利比里亚某铁矿矿床地质特征及找矿模型
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摘要
利比里亚某铁矿位于西非克拉通南部马恩(Man)地盾太古宙成矿区,是典型的沉积变质型铁矿床,规模为一大型铁矿床,由国内企业取得探矿权。太古宙马恩(Man)地盾比里姆绿岩带为区域重要的成矿带,已发现了多处铁矿床与矿点。利比里亚某铁矿为该成矿区的代表性矿床之一,矿体一般呈层状、似层状,整体呈"U"形和"W"形产出。结合1∶25万区域地质调查结果及相关地质工作成果,针对区内第四系覆盖层分布广且厚度大、区域变质程度高、矿体形态较为复杂的特点,开展了高精度磁测和EH4测量。通过地面高精度磁测获得的正磁—负磁—正磁异常分带识别含铁建造区域,根据EH4低阻异常对含铁建造与矿体进行空间定位,结合地质测量、探槽、钻探等手段的综合运用,在该区取得了找矿勘查突破。根据矿床地质特征、地球物理特征、找矿标志等构建了沉积变质型铁矿的找矿模型,并对选定的2处找矿靶区进行验证,取得了较好效果,对于该区后续找矿工作以及沉积变质型铁矿的找矿勘查工作有一定的参考价值。
An iron ore deposit in Liberia is located in the Archean metallogenic area of Man Earth Shield in the south of West Africa Craton.It is a typical sedimentary metamorphic iron deposit with a large scale and prospecting rights obtained by Chinese enterprises.The Birimian green rock belt of Archean Man Earth Shield is an important metallogenic belt in the region.There are many iron depoists and mineral occurrences are found in the metallogenic belt.The deposit in Liberia is one of the representative deposits in the metallogenic area,orebodies are generally distributed with layered and stratiform-like,and they are generally exposed with the shape of"U"and"W".Based on the 1∶250 000 regional geological survey results and some related geological working achievements,in view of the characteristics of widely distributed and thick Quaternary overburden,high degree of regional metamorphism and more complicated orebody shape,high-precision magnetic survey and EH4 survey have been conducted in the area.The iron-bearing formation area can be identified effectively by the zoning of positive-negative-positive magnetic anomalies obtained by high-precision magnetic survey,spatial orientation of iron-bearing formation and orebodies can be conducted based on the low-resistance anomalies acquired by EH4 survey,through the systematic application of geological survey,exploratory trench and drilling,breakthrough in prospecting and exploration has been achieved in the area.According to the deposit geological characteristics,geophysical characteristics and prospecting indicator,the prospecting model of sedimentary metamorphic iron deposit is established.The two delineated prospecting target areas are verified,the prospecting effects is good.The above discussion results can provide reliable reference for the further prospecting work of the area and sedimentary metamorphic iron deposit in other areas.
An iron ore deposit in Liberia is located in the Archean metallogenic area of Man Earth Shield in the south of West Africa Craton.It is a typical sedimentary metamorphic iron deposit with a large scale and prospecting rights obtained by Chinese enterprises.The Birimian green rock belt of Archean Man Earth Shield is an important metallogenic belt in the region.There are many iron depoists and mineral occurrences are found in the metallogenic belt.The deposit in Liberia is one of the representative deposits in the metallogenic area,orebodies are generally distributed with layered and stratiform-like,and they are generally exposed with the shape of"U"and"W".Based on the 1∶250 000 regional geological survey results and some related geological working achievements,in view of the characteristics of widely distributed and thick Quaternary overburden,high degree of regional metamorphism and more complicated orebody shape,high-precision magnetic survey and EH4 survey have been conducted in the area.The iron-bearing formation area can be identified effectively by the zoning of positive-negative-positive magnetic anomalies obtained by high-precision magnetic survey,spatial orientation of iron-bearing formation and orebodies can be conducted based on the low-resistance anomalies acquired by EH4 survey,through the systematic application of geological survey,exploratory trench and drilling,breakthrough in prospecting and exploration has been achieved in the area.According to the deposit geological characteristics,geophysical characteristics and prospecting indicator,the prospecting model of sedimentary metamorphic iron deposit is established.The two delineated prospecting target areas are verified,the prospecting effects is good.The above discussion results can provide reliable reference for the further prospecting work of the area and sedimentary metamorphic iron deposit in other areas.
引文
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[11]李延河,侯可军,万德芳,等.前寒武纪条带状硅铁建造的形成机制与地球早期的大气和海洋[J].地质学报,2010,84(9):1359-1373.Li Yanhe,Hou Kejun,Wan Defang,et al.Formation mechanism of Precambrian banded iron formation and atmosphere and ocean during early stage of the earth[J].Acta Geologica Sinica,2010,84(9):1359-1373.
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[13]李延河,张增杰,侯可军,等.辽宁鞍本地区沉积变质型富铁矿的成因:Fe、Si、O、S同位素证据[J].地质学报,2014,88(12):2351-2372.Li Yanhe,Zhang Zengjie,Hou Kejun,et al.The genesis of Gongchangling high-grade-iron oes,Anshan-Benxi Area,Liaoning Province,NE China:evidence from Fe-Si-O-S isotopes[J].Acta Geologica Sinica,2014,88(12):2351-2372.
[14]贾培乾,刘宝宏,江新华,等.利比里亚Bomi东部山区富铁矿(DSO)勘探报告[R].郑州:中化地质矿山总局河南地质勘查院,2012.Jia Peiqian,Liu Baohong,Jiang Xinhua,et al.Exploration report of rich iron ore(DSO)in Eastern Mountain Area of Bomi,Liberia[R].Zhengzhou:Henan Geological Exploration Institute,General Administration of Geology and Mines of China Chemical Industry,2012.
[15]李忠,肖高强,许晶.EH-4电导率成像技术和化探综合方法在镇康放羊山铅锌铁矿区勘查中的应用[J].云南大学学报:自然科学版,2017(S2):105-109.Li Zhong,Xiao Gaoqiang,Xu Jing.EH-4 conductivity imaging and geochemical comprehensive method in Fangyang Hill of Zhenkang exploration the application of lead and zinc iron mining area[J].Journal of Yunnan University:Natural Science Edition,2017(S2):105-109.
[16]杨明国,杨震,王正海,等.EH4成像技术在冈底斯斑岩铜矿勘探中的应用:以西藏尼木岗讲铜矿为例[J].地质科技情报,2017,36(4):133-137.Yang Mingguo,Yang Zhen,Wang Zhenghai,et al.EH4 imaging technology in Gangdese porphyry copper mine exploration:an example from Gangjiang Copper Mine in Nimu,Tibe[tJ].Geological Science and Technology Information,2017,36(4):133-137.
[17]黄朝阳,王核,李文铅,等.EH4在铁矿勘探的应用--以西昆仑赞坎铁矿为例[J].新疆地质,2014,32(3):405-409.Huang Chaoyang,Wang He,Li Wenqian,et al.Application of EH4in Zankan Iron Ore Deposit,West Kunlun[J].Xinjiang Geology,2014,32(3):405-409.
[18]张利明,凌丹丹.高精度磁测在多金属矿整装勘查区成矿规律研究中的应用[J/OL].地球物理学进展.http://kns.cnki.net/kcms/detail/11.2982.P.20181022.1628.138.html.Zhang Liming,Ling Dandan.The application of high precision magnetic measurement in the study of metallogenic regularity of multimetallic ore deposit exploration area[J/OL].Progress in Geophysics.http://kns.cnki.net/kcms/detail/11.2982.P.20181022.1628.138.html.
[19]王美丁,马见青.青海循化地区高精度磁异常特征及找矿预测[J].物探与化探,2018,42(3):491-498.Wang Meiding,Ma Jianqing.The High-precision magnetic anomaly characteristics and prospecting forecast in Xunhua Region of Qinghai[J].Geophysical and Geochemical Exploration,2018,42(3):491-498.
[20]范剑,邱小波,李毅,等.西秦岭国安寺-白杨沟地区高精度磁测异常特征及找矿远景分析[J].地球物理学进展,2017,32(6):2436-2443.Fan Jian,Qiu Xiaobo,Li Yi,et al.Characteristics of ground magnetic anomalies and exploration perspective analysis in Guo'an Temple-Baiyanggou area of West Qinling[J].Progress in Geophysics,2017,32(6):2436-2443.
[21]徐荣华,楼法生,刘献满,等.综合物探法在九瑞宝山-夫山地区找矿中的应用[J].地球物理学进展,2017,32(6):2571-2580.Xu Ronghua,Lou Fasheng,Liu Xianman,et al.Applied of comprehensive geophysical prospecting method for exploreing mine in Jiurui Area[J].Progress in Geophysics,2017,32(6):2571-2580.
[2]王忠,李建领.浅析利比里亚BIF型铁矿成因[J].内蒙古科技与经济,2013(23):38-40.Wang Zhong,Li Jianling.Analysis on the origin of BIF type iron ore in Liberia[J].Inner Mongolia Science Technology&Economy,2013(23):38-40.
[3]高坪仙.西非克拉通结晶基底构造分区概述[J].国外前寒武纪地质,1992(4):23-25.Gao Pingxian.Zoning summary of West African Craton crystalline basement structure[J].Precambrian Geology Abroad,1992(4):23-25.
[4]高坪仙.西非克拉通前寒武纪地体的某些特征[J].国外前寒武纪地质,1992(4):26-33.Gao Pingxian.The feature of West African Craton precambrian terrain[J].Precambrian Geology Abroad,1992(4):26-33.
[5]Hutchinson R W,张一钧.太古宙成矿作用:综合与评述[J].国外前寒武纪地质,1985(3):95-104.Hutchinson R W,Zhang Yijun.Archean mineralization:synthesis and review[J].Precambrian Geology Abroad,1985(3):95-104.
[6]张连昌,翟明国,万渝生,等.华北克拉通前寒武纪BIF铁矿研究:进展与问题[J].岩石学报,2012,28(11):3431-3445.Zhang Lianchang,Zhai Mingguo,Wan Yusheng,et al.Study of the Precambrian BIF-iron deposits in the North China Craton:progresses and questions[J].Acta Petrologica Sinica,2012,28(11):3431-3445.
[7]沈其韩,宋会侠.华北克拉通条带状铁建造中富铁矿成因类型的研究进展、远景和存在的科学问题[J].岩石学报,2015,31(10):2795-2815.Shen Qihan,Song Huixia.Progress,prospecting and key scientific problems in origin researches of high-grade iron ore of the banded iron formation(BIF)in the North China Craton[J].Acta Petrologica Sinica,2015,31(10):2795-2815.
[8]郑梦天,张连昌,王长乐,等.冀东杏山BIF铁矿形成时代及成因探讨[J].岩石学报,2015,31(6):1636-1652.Zheng Mengtian,Zhang Lianchang,Wang Changle,et al.Formation age and origin of the Xingshan BIF-type iron deposit in Eastern Hebei Province[J].Acta Petrologica Sinica,2015,31(6):1636-1652.
[9]代堰锫,朱玉娣,张连昌,等.国内外前寒武纪条带状铁建造研究现状[J].地质论评,2016,62(3):735-757.Dai Yanpei,Zhu Yudi,Zhang Lianchang,et al.An overview of studies on Precambrian banded iron formations(BIFs)in China and abroad[J].Geological Review,2016,62(3):735-757.
[10]姚春彦,董永观,张晓勇,等.浅谈巴西Carajas地区前寒武纪条带状含铁建造的成矿作用[J].地球科学进展,2012(S1):281-285.Yao Chunyan,Dong Yongguan,Zhang Xiaoyong,et al.Briefly discussion on the metallogenesis of the Carajas Precambrian BIF,Brazi[lJ].Advances in Earth Science,2012(S1):281-285.
[11]李延河,侯可军,万德芳,等.前寒武纪条带状硅铁建造的形成机制与地球早期的大气和海洋[J].地质学报,2010,84(9):1359-1373.Li Yanhe,Hou Kejun,Wan Defang,et al.Formation mechanism of Precambrian banded iron formation and atmosphere and ocean during early stage of the earth[J].Acta Geologica Sinica,2010,84(9):1359-1373.
[12]刘明军.辽宁弓长岭沉积变质型铁矿热液改造作用及其成矿意义[D].北京:中国地质大学(北京),2013.Liu Mingjun.Hydrothermal Metasomatism and Its Metallogenic Significance of the Gongchangling Iron Deposit,Liaoning,China[D].Beijing:China University of Geosciences(Beijing),2013.
[13]李延河,张增杰,侯可军,等.辽宁鞍本地区沉积变质型富铁矿的成因:Fe、Si、O、S同位素证据[J].地质学报,2014,88(12):2351-2372.Li Yanhe,Zhang Zengjie,Hou Kejun,et al.The genesis of Gongchangling high-grade-iron oes,Anshan-Benxi Area,Liaoning Province,NE China:evidence from Fe-Si-O-S isotopes[J].Acta Geologica Sinica,2014,88(12):2351-2372.
[14]贾培乾,刘宝宏,江新华,等.利比里亚Bomi东部山区富铁矿(DSO)勘探报告[R].郑州:中化地质矿山总局河南地质勘查院,2012.Jia Peiqian,Liu Baohong,Jiang Xinhua,et al.Exploration report of rich iron ore(DSO)in Eastern Mountain Area of Bomi,Liberia[R].Zhengzhou:Henan Geological Exploration Institute,General Administration of Geology and Mines of China Chemical Industry,2012.
[15]李忠,肖高强,许晶.EH-4电导率成像技术和化探综合方法在镇康放羊山铅锌铁矿区勘查中的应用[J].云南大学学报:自然科学版,2017(S2):105-109.Li Zhong,Xiao Gaoqiang,Xu Jing.EH-4 conductivity imaging and geochemical comprehensive method in Fangyang Hill of Zhenkang exploration the application of lead and zinc iron mining area[J].Journal of Yunnan University:Natural Science Edition,2017(S2):105-109.
[16]杨明国,杨震,王正海,等.EH4成像技术在冈底斯斑岩铜矿勘探中的应用:以西藏尼木岗讲铜矿为例[J].地质科技情报,2017,36(4):133-137.Yang Mingguo,Yang Zhen,Wang Zhenghai,et al.EH4 imaging technology in Gangdese porphyry copper mine exploration:an example from Gangjiang Copper Mine in Nimu,Tibe[tJ].Geological Science and Technology Information,2017,36(4):133-137.
[17]黄朝阳,王核,李文铅,等.EH4在铁矿勘探的应用--以西昆仑赞坎铁矿为例[J].新疆地质,2014,32(3):405-409.Huang Chaoyang,Wang He,Li Wenqian,et al.Application of EH4in Zankan Iron Ore Deposit,West Kunlun[J].Xinjiang Geology,2014,32(3):405-409.
[18]张利明,凌丹丹.高精度磁测在多金属矿整装勘查区成矿规律研究中的应用[J/OL].地球物理学进展.http://kns.cnki.net/kcms/detail/11.2982.P.20181022.1628.138.html.Zhang Liming,Ling Dandan.The application of high precision magnetic measurement in the study of metallogenic regularity of multimetallic ore deposit exploration area[J/OL].Progress in Geophysics.http://kns.cnki.net/kcms/detail/11.2982.P.20181022.1628.138.html.
[19]王美丁,马见青.青海循化地区高精度磁异常特征及找矿预测[J].物探与化探,2018,42(3):491-498.Wang Meiding,Ma Jianqing.The High-precision magnetic anomaly characteristics and prospecting forecast in Xunhua Region of Qinghai[J].Geophysical and Geochemical Exploration,2018,42(3):491-498.
[20]范剑,邱小波,李毅,等.西秦岭国安寺-白杨沟地区高精度磁测异常特征及找矿远景分析[J].地球物理学进展,2017,32(6):2436-2443.Fan Jian,Qiu Xiaobo,Li Yi,et al.Characteristics of ground magnetic anomalies and exploration perspective analysis in Guo'an Temple-Baiyanggou area of West Qinling[J].Progress in Geophysics,2017,32(6):2436-2443.
[21]徐荣华,楼法生,刘献满,等.综合物探法在九瑞宝山-夫山地区找矿中的应用[J].地球物理学进展,2017,32(6):2571-2580.Xu Ronghua,Lou Fasheng,Liu Xianman,et al.Applied of comprehensive geophysical prospecting method for exploreing mine in Jiurui Area[J].Progress in Geophysics,2017,32(6):2571-2580.