Contents lists available at ScienceDirect Ore Geology Reviews journal homepage: www.elsevier.com/locate/oregeorev Three-stage formation of greenstone-hosted orogenic gold deposits in the Val-d’Or mining district, Abitibi, Canada: Evidence from pyrite and tourmaline Lucille Daver a, ⁎ , Michel Jébrak a , Georges Beaudoin b , Robert B. Trumbull c a Département des sciences de la Terre et de l’atmosphère, Université du Québec à Montréal, QC, Canada b Département de géologie et de génie géologique, Université Laval, Québec, QC, Canada c German Research Centre for Geosciences GFZ, Telegrafenberg 14473, Potsdam, Germany ARTICLEINFO Keywords: Orogenic gold Tourmaline Pyrite LA-ICP-MS Element mapping Boron isotopes Val-d’Or Abitibi ABSTRACT Orogenic gold deposits are the most widespread type of gold deposit worldwide, defning important exploration targetsinPrecambriangreenstonebelts.Here,werefnethemodel fororogenicgoldformationintheworld-class Val-d’Or mining district (Quebec, Canada) using geochemical, isotopic and mineralogical data from quartz- tourmaline-carbonate (QTC) veins from several deposits across the district. Multi-element (Ag, As, Au, B, Ba, Co, Mg, Mo, Ni, and Pb) pyrite mapping, as well as major, trace, and rare earth element variations in tourmaline, defne a three-stage paragenesis across several deposits. The frst, reduced phase crystallized the quartz-carbo- nate-gold association in the veins; the second, oxidized phase favored tourmaline and barite crystallization (barite was not previously reported from this district); the third phase involved a reduced fuid and the crys- tallization of non-auriferous, As-Co-Ni-rich cubic pyrite, and tourmaline. Boron isotope ratios of tourmaline vary from −15.6 to −7.7‰, which is attributed to the mixing of at least two fuids, one related to a deep, meta- morphic source and the other to shallower, possibly relict formation water. A systematic regional pattern in B- isotope variation is found, with lighter values in the volcanic rocks and heavier ones in or close to intrusions, which suggests diferent mixing proportions in the vein feld from NE to SW. 1. Introduction Archean greenstone belts host most of the world’s high-grade oro- genic gold deposits. Among them, the Abitibi subprovince in the southeastern part of the Precambrian Canadian Shield hosts hundreds of gold deposits, distributed over more than 200 km along two major connected reverse shear zones: the Cadillac-Larder Lake Fault Zone (CLLFZ)tothesouthandthePorcupine-DestorFaultZone(PDFZ)tothe north (Fig. 1; Robert, 1994). The Val-d’Or mining district is located in the eastern part of the Abitibi subprovince along the CLLFZ. It hosts approximately 55 auriferous quartz-tourmaline-carbonate (QTC) vein deposits spread over a 40 by 15 km area (Fig. 1), which together con- tainatotalof~20millionouncesAu(Rafni, 2014). In this district, the Sigma QTC auriferous veins have become one of the archetypes of orogenic gold deposits (Sibson et al., 1988; Robert, 1994; Gaboury, 1999; Neumayr and Hagemann, 2002). Based on structural and hydrothermal characteristics (mineral as- semblages and alteration), the Abitibi gold-bearing QTC vein feld is commonly understood to represent a single hydrothermal event (Robert, 1994). Mineralization is suggested to have occurred at the end of the formation of the Superior Province (~2.6 Ga), or shortly there- after, through the process of seismic pumping, whereby fuid transport occurred in seismically-induced pulses (Sibsonetal.,1975;Boullierand Robert, 1992). This process resulted in the circulation of mineralized hydrothermal fuids into third-order fault systems of the CLLFZ during earthquake rupturing episodes. However, the precise chronology of this episodic inflling is still debated (Kerrich and Ludden, 2000; Robert et al., 2005). Previous isotopic studies in the Val-d’Or district (Beaudoin and Pitre, 2005; Beaudoin and Chiaradia, 2016) suggest a fuid mixing scenario for the mineralizing fuid two diferent fuid reservoirs where the H-O-Sr isotope values of the vein assemblage are interpreted to refect two end-member fuids: one metamorphic and another supra- crustal (Beaudoin and Chiaradia, 2016). A preliminarily tourmaline B- isotope study by Beaudoin et al. (2013) suggested the presence of a regional southwest to northeast isotopic zonation in the district. https://doi.org/10.1016/j.oregeorev.2020.103449 Received 16 March 2019; Received in revised form 14 February 2020; Accepted 3 March 2020 ⁎ Corresponding author. E-mail address: daver.lucille@uqam.ca (L. Daver). Ore Geology Reviews 120 (2020) 103449 Available online 09 March 2020 0169-1368/ © 2020 Elsevier B.V. All rights reserved. T