Geology, geochemistry, and some genetic discussion of the Chador-Malu iron oxide-apatite deposit, Bafq District, Central Iran

Abstract

The Chador-Malu iron oxide-apatite system (Bafq District, Central Iran) contains the largest known iron ore deposit in Iran (pre-mining reserve of 400 Mt @ 55 % Fe), and comprises the pipe-like northern (this study) and the sill-like southern orebodies of predominantly massive ore, and a sodic-calcic alteration envelope. The geology and geochemistry of the Chador-Malu deposit demonstrates its similar characteristics to the Kiruna-type deposits. There is circumstantial evidence for rare earth elements (REE) mobilization during apatite leaching by high-temperature fluids and associated monazite nucleation. Pervasive actinolitization of the rhyolitic country rocks led to the formation of actinolite-rich metasomatic host rocks, which represent another evidence for hightemperature fluids at Chador-Malu. Hydrothermal mineralization is suggested by small iron ore veins (2-3 cm thick) and breccias cemented by iron oxides, as well as a Fe-metasomatism which overprints all types of host rock alteration. Based on REE geochemistry and spatial relationships, it is proposed that a potential source for metals and P could be late-stage Fe-P melt differentiates of the Cambrian magmatism, which is consistent with the late Fe-metasomatism of the host rocks. The proposed Fe-P melts and the mineralization would be linked by hydrothermal media through the zones of ring fracture at Chador-Malu and similar parts of the Bafq district.

Mineralogy of various types of Th-U-REE mineralisation in the iron oxide – apatite deposits of the Bafq district, Central Iran

“…In addition, the data of other deposits (Esfordi, Gazestan, Chadormalu, Se-Chahun and Saghand Anomaly No.5) were obtained from previous studies in the Bafq district (Ramezani and Tucker 2003;Jami 2005;Jami et al 2007;Bonyadi et al 2011;Hafezian and Jamali 2015;Sabet Mobarhan Talab et al 2015;Heidarian et al 2017;Majidi et al 2017;Deymar et al 2018;Heidarian et al 2018;Sepehrirad et al 2018;Mirzababaei et al 2021).…”

“…The Chadormalu iron oxide–apatite deposit is composed of two massive orebodies including the northern pipe-like orebody (containing 80% of the total ore resource) and the southern sill-like orebody. The massive magnetite-apatite mineralisation displays faulted and brecciated contacts with metasomatised greenish host rocks, and dispersed magnetite-apatite veins crosscut altered actinolite- and/or albite-rich host rocks (Sabet Mobarhan Talab et al 2015; Heidarian et al 2017).…”