1. Deltaic Depositional Systems
Modern and
Ancient
Arno River Delta (Med)
(a wave dominated and engineered delta)

2. Deltaic Depositional Systems
Locus of voluminous terrigenous clastic sediment accumulation where fluvial dispersal systems encounter standing water
Most common in subsiding basin-settings (passive continental margins) where major river systems transport large volumes of sediment.
Modern Gulf of Mexico
And the Mississippi River Delta
(a river dominated delta)

3. Importance Of Deltas
Site of substantial fossil fuel resource accumulation
Coal, Oil, and Natural Gas

4. Importance Of Deltas Diverse and prolific ecosystems
Common site of large human population centers
Nile River Delta (Med Sea)
(an engineered, wave/river dominated delta)
Tigris & Euphrates River Delta (Persian Gulf)

5. Main Geological Characteristics Of Deltas
Isopach thick... major stratigraphic component of (Terrigenous Clastic) sedimentary basin fill
Mississippi Delta

6. Main Geological Characteristics Of Deltas
Regressive - Progradational successions
Abandonment – Transgressive Stage

7. Main Geological Characteristics Of Deltas
Contemporaneous non-marine - marginal marine - to basinal depositional systems
Numerous sub-environments (each of a scale similar to that of most other depo systems)

8. Delta Types Constructional Deltas Destructional Deltas
Dominated by the fluvial system
strongly progradational/regressive
Lobate – Elongate
Destructional Deltas
Dominated by marine processes
common marine reworking with transgressive intervals
Cuspate (transitional to interdeltaic systems)

9. Main Processes Influencing Delta Depositional Systems
Climate
Relief
Fluvial Discharge (water volume and time variation)
Sediment load and type
River mouth processes
Tidal Processes
Wave energy

10. Main Delta Sedimentary Facies
Generic River-Dominated Delta Model
large rivers
broad shelf
low wave energy
low tidal range

11. Main Delta Sedimentary Facies
Generic River-Dominated Delta Model
Upper Delta Plain
above highest high tide
low gradient/ meandering river systems
fresh water lakes & swamps

12. Main Delta Sedimentary Facies
Generic River-Dominated Delta Model
Lower delta plain
between the tides
Distributary channels
Inter-distributary bay fill
levees

13. Main Delta Sedimentary Facies
Generic River-Dominated Delta Model
Subaqueous Delta (Delta Front)
below lowest low tide
distributary mouth bar - bar finger sands
bays

14. Delta Front Progradation

15. Main Delta Sedimentary Facies
Generic River-Dominated Delta Model
Prodelta
Offshore transitional to open marine
Normal Marine Shelf
High biological productivity
Abundant slumps and syndepositional deformation

16. Generic Wave Dominated Delta Model
High wave energy, open coasts, strong longshore currents
Non-marine, swamp to Eolian dune
Arcuate to strand-parallel sand dominated facies, barrier island sequences
Rhone River Delta (Med)
(a wave dominated delta)

17. Generic Tide Dominated Delta Model
High Tidal Range
Extensive lower delta plain/tidal mudflats
Shore perpendicular, elongate sand dominated facies, tidal channel deposits
Ganges - Brahmaputra River Delta (Indian Ocean)
(a tide dominated delta)

18. Transgressive Mississippi Delta Model

19. Transgressive Mississippi Delta Model

20. Transgressive Mississippi Delta Model

21. Environmental Issues in Modern Deltas
Damming, Dredging, Diverting
Coastal Land loss (erosion/subsidence)
Coastal Pollution
Nutrient loading,
anoxic events
Petroleum contamination
Habitat Destruction
land loss,
contamination, and
development

22. Environmental Issues in Modern Deltas
Mississippi Delta Coastal Land loss
Louisiana's coastal wetlands, a national resource supporting 30% of the nation's fisheries and most of the wintering ducks in the Mississippi Flyway, are at risk from the annual conversion of an estimated mi2 of wetlands to open water.
Louisiana's wetland loss rate is the highest of any state in the nation. The processes causing wetland loss in coastal Louisiana are complex and varied.
Huge energy infrastructure
Louisiana roads, pipelines, and transmission and distribution systems transport more than 30 percent of the nation’s oil and natural gas supplies through the state

23. Coastal Elevation in Louisiana

24. Nature’s Revenge
Louisiana’s vanishing wetlands