Genesis of magnetite of the Wengquangou vonsenite deposit, Fengcheng county, Liaoning Province

Abstract：The Wengquangou vonsenite deposit, Fengcheng county, Liaoning Province, is located in the Liao-Ji Palaeoproterozoic rift and hosted in the boron-bearing series within the Lieryu Formation, lower Liaohe Group. The main ore-minerals are ludwigite, magnetite and szaibelyite, coexisting with gangue minerals including serpentine, dolomite and phlogopite. The magnetite can be distinguished in terms of occurrence from coarse-grained metamorphic (I), fine-grained hydrothermal (II) and stockworks (III). Type I is optically homogeneous and Types II and III appear to be heterogeneous. As detected using electronic microprobe and energy spectroscopy, the homogeneous magnetite has higher contents of Mg and Al and lower Si content than the heterogeneous, resulting in that Type I is harder than types II and III. It is possible that the discrepancy in element contents caused the transformation from homogeneous to heterogeneous magnetite. Study on magnetite shows that the formation process of the Wengquangou deposit includes sedimentary-metamorphism and hydrothermal overprint.