Page 73 - Carbonate Sedimentology and Sequence Stratigraphy

64 WOLFGANG SCHLAGER

for tying process to product. The most important exam- tion of ancient epeiric deposits.
ple is the Timor-Arafura Sea with the Gulf of Carpentaria, ➤ Tides in epeiric seas are highly variable, depending on
entirely located on the Australian continent. The Persian size, shape and average depth of the sea (see Leeder,
Gulf is a foreland basin but its Arabian flank shows many 1999, for overview). The basic trends related to the dis-
characteristics of an epeiric sea: it lies on a mature, gen- tance from the open ocean may be drastically altered
tly warped craton, has very low topographic gradient and by resonance between the oceanic tide and the water
water depths in the axial zone are less than 100 m. Finally, body on the shelf. Epeiric tides may also rotate around
there is the “oceanic continent” that includes the Indonesian fixed points (“amphidromic points”) determined by the
Archipelago, the Philippines and the South China Sea. Tec- interplay of Coriolis force and friction along the coast-
tonically, this area is not a continent and anything but stable. lines. The testimony of recent epeiric seas certainly in-
However, it includes large shelf seas, many of them domi- dicates that the model of "tide-less" seas entirely domi-
nated by carbonates. In addition, the recent epeiric seas with nated by storms is not generally valid (Fig. 4.12). Grow-
siliciclastic sedimentation can be used to pursue questions of ing evidence of tidalites in ancient epeiric seas support
hydrodynamics and oceanography: examples are the Arctic this view (e.g. Pratt and James, 1986; Willis and Gabel,
shelves and the Hudson Bay of North America, the Yellow 2003).
Sea of SE Asia, and the Barents Sea, the North Sea and the ➤ Restriction is also variable but probably better pre-
Baltic Sea of Europe. From the recent examples of epeiric dictable by the distance from the open ocean than the
seas we can derive the following guidelines for interpreta- tides. For instance, salinity in the Persian Gulf - in

A) 6 9 or land Fig. 4.10.— Facies of the C fac-

2 tory are well described by the ramp
model. (A) Standard distally steep-
1sl ened ramp. On the landward side, the
C factory ends in high-energy skeletal
sands bordered by cliffs or by eolian
1fl dunes and sand flats. On the seaward
side, the factory may extend into what
is morphologically the continental or
island slope. (B) Extremely intensive
6 9 or land
bare shelf wave action may preclude sediment
B) 2 accumulation on the middle part of the
1sl shelf. Sediment produced in this area
is deposited in the nearshore zone
and on the outer shelf and the slope.

A) 6 9 Fig. 4.11.— Facies models of the M
2 factory. A) Ramp model. The patterns
differ from a T-factory ramp by the oc-
1sl
currence of mud-mounds on the shelf.
In plan view, the mounds form clus-
ters or belts perpendicular to the dip
1fl of the sea floor, or they may coalesce
to a network of ridges. The landward
end of belt 2 is normally dominated
by skeletal carbonate, the high-energy
sand belt in the littoral zone may be
B) 5 7/8 9 skeletal or oolitic. B) Platform model.
Facies belts are analogous to the T
factory platforms. However, the rim
facies may extend far down the slope
and re-appear in layers and lenses on
3/4 the slope because the depth window
of production is much wider than in the
T factory. Debris usually does not ex-
1 tend far into the basin but megabrec-
cias on the slope and toe-of-slope are
common.