ISBN:

0026-4598

Keywords:

Canada, copper ores, deformation, ductile deformation, eastern canada, facies, foliation, gabbros, geologic thermometry, geometry, greenschist facies, host rocks, igneous rocks, lineation, metal ores, Metallogeny, metals, Metamorphic rocks, metamorphism, mineral composition, mineral deposits, genesis, Mineral exploration, mining geology, mobilization, nickel ores, norite, Ontario, overprinting, Penokean Orogeny, Petrology, platinum group, platinum ores, plutonic rocks, Precambrian, structural analysis, Sudbury Igneous Complex, Sudbury Ontario, sulfides, textures

Abstract:

The Garson Ni-Cu-platinum group element deposit is a deformed, overturned, low Ni tenor contact-type deposit along the contact between the Sudbury Igneous Complex (SIC) and stratigraphically underlying rocks of the Huronian Supergroup in the South Range of the 1.85-Ga Sudbury structure. The ore bodies are coincident with steeply south-dipping, north-over-south D (sub 1) shear zones, which imbricated the SIC, its ore zones, and underlying Huronian rocks during mid-amphibolite facies metamorphism. The shear zones were reactivated as south-over-north, reverse shear zones during D (sub 2) at mid-greenschist facies metamorphism. Syn-D (sub 2) metamorphic titanite yields an age of 1,849 + or - 6 Ma, suggesting that D (sub 1) and D (sub 2) occurred immediately after crystallization of the SIC during the Penokean Orogeny. The ore bodies plunge steeply to the south parallel to colinear L (sub 1) and L (sub 2) mineral lineations, indicating that the geometry of the ore bodies are strongly controlled by D (sub 1) and D (sub 2) . Sulfide mineralization consists of breccia ores, with minor disseminated sulfides hosted in norite, and syn-D (sub 2) quartz-calcite-sulfide veins. Mobilization by ductile plastic flow was the dominant mechanism of sulfide/metal mobilization during D (sub 1) and D (sub 2) , with additional minor hydrothermal mobilization of Cu, Fe, and Ni by hydrothermal fluids during D (sub 2) . Metamorphic pentlandite overgrows a S (sub 1) ferrotschermakite foliation in D (sub 1) deformed ore zones. Pentlandite was exsolved from recrystallized polygonal pyrrhotite grains after cessation of D (sub 1) , which resulted in randomly distributed large pentlandite grains and randomly oriented pentlandite loops along the grain boundaries of polygonal pyrrhotite within the breccia ore. It also overgrows a S (sub 2) chlorite foliation in D (sub 2) shear zones. Pyrrhotite recrystallized and was flattened during D (sub 2) deformation of breccia ore along narrow shear zones. Exsolution of pentlandite loops along the grain boundaries of these flattened grains produced a pyrrhotite-pentlandite layering that is not observed in D (sub 1) deformed ore zones. The overprinting of the two foliations by pentlandite and exsolution of pentlandite along the grain boundaries of flattened pyrrhotite grains suggest that the Garson ores reverted to a metamorphic monosulfide solid solution at temperatures ranging between 550 and 600 degrees C during D (sub 1) and continued to deform as a monosulfide solid solution during D (sub 2) . Copyright 2013 Springer-Verlag Berlin Heidelberg

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2014-030048<br/>Garson Mine