Mixed Siliciclastic/Carbonate Systems - Trace Fossils as Indicators of Sedimentary Environments - page 784

Pliocene

Miocene Modern Parksville

intertidal

Oligocene

Eocene

50

Green River and Wasatch
Formations

Paleocene

100

Cretaceous

150

Jurassic

200

Schei Point Group

Triassic

Baldonnel Formation

Liard Formation

Moenkopi Formation

250

Montney Formation

Permian

Chase Group

300

Carboniferous

350

FIGURE 1 Stratigraphic occurrence of mixed siliciclastic/carbonate examples used in this chapter.

sediment supply resulted inco-occurrenceof unique trace-fossil assemblages. In the
second end-member, temporal variability in the form of stratigraphic occurrence
resulted in the vertical juxtaposition of trace-fossil assemblages and ichnofacies.

2. SPATIAL VARIABILITY (LATERAL FACIES MIXING)
Mixed systems that occur through lateral variability in lithofacies distribution
are perhaps the most common type of mixed system. In many cases, differences
in trace-fossil distributions between carbonate and clastic components are a
direct function of grain size and shape and thus commonly reflect the influences
of depositional energy and environmental segregation of grain type. Resource
distribution may also be unevenly allocated in mixed systems resulting in