|Titre||Some controls on sedimentary sequences in foreland basins: examples from the Alberta Basin|
|Auteur||Cant, D J; Stockmal, G S|
|Source||Tectonic Controls and Signatures in Sedimentary Successions; par Frostick, L E; Steel, R J; International Association of Sedimentologists, Special Publication 1994 p. 49-65, https://doi.org/10.1002/9781444304053.ch4|
|Séries alt.||Commission géologique du Canada, Contributions aux publications extérieures 26191|
|Éditeur||Blackwell Publishing Ltd.|
|Document||publication en série|
|Media||papier; en ligne; numérique|
|Sujets||biseaux sédimentaires; sedimentation; analyses stratigraphiques; orogénies; talus continental; Bassin d'Alberta |
|Diffusé||2009 04 16|
|Résumé||(Sommaire disponible en anglais seulement)|
The stratigraphy and sedimentology of foreland basin clastic wedges is believed to be controlled largely by the spatial and temporal effects of 'time
lag' between the initiation of flexure-induced subsidence and the deposition of large amounts of sediment generated from the overthrust belt. The initial accretion of a terrane to an older continental margin, thereby converting the margin to a
compressional orogen, should be associated with a relatively large time-lag effect because initial loading by overthrusting takes place on the continental slope, in the absence of significant early subaerial relief across the thrust belt. The large
time-lag effect results in a succession grading from deep-water to shallow-water sediments in the early foreland basin.
Clastic wedges resulting from later overthrusting events are generally expected to show considerably reduced time-lag effects,
with composite transgressive sequences succeeded by highstand regressive sequences, both composed mainly of non-marine, marginal-marine and shallow-marine sediments of varied lithologies. This reduced time-lag effect may reflect a relatively
continuous background supply of orogen-derived sediment readily available to fill accommodation space as it is created. In extreme cases, some clastic wedges may show essentially no time-lag effect, lacking basal transgressive or deep-water
As well as orogenesis, other factors also condition foreland successions. In the Alberta Basin, the effects of some base-level change events (eustatic?) are more dramatic in cratonward areas where tectonic subsidence rates are lower.
Valley-fill and lowstand deposits reflecting base-level drops are more common and easily recognizable toward that side of the basin. The structures and lithologies of the pre-existing shelf/miogeoclinal succession also affect thicknesses and facies
of foreland units through their influence on relief of the basal unconformity and synsedimentary salt dissolution.