| Title | Deformation, metamorphism and mobilization of Ni-Cu-PGE sulfide ores at Garson Mine, Sudbury |
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| Author | Mukwakwami, J; Lafrance, B; Lesher, C M; Tinkham, D K; Rayner, N M ; Ames, D E |
| Source | Mineralium Deposita vol. 49, issue 2, 2013 p. 175-198, https://doi.org/10.1007/s00126-013-0479-y |
| Image |  |
| Year | 2013 |
| Alt Series | Earth Sciences Sector, Contribution Series 20140501 |
| Publisher | Springer Nature |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Ontario |
| NTS | 41I |
| Area | Garson Mine; Sudbury |
| Lat/Long WENS | -81.5000 -80.5000 46.7500 46.2500 |
| Subjects | economic geology; geochemistry; igneous and metamorphic petrology; metallic minerals; breccia deposits; hydrothermal deposits; magmatic deposits; metasomatic deposits; mineral deposits; sulphide
deposits; deformation; shear zones; metamorphism; igneous rocks; metamorphic rocks; pentlandite; pyrrhotite; chlorite; ultramafic rocks; amphibolite facies |
| Illustrations | geologic sketch maps; structural maps; graphs; photomicrographs; equations; tables; photographs; ternary diagrams; phase diagrams |
| Program | Targeted Geoscience Initiative (TGI-4) Mafic-Ultramafic Ore Systems |
| Released | 2013 08 06 |
| 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 D1 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 D2 at mid-greenschist facies metamorphism. Syn-D2 metamorphic titanite yields an age of 1,849?±?6 Ma, suggesting that D1 and
D2 occurred immediately after crystallization of the SIC during the Penokean Orogeny. The ore bodies plunge steeply to the south parallel to colinear L1 and L2 mineral lineations, indicating that the geometry of the ore bodies are strongly controlled
by D1 and D2. Sulfide mineralization consists of breccia ores, with minor disseminated sulfides hosted in norite, and syn-D2 quartz–calcite–sulfide veins. Mobilization by ductile plastic flow was the dominant mechanism of sulfide/metal mobilization
during D1 and D2, with additional minor hydrothermal mobilization of Cu, Fe, and Ni by hydrothermal fluids during D2. Metamorphic pentlandite overgrows a S1 ferrotschermakite foliation in D1 deformed ore zones. Pentlandite was exsolved from
recrystallized polygonal pyrrhotite grains after cessation of D1, 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 S2 chlorite foliation in D2 shear zones. Pyrrhotite recrystallized and was flattened during D2 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 D1 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 °C during D1 and continued to deform as a monosulfide solid solution during D2. |
| GEOSCAN ID | 296080 |
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