Multi-stage orogenic gold-mineralizing systematics at the Seabee gold Operation, northern Saskatchewan, Canada: Constraints from pyrite chemistry and geochronology

Gold mineralization occurs in several different deposits hosted in the Paleoproterozoic Pine Lake greenstone belt of the Trans-Hudson orogen in northern Saskatchewan, Canada, where over 2 million ounces of gold have been produced. The connections between deposits throughout the Seabee Gold Operation are not well understood, including the role of ca. 1875 Ma intrusions in the mineralization. The focus of our study is comparing the ore systems of the Santoy mine and the Fisher property, which are connected by the Santoy shear system, using sulfide mineral chemistry from LA-ICP-MS, mineral paragenesis, and geochronology (U-Pb, Re-Os) to link with regional tectonic events. Our results show i) an early influx of potentially magmatic-hydrothermal, polymetallic fluids prior to deformation (Py 1 ); ii) early- to syn -deformation mineralization (Py 2 ); iii) mainstage orogenic-style mineralization, which includes inclusion-bearing, trace metal-rich Py 3a- inclusion-free Py 3b -Cpy 2 -Po 1 -native gold mineralization from metamorphic fluids or sub-crustal fluids from slab devolatilization syn- to late-deformation; iv) and remobilization, which includes fracture-filling Py 4 -Po 2 -Cpy 3 -native gold-Tbi-Ttd mineralization. The source of the fluids is not known but was likely a combination of metamorphic fluids or from dehydration of mantle lithosphere. . New geochronology addresses the age of main-stage mineralization: ca. 1764 Ma (pyrite Re-Os) remobilized, gold-associated Py 4 at Fisher, and igneous host rocks: ca. 1882 Ma and 1886 Ma (zircon U-Pb). These data show that an intrusion-related model does not fit the main-stage mineralization. We demonstrate a multi-stage, orogenic-dominated gold-mineralizing system along the Santoy shear system that culminated in a remobilization event at ca. 1764 Ma, generating a better understanding of gold systematics within the Trans-Hudson orogen.