Contents lists available at ScienceDirect Ore Geology Reviews journal homepage: www.elsevier.com/locate/oregeorev Chemistry of magnetite-apatite from albitite and carbonate-hosted Bhukia Gold Deposit, Rajasthan, western India – An IOCG-IOA analogue from Paleoproterozoic Aravalli Supergroup: Evidence from petrographic, LA-ICP- MS and EPMA studies Rahul Mukherjee a , A.S. Venkatesh a, ⁎ , Fareeduddin b a Department of Applied Geology, Indian Institute of Technology (Indian School of Mines), Dhanbad 826004, India b Geological Society of India, No. 1532, 14th Main, Kumaraswamy Layout, Bangalore 560078, India ARTICLE INFO Keywords: Aravalli-Delhi Fold Belt Bhukia Gold Deposit Hydrothermal magnetite Fluorapatite IOCG-IOA association ABSTRACT The Bhukia gold (+copper) deposit hosted by albitite and carbonates that occur within the Paleoproterozoic Aravalli-Delhi Fold Belt (ADFB) in western India consists of magnetite, graphite, apatite and tourmaline along with sulfide mineralization. Ubiquitous presence of magnetite and apatite in gold-sulfide association, alteration patterns and shear controlled mineralization suggest it to be IOCG (Iron-oxide copper gold) type deposits. The detailed mineral chemistry of magnetite and apatite are generated and interpreted in terms of their genetic significance, hydrothermal and magmatic origin vis-à-vis their affiliation with IOCG deposition. The data suggest that the magnetite has hydrothermal affiliation. The Ni/Cr ratio is greater than 1, which is explained by dif- ferences in solubility and mobility of Ni and Cr in hydrothermal fluids and is corroborated with other key evidences including that of wide ranging Mg concentration further supports a strong hydrothermal input that is envisaged for the deposition of magnetite. Concentration of vanadium in magnetite is generally < 1000 ppm in case of barren hydrothermal occurrences while in the study area, it is relatively higher as it is attributed to the gold-sulfide-Cu mineralization. Ti vs Ni/Cr, Ni/(Cr+Mn) vs Ti+V, Ca+Al+Mn vs Ti+V and Al+Mn vs Ti+V variations are interpreted in terms of magnetite genesis. EPMA data suggests that apatite present in Bhukia is of fluorapatite variety with F content > 1 wt% and F/Cl > 1. Higher concentration of F and moderate Mn along with lower concentration of Cl attests their magmatic hydrothermal character and its derivation from meta- volcano sedimentary source. REE patterns obtained from LA-ICP-MS analysis suggest enrichment of LREE re- lative to MREE and HREE with negative Eu anomaly. Y/∑REE, La/Sm, Ce/Th and Eu/Eu * vs Ce/Ce * values of apatite is indicative of their origin in a highly oxidized environment. Presence of magnetite along with apatite is a common feature in IOCG-IOA (Iron-Oxide Apatite) association. Bhukia Gold Deposit has many similarities with Kiruna type Iron-Oxide Apatite (IOA) deposits particularly with respect to their similar tectonic setting, al- teration patterns, mineral assemblages such as abundance of magnetite, apatite and presence of late stage sul- fides based on EPMA and Laser ablation ICP-MS (LA-ICP-MS) studies. Lithological, petro-mineralogical and geochemical signatures of magnetite and apatite infer that the Bhukia is a possible IOCG-IOA type gold deposit typically associated with sulfides and graphite which may be used as petrogenetic indicators and pathfinders for exploration. 1. Introduction Magnetite is commonly found in various geological environments either as a major or an accessory mineral (Dupuis and Beaudoin, 2011; Xiaowen et al., 2014; Chen et al., 2015b; Makvandi et al., 2016). It forms at a lower temperature from hydrothermal fluids and concentrate to form hydrothermal magnetite deposits (Bookstrom, 1995; Groves et al., 2010; Nadoll et al., 2012) or it can crystallized from high tem- perature silicate and sulfide melts (Dare et al., 2014). Magnetite is a common ore mineral in many banded iron formations (BIF) (Nadoll et al., 2012, 2014; Chung et al., 2015), also found in varying amounts in a wide variety of geological environments (Philpotts, 1967; Dupuis and Beaudoin, 2011; Dare et al., 2014; Liu et al., 2015). Its universality could be attributed to its formation under relatively high temperature http://dx.doi.org/10.1016/j.oregeorev.2017.09.005 Received 22 November 2016; Received in revised form 6 September 2017; Accepted 11 September 2017 ⁎ Corresponding author. E-mail address: asvenkatesh@hotmail.com (A.S. Venkatesh). Ore Geology Reviews xxx (xxxx) xxx–xxx 0169-1368/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Mukherjee, R., Ore Geology Reviews (2017), http://dx.doi.org/10.1016/j.oregeorev.2017.09.005