摘要
播卡金矿床位于扬子西缘"康滇地轴"中南段,其与东川因民-汤丹地区元古代"东川式"铜矿成矿作用具有显著差别而备受人们关注.该矿床富矿围岩为东川群黑色碳酸盐岩-碎屑岩地层,Au产出于石英-白云石硫化物脉中,具有明显辉绿岩岩浆萃取型Au矿蚀变特征,有别于韧性剪切带型Au矿.选取新山-马家沟矿段含金黄铁矿和围岩炭质板岩分别进行Re-Os同位素和微量元素研究.结果显示,黄铁矿Re-Os等时线年龄为779±14 Ma(MSWD=11.1),说明播卡金矿床成矿时代为新元古代.黄铁矿的Os初始比值为3.03±0.42,说明播卡金矿床金属成矿物质主要来源于地壳(围岩地层)而非辉绿岩岩浆,黄铁矿和炭质板岩微量中Au(平均为402.5.00×10^(-9)和44.98×10^(-9))和Cu(平均为1733.00×10^(-6)和46.07×10^(-6))的含量远远大于克拉克值(约4×10^(-9)和60×10^(-6)),进一步证实成矿物质来源于围岩地层炭质板岩本身.东川播卡金矿成岩时代与该区新元古代岩浆岩相关的热液改造事件基本一致,表明成矿背景为该区新元古代岩浆/热液改造的成矿响应,该时期岩浆岩与富矿围岩热接触,同时萃取围岩地层中沉积预富聚的有利成矿元素,在良好的成矿空间内富集形成东川播卡金矿床.
The Boka gold deposit is located in the middle-south section of“Kangdian axis”in the western margin of Yangtze River.It is quite different from the“Dongchuan type”copper mineralization in the Yinmin-Tangdan area of Dongchuan.The rich wall rock of the deposit is black carbonate clastic rock stratum of Dongchuan group.Au occurs in quartz dolomite sulfide vein.It has obvious alteration characteristics of diabase magma extraction type Au deposit,which is different from ductile shear zone type Au deposit.In this paper,the Au-bearing pyrite and the wall rock carbonaceous slate in the Xinshan-Majiagou ore block were selected for Re-Os isotopic and trace element studies respectively.The results show that the Re-Os isochron age of pyrite is 779±14 Ma(MSWD=11.1),indicating that the Boka gold deposit was formed in Neoproterozoic.The initial Os ratio of pyrite is 3.03±0.42,indicating that the ore-forming materials of Boka gold deposit were mainly derived from the crust(wall rock strata)rather than diabase magma.The contents of Au(402.50×10^(-9) and 44.98×10^(-9) on average)and Cu(1733.00×10^(-6) and 46.07×10^(-6) on average)in pyrite and carbonaceous slate are much higher than Clark values(about 4×10^(-9) and 60×10^(-6)),which further confirms that the ore-forming materials were derived from the carbonaceous slate of the surrounding rock strata.The diagenetic age of Boka gold deposit in Dongchuan is basically consistent with the Neoproterozoic magmatic rock related hydrothermal transformation events,which indicates that the metallogenic background is the ore-forming response of Neoproterozoic magmatic/hydrothermal transformation in the area.During this period,the magmatic rock is in thermal contact with the ore rich wall rock,and the favorable ore-forming elements were extracted from the wall rock strata,The Boka gold deposit in Dongchuan was formed in a good metallogenic space.
作者
刘泽奇
江小均
李超
李文昌
刘凤祥
余海军
王长兵
Liu Zeqi;Jiang Xiaojun;Li Chao;Li Wenchang;Liu Fengxiang;Yu Haijun;Wang Changbing(Department of Earth Science,Faculty of Land and Resources Engineering,Kunming University of Science and Technology,Kunming 650093,China;National Geological Experimental Testing Center,Beijing 100037,China;Key Laboratory of Sanjiang Mineralization and Resources Exploration and Utilization,Ministry of Natural Resources,Kunming 650051,China;Yunnan Nuclear Industry 209 Geological Brigade,Kunming 650032,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2021年第12期4260-4273,共14页
Earth Science
基金
国家自然科学基金项目(Nos.41673060,41873065)。
作者简介
刘泽奇(1996-),男,硕士,主要从事地质过程与成岩成矿作用研究.ORCID:0000-0002-4859-9249.E-mail:1976674923@qq.com;通讯作者:李超,E-mail:Re-Os@163.com。
