摘要
都龙锡锌铟多金属矿床位于著名的滇东南钨锡多金属成矿区之老君山矿集区,成矿与白垩纪大规模花岗岩活动关系密切,沿隐伏花岗岩接触带周边发育石榴子石、透辉-透闪石等矽卡岩蚀变和条带状(似层状)、脉状(囊状)的锡石、闪锌矿及磁铁矿、辉钼矿、黄铁黄铜矿等矿化,形成超大规模的岩浆热液-矽卡岩成矿系统。野外观测及研究发现,早期(矽卡岩期)高温阶段形成的磁铁矿可分为I阶段交代型磁铁矿(I-Mag)和II阶段充填型磁铁矿(II-Mag)两类:前者多呈囊状、条带状,与矽卡岩矿物共生;后者为脉状,与金属硫化矿物共生。利用ICP-AES、ICP-MS对两类磁铁矿进行主、微量元素测试,从I-Mag到II-Mag,Si、Ca、Mn及ΣREE、Pb、Zn、Ti含量增加,Mg及Sn、W、In、V、Cr、Ga含量减少,REE配分型式也由平缓向右倾的逐渐变化。TiO 2-Al 2 O 3-(MgO+MnO)、(Ti+V)-(Ca+Al+Mn)、Ni/Cr-Ti、(Ti+V)-Ni/(Cr+Mn)成因判别图解表明,磁铁矿属岩浆热液-矽卡岩成因类型;Ti、V与Zr、Hf、Nb、Ta,以及Y/Ho(24~3414)、Ni/Co(<2→>2)、Ti/V(<25→>25)、Hf/Zr(003~006→004~005)存在着线性关系和规律变化特征,指示两类型磁铁矿具有相同的物质来源,为同一成矿过程不同阶段的产物。而代表成矿流体REE组成的II-Mag的REE组成继承了老君山花岗岩REE配分趋势和Eu负异常特征,表明磁铁矿与白垩纪老君山花岗岩具有一致的物质来源。Cr-V、(Ti+V)-(Al+Mn)、Ga-Mg及Ga-Sn图解显示相同的成因类型和一致的线性关系,指示磁铁矿主体形成于较高氧逸度和温度(约300℃)的成矿环境下,并且从I-Mag到II-Mag,存在着氧逸度逐渐升高、温度逐渐降低的演化趋势。
The Dulong Sn-Zn-In-polymetallic deposit lies in Laojunshan ore-concentrated area of the famous W-Sn polymetallic metallogenic zone in southeastern Yunnan.Mineralization in this deposit is closely related to the large-scale Cretaceous granite magma intrusion.It is a giant skarn(magmatic hydrothermal)mineralization system,whose skarn minerals include garnet,diopside,tremolite,actinolite,magnetite,wolframite,cassiterite,marmatite,molybdenite,chalcopyrite,pyrite,sphalerite and galenite.Based on field observation and study,the magnetite may be classified into two mineralization stages and types,including the early saccular(or banded)magnetite(I-Mag)in the skarn and the later vein magnetite(II-Mag)in the host rocks or early ore bodies.The analytical results show that from I-Mag to II-Mag,the concentrations of Si,Ca,Mn,ΣREE,Pb,Zn and Ti increase,whereas those of Mg,Sn,W,In,V,Cr and Ga decrease,and REE patterns are changed from slightly flat to right-dipping,with negative Eu anomalies.Magnetite genetic classification diagrams of TiO 2 vs.Al 2 O 3 vs.MgO+MnO,Ti+V vs.Ca+Al+Mn,Ni/Cr vs.Ti,Ti+V vs.Ni/(Cr+Mn)reveal that the magnetite is magmatic hydrothermal and skarn genetic type.The concentrations of Ti,V,Zr,Hf,Nb and Ta and the values of Y/Ho,Ni/Co,Ti/V and Hf/Zr show linear correlations.All of them show that the two types of magnetites have the same source with the Laojunshan granite intrusion,and they are products at different stages of the same mineralizing processes.The REE characteristics of II-Mag are similar to the Laojunshan granite intrusion,indicating that magnetite is genetically related to the Laojunshan granite intrusion.Plotting of Cr vs.V,Ti+V vs.Al+Mn,Ga vs.Mg and Ga vs.Sn for two types magnetite indicate that the two types of magnetites are formed in an ore-forming fluid with higher oxygen fugacity and temperature(nearly 300℃),which show increasing temperatures with decreasing oxygen fugacity.
作者
牛浩斌
孙卫东
张斌辉
陈敏华
张彬
陆生林
NIU HaoBin;SUN WeiDong;ZHANG BinHui;CHEN MinHua;ZHANG Bin;LU ShengLin(Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;Chengdu Center,China Geological Survey,Chengdu 610081,China;Center of Deep Sea Research,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第1期154-170,共17页
Acta Petrologica Sinica
基金
国家重点研发计划(2016YFC0600408)
中国地质调查局工作项目(DD20190053、DD20160020)联合资助
关键词
磁铁矿
矿物化学
都龙锡锌铟多金属矿床
滇东南
Magnetite
Mineral chemistry
Dulong Sn-Zn-In polymetallic deposit
Southeastern Yunnan
