Paralic (Marginal Marine) Siliciclastic Depositional Systems

1
Paralic (Marginal Marine) Siliciclastic
Depositional Systems

• Modern and Ancient

2
Coasts

• Fluvial energy/sediment input vs. Marine
  energy/sediment input
• Marine energy Wave vs. Tide dominated
• Transgressive vs. Regressive

• Depositional vs. Erosional
• Rocky (consolidated) vs. dis- or partially
  aggregated substrates
• Terrigenous vs. biochemical

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 Islands/Lagoons

• Barrier Island Massif
• Wave Dominated beach-shoreface
• washover channels and fans
• Main dune ridge and fore dunes

8
Zonation of the (Wave Dominated) Shoreline Profile

• Wind Waves Main source of energy to most open
  ocean coasts

9
Barrier Island Facies

• Synoptic map

• Time series sections

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
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.