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| Dammam Formation | |
|---|---|
| Name | Dammam Formation |
| Type | Geological formation |
| Period | Oligocene–Miocene |
| Primary lithology | Limestone, dolomite, marl |
| Other lithology | Gypsum, evaporite, sandstone |
| Named for | Dammam |
| Region | Eastern Province, Saudi Arabia; Persian Gulf |
| Country | Saudi Arabia, Bahrain, Qatar, UAE, Kuwait |
| Unit of | Tertiary succession of Arabian Platform |
Dammam Formation is a regional Tertiary carbonate sequence exposed and subsurface across the Arabian Platform, notably in the Eastern Province of Saudi Arabia, the Persian Gulf basin, and adjacent areas. The unit is important to studies of Paleogene–Neogene stratigraphy, petroleum geology, and regional tectonics, intersecting research by institutions such as Saudi Aramco, Petroleum Development Oman, Gulf Petrochemicals and Chemicals Association, and academic groups at King Fahd University of Petroleum and Minerals and Imperial College London.
The formation comprises predominantly shallow‑marine carbonates including massive to bedded limestone and dolomite intercalated with marl and subordinate gypsum and evaporitic horizons. Fieldwork and petrographic analysis by teams from Saudi Geological Survey, BP, and Shell plc have characterized facies ranging from bioclastic grainstone to micritic mudstone, with diagenetic dolomitization linked to burial and reflux processes studied by researchers at University of Oxford and Texas A&M University. Lithologic variability reflects influences documented in regional syntheses such as publications from American Association of Petroleum Geologists and case studies presented at the Middle East Geoscience Conference.
Biostratigraphic control using nummulitid foraminifera, larger benthic foraminifera, and planktonic microfossils ties the sequence to late Oligocene through early Miocene chronostratigraphy, corroborated by isotopic and chemostratigraphic work from teams at Columbia University and University of Cambridge. The formation is correlated with regional units including the Rus Formation, Hadrukh Formation, and other members of the Tertiary succession defined by mapping projects of Iraq Geological Survey and stratigraphic charts produced by Saudi Aramco and the United States Geological Survey.
Depositional models interpret the formation as a shallow epicontinental carbonate platform influenced by fluctuating sea level and restricted basin episodes on the Arabian Shelf, analogous to depositional settings discussed in comparisons with the Mediterranean Sea and Gulf of Mexico platforms. Research integrating sequence stratigraphy from University of Houston and paleoceanographic data from Woods Hole Oceanographic Institution indicates cycles of open marine carbonate deposition, lagoonal restricted facies, and episodic hypersaline evaporite formation tied to regional tectonism associated with the Zagros Orogeny and subsidence of the Persian Gulf basin.
Fossil assemblages are dominated by larger benthic foraminifera such as nummulitids, rotaliids, and other taxa central to biostratigraphy used by paleontologists at Natural History Museum, London and Smithsonian Institution. Additional fossils include echinoids, bivalves, gastropods, bryozoans, and algae comparable to assemblages cataloged at Muséum national d'Histoire naturelle and University of Vienna. Microfossil studies led by teams at Scripps Institution of Oceanography and University of Bremen have refined age models using planktonic foraminifera and calcareous nannofossils, while ichnological and paleoecological interpretations have been pursued in collaborations with Yale University and University of Cairo.
The unit is widely distributed across northeastern Saudi Arabia, extending beneath the Persian Gulf to outcrops and subsurface equivalents in Bahrain, Qatar, Kuwait, and the United Arab Emirates. Thickness varies significantly due to lateral facies changes and structural influences from salt tectonics and faulting; reported thicknesses by regional surveys including Saudi Aramco datasets and basin studies from King Abdullah University of Science and Technology range from a few meters in condensed shelf sections to several hundred meters in subsurface depocenters identified in seismic work by CGG and Schlumberger.
The formation and its lateral equivalents form important reservoir and seal intervals in the hydrocarbon systems of the Arabian Plate documented by Saudi Aramco, Kuwait Oil Company, and Qatar Petroleum. Carbonate porosity and permeability enhanced by dolomitization, karstification, and fracturing create productive reservoirs analogous to those described in Ghawar Field and other prolific Gulf fields; evaporitic and marl intervals act as intraformational seals and source-rock proxies investigated in petroleum systems analyses by ExxonMobil and academic consortia at King Abdullah Petroleum Studies and Research Center. Coalitions of industry and academia, including the European Association of Geoscientists and Engineers, have assessed the unit's role in maturation, migration, and trapping of hydrocarbons.
Initial description and mapping of the unit arose from early 20th‑century surveys involving geologists associated with colonial-era mapping and oil concession work, followed by systematic subsurface characterization in the mid‑20th century during exploration campaigns by Standard Oil affiliates and national oil companies. Landmark contributions include petrographic and stratigraphic syntheses published through collaborations among Saudi Aramco, University of Leeds, and UCL, plus sequence stratigraphy and basin modeling advances from researchers at Caltech and Massachusetts Institute of Technology. Recent high-resolution studies employing sequence stratigraphy, chemostratigraphy, and 3D seismic interpretation have been produced by consortia involving TotalEnergies, Halliburton, and university partners, continuing to refine models of carbonate platform evolution, diagenesis, and hydrocarbon prospectivity.
Category:Geologic formations of Saudi Arabia