Hanifa Fm

Period:

Jurassic

Age Interval:

Oxfordian - Kimmeridgian, Sa (1,2), On (1,2), Bn1

Province:
Saudi Arabia, Oman, Bahrain, Oman

Type Locality and Naming

The Hanifa Formation is considered to be one of the major source rocks for Middle East oil (Murris, 1981). Type section is Wadi Hanifa, Saudi Arabia (see Powers, 1968). Columns: Saudi Arabia Outcrop, Saudi Arabia Subsurface, Oman Subsurface, Oman Outcrop, Bahrain. Upper formation (4 of 5) in the Sahtan Gr of Oman subsurface.

Synonym:

Lithology and Thickness

Reef limestone. Colonial corals are common at several horizons in the middle and upper parts, commonly in position of growth. Cream to tan relatively soft chalky limestone with minor interbedded marl and tan clay shale; several prominent brown oolite units in middle and upper portions, with a particularly prominent one at the top. In Oman, it is a limestone sequence with argillaceous mud-/wackestone below, passing up into porous grain-supported grainstone above. Divided in Arabia into a lower Hawtah Mbr and an upper Ullayah Mbr.

Lithology Pattern:

Reef limestone

Relationships and Distribution

Lower contact

The lower boundary with the underlying Tuwaiq Mountain Limestone Fm (Tuwaiq Mountain Fm) is a very low-angle unconformity (0.1% gradient, according to Rousseau et al., 2006) as the Hanifa onlaps in a south-easterly direction. The Upper Jurassic was a period of overall high sealevel and therefore the unconformity must be partially tectonic in origin. Rousseau et al. (2006) link this unconformity with a period of uplift and erosion documented across the entire eastern edge of the Arabian Plate. Therefore, Forbes et al. (2010) show a gap (most of the Oxfordian) between the base of Hanifa Fm and the underlying Tuwaiq Mountain Fm.

Upper contact

The upper boundary is conformable with the Jubaila Fm. In Oman, if the Jubaila Formation is absent, basal Kahmah Gr sediments rest unconformably on the Hanifa Fm.

Regional extent

Saudi Arabia Outcrop, Saudi Arabia Subsurface, Oman Subsurface, Oman Outcrop, Bahrain. In Oman, the Hanifa is present only in the westernmost subsurface of Interior Oman and is truncated to the east and south.

GeoJSON

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Fossils

In Oman, the Hanifa Fm represents the base of Sub-biozone F475 (Alveosepta jaccardi) and Palynozone 4214 (Systemaphora cf. areolata). However, this Formation is relatively poorly constrained biostratigraphically (fossil ranges poorly defined).

Age

Oxfordian- early Kimmeridgian; but uncertain: "It is considered to have a probably early Kimmeridgian age by Hughes Clarke (1988). Interestingly Sharland et al. (2001) illustrate their J60, early Kimmeridgian, MFS in well Butabul-1, associated with the thin Gamma peak at the Jubaila Fm / Hanifa Fm boundary, (i.e. strictly basal Jubaila Fm) but also state that the J60 MFS cannot be recognized in Omani outcrop platform deposits. They place their Middle Oxfordian J50 MFS at the top of a wackestone-‘aphanitic’ limestone package in the lower part of the Hanifa Fm. Conversely, Rousseau et al. (2006) argue that Oxfordian deposition probably never occurred in Interior Oman and that the Hanifa is indeed Kimmeridgian in age." (Forbes et al., 2010). Therefore, pending more information on regional age span(s), shown here as late Oxfordian to early Kimmeridgian for display purposes.

Age Span:

Beginning stage:

Oxfordian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

158.16

Ending stage:

Kimmeridgian

Fraction up in the ending stage:

0.25

Ending date (Ma):

153.40

Depositional setting

Low- to high-energy shallow-marine settings are indicated by the sediments and a moderately rich microfossil content.

Depositional pattern:

Additional Information

Compiler:

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