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TitleThe flexural margin, foredeep, and orogenic margin of a northern Cordilleran foreland basin: Cretaceous tectonostratigraphy and detrital zircon provenance, northwestern Canada
AuthorHadlari, T; MacLean, B C; Galloway, J M; Sweet, A R; White, J M; Thomson, D; Gabites, J; Schroder-Adams, C J
SourceMarine and Petroleum Geology vol. 57, 2014 p. 173-186,
Alt SeriesEarth Sciences Sector, Contribution Series 20130203
Mediapaper; on-line; digital
File formathtml; pdf
ProvinceYukon; Northwest Territories
NTS96; 106
AreaCanadian Cordillera
Lat/Long WENS-136.0000 -122.0000 68.0000 64.0000
Subjectssedimentology; tectonics; stratigraphy; geochronology; sedimentary basins; basin classification; basins; basin evolution; tectonostratigraphic zones; Albian; Campanian; Cenomanian; Turonian; depositional environment; provenance; zircon dates; Keele Tectonic Zone; Cretaceous
ProgramMackenzie Corridor, Shield to Selwyn, GEM2: Geo-mapping for Energy and Minerals
AbstractReconstructions of the Albian to Campanian foreland basin adjacent to the northern Canadian Cordillera are based on outcrop and well log correlations, seismic interpretation, and reconnaissance-level detrital zircon analysis. The succession is subdivided into two tectonostratigraphic units. First is the Albian tectonostratigraphic unit. The Albian succession was deposited on the flexural margin of a foreland basin. At the base is a shallow marine sandstone that was deposited during transgressive reworking of sediment from cratonic sources east of the basin that resulted in a dominant 2.0-1.9 Ga detrital zircon age fraction. Deposition in a west-facing muddy ramp setting was followed by east-to-west shoreface progradation into the basin.
Near the Albian-Cenomanian boundary, regional uplift and exhumation resulted in an angular unconformity at the base of the Cenomanian-Campanian tectonostratigraphic unit. Renewed subsidence in the Cenomanian resulted in deposition of organic-rich, radioactive, black mudstone of the Slater River Formation in a foredeep setting. Cenomanian-Turonian time saw west-to-east progradation of a shoreface-shelf system from the orogenic margin of the foreland basin over the foredeep deposits. Detrital zircon age peaks of approximately 400 Ma, 1000 Ma, and 1300 Ma from a Turonian sample are consistent with recycling of Mississippian and older strata from the Cordillera west of the study area, and show that the orogen-attached depositional system delivered sediment from the orogen to the foreland basin. A near syndepositional detrital zircon age of ca. 93 Ma overlaps with known granitoid ages from the Cordillera. After the shelf system prograded across the study area, subsequent pulses of subsidence and uplift resulted in dramatic thickness variations across an older structural belt, the Keele Tectonic Zone, from the Turonian to the Campanian.
The succession of depositional systems in the study area from flexural margin to foredeep to orogenic margin is attributed to coupled foreland propagation of the front of the Cordilleran orogen and the foreland basin. Foreland propagation of crustal thickening and deformation is a typical feature of orogens and so the distal to proximal evolution of the foreland basin should also be considered as typical.
Summary(Plain Language Summary, not published)
This work addresses unresolved questions about Cretaceous rocks in the Mackenzie Plain region by integrating mutually consistent interpretations from well log correlation, seismic analysis, paleontology, and geochronology into a broad geological framework. Biostratigraphic age interpretations allow for a temporal evolution of the Cretaceous basin to be reconstructed that shows dramatic unconformities, lateral thickness variations, and the directions that sediment was being transported and deposited. This frameowork is needed to form the basis for subsequent work on detailed sedimentology, biostratigraphic correlation, and thermal maturity evaluation, which will ultimately allow for better estimation of the petroleum potential of the region.