摘要
斑岩型矿床作为全球Cu、Mo等金属的主要来源,蕴藏着巨大的经济价值,一直是矿业公司的重点勘查目标。本文从岩石化学和矿物化学两方面,综述了有关斑岩矿床成矿潜力评价与矿体定位方面的研究进展,总结了相应的勘查指标,以期促进该类矿床的找矿突破。研究证实,成矿岩体一般为富H_2O、高氧逸度的浅成中酸性斑岩体,发育角闪石-磁铁矿-榍石等矿物组合,显示埃达克(质)岩的地球化学性质(如高Sr、低Y和Yb、Eu异常不明显等)。斑岩体Al_2O_3/TiO_2、Sr/Y、La/Yb、V/Sc和Sr/MnO等比值可以用来反映其成矿潜力。黑云母中Cu的含量、Cl/F比值以及特殊结构的石英(如UST、石英眼)等也可作为成矿潜力评价的重要指标。近年来,锆石、磷灰石和榍石等副矿物的化学组成被广泛用来评价岩浆的温度、压力、氧逸度以及H_2O含量,进而反映其成矿潜力。此外,某些岩石化学和矿物化学参数还是岩浆成矿专属性的灵敏指标。斑岩矿床独特的蚀变-矿化-元素分带模式是找矿勘查的基本准则。针对不同蚀变带发育的特征矿物(如钾化带的金红石、青磐岩化带的绿泥石和绿帘石、绢英岩化带的绢云母等)开展原位微区成分分析和(或)短波红外光谱分析,不仅能够明确勘查方向,还有助于确定主矿体的位置。鉴于不同矿区成矿母岩的成分、侵位深度、围岩性质、蚀变分带模式等可能均存在明显差异,因此在找矿实践中应综合考虑各项找矿指标,进而提升发现新矿产的能力和效率。
Porphyry Cu deposits,globally the main sources of Cu and Mo,have great economic value and are a significant exploration target for mining companies.This study reviews the research progress in evaluation of mineralization potential of the porphyry deposits and position of mineralization center from both whole-rock geochemistry and mineral chemistry perspective,and summarizes the corresponding exploration indicators in order to promote the prospecting and exploration efficiency of such deposits.Previous studies showed that the fertile porphyries are usually water-rich and oxidized,intermediate to felsic in composition,and are characterized by presence of amphibole-magnetite-titanite assemblages with adakitic rocks affinities(such as with high Sr,low Y and Yb contents,and negligible Eu anomalies).The whole-rock Al2O3/TiO2,Sr/Y,La/Yb,V/Sc and Sr/MnO ratios can be used to indicate the magma fertilities.Besides the Cu contents and Cl/F ratios of the biotite,special textures of the quartz(like UST,and quartz eye,etc.)are also important indicators for the evaluation of the porphyry Cu mineralization potential.Recently,geochemical compositions of the accessory minerals like zircon,apatite,and titanite are widely used to assess the magma temperature,pressure,oxygen fugacity,water content etc.to estimate magma fertility.Furthermore,some whole-rock geochemistry and mineral chemistry parameters are also sensitive indicators of magmatic metallogenic specificity.The unique alteration-mineralization-element zoning patterns of porphyry deposits are the basic criterion for mineral exploration.The characteristic minerals developed in different alteration zones,such as rutile in the potassic zone,chlorite and epidote in the propylitic zone,and sericite in the phyllic zone,in-situ composition analysis and/or short-wave infrared spectroscopy can not only clarify the exploration direction,but also help to determine the location of the main ore body.Considering the obvious differences in the composition of the parental magma,the depth of porphyry emplacement,the nature of the host rock and the model of the alteration zoning in different deposit districts,different prospecting indicators should be integrated to improve the ability and efficiency of new deposit discovery.
作者
冷成彪
陈喜连
张静静
马晓花
田丰
郭剑衡
张乐骏
LENG Chengbiao;CHEN Xilian;ZHANG Jingjing;MA Xiaohua;TIAN Feng;GUO Jianheng;ZHANG Lejun(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,330013,China;College of Earth Sciences,East China University of Technology,Nanchang,330013,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang,550081,China;Centre for Ore Deposit and Earth Sciences(CODES),University of Tasmania,Hobart 7001,Australia)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2020年第11期3189-3212,共24页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41673051、42022021)
江西省双一流学科建设专项(编号2400100017)
江西省“双千计划”项目
东华理工大学科研启动基金(编号DHBK2019317)
矿床地球化学国家重点实验室开放基金(编号201808)资助成果。
关键词
斑岩矿床
找矿勘查
成矿潜力
岩石地球化学
矿物化学
porphyry deposits
mineral exploration
magma fertility
lithogeochemistry
mineralgeochemistry
