Geology Reference
In-Depth Information
Fig. 13.20
Model of depositional succession on transgressive
tidal shelves, supposing that all of the facies tracts are superim-
posed on each other. The succession begins with a valley-fill
deposit that is capped by tidal-current ridges that formed on the
shelf.
LST
,
TST
,
HST
lowstand, transgressive, and highstand
systems tracts;
SB
sequence boundary;
RS
transgressive
ravinement surface;
MFS
maximum flooding surface (After
Dalrymple
2010b
)
Fig. 13.21
(
a
) Seismic section from the East China Sea, offshore
from the Changjiang River (see location in Fig.
13.6b
, ridge field 2).
Laterally migrating tidal ridges are present on the modern sur-
face; older ridges are present near the bottom of the section, bur-
ied beneath prodeltaic mud. (
b
) Interpretation of the succession,
as determined from seismic attributes and facies in cores.
Depositional environments in (
a
) and (
b
):
1
prodeltaic deposits,
2
deltaic/estuarine channels of the falling-stage and lowstand sys-
tems tracts,
3
fluvial deposits of the lowstand systems tract,
4
early
transgressive estuarine channels, and
5
transgressive shelf ridges.
RSME
regressive surface of marine erosion,
TSME
transgressive
surface of marine erosion,
SB
sequence boundary,
MFS
maxi-
mum flooding surface. (
c
) Schematic vertical succession through
the ridge (location shown by the
gray rectangle
in
b
). The coars-
ening-up succession reflects the increase of hydrodynamic energy
toward the ridge crest. Note the coarse lag at the bottom of the
ridge, which is interpreted as the tidal ravinement surface (From
Berné et al.
2002
)
