| Title | Sulfide immiscibility induced by wall-rock assimilation in a fault-guided basaltic feeder system, Franklin Large Igneous Province, Victoria Island (Arctic Canada) |
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| Author | Hayes, B; Bédard, J H; Hryciuk, M; Wing, B; Nabelek, P; MacDonald, W D; Lissenberg, C J |
| Source | Economic geology and the bulletin of the Society of Economic Geologists vol. 110, 2015 p. 1697-1717, https://doi.org/10.2113/econgeo.110.7.1697
 Open Access |
| Year | 2015 |
| Alt Series | Earth Sciences Sector, Contribution Series 20140542 |
| Publisher | Society of Economic Geologists |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Nunavut |
| NTS | 77 |
| Area | Victoria Island |
| Lat/Long WENS | -120.0000 -107.0000 73.0000 71.0000 |
| Subjects | igneous and metamorphic petrology; igneous rocks; igneous petrology; magmatism; dykes; diabase dykes; dykes, mafic; sills; petrography; petrographic analyses; Franklin Lip; Franklin Large Igneous
Province; Minto Inlier |
| Illustrations | location maps; tables; block diagrams; plots; stereonets |
| Program | GEM: Geo-mapping for Energy and Minerals PGE/Base Metals - Victoria Island (NWT and Nunavut) |
| Released | 2015 09 22 |
| Abstract | The Southern Feeder Dike Complex is part of the Franklin Large Igneous Province (LIP), exposed in the Minto Inlier of Victoria Island in the Canadian Arctic. Previous field and geochemical studies on
the Franklin LIP considered its igneous rocks to be prospective for Fe-Ni-Cu mineralization. The Southern Feeder Dike Complex comprises a series of NW-SE-trending gabbroic intrusions and sedimentary hosts. Field and textural relationships show that
the Complex intrusions were emplaced contemporaneously with Neoproterozoic normal faulting. Faulted contact zones correspond to prominent first derivative magnetic lineaments. Gabbroic dikes have intrusive contacts against brecciated country rock,
and diabasic microxenoliths in basaltic matrices indicate multiple intrusive/brecciation events. Intrusive breccias are commonly overprinted by hydrothermal greenschist facies assemblages, with calcite + pyrite veins filling open spaces between
breccia fragments. Late dikes emplaced into these heterogeneous breccias contain disseminated globular and net-textured sulfides suggesting that sulfide immiscibility was triggered on a local scale by assimilation of local wall rock. This inference
is supported by elevated d34S values of sulfides in these dikes, consistent with assimilation of country rocks. Wall-rock assimilation would have been facilitated by fault-related brecciation and cataclasis, which would expose extensive xenolith
surface areas to fresh magma. Gossanous and meter-scale semimassive sulfide showings associated with dikes and sills located upsection from the Southern Feeder Dike Complex suggest that immiscible sulfide liquids may have been flushed downstream (or
upsection) during replenishment of composite dike systems. Fault-mediated melt ascent along northwest-southeast faults has been documented elsewhere in the Minto Inlier, providing equivalent opportunities for wall-rock assimilation and consequent
triggering of sulfide immiscibility and sulfide melt redistribution. The evidence preserved in the Complex confirms the Fe-Ni-Cu potential of the Franklin LIP and informs current models of ore deposit formation in conduit-type magmatic plumbing
systems. |
| Summary | (Plain Language Summary, not published)
This paper provides detailed observations of a fault-guided magmatic feeder system to the Franklin magmatic suite on Victoria island. Some of the
basaltic intrusions have elevated sulfur isotope signatures (34S) and contain immiscible blebs of sulfide, suggesting that assimilation of sedimentary wallrock triggered sulfide immiscibility. This implies that Franklin magmas with elevated 34S
isotopic signatures may be most prospective for Cu-Ni-PGE deposits. |
| GEOSCAN ID | 296174 |
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