新疆准噶尔北缘乔夏哈拉和老山口铁铜金矿床地质特征及磁铁矿成分分析

Analysis of Magnetite Composition and Geological Characteristics of Qiaoxiahala and Laoshankou Fe-Cu-Au Deposits in the Northern Junggar,Xinjiang

乔夏哈拉和老山口铁铜金矿床位于准噶尔北缘,矿体主要呈似层状、透镜状、脉状赋存于北塔山组中基性火山-沉积岩及火山碎屑岩中。两个矿床磁铁矿中广泛发育"溶解-再沉淀"现象,可划分为Mt1和Mt2两个阶段。通过电子探针研究,得出Mt2比Mt1富铁、低杂质元素(SiO_2、K_2O、Al_2O_3、MgO、Na_2O)的结果,结合镜下Mt2包裹、交代Mt1特征,认为成矿过程至少存在两个阶段性,为富铁矿的形成机制提供了有利线索。

The Qiaoxiahala and Laoshankou Fe-Cu-Au deposits on the northern margin of the Junggar are hosted by intermediate-mafic volcanic-sedimentary and volcaniclastic rocks of the Beitashan Formation.The orebodies are podiform,veined,and lenticular in form.Dissolution and re-precipitation processes have been extensively identified in magnetite of these two deposits.Magnetite can be divided into Mt1 and Mt2 stage.Based on electron microprobe analyses,this paper obtains that Mt2 contains higher Fe,lower SiO_2,K_2O,Al_2O_3,Mg O,and Na_2O concentrations than Mt1.Combined with characteristics that Mt1 is wrapped and replaced by Mt2,the authors hold the view that mineralization process had at least two stages,which provided favorable clues for the mechanism to form high-grade Fe deposit.