The Rise of Rudists; Middle Cretaceous Facies in Mexico and the Middle East

Abstract

Geologists have long recognized the Cretaceous as a time of outstanding development of carbonate platforms and offshore banks. These are known in an equatorial belt from 40° N to 20° S along the Tethyan seaway through southern Europe, in the Middle East, across southern Asia and the sunken Mid-Pacific and around the Gulf of Mexico-Caribbean region. This Chapter focuses particularly on Middle Cretaceous strata in these areas and on the role played in carbonate accumulation by the rudist bivalves within them. Rudists added immensely to the volume of material in Cretaceous buildups, forming a framework both within shelf mounds and along shelf margins. They are significant constituents of reservoir rock in some of the world’s greatest oil fields. In this Chapter a discussion of rudist morphology and paleoecology is followed by a description of some typical Middle Cretaceous facies patterns.