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敦德铁矿是新疆阿吾拉勒铁矿带内近年新发现的大型铁矿之一,矿体赋存于下石炭统大哈拉军山组火山岩地层中,与矽卡岩密切共生。岩相学、矿相学及矿物化学研究表明,敦德铁矿矽卡岩主要分为火山变质成因矽卡岩和热液交代成因矽卡岩两种类型。火山变质期矽卡岩中石榴子石的端元组分以钙铝榴石为主,辉石端元组分主要为透辉石。热液交代期矽卡岩中石榴子石的端元组分以钙铁榴石为主,辉石端元组分主要为透辉石。火山变质期磁铁矿具有富Al2O3、贫MgO、高TiO2的特点,属于岩浆成因的磁铁矿。热液交代期磁铁矿具有富Al2O3、MnO,贫MgO、低TiO2的特点,为热液交代成因磁铁矿。本区矽卡岩与地层中的凝灰岩无论在稀土总量上还是在配分模式均十分相近。这暗示敦德铁矿床中的矽卡岩与正常的矽卡岩形成方式不同,不是中酸性岩浆与碳酸盐岩地层接触交代的产物,而是安山质凝灰岩经热变质及热液交代两种作用形成。磁铁矿矿石与矽卡岩在空间上共存,在时间上也经历了大致相同的发展演化。
The Dunde Iron Ore is one of the newly discovered large-scale iron ores newly discovered in the Udolale iron ore belt in Xinjiang. The ore body occurs in volcanic formations of the Lower Halajushan Formation of the Lower Carboniferous and is closely interbedded with skarn. Petrographic, mineralogical and mineral chemistry studies show that the Dunde iron ore skarns are mainly divided into two types: volcanic metamorphic skarn and hydrothermal metasomatic skarn. The end-element component of garnet in skarn in volcanic metamorphism is dominated by almandine, and the terminal element of pyroxene is mainly diopside. The terminal element of garnet in skarn in the hydrothermal stage is dominated by dacite, and the terminal element of pyroxene is mainly diopside. Magmatic volcano metamorphic Al2O3-rich, poor MgO, high TiO2 characteristics, belonging to the magmatic origin of magnetite. In the hydrothermal stage, the magnetite has the characteristics of rich Al2O3, MnO, poor MgO and low TiO2. The skarn in the area and the tuffs in the strata are very similar both in the total amount of rare earths and in the distribution pattern. This suggests that the skarn in the Dundee iron deposit is different from the normal skarn formation in that it is not the product of metasomatic magmatic contact with the carbonate strata but that the andesitic tuff was thermally metamorphosed and replaced by hydrothermal fluids Two kinds of action form. Magnetite ore and skarn coexist in space, in time also experienced roughly the same evolution.