Updated depositional and stratigraphic model of the Lower Jurassic Åre Formation, Heidrun Field, Norway - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 272

Low sinuosity fluvial channel. Probably
vertically accreted

Arcuate wave-dominated
shoreline of lobate sandy
delta, prograding across former
inter-deltaic embayment.

Peat swamp

Meander belt

Wave
approach

Crevasse splay
lobes

Tide-influenced
distributary channel

Extensive shallow
brackish-water
embayment

Seaward fringe of
subsiding abandoned
delta lobe.

Protected low wave energy shoreline
fringed with saltmarsh (peat swamp)

Fig. 15. Conceptual model for the lower delta plain and interdistributary bay depositional setting of the Åre Formation.

Top of bay-fills are locally truncated and suc-
ceeded by fining-upward, medium-grained to
coarse-grained, cross-stratified distributary chan-
nel sandstones (FA 6; Figs 14 and 16). Channel
sandstones display possible tidal influence in the
form of silty drapes on foresets and troughs within
current ripple sets (e.g. Dalrymple & Choi, 2007).
Presence of both Planolites montanus and
Arenicolites carbonarius indicates brackish water
within distributary channels. The upper bound-
ary of bay-fill deposits may also show rooting and
the preservation of coastal plain peat swamp coals
(FA1).
Wave-influenced bay-fill deposits and distrib-
utary channel sandstones are typically interbed-
ded with organic-rich mudstones characterised
by rootlets, wave and current ripples and
synaeresis cracks (FA 9; Figs 14 and 16). The
general depositional setting for this facies asso-
ciation is interpreted to have been a sheltered,
low-energy bay margin or sub-bay (Fig. 15; cf.
Kjærefjord, 1999), which was shallow enough to
allow colonisation by salt-tolerant vegetation
(halophytes).
Bay-fill deposits probably accumulated in
muddy, brackish interdistributary embayments,
which were locally fringed with wave-reworked
prograding lobate deltas alongshore (Fig. 15)
(cf. Coleman & Gagliano, 1964; Elliot, 1974).

(A)

Fig. 16. (A) Core photograph showing typical brackish-
water interdistributary bay facies (example from the Åre
4.4 Sub-zone in well 6507/7-A-46). The ruler is 1 m long).