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TitleCompleting the bedrock mapping of southern Baffin Island, Nunavut: plutonic suites and regional stratigraphy
AuthorWeller, O M; Dyck, B J; St-Onge, M R; Rayner, N; Tschirhart, V
SourceCanada-Nunavut Geoscience Office, Summary of Activities 2015 p. 33-48
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20150290
PublisherCanada-Nunavut Geoscience Office
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut
NTS26B/09; 26B/10; 26B/11; 26B/12; 26B/13; 26B/14; 26B/15; 26B/16; 26C; 26F; 26G; 26J; 26K
AreaBaffin Island
Lat/Long WENS -70.0000 -66.0000 67.0000 64.0000
Subjectsgeneral geology; igneous and metamorphic petrology; structural geology; geophysics; regional geology; magmatic rocks; bedrock geology; mafic metavolcanic rocks; metamorphic facies; metasedimentary rocks; ultramafic metavolcanics; orogenies; petrography; Trans-Hudson Orogen; Precambrian; Cambrian
Illustrationslocation maps; geological maps; photographs; p-t graphs; phase diagrams
ProgramBaffin Bedrock Mapping, GEM2: Geo-mapping for Energy and Minerals
LinksOnline - En ligne
AbstractThis paper summarises the field observations and initial interpretations following eight weeks of regional and targeted bedrock mapping on south-central Baffin Island, Nunavut. The 2015 field campaign completes a two-decade mission to update the geoscience knowledge for the whole of Baffin Island south of latitude 70 °N. The bedrock in the area is dominated by a Paleoproterozoic metaplutonic suite, ranging in composition from gabbro/quartz diorite to syenogranite, with cross-cutting relations indicating a progression from mafic to silicic magmatism. Phase equilibria modelling reveals that the prevailing upper amphibolite-lower granulite facies metamorphic conditions overlap the stability limits of magnetite and orthopyroxene for a typical granitoid bulk composition, which is consistent with field observations of the discontinuous presence of both phases throughout the field area. This result is also consistent with regional aeromagnetic data that show complex structures within relatively homogeneous map units, which are primarily attributed to variable magnetite mode. The granitoids are interpreted as part of the middle Paleoproterozoic Cumberland batholith.
This paper summarises the field observations and initial interpretations following eight weeks of regional and targeted bedrock mapping on south-central Baffin Island, Nunavut. The 2015 field campaign completes a two-decade mission to update the geoscience knowledge for the whole of Baffin Island south of latitude 70 °N. The bedrock in the area is dominated by a Paleoproterozoic metaplutonic suite, ranging in composition from gabbro/quartz diorite to syenogranite, with cross-cutting relations indicating a progression from mafic to silicic magmatism. Phase equilibria modelling reveals that the prevailing upper amphibolite-lower granulite facies metamorphic conditions overlap the stability limits of magnetite and orthopyroxene for a typical granitoid bulk composition, which is consistent with field observations of the discontinuous presence of both phases throughout the field area. This result is also consistent with regional aeromagnetic data that show complex structures within relatively homogeneous map units, which are primarily attributed to variable magnetite mode. The granitoids are interpreted as part of the middle Paleoproterozoic Cumberland batholith. Metasedimentary rocks, including quartzite, pelite, marble and greywacke, are present as screens and enclaves between and within plutonic bodies. A compilation of the 'ghost' stratigraphy suggests that the metasedimentary rocks throughout most of the field area can be correlated with the middle Paleoproterozoic Lake Harbour Group, except in the north-east, where the unique presence of greywacke suggests a middle Paleoproterozoic Piling Group affinity. This transition in strata is consistent with the proposal that a middle Paleoproterozoic tectonic suture (the Baffin suture) associated with the Trans Hudson Orogen runs through Cumberland Sound. Completion of the bedrock mapping in southern Baffin Island indicates that the region offers world-class exposure of a reworked Paleoproterozoic convergent margin, which affords valuable insight into a variety of magmatic and tectonic processes that can be applied to younger collisional belts.
Summary(Plain Language Summary, not published)
During the summer of 2015, the Geological Survey of Canada, in collaboration with the Canada-Nunavut Geoscience Office, the Government of Nunavut, and students from Nunavut Arctic College, Carleton University and Oxford University, led a successful eight-week geological mapping campaign in south-central Baffin Island. The objective of the fieldwork was to improve the geological knowledge and document the economic potential of the region. Field observations established the distribution of rock types across the study area, and samples were collected for future analysis, including age determination, carving stone potential, and concentration of economically significant minerals. The data collected will be used to update the current model of the geological evolution of Nunavut, and will inform future geoscience projects on Baffin Island. With the completion of the 2015 fieldwork, all of Baffin Island south of latitude 70 °N has been mapped with modern geoscience techniques.
GEOSCAN ID297290