FLUID INCLUSION AND STABLE ISOTOPE STUDY OF THE ESFORDI APATITE-MAGNETITE DEPOSIT, CENTRAL IRAN--A REPLY

Abstract

Sir: We are pleased that our recent paper in Economic Geology (Jami et al., 2007), presenting the geologic setting, a description of the mineralization, fluid inclusion, and O isotope analyses of the Esfordi P-Fe oxide deposit in central Iran, has been of interest to Aftabi and his colleagues (Aftabi et al., 2009). The opportunity to discuss further some aspects of our paper is appreciated, including support for a hydrothermal-dominated depositional model for Esfordi. Aftabi et al. (2009) focus their comments on the question of the affinity of the Esfordi P-Fe oxide deposit. In particular, they argue that Esfordi and, by inference, other diverse Fe oxide deposits within the Bafq district of central Iran should be considered Rapitan-type banded iron formations, i.e., BIF (Klein, 2005) rather than Kiruna-type (Hitzman, 2000). In discussing our results and conclusions in the light of previous work (particularly, Forster and Jafarzadeh, 1994), Aftabi et al. (2009) have misconstrued our interpretation of some of the textural and isotopic data as providing support for an orthomagmatic model for the Esfordi P-Fe oxide deposit. Based on the structure, relationships between mineralization and host rocks, fluid inclusion and isotopic data, we concluded that Esfordi exhibits strong evidence of hydrothermal origin, though we did not preclude some component of precursor orthomagmatic processes in formation of the P-Fe mineralisation. It is noted that some examples of the Kiruna end member of the continuum of Fe oxide deposits discussed by Hitzman (2000) are controversial, particularly in regard to their evolution (Sillitoe and Burrows, 2002; Henriquez et al., 2003). We have shown that Esfordi has a number of features typical of the Kiruna-type deposits and does not exhibit features consistent with an affinity to Rapitan-type Fe-oxide deposits. This evidence will be discussed briefly, with further data …