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doming would leave an apparently similar record
to that of the palaeovalley model (Fig. 16), with
Bunter and Skagerrak formation sandstones
restricted to zones between grounded Smith Bank
Formation minibasins. However, this configuration
would not be a reflection of the original geomor-
phology, but would be entirely the product of
the distribution of localised, long-term preserva-
tion space (Kocurek & Havholm, 1993). The UK
Western Platform may provide some clues to dif-
ferentiate these models and provide support for a
biased preservation model. In this area core from
interpod areas is entirely composed of fine-
grained, distal sheetflood and playa margin depos-
its of Bunter Formation-lower Judy Sandstone
Member character, which show no evidence of
fluvial confinement. Facies changes are gradational
across successive interpod regions, suggesting that
although now preserved in areally restricted fair-
ways, these Skagerrak Formation sandstones were
originally deposited on an unconfined alluvial
plain and in a relatively distal position on the flu-
vial drainage rather than channel confined, proxi-
mal feeder zones. Their current distribution within
a complex network of interpod lows is more likely
to be a reflection of their localised preservation due
to continued subsidence of the interpod areas as
salt continued to be evacuated (McKie & Audretsch,
2005), both during the Triassic and subsequently
into the Upper Jurassic (following Middle Jurassic
erosion) when interpod areas again became sites
of preferential preservation of open marine Fulmar
(A)
Smith Bank Formation
minibasin (pod)
development during early
Tr iassic halokinesis
(B)
Skagerrak Formation
terminal splay progradation
across the basin, initial
minibasin grounding of the
Smith Bank Formation.
(C)
Ongoing deposition of
Skagerrak Formation fluvial
systems, interpod areas
become sites of enhanced
differential subsidence
although fluvial deposition
remained widespread.
(D)
Middle Jurassic thermal
doming and regional
denudation. lnterpod areas
preserve more complete
early Skagerrak Formation
sections
Fig. 16.
Conceptual model for pod-interpod accumulation and preservation in areas of early pod grounding such as the UK
Western Platform. Initial minibasin formation during deposition of the Smith Bank Formation (A) evacuated the underlying
halite, resulting in pod grounding on the Rotliegend Group (B). Subsequent progradation of Bunter Formation and lower
Judy Sandstone Member terminal splay complexes occurred across the region, with localised thickening in interpod areas
where salt continued to be evacuated and/or dissolved (B). This process continued through the Middle and Late Triassic
as the region was blanketed by sediment as the basin continued to subside (C), but subsequent erosion during Middle
Jurassic thermal doming (D) eroded much of the Triassic stratigraphy, leaving erosional remnants of Skagerrak Formation
terminal splays in interpod troughs. The geometries of the troughs do not reflect the depositional geomorphology and are
sites of preferential preservation of formerly unconfined distal sheets.
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