Sequence stratigraphy

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Sequence stratigraphy
2014-03-26 13:28:07

Glacial sequence stratigraphy
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  1. Focus on glacialmarine
    • Temperate=Alaska
    • polythermal=Svalbard 
    • polar=Antarctica
  2. Low mid latitude
  3. Glacial continental margins differ
    • Glacio-isostacy
    • base level is grounding line (May also be sea level)
    • grounding line movement and sea level maybe asynchronous
    • different deposystems
  4. base level varies with
    Grounding line, which need not vary with shoreline
  5. Accommodation space on glacial shelves
    • Complex interaction of:
    • glacial advance and retreat type of glacial terminus in controlling sediment
    • rates and styles of sediment delivery to the sea
    • marine dispersal and re-depositional processes
    • continental shelf morphology
    • eustasy
    • glacial and sediment isostatic loading
    • local tectonic movements

    • largest problems:
    • paleo-depth indicators are commonly few
    • changes in facies driven by glacial proximity versus relative sea level changes are often debatable
  6. To what degree can debris and sediment flux help stabilize a marine glacier terminus and hence influence it's position independent of sea level?
    • Depends on:
    • glacial regime
    • balance of rates - ice marine melt, vs ice flux, vs sediment accumulation
  7. Use basic data principles from modern settings
    Conclude that there are many
  8. First first look at sedimentation and sediment accumulation rates on different time scales:
    • Today from suspended sediment traps
    • today from differential bathymetry
  9. Sediment volume (erosion) mainly controlled by glacial regime
    Glacial erosion tends to be more efficient than non-glacial processes in similar climatic regimes
  10. Quaternary glacial erosion/denudation rates
    Take a picture from slide
  11. Most glacial sediment accumulates in or near a grounding zone
    • Sediment accumulation decays by power and exponential functions away from a grounding line
    •  to only need fluxes to the grounding line, but also net sediment budget at the grounding line
    • -sediment dispersal processes in the sea
    • -sediment stability criterion slopes
  12. Sediment depocenters move through time
    • Glacial stage
    • minimum
    • early advance
    • late advance
    • maximum
    • early retreat
    • late retreat
    • minimum
  13. Sediment depocenters are significant parameters to consider in predicting behavior of marine termini
    • (Insufficient data from non-temperate systems)
    • 1. Glacial regimes differ in their sediment accumulation rates.
    • 2. Sediment accumulation decays
  14. Different glacial regmes produce different sedimentary facies
    Facies produced in different
  15. Different glacial regimes and termini produce different grounding zone systems
    • Geometries mainly - bank vs wedge
    • banks - decrease ice surface melting area
    • - apply back pressure
    • wedges -
  16. Grounding zone wedge
    Wedge causes ice
  17. Annual fluctuations of grounding lines are well defined
    • If recovery complete - build compound grounding line systems, assist stability
    • if recovery incomplete - lone forms (commonly annual), no assist in stability