Middle East Aptian rudist-foraminiferal-algal associations and their possible modern Arabian Gulf analogue

Abstract

The depositional history of the rudist-dominated facies of the Shu'aiba Formation of the Arabianpeninsula may be best understood by studying a possible analogue such as the Great Pearl Bank Barrier, located on the southern flanks of the Arabian Gulf. The favourable hydrocarbon reservoir properties of the Shu'aiba carbonates are primarily attributed to the presence of the rudists and their associated debris, which accumulated along the margins of an intra-shelf basin. The possibly fault-based rudist banks caused differentiation of an earlier carbonate platform into lagoon, back-bank, bank, fore-bank and open marine environments. Understanding of the orientation of these banks has been significantly assisted by micropalaeontological analysis of the rudist-associated sediment, but may be enhanced by the study of extant large bivalves, such as the constratal “fan mussel” Pinna spp. The Great Pearl Bank Barrier is a submarine ridge that extends for approximately 200km between the Qatar peninsula and Abu Dhabi in the southern Arabian Gulf, and is located in water depths of less than 8 m. This prominent, possibly fault-controlled, submarine feature consists primarily of bivalve shells, sands and mud, in which are embedded locally dense populations of the large bivalve species Pinna bicolor Gmelin and P. muricata Linnaeus, that may serve as Recent counterparts for the extinct Aptian constratal elevator rudists.