内蒙古赤峰市阿根他拉钠长斑岩型铁矿矿床地质特征与成因探讨

Geological Characteristics and Genesis of Albitophyre Iron Deposit in Agentala,Chifeng,Inner Mongolia

内蒙古赤峰市阿根他拉铁矿是一个可以小规模开采的铁矿与钠长石矿。铁矿所赋存的岩体为原生钠长斑岩,其可能由深部的花岗闪长岩岩浆演化而来。铁矿化可分为两个阶段,第一阶段为黑云母/绿泥石—石英—磁铁矿阶段,为本区主要的铁矿化阶段,形成网脉状—浸染状的磁铁矿矿石。该阶段成矿岩体为斑岩、网脉状矿化、伴生矿化组合与斑岩型矿床可类比及磁铁矿的(Ca+Al+Mn)—(Ti+V)图解位于斑岩型矿床中,表明该阶段具有类似于斑岩型矿床的特征。第二阶段为绿帘石—磁铁矿/赤铁矿阶段,形成可达工业品位的团块状磁铁矿/赤铁矿矿石。该阶段类似于矽卡岩型铁矿的团块状矿石,及磁铁矿的(Ca+Al+Mn)—(Ti+V)图解位于矽卡岩型铁铜矿床中,表明该阶段具有类似于矽卡岩型铁矿床的特征。将如上与钠长斑岩有关,前期表现为类似斑岩型矿床特征,后期表现为类似矽卡岩型铁矿床特征的铁矿,称为钠长斑岩型铁矿。这类铁矿应注重与绿帘石伴生的团块状铁矿的寻找。对比研究表明,钠长斑岩型铁矿明显有别于长江中下游的玢岩铁矿。

The Agentala iron deposit is a small iron and albite deposit in Chifeng,inner Mongolia. The rocks hosting iron deposit is albitophyre,and it may from the evolution of granodiorite magma chamber in deep. The iron deposit can be divided into two stages. The first stage with the mineral components of biotite（ chlorite） —quartz—magnetite,is the mainly iron mineralization stage in the deposit. This stage formed the net-vein magnetite ores and disseminated magnetite ores. Porphyry of metallogenic rock,the net vein mineralization,accompanying mineral components can be analogy with porphyry deposit,and in（ Ca ＋ Al ＋ Mn） —（ Ti ＋ V） diagram,magnetite of this stage is in porphyry Cu deposit,all of above,indicates the genesis of net-vein magnetite ores and disseminated magnetite ores is similar to porphyry deposit. The second stage with the mineral components of epidote—magnetite /hematite,formed the massive magnetite / hematite ores of industrial grade. Massive ores in this stage is similar to massive ores of skarn deposit,and in（ Ca ＋ Al ＋ Mn） —（ Ti ＋ V） diagram the magnetite of this stage is in skarn Fe—Cu deposit,indicates the genesis of massive magnetite / hematite ores is similar to skarn Fe deposit. The above deposit which relatied with albitophyre and has geological characteristics similar to porphyry deposit in earlier stage and has geological characteristics similar to skarn iron deposit in later stage,can be named albitophyre iron deposit.We should pay more attention to massive iron ores accompanied with epidote when prospect this kind of iron deposit. Contrast between porphyrite iron deposits in middle and lower reaches of the Yangtze River and albitophyre iron deposit,it is found they are obvious different.