Dammam Fm

Period:

Paleogene

Age Interval:

Lutetian – Rupelian, On1, Iq1, Sa (1,2), Bn1, Qa1, Kw1, UAE1

Province:
Oman, Iraq, Saudi Arabia, Bahrain, Qatar, Kuwait, United Arab Emirates

Type Locality and Naming

Dammam Dome, along the Dhahran-Al’Alah road, Saudi Arabia (Powers, 1968; Weijermars, 1999). Columns: Oman Subsurface, S Iraq, Saudi Arabia Outcrop, Saudi Arabia Subsurface, Bahrain, Qatar, Kuwait, United Arab Emirates. Uppermost formation in Hasa Gr in Kuwait. Uppermost formation of the Hadhramaut Gr in Oman. Subsurface reference sections in Oman are Dhulaima-2 and Barik-8. The previous reference section in Oman was well Biladi-1.

Synonym: "Hughes Clarke (1988) describes an Andhur Fm as a more argillaceous, lateral facies equivalent of the Dammam Fm. However, such a unit has proved difficult to consistently pick and differentiate from the more marly Dammam Fm sections and it has never been consistently applied to the subsurface. Hence the practical definition of the Dammam is expanded (in Oman?) to include a more argillaceous composition. . . . The Qara fm, as defined in Dhofar, is here considered as a synonym of the Dammam Fm."

Lithology and Thickness

Light-gray marls and limestones with rare molluscs. In Oman: a unit mainly of chalky limestone, but with some variability in dolomitization, minor marl interbeds and a basal calcareous shale unit. Locally, marl and shale content may increase.

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

Regionally, the lower boundary is conformable onto the Rus Fm

Upper contact

The upper contact is a hiatus overlain by Fars Gr carbonates (Taqa Fm) or clastics (Dhulaima Fm), which, if fossiliferous, can give evidence of an age-gap of latest Eocene through middle Oligocene. Fars Gr (Taqa Fm). In Kuwait, it overlain by the Ghar Fm

Regional extent

Widespread. Oman Subsurface, S Iraq, Saudi Arabia Outcrop, Saudi Arabia Subsurface, Bahrain, Qatar, Kuwait, United Arab Emirates. In Oman: " The Dammam Fm is potentially present throughout Interior Oman, except in areas of young outcrop erosion. … The thin basal shale is found throughout North Oman where it is best developed. It is not present in South Oman. This has implications for the hydrogeology of the Formation, with better aquifer potential in the limestones than in the argillaceous limestone/marls/claystones."

GeoJSON

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Fossils

There is an abundance of Middle Eocene fauna - mainly the larger forams Nummulites e.g., N. fabianii, N. discorbinus, N. bayhariensis and N. beaumonti. Biozones F76 and F75.

Age

Latest Ypresian through Bartonian in Oman: " Early–Middle Eocene age, ca. 50–37.2 Ma. Possible Late Eocene in the most northerly sequences in Interior Oman. Sharland et al. (2001) suggest a latest Ypresian (Early Eocene) age for the basal Dammam Fm, where they place their MFS Pg20 regionally."

Age Span:

Beginning stage:

Ypresian

Fraction up in beginning stage:

0.8

Beginning date (Ma):

49.66

Ending stage:

Bartonian

Fraction up in the ending stage:

1.0

Ending date (Ma):

37.71

Depositional setting

Lithologies and fossils provide evidence for a shallow-marine environment.

Depositional pattern:

Additional Information

Compiler:

From Forbes, G.A., Hansen, H.S.M., and Shreurs, J., 2010. Lexicon of Oman: Subsurface Stratigraphy. Gulf Petrolink, 371 pp. (plus enclosures and CD); and Middle East Geological Timescale 2008 Al-Husseini, Journal of Middle East Petroleum Geosciences v 13, no. 4. Steineke et. al., 1958, Page 1312