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TitleMapping ultramafic cumulates at the Tulameen ultramafic-mafic Alaskan-type intrusion, south-central British Columbia, aided by remotely piloted aircraft system photogrammetry
AuthorSpence, D W; Crawford, H; Scoates, J S; Nott, J; Nixon, G T; Milidragovic, DORCID logo
SourceBritish Columbia Geological Survey Geological Fieldwork Paper 2022-01, 2022 p. 103-122 Open Access logo Open Access
LinksOnline - En ligne (PDF, 51.1 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20210517
PublisherBritish Columbia Geological Survey
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS92H/01; 92H/02; 92H/07; 92H/08
AreaTulameen River
Lat/Long WENS-120.9167 -120.7500 49.5833 49.4167
Lat/Long WENS-136.0000 -116.0000 58.0000 50.0000
Subjectsregional geology; geophysics; Science and Technology; Nature and Environment; alaskan-type ultramafic complex; ultramafic rocks; remote sensing; photogrammetric surveys; photogrammetric techniques; bedrock geology; lithology; ultramafic rocks; mafic rocks; dunites; olivine; clinopyroxenites; modelling; magmatism; intrusions; dykes; shear zones; remobilization; Upper Triassic; Tulameen Complex; Tulameen Ultramafic Complex; Quesnel Terrane; Canadian Cordillera; Nicola Group; drones; Digital elevation data; geological contacts; Phanerozoic; Mesozoic; Triassic
Illustrationslocation maps; ternary diagrams; photomicrographs; photographs; aerial photographs; geological sketch maps; flow charts; tables; digital elevation models
ProgramTargeted Geoscience Initiative (TGI-6) Ore systems
Released2022 01 31
AbstractThe Tulameen intrusion (Late Triassic), an 18 by 6 km ultramafic-mafic body in the Quesnel terrane of southern British Columbia, is hosted by metavolcanic and metasedimentary rocks of the Nicola Group (Upper Triassic). The intrusion is zoned, with a dunite core passing outwards through olivine clinopyroxenite and clinopyroxenite, to hornblende clinopyroxenite and hornblendite at the margin. It contains widespread gabbroic rocks and a dioritic-syenodioritic phase along the southeastern margin. Detailed mapping along a >4 km transect of near-continuous exposure in the Tulameen River during a period of low water level was assisted by a remotely piloted aircraft system (RPAS). Overlapping, highresolution digital imagery acquired by the RPAS was used to create 3-dimensional (3D) models, digital elevation models, and orthomosaics using Structure-from-Motion (SfM) photogrammetry. The transect along the Tulameen River includes dunite, chromitite, olivine clinopyroxenite, hornblende clinopyroxenite, gabbro, and minor olivine wehrlite. These rocks are cut by layered gabbro-diorite tabular bodies and fine-grained mafic to intermediate dikes. Contacts between the major map units are predominantly north-trending shear zones. Primary intrusive contacts are rarely exposed, and are typically limited to olivine clinopyroxenite, hornblende clinopyroxenite, and gabbro. Zones of intermingled ultramafic cumulates defi ned by entrained and variably deformed enclaves of dunite and olivine wehrlite in olivine clinopyroxenite are typical of the section. These zones are interpreted to record magma recharge and remobilization of crystal-rich magma mushes across a range of physical and rheological conditions.
Summary(Plain Language Summary, not published)
The Tulameen intrusion is a body of mafic-ultramafic magma emplaced into the middle to upper crust of Quesnel terrane of southern British Columbia during Late Triassic arc-related volcanism. Fieldwork conducted during the summer of 2021 incorporated sampling and bedrock mapping, with the assistance of a remotely piloted aircraft (RPA), to constrain magmatic and structural relationships between different rock units of the intrusion. The survey took place during a period of low water level in the Tulameen River. Overlapping, high-resolution digital imagery acquired by the RPA system was used to create 3-dimensional (3D) models, digital elevation models, and orthomosaics using Structure-from-Motion (SfM) photogrammetry. An extensive 3D archive of the spatial patterns of outcrop-scale relationships preserved in an arc magmatic conduit system was compiled through combination of SfM photogrammetry and traditional mapping. The results of this study contribute to our understanding of the magmatic processes operating in convergent margin ultramafic-mafic intrusions within the Canadian Cordillera and globally.

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