摘要
中国航磁调查已基本覆盖全国,尤其是近二十年来开展了大面积1∶5万高精度航磁调查,为铁矿的成矿规律研究及找矿预测提供了重要的基础数据。文章基于全国航磁编图(1∶100万)和大比例尺(≥1∶5万)航磁数据集,开展区域、矿集区、矿床3个不同尺度的研究,旨在总结4种主要类型铁矿在区域和局部磁场上的响应模式,指导找矿应用。研究表明,不同类型的铁矿在区域磁场上呈现出不同的特征,沉积变质型铁矿主要位于条带状磁异常边部负背景场中的局部高磁异常,岩浆型铁矿主要位于线性磁异常带,接触交代-热液型铁矿(矽卡岩型)主要沿带状或等轴状磁异常边缘分布,火山岩型铁矿通常沿带状磁异常分布。不同的区域磁异常特征通常反映了特定的控矿要素,主要刻画了火山-沉积建造、基性-超基性杂岩、中酸性侵入岩、火山岩由浅部至深部的分布特征,为成矿地质背景研究提供了大量深部信息。岩浆活动强烈的构造带,会导致地壳内基底隆起和较高的地温梯度,呈现出磁性基岩深度和居里面深度较浅的特征,有利于铁矿物的富集成矿。大比例尺航磁资料(≥1∶5万)大都能够直接反映矿体或含矿地质体的特征,磁异常都对应了铁矿体或矿化的中心,但矿体的规模、产状、埋深、品位等特征的变化都会造成磁异常幅值、形状、大小的变化,通过约束条件下2D和3D正反演计算获得深部矿体或含矿地质体的特征,对找矿勘查最具指导意义。概括来讲,中小比例尺航磁资料主要用于成矿地质背景研究,分析成矿控矿要素,达到区域成矿预测的目的。大比例尺航磁资料可用于隐伏矿体或含矿地质体预测,建立深部矿体或含矿地质体二维或三维模型,指导勘探工作。
The aeromagnetic survey has almost covered the Chinese continent,including a large area of 1∶50 000 highprecision aeromagnetic survey which has been carried out in the past 20 years,and provides important basic data for the study of iron ore metallogeny and prospecting.Based on the compiled aeromagnetic map of China(1∶1million) and large-scale(≥1∶50 000) aeromagnetic data,this paper aims to summarize the regional and local magnetic characteristics of four iron ore types by the research of three different scales:region,ore concentration area and ore deposit and guide ore prospecting.Studies have shown that different types of iron ore show different characteristics in the regional magnetic field.Sedimentary metamorphic iron ore deposits show local high magnetic anomaly in the negative magnetic anomaly area.Magmatic-type iron ore deposits are mainly located along with magnetic anomaly belts.Contact metasomatic-hydrothermal iron ore deposits(skarn iron deposits) are mainly distributed along the edge of the magnetic anomaly belt or equiaxed magnetic anomaly.Volcanic-type iron ore deposits are usually distributed along with banded magnetic anomalies.These different regional magnetic anomalies usually reflect specific ore-controlling factors,and mainly describe the distribution of volcanic-sedimentary formations,basic-ultrabasic complexes,intermediate-acid intrusive rocks,and volcanic rocks from shallow to deep.The magnetic anomalies provide a lot of deep information for the study of mineralization.Usually,tectonic belts with strong magmatic activity will lead to basement uplift and high geothermal gradient in the crust,showing the characteristics of shallow burial depth of magnetic bedrock and curie depth,which is beneficial to the enrichment of iron minerals.Generally,large-scale aeromagnetic data(≥1∶50 000) can reflect the characteristics of ore bodies or ore-bearing geological bodies directly,and the magnetic anomalies almost correspond to iron ore bodies or mineralization centers.However,changes in the scale,occurrence,burial depth,grade and other characteristics of the ore body will cause changes in the amplitude,shape and size of the magnetic anomaly.Through the constraints of geological prior information,2D and 3D forward and inversion calculations are performed to obtain the characteristics of deep ore bodies or ore-bearing geological bodies,which is the most instructive for exploration.In general,small and medium-scale aeromagnetic data are mainly used for the research of geological background and ore-controlling factors to achieve the purpose of regional iron ore prospecting.Large-scale aeromagnetic data can be used to predict concealed ore bodies or ore-bearing geological bodies,and establish two-dimensional or three-dimensional models of deep ore bodies or ore-bearing geological bodies to guide field exploration.
作者
杨海
熊盛青
杨雪
范正国
李芳
贾志业
刘前坤
YANG Hai;XIONG ShengQing;YANG Xue;FAN ZhengGuo;LI Fang;JIA ZhiYe;LIU QianKun(China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Key Laboratory of Airborne Geophysics and Remote Sensing Geology,Ministry of Natural Resources,Beijing 100083,China)
出处
《矿床地质》
CAS
CSCD
北大核心
2022年第5期893-916,共24页
Mineral Deposits
基金
中国矿产地质志项目(编号:DD20160346、DD20190379)
中国地质调查项目(编号:DD20221640)联合资助。
关键词
地质学
磁异常
沉积变质型铁矿
岩浆型铁矿
接触交代-热液型铁矿
火山岩型铁矿
成矿规律
找矿预测
geology
aeromagnetic anomaly
sedimentary metamorphic iron ore
magmatic-type iron ore
contact metasomatic-hydrothermal iron ore
volcanic-type iron ore
metallogeny
ore prospecting
