Mauddud Fm
Type Locality and Naming
Q.P.C. well Dukhan No. 1, lat. 25°25’16” N, long. 50°47’01” E, elevation 39 m (128 ft), completed 9.1.1940, between drilled depths 734 and 789 m (2408 and 2589 ft). The formation takes its name from Ain Mauddud, a locality near Dukhan, Qatar. F.R.S. Henson, 1940 (unpublished report)
Synonym: “Second Pay Limestone” of Bahrain, Anon., 1937. “Mauddud Limestone”, Smout, 1956. “Mauddud Formation”, Owen and Nasr, 1958. “Mauddud Formation”, Dunnington, 1959. “Mauddud Formation”, Dominguez, 1965. “Mauddud Member”, James and Wynd, 1965. “Mauddud Member”, Powers et al., 1966. “Mauddud Formation”, Dunnington, 1967.
Reference Section:
Lithology and Thickness
Grey, foraminiferal limestone, varying from predominantly compact lime mudstone at the base through wackestones to pellety, skeletal packstones and wackestones at the top. At many levels the rock is composed predominantly of tests of Orbitolina and Trocholina. Its thickness is 55 m (181 ft).
Relationships and Distribution
Lower contact
Nahr Umr Fm, contact conformable. Defined by change from arenaceous sediments of the Naht Umr, below, to limestone of the Mauddud, above.
Upper contact
Regional extent
Encountered in all deep wells drilled in onshore Qatar. Known also in Iraq, Kuwait, Saudi Arabia, Bahrain, parts of Abu Dhabi and Oman. Recorded from southwest Iran.
GeoJSON
Fossils
Orbitolina concava (Lamarck) var. qatarica Henson, Trocholina arabica Henson, Trocholina lenticularis Henson, Trocholina altispira Henson, Cyclammina whitei Henson.
Age
Depositional setting
Additional Information
No formal description of the type section of the Mauddud Fm has previously been published. The name has, however, been applied for many years to the widespread “Orbitolina concava Limestone” found in many parts of the Middle East. The lithofacies of the Mauddud is so distinctive that there is little doubt that the formation has been correctly identified in the majority of cases.
The Mauddud Fm represents a quiet phase of widespread shallow shelf carbonate deposition, marking the close of an Albian cycle of sedimentation which commenced with deposition of the terrigenous clastic of the Nahr Umr Fm.
H.V. Dunnington (1967) records the presence of an unconformity at the top of the Mauddud in Kuwait and S. Iraq. He believed this sedimentary break to be region-wide and to separate Albian from younger Cretaceous rock units. No physical evidence of such an unconformity is discernible in Qatar or neighbouring areas.