摘要
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 deposit,discovered in recent years,is one of the large-scale iron deposits in the Awulale ore belt in Xinjiang.The ore body is hosted in the metamorphosed volcaniclastic-sedimentary sequence of Dahalajunshan Formation of Lower Carboniferous,and is obviously controlled by fracture and closely associat-ed with skarn.Detailed study on main skarn minerals such as garnet,diopside and magnetite by means of electron microprobe analysis and microscopic observation show that the skarn from the Dunde iron deposit can be divided into two types,i.e.volcanic metamorphic skarn and hydrothermal metasomatic skarn.Volcanic meta-morphic skarn is composed of garnet (mainly grossularite)and augite(mainly diopside)and was formed in a reductive environment.Hydrothermal metasomatic skarn is composed of garnet (mainly andradite)and augite (mainly diopside),and was formed in a oxidizing environment.Volcanic metamorphic stage magnetite contains high Al2 O3 ,TiO2 and low MgO,belonging to magmatic origin type.Hydrothermal metasomatic stage magnetite contains high Al2 O3 ,MnO,low MgO,TiO2 ,belonging to hydrothermal metasomatic type.The skarn has simi-lar total REE content to that of the andesitic tuff in the stratum,and both show similar patterns.The above char-acteristics indicate that the skarn in the Dunde iron deposit might be resulted from thermal metamorphim and hydrothermal metasomatism.The iron ores and skarn spatially coexist and have experienced similar development and evolution.
出处
《现代地质》
CAS
CSCD
北大核心
2014年第1期61-72,共12页
Geoscience
基金
中国地质调查局项目"天山成矿带地质矿产调查评价"(1212011120497)
