute of Geological&Mineral Resources Survey of Henan,Zhengzhou,Henan China)

机构地区：[1]河南理工大学资源环境学院,河南焦作454000 [2]河南省地质矿产勘查开发局第二地质矿产调查院,河南郑州450000

出　　处：《矿物岩石》2022年第1期33-41,共9页Mineralogy and Petrology

基　　金：中国地质调查局科研项目(编号:12120114035401)。

摘　　要：董家埝银矿床位于小秦岭成矿带中南部,受小河断裂次级构造的控制,是近年来新发现的一大型银矿床,预计资源远景达到3000 t。为了研究董家埝银矿床的成矿时代,打开区域找矿的新思路。本次研究通过对董家埝银矿床中的矿化蚀变绢云母进行^(40)Ar-^(39)Ar同位素定年的研究。研究结果表明,绢云母的坪年龄308.9±4.11 Ma,等时线年龄为298.82±10.07 Ma,认为董家埝银矿床形成于古生代晚期。依据银矿石、岩浆岩、蚀变岩及沉积岩等岩矿石的LREE/HREE-ΣREE与(Sm/Eu)_(样品)/(Sm/Eu)_(球粒)-(Sm/Eu)_(样品)投图结果,认为岩浆岩、蚀变岩及沉积岩都参与了成矿作用,其中蚀变岩与银矿石的关系最为密切。结合大地构造背景,认为董家埝银矿床形成于古生代晚期,在板块俯冲的构造背景体系下,深源岩浆向上侵入,与地壳物质发现相互作用,最终在构造及破碎带等开放的空间富集成矿,形成以蚀变岩型矿床为主的热液型银矿床。董家埝银矿床成矿年龄的确定对于认识小秦岭地区银矿成矿演化及区域找矿具有重要的指示意义。Dongjiaba Ag deposit,located in the middle and southern Xiaoqinling metallogenic belt,is a newly discovered large scale silver deposit with resource prospect of the deposit estimated to reach 3000 t.The deposit and ore bodies are controlled by the secondary structure of Xiaohe fault in the area.^(40)Ar-^(39)Ar isotopic dating of mineralized altered sericite in Dongjianian silver deposit is carried out in order to study the ore-forming age of Dongjianian silver deposit and to open a new way of regional prospecting.The results show that the flat age of sericite is 308.9±4.11 Ma,and the isochron age is 298.82±10.07 Ma,indicating that the Dongjianian silver deposit was formed in the late Paleozoic.According to the LREE/HREE-ΣREE mapping results of silver ore,magmatic rock,altered rock and sedimentary rock and(Sm/Eu)_(sample)/(Sm/Eu)_(chondrite)-(Sm/Eu)_(sample),it is believed that magmatic rock,altered rock and sedimentary rock are all involved in the mineralization,among which the altered rock is most closely related to the silver ore.Under the tectonic setting system of plate subduction in the late Paleozoic,it is considered that the Dongjianian Ag deposit was enriched and ore accumulated in the open space of structure and fracture zone,forming a hydrothermal Ag deposit dominated by altered rocks.The determination of metallogenic age of Dongjiafeian Ag deposit is of great significance for understanding the metallogenic evolution of silver ore and regional prospecting in Xiaoqinling area.

关 键 词：^(40)Ar-^(39)Ar同位素测年 古生代晚期 董家埝银矿 小秦岭成矿带 

分 类 号：P597[天文地球—地球化学]