Diversity of Net-Textured Sulfides in Magmatic Sulfide Deposits: Insights from the Eagle’s Nest Ni-Cu-(Platinum Group Element) Deposit, McFaulds Lake Greenstone Belt, Superior Province, Canada

Abstract The Eagle’s Nest Ni-Cu-(platinum group element; PGE) deposit occurs within the 2.73 Ga Esker intrusive complex of Ring Fire suite in McFaulds Lake greenstone belt northern Ontario. Mineralization along margin a formerly ~500-m-high, ~85-m-thick, >1,500-m-long subvertical structurally rotated blade-shaped dike composed harzburgite, lherzolite, and wehrlite. Three sulfide textural facies are present (percentage as proportion total mineralization): (1) disseminated (~5%), (2) net texture (~80%), (3) semimassive to massive (~15%). Five subfacies have been identified: bimodal olivine-bearing leopard (~50%), inclusion orthopyroxene-bearing pinto (<1%), (4) localized zones disrupted (~30%) containing 3- 5-cm-thick barren amoeboid crosscutting pyroxenite, (5) fine-grained patchy All characterized by typical magmatic pyrrhotite-pentlandite-chalcopyrite-(platinum mineral) assemblages. Massive sulfides two embayments basal contact separated topographic high, grading upward rare semimassive, laterally more continuous net-textured, sulfides, with gradational contacts between all textures except massive. Similar mean ore tenors different (Ni100 ~7.5, Cu100 ~4.8), suggest that majority mineralization formed from similar magma compositions at magma/sulfide ratios, but presence populations (peridotite, gabbro, chromitite) indicates olivine, inclusions, melts accumulated multiple pulses dynamic system. smaller, blade-shaped, sulfide-rich, chromite-poor body does not appear be feeder overlying larger, oblate, sulfide-poor, chromite-rich Double Eagle body. This highlights need understand fluid dynamics entire plumbing systems when exploring for these types significance conduits environments favorable Ni-Cu-(PGE) mineralization.