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Paralic (Marginal Marine) Siliciclastic Depositional Systems

Paralic (Marginal Marine) Siliciclastic Depositional Systems. Modern and Ancient. Depositional vs. Erosional Rocky (consolidated) vs. dis- or partially aggregated substrates Terrigenous vs. biochemical. Fluvial energy/sediment input vs. Marine energy/sediment input

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Paralic (Marginal Marine) Siliciclastic Depositional Systems

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  1. Paralic (Marginal Marine) Siliciclastic Depositional Systems Modern and Ancient

  2. Depositional vs. Erosional Rocky (consolidated) vs. dis- or partially aggregated substrates Terrigenous vs. biochemical Fluvial energy/sediment input vs. Marine energy/sediment input Marine energy: Wave vs. Tide dominated Transgressive vs. Regressive Coasts:

  3. Inter/non-deltaic Siliciclastic Shorelines: Paralic Environments • Ancient deposits • Modern Environmental Hazards

  4. Inter/non-deltaic Siliciclastic Shorelines: Paralic Environments • Importance of Holocene Transgression on modern coastal environments

  5. Shoreline Geomorphology in Non-Deltaic Coasts • Reflects the interaction b/w sediment supply vs. marine reworking • Marine reworking is accomplished mainly by: • Fair weather waves • Tides • Storm waves

  6. Barrier Islands/Lagoons • Most Typically associated with low sediment supply and rising sea level • Lagoon: landward estuaries • fluctuating water salinity, temperature, and level; typically highly biologically productive • influence on lagoon ecology; abundance/diversity • flood tidal deltas • tidal channels, mudflats • bay deltas

  7. Barrier Island Massif Wave Dominated beach-shoreface washover channels and fans Main dune ridge and fore dunes Barrier Islands/Lagoons

  8. Zonation of the (Wave Dominated) Shoreline Profile • Wind Waves; Main source of energy to most open ocean coasts

  9. Time series sections Synoptic map Barrier Island Facies

  10. Barrier Islands/Lagoons • Tidal channels, inlets or passes (most abundant and more stable in mesotidal settings) • Drumstick barrier model • Ebb tidal (tide dominated) vs flood tidal (wave dominated) deltas

  11. Transgressive Barrier Island Sequences

  12. Regressive Barrier Island Sequences

  13. Coasts in Crisis • Coastal land loss and the increasing occupation of the coastal zone

  14. Coastal environment factors Coasts in Crisis • Coastal erosion at widely varying rates affects all 30 coastal States and all of the U.S. Island Territories. • During the past 200 years, more than half of our valuable wetlands have been lost due to a combination of natural processes and human intervention. • Pollution of coastal areas has forced the closing of one-third of the Nation's shellfish beds, has restricted beach use, and has permanently contaminated ground water in some communities. • In many coastal urban areas, hard-mineral resources such as sand and gravel for construction and beach nourishment are no longer available onshore. Offshore deposits may provide an alternative but pose environmental and economic dilemmas.

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