Tectonic control on sedimentation, erosion and redeposition of Upper Jurassic sandstones, Central Graben, North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 488

West Central
Shelf West Central

Shelf

West Central
Graben

Time 1 Time 2

West Central
Graben

East Central
Graben

East Central
Graben

Rotliegend

Rotliegend

Type A Type B

West Central
Shelf

Time 3 West Central

Graben

East Central
Graben

Sea
level
rise

Rotliegend

Type C

Fig. 9. Successive stages are illustrated in the development of Upper Jurassic sandstones highlighting successive tectono-
sedimentary settings. At Time 1, Oxfordian rift related deposition occurs in the East Central Graben against the foot wall
producing a 'Type A - Hanging Wall Trap Door Setting' for shallow marine and turbidite sandstone accumulation. At Time
2, the graben broadens as a result of ongoing extension and marine transgression causing a pod structure initiated in the
Triassic to become reactivated with a fill of Upper Jurassic shoreface deposits, namely a 'Type B - Reactivated Pod Setting'.
At Time 3, contemporaneous transgressive sandstone deposition takes place within drowned salt cored valleys producing a
'Type C - Interpod Setting' for shallow marine sandstone accumulation (adapted after Fraser et al ., 2002).

Type C: Tectono-sedimentary setting

Supra-salt minibasins of this kind can form net-
works surrounding highs formed by grounded and
inverted Triassic minibasins. The Upper Jurassic
sandstone trends shown on Fig. 8 are influenced
by the location of Triassic minibasins that are
known to have served as sediment source terrains
on both margins of the Central Graben (Stewart et
al ., 1999).
Type C tectono-sedimentary settings typically
occur over structurally high areas that corre-
spond to relatively thin original Zechstein
isopachs (Stewart & Clark, 1999). In such regions,

A Type C tectono-sedimentary setting resulted
from the marine flooding of former salt highs
(swells, walls and diapirs) at the margins of Triassic
minibasins (Goldsmith et al ., 2003; Vendeville &
Jackson, 1992a, 1992b; Stewart & Clark, 1999).
These small, Upper Jurassic, interpod basins often
became infilled with littoral sandstones (Fig. 9).
The basins originated as valleys where salt defla-
tion has occurred (dissolution or withdrawal
of salt) and can be subsequently enlarged by
continued salt withdrawal or sediment loading.