Aruma Gr
Type Locality and Naming
The Aruma Group (or Aruma Fm in some regions) is widely used around the Gulf to comprise all units between the regional hiatus/ disconformity above the Wasia Gr and the Cretaceous – Cenozoic boundary, which is usually also a hiatus. Type and reference sections: Not specified, but implied to be south Iraq-Kuwait (see van Bellen et al., 1959/2005). In southern Iraq and Kuwait, the Group is divided into six formations, none of which extend to the southern Gulf areas. In Interior Oman, a simple two-fold subdivision of the Aruma Gr into a lower Fiqa Fm and an upper Simsima Fm is used. Reference sections at Formation level in Oman are Suneinah-1 and Al Huwaisah-6 in North Oman and Hawmyat-1 in South Oman Column: Oman Subsurface.
Synonym:
Lithology and Thickness
In Oman it consists of the Fiqa Fm shales overlain by the Simsima Fm (a very fossiliferous carbonate unit, commonly dolomitized). In Kuwait, it is yellowish-tan to yellowish-brown dolomitic and calcareous shale, argillaceous dolomite and olive shale with minor interbedded limestone and dolomite. Blue-gray to cream, massive dolomite and limestone. Cream-colored, soft, chalky, fine-grained limestone, with minor interbedded olive to olive-green calcareous shale in the lower part. Cream-colored, massive, nodular, chalky, fine-grained limestone with abundant small fragmental organic remains. Sequence Stratigraphy: Megasequence AP9 (Sharland et al., 2001). Sharland et al. (2001) correlate their Late Cretaceous MFS surfaces K180 through to K150 into the Aruma Gr of Oman (see formational discussions for detail).
Relationships and Distribution
Lower contact
Upper contact
An absence of Late Maastrichtian – Danian (Early Paleocene) sediments across much of the Arabian Plate is noted by Sharland et al. (2001). It is unconformably overlain by the Umm er Radhuma Fm (its basal Shammar Shale). In Kuwait it is overlain by the Tayarrat Fm.
Regional extent
"The Group is widespread through Oman, although commonly cut-out over structural highs, many of which had growth phases late in the Cretaceous. It is very thick close to the Al Hajar Mountains, in a foredeep related to the Late Cretaceous nappe emplacement (Robertson 1987a,b; Warburton et al., 1990). Proximity to and involvement with this deformation is the basis for different subdivisions in this area (Boote et al., 1990; Rabu et al., 1990). To the south and east, it is a thin shallow-marine unit wedging out onto the Al Huqf-Haima High axis, but then thickening over it into the partially-offshore down-faulted blocks bounding the Arabian Sea."
GeoJSON
Fossils
Microfossils, nannofossils, palynology biostratigraphy zonations.
Age
Depositional setting
The Fiqa Fm is interpreted to represent the deposition and fill of a foreland basin (Boote et al., 1990; Warburton et al., 1990), ahead of the southward advancing thrust sheets of the Hawasina nappes and Semail Ophiolite. The following Simsima Fm represents the re-establishment of marine sedimentation over Oman after the disturbance caused by the nappe emplacement along Oman’s northeast margin associated with the closure of the Neo-Tethys Ocean.
Additional Information