Marginal Marine: Deltaic Facies Models
Result of progradation is a relative upward shallowing sequence
Deltaic Systems = triangular or lobe-shaped alluvial fans at
mouths of rivers
a. prevelant in the modern because of sea level rise trapping
sediments
b. occur on all continents except Antarctica
c. most extensive where rivers drain large areas, providing sediment
loads
d. largest and best studied are the Ganges-Brahamputra, Amazon,
Mississippi, Sao Francisco
Delta Types (Galloway Classification Fig 10.3, p. 324)
a. alluvial
river deltas
braidplain delta
alluvial fan delta
scree cone delta
b. non-alluvial
pyroclastic delata
lava delta
Environments (Fig. 10.8, p. 329)
a. differences between clastic and carbonate seaward successions
b. prodelta - muds
c. delta fronts - sands and muds
d. bar-finger sands - channel and mouth
e. natural levees
f. marsh
Ancient Deltaic Successions - shallowing upward
Carbonfierous example - (Fig. 10.21, p. 342)
Marginal Marine: Barrier Beach Facies
Beaches - parallel to mainland or deltaic coastline
extremely dynamic systems
sediment supply versus lateral transport
tidal range control
currents - long-shore and rip currents (Fig. 10.25, p. 345)
Environments (Fig. 10.26, p. 346)
a. mainland attached
b. beach strand plain (chenier plain)
c. regressive barrier island
tidal channel
lagoon
marsh
tidal delta
tidal flats
d. transgressive barrier island
Successions (Fig. 10.29, p. 350)
low-angle tablar cross beds
beach rock clasts
well sorted and winnowed