鞍山—本溪地区南芬BIF铁矿床流体包裹体特征研究  

Characteristics of the fluid inclusions from the Nanfen BIF in Anshan—Benxi area

作　　者：骆念岗 崔建宇 翟富荣 李志锋 蔡超[1] 田晓辉 梁帅 姚玉健 许卫江 白博文 时彬 LUO Niangang;CUI Jianyu;ZHAI Furong;LI Zhifeng;CAI Chao;TIAN Xiaohui;LIANG Shuai;YAO Yujian;XU Weijiang;BAI Bowen;SHI Bin(Sheyang University of Technology,Shenyang,110870;Liaoning Provincial Geological and Mineral Survey Institute Co.,Ltd.,Shenyang,110000;Langfang Natural Resources Comprehensive Survey Center,China Geological Survey,Langfang,Hebei,065000;Shenyang Center of China Geological Survey,Shenyang,110000;Mudanjiang Natural Resources Comprehensive Survey Center,China Geological Survey,Mudanjiang,Heilongjiang,157021)

机构地区：[1]沈阳工业大学,沈阳110870 [2]辽宁省地质矿产调查院有限责任公司,沈阳110000 [3]中国地质调查局廊坊自然资源综合调查中心,河北廊坊065000 [4]中国地质调查局沈阳地质调查中心,沈阳110000 [5]中国地质调查局牡丹江自然资源综合调查中心,黑龙江牡丹江157021

出　　处：《地质论评》2025年第2期471-487,共17页Geological Review

基　　金：辽宁省省级地质勘查项目(编号:JH21-210000-05453)成果。

摘　　要：南芬BIF(Banded iron formation,条带状含铁建造)是鞍山—本溪地区重要的铁矿床之一,呈层状、似层状赋存于新太古代鞍山群茨沟岩组含铁岩段中,自下而上由Fe1、Fe2和Fe33个铁矿体组成。矿石类型主要为磁铁石英岩、透闪磁铁石英岩、赤铁磁铁石英岩和赤铁石英岩。根据矿物组合和共生序列,成矿演化期次可分为5期:沉积期、成岩期、区域变质变形期、热液改造期、表生氧化期。为了查明南芬BIF的成矿流体特征,本文在对矿床地质特征、矿物共生关系进行了野外调查和室内镜下研究的基础上,利用岩相学、显微测温等技术手段,对该矿床中不同类型磁铁石英岩中的石英开展了详细的流体包裹体特征研究。流体包裹体岩相学结果显示,南芬铁矿主要发育3类包裹体,分为Ⅰ类次生包裹体、Ⅱ类气液两相原生包裹体(Ⅱa类液相包裹体、Ⅱb类气体包裹体)和Ⅲ类含液相CO_(2)三相包裹体。流体包裹体显微测温结果显示,南芬铁矿绿帘—角闪岩相变质作用峰期发育Ⅲ类和Ⅱb类包裹体,峰期变质流体均一温度为283.2~423.5℃,盐度范围为3.39%~9.47%NaCleqv,显示高温低盐度特征;而绿帘—角闪岩相变质作用峰期后发育Ⅰ类、Ⅱa类包裹体,均一温度范围为191.3~308.8℃,盐度范围为2.24%~10.61%NaCleqv,均一温度及盐度范围均较宽。综合流体包裹体特征和其他地质证据,认为区域变质峰后阶段变质流体具有多期性的特点。Objectives:Nanfen BIF(Banded iron formation)is one of the important iron deposits in the Anshan—Benxi area,which is distributed in a laminate or quasi laminate manner in the ore-bearing rock series of the Cigou Formation of the Neoarchean Anshan Group.It is composed of three iron ore bodies,Fe1,Fe2,and Fe3,from bottom to top.Based on mineral assemblage and paragenesis,the evolutionary phases of mineralisation can be divided into five phases:①primary depositional,②diagenetic,③regional metamorphism and deformation,④hydrothermal transformation and⑤supergene oxidation stages.The natural types of ore are mainly magnetite quartzite,tremolite magnetite quartzite,hematite magnetite quartzite and hematite quartzite.This study devotes to ascertain the characteristics of oreforming fluids and further understand the ore genesis of the Nanfen iron deposit.Methods:Based on field investigation and indoor microscopic study,the petrographic observation,microthermometric measurements on the fluid inclusions hosted in different stage quartz from the Nanfen BIF,were systematically carried out in this study.Results:The petrographic results of fluid inclusions show that there are mainly three types of inclusions developed in Nanfen iron ores:type-Ⅰsecondary fluid inclusion,type-Ⅱprimary fluid inclusion(including type-Ⅱa liquid-rich two-phase inclusion and type-Ⅱb vapor-rich two-phase inclusion),type-ⅢCO_(2)-rich three-phase fluid inclusion.The results show that two kinds of fluid inclusions formed in the peak stage of epidote—amphibolite facies metamorphism:type-Ⅱb vapor-rich inclusion andⅢ-type three-phase inclusion containing liquid CO_(2).The homogenization temperatures of these inclusions range from 283.2~423.5℃and salinity values vary in the range of 3.39%~9.47%NaCleqv,indicating that the metamorphic fluid is characterized by high temperature and low salinity.Two kinds of fluid inclusions formed after the peak stage of epidote—amphibolite facies metamorphism:type-Ⅱa liquid inclusion and type-Ⅰs

关 键 词：流体包裹体 均一温度 盐度 南芬BIF 鞍本地区 

分 类 号：P61[天文地球—矿床学]