Stratigraphic Nomenclature of Iranian Oil Consortium Agreement Area

ABSTRACT The stratigraphy and correlation of Triassic to Plio-Pleistocene sediments within the Iranian Oil Consortium Agreement Area are discussed. Rock-stratigraphic units are named and defined. These are correlated with the Iraq, Kuwait, and Saudi Arabian stratigraphic successions. The Agreement Area, situated northeast of the Arabian shelf and including part of the Zagros orogenic area, has been the site of more or less continuous sedimentation from Triassic to Plio-Pleistocene time. Regional disconformities occur at the top of the Aptian, the Cenomanian-Turonian, the Cretaceous, and the Eocene. A major angular unconformity produced by Mio-Pliocene folding occurs at the top of the Fars Group. Carbonate and shale deposition controlled by epeirogenic movements dominated until Late Cretaceous time when movements within the Zagros area began to influence sedimentation. Upper Cretaceous, Paleocene, Eocene, and Oligocene deposits are characterized by sharp facies and thickness changes as a result of orogenic movements in the Zagros area. Following deposition of the Oligocene-lower Miocene Asmari Formation the Agreement Area was part of a trough trending northwest-southeast. After initial evaporitic and marine phases, this trough was filled by clastics derived from the rising Zagros Mountains on the northeast. Conglomerates of the Bakhtyari, deposited unconformably upon the Fars Group, mark the end of this basinal filling.