Sequence Stratigraphy - Trace Fossils as Indicators of Sedimentary Environments - page 174

FIGURE 9 TRS/SU of wave-dominated estuarine valleys. Core box photo (A) and close-up photo
(B) of the TRS/SU developed near the mouth of the estuarine valley. Shelf mudstones of the regional
Viking Formation parasequences are truncated by the SU, which has been subsequently eroded by
the TRS representing initial transgression. The discontinuity hosts firmground Rhizocorallium ( Rh )
of the Glossifungites Ichnofacies. The overlying facies comprise part of the estuary mouth complex.
Willesden Green Field, Alberta. Core box photo (C) showing offshore mudstones of the regional
Viking Formation parasequences, erosionally overlain by tidal channel trough cross-stratified
sandstone. The discontinuity (arrow) represents a tidal ravinement surface cutting the subaerial
unconformity (TRS/SU). The surface is demarcated by firmground Diplocraterion and Skolithos
of the Glossifungites Ichnofacies, but in this example, they are visible only on the bedding plane.
Crystal Field, Alberta. (D) Close-up photo of tidal-inlet trough cross-stratified sandstone containing
Ophiomorpha ( O ), erosionally overlying offshore bioturbated mudstones. The discontinuity repre-
sents a composite TRS/SU, akin to that of photo C. In this example, firmground Thalassinoides ( Th )
and Rhizocorallium ( Rh ) of the Glossifungites Ichnofacies represent the omission suite. Willesden
Green Field, Alberta. See Fig. 3 for sequence-stratigraphic surface names. Scale bar

15 cm

¼

(A and C).