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TitleBiostratigraphic evidence for incremental tectonic development of Early Cambrian deep-water environments in the Misty Creek Embayment (Selwyn Basin, Northwest Territories, Canada)
AuthorScott, W R; Turner, E C; MacNaughton, R BORCID logo; Fallas, K MORCID logo
SourceCanadian Journal of Earth Sciences 2022 p. 1-16, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210256
PublisherCanadian Science Publishing
Mediapaper; digital; on-line
File formatpdf; html
ProvinceNorthwest Territories
AreaMackenzie Mountains
Lat/Long WENS-132.0000 -129.0000 65.0000 63.0000
Subjectstectonics; paleontology; stratigraphy; geochemistry; Science and Technology; Nature and Environment; Lower Cambrian; sedimentary basins; tectonic evolution; subsidence; faulting; biostratigraphy; fossils; fossil zones; taxonomy; paleoenvironment; lithostratigraphy; lithofacies; depositional environment; systematic stratigraphy; type sections; isotopic studies; carbon isotopes; isopachs; bedrock geology; lithology; sedimentary rocks; limestones; shales; sandstones; dolostones; structural features; faults, normal; Misty Creek Embayment; Selwyn Basin; Sekwi Formation; Hess River Formation; Canadian Cordillera; Laurentia; Laurentian Margin; Trilobites; Phanerozoic; Paleozoic; Cambrian
Illustrationslocation maps; geoscientific sketch maps; stratigraphic columns; geochronological charts; lithologic sections; profiles; tables; photographs; correlation sections; schematic cross-sections
ProgramGEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals Western Arctic Research Priority Area
Released2022 02 23
AbstractThe early evolution of the Misty Creek embayment (MCE), a prominent, northwest-trending sub-basin of the economically important Selwyn basin, is poorly understood. The abrupt contact between Cambrian Stage 4 (traditional lower Cambrian) carbonate ramp strata of the Sekwi Formation and overlying Miaolingian (traditional middle Cambrian) deep-water, calciturbiditic strata of the Hess River Formation has been regarded as diachronous. This important transition, which marks the onset of long-lived, deep-water conditions in the MCE, remains unexplained. This study uses biostratigraphic data from a previously undescribed location in the MCE, existing biostratigraphic and lithostratigraphic data from the 1970s, and regional thickness patterns to characterise the sharp yet diachronous transition from lithofacies typical of the Sekwi Formation to those typical of the Hess River Formation. The dramatic change in depositional environments was diachronous yet non-gradational, precluding a eustatic cause. The change was geologically abrupt, probably through two extension-related subsidence events, with different geographic extents, which heralded the MCE's long life as a deep-water basin. The onset of deep-water conditions in the MCE occurred semi-contemporaneously with other extension-related events that are recorded in the northern Canadian Cordillera, demonstrating that Cambrian Series 2 - Miaolingian was a time of widespread extension and subsidence along the western margin of Laurentia.
Summary(Plain Language Summary, not published)
The Misty Creek embayment is a little studied deep-marine basin in the Mackenzie Mountains of northwestern Canada. It existed for nearly 100 million years from the Cambrian to the Silurian periods of Earth history. This study uses new and previously published data from trilobites to date the contact between older shallow-water rocks and younger deep-water rocks that marks the beginning of the embayment's development. The results show that the embayment formed through a series of tectonically caused deepening events, confirming and expanding on previous ideas about its origin. Understanding the origin of the embayment is important because it may be a target for base-metal and gold exploration.

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