Fiqa Fm

The Fiqa Formation comprises a new phase of sedimentation after a widespread regional emergence at the end of Natih Fm deposition. Column: Oman Subsurface, Kuwait, Abu Dhabi. Type and reference sections: Murban-44, Abu Dhabi, thickness drilled 350 m. The reference section in Oman is well Al Huwaisah-6. Additional reference sections are Hawmyat-1 in South Oman and Haima-3 in Central Oman Lowermost formation in Aruma Gr

Synonym:

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.

"In Oman Outcrop, it is essentially two facies are separated as members: a shale facies, the Shargi Mbr, and a carbonate facies, the Arada Mbr. The Arada carbonates usually overlie the shales of the Shargi Mbr, but alternation occurs, pointing to lateral interfingering. In North Oman a mid Shargi sand-prone level is thought to be equivalent to the Batain Coast, Fayah Fm sandstones (Shackleton et al., 1990; see also Osterloff et al., 2001 and Packer, 2002). Similarly in North Oman the basal Shargi Mbr has an Early Santonian silty/sandy level rich in chamosite ooids and glauconite. ... Sandstones are locally developed in the middle of the Shargi Member as the Fayah sandstone equivalent and in the basal Shargi as the Qitqawt Fm sandstone equivalent. The Upper Fiqa in North Oman is defined as Juweiza Fm facies (Boote et al., 1990), derived from the allochthonous wedge to the northeast, containing coarse detritus rich in chert. ... Locally, Coniacian clastics and lignitic shales, equivalent to the outcropping Qitqawt Fm (Platel et al., 1995), may constitute the earliest phase of Fiqa deposition. … Locally, lignitic black shales, silts and sands may be associated with the basal Shargi. … Sharland et al. (2001) position their Santonian MFS K160 surface towards the base of the Shargi Mbr, and their MFS K170 (Campanian) surface in a mid-Fiqa position. The Coniacian MFS K150 surface is recognized in outcrop equivalent sections from western Oman (Laffan Fm)."

"The Fiqa Formation contains Biozones F67 (Globotruncanita calcarata) to F63 (Whiteinella baltica) (see Group discussion). Recent studies (Packer, 2002) have provided a much higher resolution in the Shargi Member (F65 (Pseudedomia aff. multistriata) to F63 Biozones). The key to the detailed breakdown of the Shargi Member is this highly refined micropaleontological calibration (13 Sub-biozones/events) made possible by rich and varied faunal recovery. Detailed and rigorous micropaleontological analysis is the key to the full understanding of this unit. In addition to the plant remains observed near the base (Sub-biozone F63b shales) the top (upper Zone F65) of the Shargi Member can be similarly organic/plant-rich."

"Dominantly deeper-marine pelagic facies in the north, passing to shallow-marine carbonates in the south. In the north there are more cherts, conglomerates and calciturbidites than their equivalents in the south. The Fiqa Fm comprises a new phase of sedimentation after a widespread regional emergence at the end of Natih Fm deposition. 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. These were emplaced on the northern margin of the Arabian Plate, associated with the Late Cretaceous closure of the Neo-Tethys Ocean. The Muti Fm, time equivalent with the Shargi Mbr of the Fiqa Fm, was deposited in close proximity to these advancing thrust sheets and became partly overridden by them. In North Oman, an initial, northwards prograding, Coniacian to Santonian deltaic complex (incorporating the Qitqawt Fm sand equivalents) ultimately gave way to deeper-marine facies in the Campanian via a widespread erosional surface at the base of sandy silty turbidites (Fayah Fm sandstone equivalent). This surface is thought to represent the shelf break delineating the deeper foreland basin to the north, with the Hawasina and Semail thrusts defining the northern boundary of this basin (see Filbrandt et al., 2001, 2004)."