Newly identified iron oxide-apatite deposit in Carboniferous marine volcanic rocks in the Beishan area and its implications for regional metallogeny: A case study of the Biyushan iron deposit, Inner Mongolia

Abstract

Objective Numerous iron deposits hosted in Carboniferous marine volcanic rocks occurred in the Beishan Orogenic Belt, Eastern Tianshan.The Biyushan iron deposit, located at the northwestern margin of Inner Mongolia, is a typical iron deposit hosted in Carboniferous marine volcanic rocks. Methods In this study, we utilized field observation, microscope imaging, and scanning electron microscopy to charaterize the mineral assemblages of iron ores and microtextures of magnetite and apatite, in order to decipher the genesis of iron ores. Results Our preliminary work has revealed that iron ores in the Biyushan deposit commonly have a mineral assemblage of magnetite-apatite, with apatite having abundant monazite inclusions due to the dissolution-reprecipitation processes.In addition, magnetite grains commonly have high Ti contents with ilmenite exsolution.Thus, the mineral assemblage of iron ores and mineralogical features of apatite and magnetite are similar to these of typical Kiruna-type deposits. Conclusion Based on our preliminary analysis of geological characteristics, we suggest that the Biyushan iron deposit in Inner Mongolia is likely a Kiruna-type iron deposit hosted in submarine volcanic rocks that has not yet been documented.Therefore, these findings can guide future exploration of iron oxide-apatite deposits in this region.

Keywords

• kiruna (iron oxide-apatite) deposit
• biyushan iron deposit
• magnetite
• apatite
• ore genesis