Geology Reference
In-Depth Information
Fig. 9.26
Sedimentary beddings and internal structures of the
tidal-flat deposits in the Changjiang Delta. Semidiurnal tile
observations showing (
a
) one sand-mud couplets pair with small
symmetrical wave ripples capped by a thick frozen fluid-mud
layer and a thin algal mat on the surface, and (
b
) two sand-mud
couplets with the ebb-current ripples laid on the stoss-side of the
underlying flood-current ripples. Diurnal tile observations exhib-
iting two thin sand laminae separated by a thick mud layer (
c
), or
by a hiatus surface with different color and composition (
d
). On
the fortnightly observation tiles, 3-6-cm-thick deposits consist-
ing of d7 sand-mud couplets, exhibiting thinly interlayered bedding
(
e
); two thin sand layers sandwiched by a thick mud layer with a
few thin sand lenses (
f
); fining-upward successions with massive
sand layer at the bottom and parallel to wavy beddings on the
top
(
g
), or developing load structures with the lower heterolithic bed-
ding (
h
). The erosion cliff of the mud patches showing finely
laminated bedding (
i
), fining-upward succession with parallel to
wavy bedding (
k
, similar with (
g
) and (
h
) on the fortnightly ties),
and thick massive mud layer capped by thin sand layer (
j
, like
those of (
f
)). The underlying sandy deposits exposed by deep ero-
sion containing parallel bedding (
l
) and mud-pebble concentra-
tion layer (
m
). Ballpoint pen always pointed to the sea
