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TitleMagnetic models of the Moyie anticline, Purcell anticlinorium, southeastern Canadian Cordillera
AuthorThomas, M D
SourceCanadian Journal of Earth Sciences vol. 52, no. 6, 2015 p. 368-385,
Alt SeriesEarth Sciences Sector, Contribution Series 20140344
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS82F/01; 82F/08; 82G/04; 82G/05
Lat/Long WENS-116.5000 -115.5000 49.5000 49.0000
Subjectsgeophysics; igneous and metamorphic petrology; mineralogy; regional geology; structural geology; tectonics; anticlines; magnetic modelling; modelling, structural; sills; sedimentary wedges; faults; faults, thrust; drillholes; magnetic anomalies; metasedimentary rocks; seismic data; seismic interpretations
Illustrationslocation maps; magnetic anomaly maps; geological sketch maps; seismic profiles; cross-sections, structural
ProgramTargeted Geoscience Initiative (TGI-4) Sedimentary Exhalative Ore Systems
Released2015 06 01
AbstractTwo-dimensional magnetic models of the Moyie anticline contribute to an independent project targeting development of a regional three-dimensional (3D) model of much of the Purcell anticlinorium by compensating for shortcomings in reflection seismic signatures and distributions of drill holes and surface structural data. Modelling has focused on prominent anomalies related to relatively strong magnetizations within the Creston Formation and Moyie sills. Models of the western flank of the anticline indicate the Creston Formation forms the bulk of a westward-thickening, wedge-shaped sedimentary package whose west-dipping layers are truncated by a steeply west-dipping Moyie fault, truncating also Moyie sills on the opposite side. Near-surface dips of the fault range from 54° to 87°. Stratigraphic comparisons across the fault indicate minimum reverse dip displacements ranging from 5.6 to 8.5 km. The eastern flank of the Moyie anticline is modelled consistently as a monoclinal, eastward-dipping stratigraphic package comprising mainly Lower Aldridge Formation (with intruded Moyie sills) through Kitchener Formation, in general accord with geological models. One magnetic model, however, shows stratigraphy disrupted by shallow thrust faults, above which a series of near-vertical blocks is modelled. The Yahk River syncline is modelled as a symmetrical fold having an axial depth of 4.2 km to the top of the Upper Aldridge Formation. Collectively, the models outline a broad domal pattern of Moyie sills in the core of the anticline to 12 km depth, supporting a proposal that a gravity high correlating with the Moyie anticline relates to high-density Moyie sills at relatively shallow depths, rather than deeper highdensity basement.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. Variations in the Earth's magnetic field related to variable content of magnetic minerals (commonly magnetite) in different rock units are quantitatively modelled to produce two-dimensional sections of the Earth's crust to depths of about 12 km. Modelling focuses on the Moyie anticline in southeast British Columbia, that has significant potential for economic metals such as copper, lead, zinc, silver and gold. A regional three-dimensional model of the Purcell anticlinorium is currently being developed independently by Geological Survey of Canada scientists to provide a new perspective on geology of the region.

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