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transition facies associations (FA1a, 1b and 1c;
Table 2) with abundant marine body fossils
and trace fossils (similar to Fig. 10C). These
facies associations pass laterally into the tidal
channel infill facies associations (FA3a and 3b)
north of locality S4 (Fig. 7; Table 2).
In the northern area, allostratigraphic unit 4 is
initiated by the SU1/TS3 surface that separates
either poorly cemented silty sandstones of the
TDDP element of allostratigraphic unit 2 from over-
lying sandy heterolithic deposits of allostrati-
graphic unit 4 (locality N1), or inclined heterolithic
deposits of the TDDP element of allostratigraphic
unit 2 from overlying muddy heterolithic deposits
of allostratigraphic unit 4 (localities N2 to 4; Fig. 7).
At locality N1, the 24 m thick allostratigraphic unit
4 is composed of sandy heterolithic tidal channel
infill facies associations (FA3c, 3d, 3e; Table 2).
These facies associations are coarse-grained, poorly
sorted and rich in mudstone pebbles and beds are
thinner than at localities S5 to 6. At localities N2
to 4, the 25 to 38 m thick allostratigraphic unit 4 is
composed of sandy fluvial-tidal transition facies
associations (FA1a and 1b) and the wave-influenced
brackish embayment mudstone facies association
(FA6c) with both terrestrial and brackish palyno-
morphs (Tables 1 and 2) (Ahokas
et al
., 2014).
Allostratigraphic unit 4 is topped in the south-
ern area by a sharp facies shift into brackish-
marine silty shale, whereas in the northern area
the corresponding unconformity is defined by a
change into tidal sandstones.
probably existed around locality S5. The changing
depositional architecture along the combined sur-
face SU1/TS3 from south to north suggests that the
initial basinward shift in facies (i.e. towards west)
was greater in the south than in the north. This
resulted in deposits of more proximal character
and more subtle shift in facies in the north. Above
the SU1/TS3 unconformity, the tide-dominated
subtidal sandy shoal (TDSS) and fluvial-tidal tran-
sition (FTT) elements appear to fill in a relatively
low relief depression cut by that initial subaerial
erosion (Fig. 7). This erosional feature is inter-
preted to be part of a wide topographic depression,
itself interpreted as an incised valley system.
Maximum flooding surface MFS3 is difficult to
pick because allostratigraphic unit 4 is sand-rich
and without any apparent marine shale unit. MFS3
is therefore placed at the base of the FTT element
in the southern area. In the northern area, MFS3 is
put right above the TDSS element and within the
FTT element where marine palynomorphs become
dominant. The top bounding surface of allostrati-
graphic unit 4 is interpreted as the next transgres-
sive surface (TS4). In the northern area this surface
is cut by a major unconformity (SU2/TS5) (Fig. 7).
Allostratigraphic unit 5
Description: Retrogradational to progradational
architectural elements
The muddy and sandy heterolithic allostrati-
graphic unit 5 overlies the transgressive surface
TS4 and is restricted to the southern area (Figs 5D
and 7). At localities S3 to 4 and S6 the TS4 uncon-
formity is characterised by a cm-thick bed of angu-
lar quartz and quartzite gravel. The boundary is
associated with a sharp facies change from under-
lying sandstones of allostratigraphic unit 4 into
wave-dominated brackish marine embayment
mudstone and siltstone and offshore marine mud-
stone facies associations (FA6a and FA7b, respec-
tively) of allostratigraphic unit 5 (Figs 7 and 10A to
B; Table 2). The mudstone facies associations are
rich in mixed marine palynomorphs and terrestrial
debris (Koppelhus & Dam, 2003; this study).
At locality S5, the up to 35 m thick allostrati-
graphic unit 5 is composed of heterolithic tidal del-
taic clinoform facies association (FA5c) (Fig. 12A
to C and 12E; Table 2). The stacked individual het-
erolithic clinothems are upward-coarsening and
up to 21 m thick; their geometry and orientation
are relatively uniform with strata dipping towards
west-north-west. To the north and south of locality
Interpretation: Allostratigraphic unit 4
Based on tide-influenced shallow marine to flu-
vial facies associations and variable palynomorph
assemblage (Koppelhus & Dam, 2003; this study),
the allostratigraphic unit 4 is interpreted to be
composed of the tide-dominated subtidal sandy
shoal (TDSS) and the fluvial-tidal transition (FTT)
architectural elements (Figs 7, 10A and B, 11A,
11E to G and 12; Table 3). Collectively, allostrati-
graphic unit 4 records an overall retrogradational
to progradational depositional architecture formed
subsequent to drowning of the original subaerial
unconformity SU1 (Fig. 7). During marine flood-
ing and transgression, the fluvial deposits on top
of the subaerial unconformity were reworked by
tidal currents. Deposition took place in contempo-
raneous tide-dominated estuarine and more open
wave-influenced environments with constant high
rate of sediment input and variable water depths.
At this stage, a deltaic distributary environment
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