Carbonate ramps and the Pleistocene-Recent depositional systems of the Arabian Gulf

Abstract

Abstract The term ramp was devised to be helpful. It was to provide an interpretative model with genetic significance for a specific category of carbonate body and one with predictive value in oil exploration. The present-day southern Arabian Gulf is commonly cited as a ramp but it fails to provide a good example. In contrast with most of its pre-Miocene history, the Arabian Gulf is a foreland basin with a tectonically, climatically and glacioeustatically controlled mixed carbonate-clastic fill. Because of glacioeustasy and its relatively shallow depth, the Gulf has spent much of the last 2.5 Ma emergent. Three separate and equally important sedimentary systems currently contribute to its development: the Arabian Gulf marine carbonate system, the Mesopotamian fluviodeltaic system and the Arabian continental aeolian system. The Arabian Gulf carbonate system is a ‘high stress’ regime that is in tectonic, eustatic and depositional disequilibrium. Its structural, morphological and sedimentological diversity discount it as a Recent analogue for the thick carbonate bodies in the geological record that show persistent accumulation of depth-related facies developed across gentle slopes lacking a marked shelf-slope break. The Arabian Gulf fails some fundamental tests for whether it should be regarded as a stable carbonate ramp depositional system and its use as an example of a ramp is not helpful.