Posht-e-badam metallogenic block (Central Iran): A suitable zone for REE mineralization

Abstract

One of the most important ores for REE mineralization are iron oxide:apatite (IOA) deposits. The Posht:e:Badam Block (PBB) is a part of the Central Iranian geostructural zone which is the host of most important Fe deposits of Iran. Exploration studies of the IOA deposits within the PBB (e.g. Esphordi, Gazestan, Zarigan, Lak:e-Siah, Sechahoun, Chahgaz, Mishdovan, Cheshmeh Firouzi and Shekarab) demonstrate that these deposits contain high contents of REE. Concentrations of σREE in the most important IOA deposits of the PBB include the following: the Esphordi deposit varies between 1.2 and 1.88%, the Gazestan deposit between 0.17 and 1.57%, the Zarigan deposit between 0.5 and 1.2% and the Lak-e-Siah deposit varies between 0.45 and 1.36%. Concentrations of σREE within the apatite crystals present within the IOA ores in the Esphordi, Lak-e-Siah and Homeijan deposits have ranges between 1.9-2.54%, 1.9-2.16% and of 2.55%, respectively. These elements are mainly concentrated in apatite crystals, but other minerals such as monazite, xenotime, bastnasite, urtite, alanite, thorite, parisite-synchysite and britholite have been recognized as hosts of REEs, as small inclusions within the apatite crystals, and in subsequent carbonate, hematite:carbonate and quartz veins and veinlets. Given the extent of this block and the presence of several IOA deposits within this block, and also the high grades of REEs within these deposits, one can reasonably state that it is obvious that there are significant resources of REEs in this part of Iran.