Diyab Fm
Type Locality and Naming
Q.P.C. Well Dukhan No. 51 (formerly Juh. No. 1), lat 24°53’48” N, long 50°59’55” E, elevation 76.5m (252 f.), completed 14.10.1952, between drilled depths 2377 and 2476m (7800 and 8125 ft). The formation takes its name from a locality on the south part of the Dukhan anticline. W. Sugden (unpublished report)
Synonym:
Reference Section:
Lithology and Thickness
Top. 1. Limestone, dark grey, fine grained lime mudstone, dense, thin bedded, very argillaceous, with thin interbeds of dark grey marl and of grey, dense, fine, calcarenite containing some quartz grains. 23m (77 ft). 2. Anhydrite, white, 0.6m (2 ft). 3. Limestone, dark grey, fine grained, argillaceous lime mudstone, thin bedded, with streaks of grey, dense, fine calcarenite, as in unit 1 but with less quartz. Very rare thin beds of chert. 23 m (72 ft). 4. Anhydrite, white. 1.8 m (6 ft). 5. Limestone, grey, fine grained lime mudstone, dense. 9.4 m (31ft). 6. Limestone, dark grey to black, very argillaceous, silty, slightly dolomitic, in part finely fissile, carbonaceous, particularly in lower part; occasional thin streaks of fine grained calcarenite. 40 m (132 ft). Base. Thickness is 99m (325 ft).
Relationships and Distribution
Lower contact
Upper contact
Regional extent
Recognized as a separate formation only in Qatar, where it has been encountered in many deep wells. Dark grey argillaceous limestones occur above the Araej Formation to the east in Abu Dhabi, but a distinct Diyab Formation has not been distinguished.
GeoJSON
Fossils
In 1. Nautiloculina oolithica Mohler, Glomospira sp. In 3. N. oolithica, Glomospira sp., Exogyra nana (J. Sowerby), Perisphinctes sp., In 6. Pholadomya cf. inornata (J. de C. Sowerby), Gryphaea balli (Stefanini), Liostrea arabica Stefanini, Chlamys macfadyeni Cox, E. nana, Modiolus imbricatus (J. Sowerby), Dichotomoceras cf., D. anomalus Spath.
Age
Depositional setting
Additional Information
Powers, 1968, states that the basal, argillaceous unit of the Hanifa Fm is separated by a hiatus from the lower, Cuneolina-bearing beds of the Tuwaiq Mountain Limestone in the central coastal area of Saudi Arabia, close to Qatar. The Diyab Fm may be the equivalent of the basal Hanifa. The Cuneolina-bearing beds have not been recognized in Qatar, although their equivalent may occur to the east, in Umm Shaif, where additional section containing Meyendorffina sp. occurs between typical Araej and Diyab lithologies. The upper unit of the Araej in Qatar is equated with the Hisyan Member of the Dhruma Fm. Thus, the Diyab-Araej contact could represent a considerable break in sedimentation, spanning the Oxfordian and possibly part of the Callovian eras, resulting from uplift over the Qatar arch. Should the Diyab contain equivalents of part of the Tuwaiq, there probably still remains a break between it and the Araej, represented by the Cuneolina-bearing beds and their equivalents (the Meyendorffina-bearing bed) which are present on either side of the Qatar axis.