神农架式铁矿特征简介

神农架铁矿位于华中第一高峰——鄂西神农架原始林区。目前发现具有工业价值的矿区主要有两个:一个在铁厂河,另一个在大神农架主峰附近(图1)。铁矿露头一般在标高2000—2500米以上。虽然该铁矿沉积形成于元古代,但由于它至今几乎未受变质,使它具有独特的矿石类型,以区别于一般前寒武纪沉积变质铁矿,因此人们专称它为神农架式。现将该铁矿特征简要报道如下。

A Brief Introduction Of The Characteristics Of The Shennongjia Type Iron Deposit

Located in Shennogjia mountainous area, western Hubei Province and formed in Proterozoic era, the ore deposit under investigation differs from Precambrian .metamorphic-sedimentary iron ore deposits in that it hasn-tundergone metamorphism. Occurring stratoid and lenticular forms, its ore bodies are confined to Kuaigshishan Formation of Shennorigjia Group. From bottom to top, the ore-bearing sequence changes lithologically in order of sandstone-silty pelite-iron ore beds-clay slate with the main ore beds lying where clastic rocks grade into clay slates. Iron ores consist mainly of hematite and Fe-rich chlorite associated with such accessory minerals as quartz and hydromica; they show predominantly clastic and oolitic textures and are characterized in chemical composition by SiO₂ +Al₂O₃>MgO + CaO. An investigation into the ore-bearing sequence suggests evidently the formation of ore bodies in epicontinental environment; hematite, magnetite and Fe-rich chlorite are considered to be syngenetic minerals formed under favorable physico-chemical conditions.