The newly identified iron oxide-apatite deposit in the Beishan area and its implication for regional metallogeny: a case study of Biyushan deposit, Inner Mongolia

Numerous iron deposits hosted in Carboniferous marine volcanic rocks have developed in the Beishan Orogenic Belt, eastern Tianshan. Biyushan iron deposit is a typical iron deposit hosted in Carboniferous marine volcanic rocks. This deposit is located at the northwestern margin of Inner Mongolia. Our preliminary work has revealed that iron ores in the Biyushan deposit commonly have the 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 content with ilmenite exsolution. Thus, the mineral assemblage of iron ores and mineralogical features of apatite and magnetite are similar to the typical Kiruna-type deposits. Based on our preliminary analysis of the geological characteristics, we suggest the Biyushan iron deposit in Inner Mongolia is likely a Kiruna-type iron deposit hosted in submarine volcanic rocks which have not yet been documented before. Therefore, this finding can provide guidance for future exploration of iron oxide-apatite deposits in this region.