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Carbonate Storm Deposits Indicators of Sea Level
Position?
Professor Christopher G. St. C.
Kendall University of South Carolina kendall_at_sc.
edu 803 777 2410
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Carbonates Storm Deposits

• Represented by cycles of carbonate that are
  coarse at base fine up to shale
• Coarser portion of each cycle is interpreted to
  be result of water being shallow enough for
  storms to sort sea floor, while fines represent
  water deep enough to afford protection from
  effects of similar storms

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Setting of Storm Deposits
Carbonate storm deposits associated with ramp
margins that lack organic binding or cementation
enabling sediment dispersal

• Presence of storm deposits are indices of lack of
  cementation and/or organic binding
• Occurrence of larger metazoan skeletons enhances
  capacity for surface of ramp to build above a
  shelf equilibrium profile

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Bioclastic packstones , calcareous shales -
Kope Fm
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Bioclastic packstones , hummocky bedded
calcareous silts - Fairview Fm
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Bioclastic packstones , hummocky bedded
calcareous silts - Fairview Fm
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Mid Slope - Storm Deposits
Note lack of Tidal Flat fill
High-stand Surface of Condensation
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Lower Slope - Storm Deposits
Note lack of Tidal Flat fill
High-stand Surface of Condensation
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Upper Slope - Storm Deposits
Note lack of Tidal Flat fill
High-stand Surface of Condensation
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Crest of Margin - Storm Deposits
Note Tidal Flat Standard Sequence Stratigraphic
Surfaces
Maximum Flooding Surface
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Examples of Storm Deposits
Carbonate storm deposits associated with ramp
margins include

• Upper Jurassic Hanifa Jubaila Fms of Arabian
  cratonic margin basin
• Lower Cretaceous of Arabian Gulf
• Oligocene/Miocene of the Murray Basin
• Upper Ordovician of Kentucky Ohio.

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Paradoxes of Storm Deposits?

• Wide spread storm events have been identified on
  ramps explaining occurrence of shallow water
  cycles that do not make it to sea level
• Surface of ramps on which storm deposits occur
  related to
• An ecological base level that does not match
  hydrodynamic base level but is connected to it (
  Pomar(2001)
• Lack of local cementation
• Ramp response to increase of accommodation is
  ascribed to
• Eustasy
• Tectonic events
• Storm deposits can be sorted, rounded,
  incorporate several generations of sediment
  component that are product of
• Single large storms at sea level low?
• Multiple storms?
• Cannibalism supports lack of cementation
  binding on ramp?
• Micritization of the surfaces of gravels grains
  can be common but more often it is not
• Time spent exposed on sea floor insufficient for
  cyanobacteria colonization?

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Conclusions

• Wide spread sea level events matched to storm
  prone portions of geological section
• Accommodation controls carbonate productivity
• Lows favor carbonate production and storm sorting
• Highs reduce carbonate productivity and induce
  condensation of section
• This response explains the lack of tidal flat
  fill on ramps

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Lecture Ends!!

• And so for a drink!!!