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Carbonate Storm Deposits Indicators of Sea Level Position?

Carbonate Storm Deposits Indicators of Sea Level Position?. Professor Christopher G. St. C. Kendall University of South Carolina kendall@sc.edu 803 – 777 2410. Carbonates Storm Deposits. Represented by cycles of carbonate that are coarse at base & fine up to shale

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Carbonate Storm Deposits Indicators of Sea Level Position?

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  1. Carbonate Storm Deposits Indicators of Sea Level Position? Professor Christopher G. St. C. Kendall University of South Carolina kendall@sc.edu 803 – 777 2410 “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  2. 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 “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  3. 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 “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  4. Bioclastic packstones , & calcareous shales - Kope Fm “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  5. Bioclastic packstones , & hummocky bedded calcareous silts - Fairview Fm “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  6. Bioclastic packstones , & hummocky bedded calcareous silts - Fairview Fm “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  7. Mid Slope - Storm Deposits Note lack of Tidal Flat fill High-stand Surface of Condensation “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  8. Lower Slope - Storm Deposits Note lack of Tidal Flat fill High-stand Surface of Condensation “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  9. Upper Slope - Storm Deposits Note lack of Tidal Flat fill High-stand Surface of Condensation “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  10. Crest of Margin - Storm Deposits Note Tidal Flat & Standard Sequence Stratigraphic Surfaces Maximum Flooding Surface “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  11. 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. “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  12. Drafted by Waite 99, after James 1984) “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  13. 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? “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  14. 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 “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

  15. Lecture Ends!! • And so for a drink!!! “Storm Deposits - Sea Level Indicators” Christopher G. St. C. Kendall

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