‘The Stillwater Complex: Integrating Zircon Geochronological and Geochemical Constraints on the Age, Emplacement History and Crystallization of a Large, Open-system Layered Intrusion’: a Reply to the Comment by Rais Latypov on Wall et al. (J. Petrology, 59, 153–190, 2018)

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We are pleased to have the opportunity to discuss the comments of Latypov (2019) on the interpretations and significance of the extensive U–Pb zircon–baddeleyite–rutile–titanite geochronological and zircon trace element dataset reported by Wall et al. (2018) from the Neoarchean Stillwater Complex in southern Montana (USA). Layered intrusions are the crustal repositories for minerals crystallized from mantle-derived magmas and have long fascinated geologists with their remarkable records of magmatic differentiation (Bowen, 1928; Wager & Brown, 1967; Parsons, 1987; Cawthorn, 1996; Charlier et al., 2015). Establishing the timescales of emplacement and crystallization of mafic intrusions (layered intrusions, dikes, sills) is critical to the assessment of a wide range of processes, including rates of mantle melting and magma transport through the crust, crystallization timescales in magma reservoirs and crystal mushes, relationships to mineralization, evolution of crustal magmatism, and potential links between magmatic degassing and global environmental impacts (e.g. LeCheminant & Heaman, 1989; Premo et al., 1990; Hamilton et al., 1998; Schwartz et al., 2005; Heaman et al., 2009; Mackie et al., 2009; Chamberlain et al., 2010; Scoates & Scoates, 2013; Burgess & Bowring, 2015; Scoates & Wall, 2015; Mungall et al., 2016; Burgess et al., 2017; Scoates et al., 2017). As a community, we now have the tools to precisely (i.e. significantly less than 1%) and accurately date individual, or even parts of, zircon grains that yield concordant U–Pb systematics (e.g. Mattinson, 2005; Schmitz & Kuiper, 2013; Schoene, 2014; Samperton et al., 2015). We can also now track the petrochronological evolution of individual zircon grains by integrating these dates with trace element geochemistry and Ti-in-zircon thermometry determined in situ by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) (e.g. Ferry & Watson, 2007; Grimes et al., 2009; Claiborne et al., 2010; Kylander-Clark et al., 2013; Samperton et al., 2015; Ver Hoeve et al., 2018).