Mansiyah Fm
Type Locality and Naming
Mansiyah Formation is a middle Miocene massive salt succession in the subsurface of Saudi Arabia Red Sea. The Mansiyah Formation is named and defined in the Auxerap exploration well Mansiyah-1 (MNSY-1: 17°12′00.2″N, 42°22′10.4″E) between 7,500–11,371 ft, onshore coastal Saudi Arabian Red Sea, 40 km north of Jizan. The reference section is the Saudi Aramco exploration well Midyan S-1 (MDYN-1) between 5,804 and 6,561 ft. Column: Red Sea Saudi Arabia
Synonym: The Mansiyah Formation in the Midyan area has, at various times, been considered as part of the middle Raghama Fm of Skipwith (1973), the upper part of the Al Bad Fm (Dullo et al., 1983), part of the Bad Fm of the Raghama Gr of Clark (1986), the Raghama Fm of Brown et al. (1989), and within the Bad Fm of Jado et al. (1990).
Lithology and Thickness
Halite. "The Mansiyah Formation consists of massive halite, gypsum, and anhydrite, with thin interbeds of calcareous shales and mudstones, and subordinate sandstones and siltstones. In the Mansiyah-1 type section, the Mansiyah Formation consists almost entirely of halite, except for a thin bed of dolomite towards the upper part of the section. In the Midyan-1 reference section, the Mansiyah Formation has a varied lithology and consists of interbedded anhydrite, halite, shale and silt. In the type section, the Mansiyah Fm is 3,871 ft (1,180.2 m) thick, and in the reference section 757 ft (230.8 m) thick." (Hughes and Johnson, 2005)
Relationships and Distribution
Lower contact
In the field sections, the Mansiyah Formation overlies the Kial Fm with apparent conformity.
Upper contact
The Mansiyah Formation is overlain with probable conformity by the Ghawwas Fm.
Regional extent
The Mansiyah Formation is well represented in the subsurface, but it is difficult to distinguish in outcrop from the underlying Kial Fm.
The Mansiyah Formation is equivalent and lithologically comparable to the South Gharib Fm in the Gulf of Suez and other areas of the Red Sea (Hughes et al., 1992; Hughes and Beydoun, 1992) and to the lower part of the Dungunab Fm of Sudan (Carella and Scarpa, 1962; Sestini, 1965; Hughes and Beydoun, 1992). The Mansiyah Formation is also equivalent to the open-marine syn-rift tectono-sedimentary unit B of Plaziat et al. (1990).
GeoJSON
Fossils
"Palynological age criteria in the inter-evaporitic siliciclastics are as for the Jabal Kibrit Fm but supplemented by the presence of the dinoflagellate cyst species Systematophora ancyrya/placacanatha (extinction at top middle Miocene); Pentadinium laticinctum (extinction near top middle Miocene) (Hughes and Filatoff, 1995)." (Hugest et al., 1999)
Age
Depositional setting
"The depositional environment was moderate to very deep marine and conditions of extremely hypersalinity led to the precipitation of evaporites. A marine environment is indicated by the presence of dinoflagellate cysts in inter-evaporitic shales; anoxic conditions are suggested by an abundance of pyrite-impregnated amorphous kerogen (Hughes and Filatoff, 1995). The hypersaline episode was probably regional in extent and, based on the traditional silled deep-basin model, resulted from the isolation of the Red Sea from the Gulf of Aden and/or the Mediterranean (Hughes and Beydoun, 1992; Crossley et al., 1992)." (Hughes et al., 1999)
Additional Information