内蒙古阿拉善左旗查干德日斯超贫磁铁矿地质、磁异常特征:对阿拉善地块火山沉积变质型铁矿资源前景的指示

矿区查干德日斯位于阿拉善地块巴音乌拉山断隆东缘。野外地质、地球物理勘探工作表明该地区存在较大规模的超贫磁铁矿,磁铁矿体TFe平均含量为14.04%(12.32%~14.98%),m Fe 6.55%(5.32%~7.47%)。该磁铁矿主要赋存于灰黑色斜长角闪片麻岩,具明显层控特点,赋矿原岩应为富铁基性火山岩建造,由区域中-深程度变质作用形成,属火山沉积变质型铁矿床。类比阿拉善地块区域磁场特征认为,阿拉善地块弱磁结晶基底中广泛分布的斜长角闪片麻岩类为寻找超贫磁铁矿提供巨大的找矿空间。

Geological and Magnetic Anomaly Characteristics of the Chaganderisi Ultra-low-grade Magnetite in Alxa Left Banner, Inner Mongolia: Implication for the Volcano-sedimentary Metamorphic Iron Ore Resources' Prospect on the Alxa Block

Chaganderisi mining area is located at the eastern margin of the Alxa Block. Through the completed geological and geophysical exploration, A large scale ultra-low-grade magnetite deposit has been found in this mining area. The mean total iron content (TFe) of the magnetite ores is 14.04% (ranging from 12.32% to 14.98%), and the mean magnetic iron content (mFe) is 6.55% (ranging from 5.32% to 7.47%). The ores are obviously characterized by stratobound control, almost hosted in anorthosite hornblende gneisses. The original rock that bears ores could be the iron-rich basic volcanic formation. It can be concluded that the Chaganderisi ultra-low-grade magnetite belongs to volcano-sedimentary metamorphic iron deposit, formed in regional mesometamorphism. By analogy with regional magnetic field of the Alxa Block, We conclude that the mesometamorphic iron-rich basic volcanic rocks , which are widely distributed on Alxa Block, could provide great prospecting perspective for ultra-low-grade magnetite deposit.