Carbonate Storm DepositsIndicators of Sea Level Position? Professor Christopher G. St. C. Kendall

University of South Carolinakendall@sc.edu 803 777 2410

Carbonates Storm DepositsRepresented 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

Setting of Storm DepositsPresence 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 profileCarbonate storm deposits associated with ramp margins that lack organic binding or cementation enabling sediment dispersal:

Bioclastic packstones , & calcareous shales - Kope Fm

Bioclastic packstones , & hummocky bedded calcareous silts - Fairview Fm

Bioclastic packstones , & hummocky bedded calcareous silts - Fairview Fm

High-stand Surface of CondensationMid Slope - Storm DepositsNote lack of Tidal Flat fill

High-stand Surface of CondensationLower Slope - Storm DepositsNote lack of Tidal Flat fill

High-stand Surface of CondensationUpper Slope - Storm DepositsNote lack of Tidal Flat fill

Maximum Flooding SurfaceCrest of Margin - Storm DepositsNote Tidal Flat& StandardSequenceStratigraphicSurfaces

Examples of Storm DepositsUpper Jurassic Hanifa & Jubaila Fms of Arabian cratonic margin basinLower Cretaceous of Arabian GulfOligocene/Miocene of the Murray Basin Upper Ordovician of Kentucky & Ohio. Carbonate storm deposits associated with ramp margins include:

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 EustasyTectonic eventsStorm 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?

ConclusionsWide spread sea level events matched to storm prone portions of geological sectionAccommodation controls carbonate productivityLows favor carbonate production and storm sortingHighs reduce carbonate productivity and induce condensation of sectionThis response explains the lack of tidal flat fill on ramps

Lecture Ends!!And so for a drink!!!