A Cenomanian–Santonian rudist–bearing carbonate platform on the northern Arabian Plate, Turkey: facies and sequence stratigraphy

Abstract

Recent studies have shown that Cenomanian–Santonian carbonate sedimentary rocks rich in rudists are widespread throughout southeastern Turkey. The Derdere and Karababa formations have been analysed in the Sabunsuyu section (Kilis Province). On a field scale, we can distinguish rudist–rich beds that rhythmically alternate with bioclastic levels composed of bivalves, gastropods and roveacrinids in these formations. Although pelagic faunal elements (predominantly planktic foraminifera and pithonellids) are documented in the lowermost part of the series, the rudist–rich facies are represented mainly in the Derdere and Karababa formations. Rudists, benthic and planktic foraminifera indicate middle–late Cenomanian and Turonian–Santonian ages for the Derdere and Karababa formations, respectively. Based on studied facies, five microfacies have been recognised and categorised in three facies groups: inner ramp, mid ramp and outer ramp. Evidence such as gradual changes in facies and absence of extensive uninterrupted barrier reefs indicate that the Derdere Formation was deposited in a ramp depositional system. The sedimentology and taphonomic signature of the rudist shell beds have been described in order to obtain a better understanding of the depositional environment and the physical processes that controlled Cenomanian–Santonian sedimentation. Monospecific tabular beds characterise mainly the upper part of the series (topmost part of Derdere Formation and Karababa Formation); more complex rudist concentrations, characterised by moderate species diversity, increase upsection. The rudist levels are associated with highstand systems tract deposits because of the suitability of trophic conditions in the rudist–dominated ramp.