Gezira Fm

Khartoum Basin, central Sudan. The term Gezira Formation (from Arabic Gezira = island) was first introduced by ANDREW (1948) to describe the unconsolidated clays, sands and gravels in the Gezira area; that is in the area between the White and Blue Nile. The formation has been divided formerly into three members by ABDEL SALAM (1966) who proposed El Ghubsha (14° 14'N, 33° 02’E, southwest of Wad Medani) as type locality. In stratigraphically ascending order, these members are the Mungata Member, the Sandy Member, and the Upper Clay Member.

Reference: Awad (1994), A. Gibreel (2015)

[Fig. 1: Khartoum Basin is #8 on map (Fig.3 in Awad, 1994)]

[Fig. 2: Khartoum Basin stratigraphy and depositional sequences (pg. 17 in A. Gibreel, 2015)]

Upward succession of (1) lower Mungata Mbr of ca. 75% clays, with some arkosic sands and clay fragments, and is known only from the subsurface where it attains a thickness of more than 111 m; (2) middle Lower Sandy Mbr of mainly sands with occasional gravel, silt and clay lenses; with a variable thickness from 20 m to more than 60 m; and it is preserved mainly in buried distributary channels of former fan deltas; (3) Upper Clay Mbr of mainly clays, subordinate sands, frequent kankar nodules (calcareous duricrusts), and locally of volcanic ash. (Awad, 1994)