The Sisson Brook deposit is a low-grade, large-tonnage W-Mo deposit with notable Cu located in west-central New Brunswick, Canada, and is one of several W-Mo deposits in New Brunswick associated with fluids sourced from granitic plutons emplaced during the Devonian Acadian Orogeny. The younger Devonian-aged stockwork and replacement scheelite-wolframite-molybdenite (and chalcopyrite) mineralization straddles the faulted boundary between Cambro-Ordovician metasedimentary rocks with Ordovician felsic volcaniclastic rocks and the Middle Silurian Howard Peak Granodiorite, with dioritic and gabbroic phases. U-Pb dating of magmatic titanite in the host dioritic phase of the Howard Peak Granodiorite using LA ICP-MS resulted in a ²⁰⁴Pb-corrected concordant age of 432.1 ± 1.9 Ma. Petrologic examination of selected mineralization combined with elemental mapping of vein selvages using micro-XRF and metasomatic titanite and ilmenite grains using LA ICP-MS indicates that saturation of titaniferous phases influenced the distribution of scheelite versus wolframite mineralization by altering the aFe/aCa ratio in mineralizing fluids. Ilmenite saturation in Ti-rich host rocks lowered the relative aFe/aCa and led to the formation of scheelite over wolframite. Altered magmatic titanite and hydrothermal titanite also show increased W and Mo concentrations due to interaction with and/or saturation from mineralizing fluids.

Dykes intruding along the Melanson Brook Fault record two magmatic episodes in northern New Brunswick. Dykes at the South Gold Zone of the Elmtree gold deposit are aphanitic and magnesian–calcic, whereas those at Ellis Brook (2.5 km to the west) are ilmenite-series and weakly peraluminous with hornblende– and plagioclase–porphyritic phases. Elevated ¹⁴⁷Sm/¹⁴⁴Nd generated by partial melting, titanium depletion, absence of rare earth element fractionation, and trondhjemite-like compositions indicate that the South Gold Zone dykes were sourced from low-volume fluid-fluxed melting of gabbroic crust. An Sm–Nd-depleted model mantle age of 1.1 Ga for the Ellis Brook dykes suggests that they were sourced from melting of Ganderian crustal rocks rather than the sinking Acadian slab. ¹⁴³Nd/¹⁴⁴Nd evolution curves for the South Gold Zone dykes intersect that of the Ellis Brook dykes at 432 and 427 Ma. This suggests that the magma from which the South Gold Zone dykes crystallized was extracted from a similar source area as the magma that generated the Ellis Brook dykes. Evidence of fluid exsolution in the Ellis Brook dykes indicates that they could be a potential source for reduced intrusion-related gold mineralization. The Ellis Brook dykes yielded a U–Pb zircon age of 391 ± 5 Ma, which is consistent with the timing of oceanic slab break-off at the end of the Acadian orogenic cycle. Extraction of South Gold Zone magma occurred up to 40 Myr earlier, likely during the Salinic orogenic cycle.