A fluid inclusion and isotopic study of an intrusion-related gold deposit (IRGD) setting in the 380 Ma South Mountain Batholith, Nova Scotia, Canada: evidence for multiple fluid reservoirs

摘要

A set of sheeted quartz veins cutting 380 Ma monzogranite at Sandwich Point, Nova Scotia, Canada, provide an opportunity to address issues regarding fluid reservoirs and genesis of intrusion-related gold deposits. The quartz veins, locally with arsenopyrite (<5%) and elevated Au-(Bi-Sb-Cu-Zn), occur within the reduced South Mountain Batholith, which also has other zones of anomalous gold enrichment. The host granite intruded (P= 3.5 kbars) Lower Paleozoic metaturbiditic rocks of the Meguma Supergroup, well known for orogenic vein gold mineralization. Relevant field observations include the following: (1) the granite contains pegmatite segregations and is cut by aplitic dykes and zones (<1-2 m) of spaced fracture cleavage; (2) sheeted veins containing coarse, comb-textured quartz extend into a pegmatite zone; (3) arsenopyrite-bearing greisens dominated by F-rich musco-vite occur adjacent the quartz veins; and (4) vein and greisen formation is consistent with Riedel shear geometry.