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FIGURE 4
Ichnofabrics in vertically slabbed cores from wells in the marginal-marine Cook For-
mation (Lower Jurassic), offshore Norway (Block 34/2 and 35/10). (A) Laminated siltstone with
sparse
Phycosiphon
(
P
), sharply eroded at its top and overlain by coarse-grained sandstone with
rip-up clasts (c). This erosion surface occurs regionally and is associated with deeply penetrating,
sand-filled, uncompacted burrows (b) indicative of a firmground omission surface. (B) Complex,
intensely bioturbated ichnofabric, including
Siphonichnus
(
Si
),
Palaeophycus
(
Pa
),
Teichichnus
(
T
),
Rosselia
(
R
),
Phycosiphon
(
P
), and
Schaubcylindrichnus
(
S
). This interval is interpreted as a lower
shoreface deposit. (C) Heterolithic, ripple-laminated sandstone with monoichnospecific occurrence of
minute
Siphonichnus
as indicative of a restricted environment (e.g., decreased salinity) on a tidal flat.
(D) Sandstone with the complex trace fossil
Hillichnus
, probably resulting from the deep-infaunal
activity of a tellinacean bivalve.
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