Slopes - Trace Fossils as Indicators of Sedimentary Environments - page 602

FIGURE 5 Summary of trace-fossil distribution within background slope, slope gully, and subma-
rine canyon deposits of the Eocene Ainsa Basin, Spain (upper schematic redrawn, and data com-
piled, from Heard and Pickering, 2008 ).

10 ichnogenera ( Fig. 5 ). Post-depositional trace fossils are associated with
BI 2-3. A single submarine canyon-fill succession was assessed by Heard

and Pickering (2008) and consists of mass-transport deposits associated with
a post-depositional suite of Ophiomorpha annulata, O. rudis , Thalassinoides
suevicus , and Thalassinoides isp.
Heard and Pickering (2008) speculate that the trace-fossil suites associated
with high-energy canyon- and gully-fills are largely a consequence of (1) the
low preservation potential of pre-depositional forms in these conduits due to
erosion and (2) the lack of stable conditions in these settings, which favors
opportunistic burrowing strategies. Their comprehensive analysis shows that
proximal fine-grained slope units, characterized by active turbiditic accumula-
tion, possess relatively impoverished trace-fossil assemblages that lack the
diverse graphoglyptid-rich suites typifying lithologically similar facies in
basin-floor fan subenvironments (cf. Uchman and Wetzel, 2012 ).

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4.3 Ambient Slope Deposits, Cretaceous Nise
Formation, Norwegian Shelf
The Late Cretaceous Nise Formation of offshore Norway forms part of the
K85-K90 Sequence ( Vergara et al., 2001 ), and is well developed in the Vøring
and Møre basins. In these Norwegian Sea basins, the Late Jurassic basement
structural template controlled Early Cretaceous deep-water sedimentary