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TitreCharacter and origin of thick sandstone bodies in the Middle Triassic Doig Formation of Western Canada
AuteurDixon, J
SourceCommission géologique du Canada, Dossier public 6431, 2010, 20 pages, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Medianumérique; en ligne
Formatspdf (Adobe® Reader®)
SNRC83M/03; 83M/04; 83M/05; 83M/06; 83M/11; 83M/12; 83M/13; 83M/14; 84D/03; 84D/04; 84D/05; 93P/08; 93P/09; 93P/10; 93P/15; 93P/16; 94A/01; 94A/02; 94A/03; 94A/05; 94A/06; 94A/07; 94A/08
Lat/Long OENS-122.0000 -119.0000 56.5000 55.0000
Sujetslithologie; lithostratigraphie; roches sédimentaires; grès; silstones; schistes; carottes; analyse de carottes; stratigraphie systématique; corrélations stratigraphiques; Formation de Doig ; Formation d'Halfway ; Formation de Montney ; Formation de Charlie Lake ; Formation de Baldonnel ; stratigraphie; tectonique; Trias; Mésozoïque
Illustrationsstratigraphic correlations; stratigraphic sections; photographs; cross-sections
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
ProgrammeCorridor et delta du Mackenzie, GEM : La géocartographie de l'énergie et des minéraux
Diffusé2010 05 10
Résumé(disponible en anglais seulement)
Within the Middle Triassic Doig Formation of western Canada there are thick sandstone bodies encased in muddier sediment, for which the name "anomalously thick sandstone bodies" (ATSBs) has been coined. Twenty years of investigating these thick sandstone bodies has not resulted in a consensus but there are a number of common points between the various studies that may help formulate a reasonable hypothesis for their origin. Many authors have interpreted the facies within the sandstone bodies to be shoreface deposits, although incised-valley fills (estuarine) and deltaic deposits also have been cited. Another common element is that the thick sandstone bodies were deposited during a transgressive-regressive period. The main point of contention is how these ATSBs relate to the adjacent strata, were they deposited contemporaneously or are they younger? Abrupt basal contacts, apparently abrupt lateral contacts, and stratigraphic relationships favour the sandstone bodies to be post-mudstone deposits, formed during late regression. If they are post-mudstone deposits how can an isolated, thick sandstone body be produced? A number of authors have suggested that the ATSBs were deposited in structurally created depressions (slumps or growth fault grabens), accounting for the thickness, isolation, abrupt appearance, and variable shapes and sizes. Based on the data produced to date the most probable explanation for the origin of the ATSBs is that during late regression slumps and/or growth fault grabens formed on a muddy, pre-existing shelf and were filled by sandy sediment. Initial deposits are commonly debris-flow and/or slump deposits that filled in the deeper parts of the depression. As the depression filled, sediment entered wave and current influenced water depths and more typical shoreface deposits began to form. As regression proceeded some of these sandstone bodies were truncated by a regressive surface of marine erosion curtailing deposition within the depressions. Finally, base-level rise initiated transgression and all ATSBs and adjacent sediment are capped by a thin veneer of transgressive sediment.