Monitoring Variations in Carbonate Biofacies: Studies from Tertiary Outcrops of Oman
IPAL Erlangen University, Germany
The most complete succession of Tertiary carbonates in the Middle East is exposed along the southeastern Arabian Platform margin in Oman, which serves well for outcrop studies. The Late Paleocene-Early Eocene time slice involved widespread subsidence, extensive transgression over the Arabian Platform and aggradation of the first carbonate platform stage. The shallow-shelf environment is represented by the deposition of carbonates with alveolinid foraminifera, coralline algal nodules and scleractinian corals. In the Mid-Eocene, regional subsidence of the Arabian Plate was accompanied by extensive transgression and aggradation of the second carbonate platform stage. Thick nummulite shoals and banks accumulated along the platform margin. The Upper Eocene calcarenitic shallow-shelf deposits are characterized by a rich macrofauna (molluscs, echinids and corals). In the Oligocene, the emergence of the Arabian Platform was related to the opening of the Gulf of Aden. Forced regression and shelf-margin platform progradation-aggradation developed at the edge of the Arabian Plate. Carbonate platform collapse and resedimentation along the margin occurred at the beginning of this stage. The limestones with marly and sandy intercalations contain patch reefs with scleractinian corals and an abundant macrofauna of echinoids, gastropods and bivalves. During the Tertiary mechanisms like climate, tectonic movements, eustatic sea-level changes and siliciclastic influx controlled the dimension and biofacies distribution on the platform. These triggering mechanisms influenced the fauna (foraminifera) and flora (calcareous algae) during the different time-slices causing changes in the sedimentologic and biotic composition.
AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain