Usfan Fm

Period:

Paleogene, Cretaceous

Age Interval:

Campanian – Bartonian, Sa3

Province:
Red Sea (Saudi Arabia)

Type Locality and Naming

The name Usfan Formation was originally used by Karpoff (1957) to define surface exposures first noted in the Jiddah area of Saudi Arabia. The Usfan Formation was first named by Karpoff (1957) as the Usfan series after the Usfan Village. Type Section: A locality situated 2.5 km north of Usfan Village (21°57’N, 39°21’E). Brown et al. (1963) renamed the “series” as the Usfan Formation. Reference Section: Saudi Aramco onshore well Jiddah-1 (JIDH-1) between 2,458–3,662 ft, Saudi Arabian Red Sea. Column: Red Sea Saudi Arabia. Middle formation in Siqaj Gr

Synonym:

Lithology and Thickness

Marly limestones, sandstones, coquinas and conglomerates. "The Usfan Formation consists of marine and littoral sediments, … it is also fossiliferous and phosphatic in places. Black shales and light-colored siltstones are found interbedded with mature sandstones along with rare bioclastic limestones, coals and oolitic ironstones in the upper part. Poorly-sorted, locally kaolinitic, pebbly sandstones are also found interbedded with minor siltstones. Oolitic ironstones are a characteristic feature of the Usfan Formation (Al Shanti, 1966; Hamilton, 1973), and are considered to form a regionally correlative stratigraphic layer near the top of the marine section (G.S. Ferguson, 1993b, Saudi Aramco Report). The color varies from beige to brown to reddish purple, and basalt is locally intruded. In the Jiddah-1 well, a 332-foot-thick (101.2 m) gabbro occurs between 3,030–3,362 ft. The Usfan Formation contains one significant limestone bed exposed as the “Great Wall’ limestone near the town of Usfan. … Thickness: In Jiddah-1, the Usfan is 1,204 ft (367 m) thick; and Vail et al. (1983) (in Moore and Al-Rehaili, 1989) state that it is 215 m (705 ft) thick." (Hughes and Johnson, 2005)

Lithology Pattern:

Shallow-marine marl

Relationships and Distribution

Lower contact

It unconformably overlies the Adaffa Fm

Upper contact

It is unconformably overlain by the volcanics of the Matiyah Fm following the Red Sea Rift unconformity of early Oligocene. In Wadi Ash Sham, the Usfan Formation is reported to be conformably overlain by the Shumaysi Fm and also by sub-horizontal Upper Miocene to Pliocene basalts of the Hammah Fm (Abou Ouf and Gheith, 1998; Moore and Al-Rehaili, 1989).

Regional extent

"Undefined specifically, but the Usfan Formation is present in the Jiddah region of the Saudi Arabian Red Sea (Karpoff, 1957; Al Shanti, 1966; Brown et al., 1963; Ramsay, 1986). . . . The siliciclastic Usfan Formation is considered to be equivalent of the Sudr Fm (Upper Campanian-Maastrichtian carbonates), Dakhla Fm (Maastrichtian-Lower Paleocene claystones, marls and carbonates), Esna Fm (Upper Paleocene shales) and Thebes Fm (Lower Eocene carbonates) of the Gulf of Suez. It is also probably equivalent to the Medjzir Fm of the Upper Tawilah Gr of west Yemen (Al-Subbary et al., 1998), the Mukawwar Fm of Sudan (Whitman, 1971), and the Umm Himar Fm inland western Saudi Arabia (Whybrow and Madden, 1995)." (Hughes and Johnson, 1999).

GeoJSON

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Fossils

Palynological assemblages are generally rich and well-preserved and dominated by Palmae pollen. Dinocysts are common and kerogen typically consists of coarse well-preserved terrestrial vegetal fragments. Microfauna are generally rare, but assemblages of small agglutinated benthonic foraminifera are sporadically distributed with charophytes, thus providing evidence for brackish and freshwater environments, respectively. See "Age" discussion below:

Age

Late Campanian – Bartonian, but with internal hiatus spanning lower Danian through middle Selandian used on 2008 Mideast time scale column. " The Usfan Fm was originally dated by Karpoff (1957) as late Maastrichtian to Eocene based on molluscs and shark teeth. Brown (1970) dated a glauconitic bed beneath the “Great Wall” limestone as 43–55 Ma using K-Ar dating, although he suspected that this may be an anomalously young age due to the poor quality sample. Maastrichtian nautiloids and baluchicardid molluscs from a phosphatic bed in the lower Usfan Fm were identified by Basahel et al. (1982). Abou Ouf and Gheith (1998) state that radiometric and biostratigraphic evidence indicate that the Usfan Fm is clearly of Maastrichtian to Eocene age whereas the Shumaysi Fm is late Oligocene to early Miocene in age. The Umm Himar Fm, a possible lateral equivalent, is dated as Paleocene based on the rich vertebrate fossils (Whybrow and Madden, 1995). Saudi Aramco palynological work supports a Maastrichtian to middle Eocene age for the Usfan Fm. The spore Gabonisporis vigourouxi and dinoflagellate Dinogymnium spp. indicate a Maastrichtian age for part of the succession. The palm pollen Proxapertites spp. and the dinoflagellates Apectodinium/Wetzeliella spp., which evolved at the beginning of the late Paleocene, and palm pollen Longapertites vaneendenburgii and pollen Retidiporites magdalenensis and Saturnia enigmaticus, with extinctions at end of the Paleocene, indicate a Paleocene age for at least part of the formation. Eocene sediments are confirmed by the presence of the pollen Spirosyncolpites bruni and Retibrevitricolpites triangulatus. The absence of the upper Eocene pollen Verrucatosporites usmensis restricts the formation to an age not younger than middle Eocene. Moltzer and Binda (1984) provided palynological evidence to support an early Eocene age for rocks assigned to the Shumaysi Fm. A lava flow east of Jiddah has been dated as 32 and 25 Ma based on K-Ar age determinations and provides a late Oligocene to Miocene age limit to the underlying rocks assigned to the Shumaysi Fm by Brown (1970). In the Medj-zir Fm of the upper Tawilah Gr of west Yemen (Al-Subbary et al., 1998), the presence of gastropod genera Tarebia and Coptostylus indicate Paleocene to Holocene and Paleocene to late Oligocene ages, respectively." (Hughes and Johnson, 2005)

Age Span:

Beginning stage:

Campanian

Fraction up in beginning stage:

0.7

Beginning date (Ma):

75.61

Ending stage:

Bartonian

Fraction up in the ending stage:

0.5

Ending date (Ma):

39.37

Depositional setting

Interpreted as shallow, nearshore marine at the base (deltaic/estuarine) grading to non-marine low-energy fluviatile at the top, with localized areas of shallow carbonate sedimentation between the estuaries and deltas. Abou Ouf and Gheith (1998) concluded a fluviatile environment for the “sands and conglomerates, capped by a transgressive-regressive unit of limestones, dolomites and gypsiferous shales”. (Hughes and Johnson, 2005)

Depositional pattern:

Additional Information

"The Shumaysi Fm (Shumaysi series of Karpoff, 1957), previously considered to be stratigraphically younger than the Usfan Fm (Karpoff, 1957; Al-Shanti, 1966; Moltzer and Binda, 1984; Ramsey, 1986; Abou Ouf and Gheith, 1998) is considered to be a facies equivalent of the Usfan Formation (Spencer, 1987; G.S. Ferguson, 1993a, b, Saudi Aramco Reports). Recent work by Abou Ouf and Gheith (1998), however, supports a separation of the formations based on their different age assignments (see below). The Usfan Fm is confined to the Suqah trough and the Shumaysi Fm crops out both in the Suqah trough and Wadi Shumaysi. .. . . We have not seen sufficient sections of this age in the subsurface to confidently differentiate between the Usfan Fm and Shumaysi Fm rocks. The descriptions and stratigraphic discussions of both formations by Abou Ouf and Gheith (1998, p. 138-141) are very convincing, and we tend to agree with their conclusions that “the Usfan Fm is both lithologically distinct and older (late Cretaceous to Eocene) than the Shumaysi Fm (late Oligocene to early Miocene)”. While they may divide it into three units, the overall age of the Shumaysi Fm in Abou Ouf and Gheith (1988, their Figure C2.4) extends from the Eocene to the middle Miocene, and is therefore considered equivalent to the syn-rift sediments reviewed in detail in this study. This very broad definition of the Shumaysi Fm would not be in agreement with earlier considerations of Usfan equivalence, and we find it difficult to agree that the fundamental changes within the sediments of this age range in the Red Sea region should be contained within a single formation." (Hughes and Johnson, 2005)

Compiler:

Hughes, G.W., Johnson, R.S., 2005. Lithostratigraphy of the Red Sea Region. GeoArabia, 10: 49-126. And Middle East Geological Timescale 2008 Al-Husseini, Journal of Middle East Petroleum Geosciences v 13. no. 4