Sequence Stratigraphy - Trace Fossils as Indicators of Sedimentary Environments - page 165

FIGURE 3 Schematic model differentiating incised shorefaces of the Falling Stage Systems Tract
(FSST), Lowstand Systems Tract (LST), and Transgressive Systems Tract (TST). SU, Subaerial
Unconformity; RSME, Regressive Surface of Marine Erosion; BSFR, Basal Surface of Forced
Regression; CC, Correlative Conformity; MRS, Maximum Regressive Surface; WRS, Wave
Ravinement Surface; FS, Flooding Surface; MFS, Maximum Flooding Surface. See text for expla-
nation. Modified from MacEachern et al. (1999a) .

these autogenically induced scour surfaces are mantled by storm beds, shielding
them from omission colonization. Seaward of fair-weather wave base, the
RSME passes into the non-erosional BSFR ( Fig. 5 C and D). The RSME typi-
cally reworks the BSFR, which is the lower bounding surface of the FSST (i.e.,
the sea floor at the onset of forced regression). The BSFR is preserved seaward
of the downdip termination of the RSME as a conformable surface across which
an abrupt increase in sediment caliber is typically recorded ( Fig. 5 C and D;
MacEachern et al., 1999a ). The upper bounding surface of the forced regressive
shoreface can be quite variable; in proximal positions, it is marked by the SU,
whereas in distal locations it is capped by the CC.
The Viking Formation in the Kaybob-Fox Creek Field provides an excellent
example of a forced regressive shoreface generated during the early stages of
RSL fall ( Pemberton and MacEachern, 1995 ; Fig. 4 ). This shoreface shows
marked incision into the underlying marine parasequences of the previous
HST. The truncated highstand parasequences form well-developed, upward-
coarsening successions that consist of intensely bioturbated (BI

5) silty mud-
stones of the lower offshore, grading through pervasively burrowed (BI ¼ 5)

¼