154
SMALL LAGOON, POND
(WITH MUD DEP.
BEACH RIDGE
(BLOCK &
GRAVEL)
FORESETS
FLUVIAL-DOMINATED
BIRD-FOOT DELTA
(ELONGATE)
MIXED FLUVIALTO WAVE-DOMINATED
"CLASSICAL" DELTA
(LOBATE) ± TIDAL INFLUENCE
c
BEACH RIDGE BARRIER
(CHENIER)
RIVER MOUTH
SAND BAR
POSSIBLY
TRANSPORT
TO DEEP-SEA FAN
Fig. 3.31. a Marine fan delta caused by seaward
prograding alluvial fans or braidplain. Note coarsegrained beach ridges (blocks and gravel) protecting
small lagoons or ponds from wave and current action. Older beach ridges and lagoonal silts and muds
may be overridden by fluvial deposits. b Different
types of large marine deltas controlled by waves and
Chapter 3 Coastal and Shallow Sea Sediments
a
PROGRADING
ALLUVIAL FANS OR
COASTAL BRAIDPL AIN
FLATS
SUBAQUEOUS
SAND RIDGES
FLUVIAL PLAIN
SHALLOW LAKE
:>-O~:::K..
ABANDONED
tidal currents (LE low energy; ME medium energy;
HE high energy conditions) as weIl as sediment input
(HI, high input; MI, medium input). c Different
subenvironments of a large, lobate, wave- and tideinfluenced delta system (sirnilar to the modem Niger
delta)