Sixth Arabian Plate Geology Workshop

This paper provides facies and depositional environments of the Dammam Formation in Kuwait. Both subsurface core data and a quarry outcrop was used for facies evaluation.

An outcrop in the Ras Al Hamra area and two nearby shallow cores were studied. The main focus of the project is the description of lithofacies, identification of paleofauna and -flora, the regional distribution and the correlation between surface and subsurface facies.

The limestone is of Paleocene-Eocene age covering a part of the Arabian Plate Megasequence AP 10. The microfossils observed in the outcrop and cores indicate a Late Paleocene/Early Eocene age. the time-equivalent facies of the outcrop is Jafnayn Formation and the sub-surface equivalent is the Umm Er Radhuma Formation.

The main lithofacies types identified are foraminifera and dasycladacean wackestone deposited in an inner platform low energy environment and larger benthic foraminifera (LBF) grainstone and packstone and coral boundstone from a medium to higher energy environment.

In terms of diagenesis it has been witnessed that the Ras Al Hamra carbonates have undergone physical compaction, chemical compaction (pressure solution), dissolution and cementation. This has influenced the porosity in which most of the primary porosity was destroyed by cementation.

Similar facies can be observed in both the outcrop and the cores examined, however due to diagenetic processes it is concluded that the Ras Al Hamra outcrop is not a good analogue to the subsurface.

For doing sequence stratigraphy on Eocene rocks of the High-Zagros in Iran, finding accurate age of samples was necessary, so we chose two sections (Hamzeh-Ali and Shalamzar) and studied on benthic and pelagic foraminifers, but age of some index benthic foraminifera was too long and extension of pelagic foraminifera narrow thus we used of strontium dating for earning the precise age of the sections for understanding this momentous. Some samples were selected for strontium dating analyses because of lithology and texture. The strontium isotope seawater curve for the Early to Middle Eocene has been earned by samples from sections. The lowest 87Sr/86Sr values belonged to Early Eocene at ~52 Ma and generally increased throughout the Middle Eocene at ~45 Ma. These results are exactly confirmed by benthic and pelagic foraminifera. A credible explanation for the 87Sr/86Sr increased between 52 to 45 Ma is stagnancy for volcanic activities at Middle Eocene. Although, the strontium isotope values increased toward middle Eocene but sea level changed to be shallower environment.