The Jeffers Brook diorite–granodiorite pluton: style of emplacement and role of volatiles at various crustal levels in Avalonian appinites, Canadian Appalachians

O and H isotopic evidence for a mantle source of water in appinite magma: An example from the late Neoproterozoic Greendale Complex, Nova Scotia

“…Although the thermobarometer of Ridolfi and Renzulli (2012) is suitable for the host rock composition, we deem it unsuitable for the purposes of this study as its sensitivity to compositional variations in amphibole may introduce large uncertainties in estimations of crystallization conditions (Ulrych et al, 2018). Although the Al content of hornblende indicates crystallization at 5-7 kbar and between 650-750 °C (Anderson and Smith, 1995;Pe-Piper and Piper, 2018), Figure 10a suggests that temperature conditions could have been closer to 650 °C which supports crystallization between 5-8 kbar. The empirical barometer of Pál-Molnár et al…”

Mineralogy of an Appinitic Hornblende Gabbro and Its Significance for the Evolution of Rising Calc-Alkaline Magmas

“…The Jeffers Brook pluton [5] is a laccolith of a slightly younger age [2], situated about 80 km west of the Frog Lake pluton (Figure 1a). The Jeffers Brook pluton consists mainly of tonalite-granodiorite, but the base of the laccolith and the underlying sills include gabbro, hornblende gabbro and diorite, and similar hornblende gabbro occurs as discrete bodies and enclaves in the main tonalite-granodiorite.…”

“…Also present are irregular segregations or enclaves of granitic composition that may represent patches of immiscible felsic magma [41]. The Jeffers Brook pluton is a compositionally-differentiated laccolith at a shallow depth that appears to involve fewer magma emplacement events, with mafic magmas forming pods with chilled margins and mafic microgranular enclaves within the main tonalite-granodiorite [5].…”

“…The Frog Lake and Jeffers Brook plutons represent strongly-contrasting styles and depths of emplacement. The Jeffers Brook pluton was emplaced as a laccolith with a gabbroic floor at an upper crustal structural level into Neoproteroic supracrustal rocks of lower greenschist facies [5]. The present study investigates the mineralogy of the Frog Lake hornblende gabbro pluton [4], which was emplaced into upper greenschist Mesoproterozoic country rock including biotite-quartz-chlorite-garnet schists [8].…”

“…In the Avalon terrane of northern mainland Nova Scotia, Canada (Figure 1), calc-alkaline hornblende gabbro to granodiorite plutons, resembling appinites, were emplaced at 620 to 605 Ma [2]. Three appinite complexes are well known in Nova Scotia: the Frog Lake pluton [3,4] and the Jeffers Brook pluton [5] in the Cobequid Highlands, and the Greendale complex in the Antigonish Highlands [6] (Figure 1a). The Greendale complex was emplaced in a dextral fault zone into greenschist to sub-greenschist Neoproterozoic country rock [7].…”