C1_Coastal_systems_general.pdf
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Transcript of C1_Coastal_systems_general.pdf
Gary Nichols
Coastal 1 - 1
Coastal plain – estuary – delta: how the balance
between sediment supply and accommodation
determines the nature of deposits at the continental
to marine interface.
Gary Nichols
Coastal 1 - 2
Boyd et al., 1992
Coastal depositional environments
These environments all fall within a 3D
spectrum of wave, tide and river
influences in progradational or
retrogradational settings
Gary Nichols
Coastal 1 - 3
Sediment supply < Accommodation
Wave-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 4
Sediment supply < Accommodation
Tide-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 5
Accommodation < Sediment supply
Wave-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 6
Accommodation < Sediment supply
Tide-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 8
No fluvial sediment supply
Wave-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 9
No fluvial sediment supply
Tide-influenced
Coastal depositional environments
Gary Nichols
Coastal 1 - 12
Sand bar at the mouth of a wave-dominated estuary
Wave-dominated estuaries
Gary Nichols
Coastal 1 - 17 Wave-dominated estuary
Beach
Estuary mouth
Central lagoon
Bay head delta
metr
es -
10s m
etr
es
Sedimentary log of a wave-dominated estuary
Gary Nichols
Coastal 1 - 27
Depositional settings in a tidally-dominated estuary
Tide-dominated estuaries
Gary Nichols
Coastal 1 - 28
Upper tidal flat
Tidal creek
Lower tidal flat
Tidal channel – tidal flow
indicators
Scoured base of channel
metr
es -
10s
metr
es
Tide-dominated estuaries
A sedimentary
log of a tidal
estuary
Gary Nichols
Coastal 1 - 30
Wave-dominated coastline: coastal plain and sandy beach
Barriers and lagoons
Gary Nichols
Coastal 1 - 31
Barrier islands - beaches not attached to the coastal plain
Barriers and lagoons
Gary Nichols
Coastal 1 - 35
Beach barrier with
lagoon (right) and
open sea (left)
Barriers and lagoons
Gary Nichols
Coastal 1 - 36
Lagoons are low energy, shallow water behind a barrier
Barriers and lagoons
Gary Nichols
Coastal 1 - 37
Lagoons are low energy, shallow water behind a barrier
Barriers and lagoons
Gary Nichols
Coastal 1 - 38
Bioturbated muds
Wave rippled
washover sands
metr
es
Barriers and lagoons
A graphic
sedimentary
log of a clastic
lagoon
Gary Nichols
Coastal 1 - 39
With mixed wave and tidal processes the barrier is breached by more inlets – ebb and flood tidal deltas
Coastal morphology
Gary Nichols
Coastal 1 - 42
Beach dunes
Washover sands
Flood tidal delta
deposits
Lagoon
metr
es -
10s
metr
es
Coastal morphology
A graphic
sedimentary log
of a transgressive
coast
Gary Nichols
Coastal 1 - 43
Boyd et al., 1992
Coastal depositional environments
These environments all fall within a 3D
spectrum of wave, tide and river
influences in progradational or
retrogradational settings
Gary Nichols
Coastal 1 - 46
Delta plain Delta channel Distributary mouth bar Delta front
10
s m
etr
es
River-dominated delta
Gary Nichols
Coastal 1 - 48
Delta plain Beach Distributary mouth bar Delta front Pro delta
10
s m
etr
es
Wave-influenced delta
Gary Nichols
Coastal 1 - 50
Tidal flats Tidal channel (mud drapes, bidirectional flow) Tidal sand bars of delta front Pro-delta
10
s m
etr
es
Tide-influenced delta