Sequence Stratigraphy - Trace Fossils as Indicators of Sedimentary Environments - page 168

FIGURE 6 Shoreface deposits of the LST. Core box photo (A) and close-up (B) from a LST
incised shoreface (see Fig. 3 for context). In the landward position, bioturbated muddy lower shore-
face sandstones of the FSST coarsen upward and are overlain by the correlative conformity (CC),
which marks the base of the LST shoreface. The LST shoreface consists of finer-grained lower
shoreface muddy sandstones that coarsen upward and are sharply overlain by medium-grained
cross-stratified sandstones interpreted as fluvial topset beds. These are capped by the maximum
regressive surface (MRS) (white arrow in A), which has been erosionally modified by the wave ravi-
nement surface (WRS). The composite surfaceWRS/MRS is overlain by transgressive mudstones of
the TST. Core box photo (C) and close-up (D) of the same lowstand shoreface, but lying in a seaward
position. Fluvial topset beds are not present and the LST shoreface is entirely marine. Common trace
fossils are Thalassinoides ( Th ), Skolithos ( Sk ), Ophiomorpha ( O ), and Rhizocorallium ( Rh ). The
shoreface is terminated by marine transgression across the MRS and capped by transgressive mud-
stones of the TST. Early Cretaceous Viking Formation, Judy Creek Field. See text for explanation.
Scale bar ¼ 15 cm (A and C) and 3 cm (D).