Amal Fm

Muglad Basin -- SW Sudan and the northwestern part of South Sudan

Reference: Makeen et al., 2013; Jingyao, 2015

[Fig. 1: Western and Central African rift system. West African rift subsystem and Central African]

[Fig. 2: General stratigraphic column - Muglad Basin, Sudan, showing three geological cycles – Neocomian to Barremian, Aptian to Maastrichtian, and Paleocene to Pliocene - Miocene, or Quaternary and Petroleum Systems (from Ahmed and Ozumba, 2017)]

[Fig. 3: Comprehensive stratigraphic columns in the Muglad Basin (from Dou et al., 2023)]

[Fig. 4: Regional stratigraphy of the Muglad basin, SW Sudan (after Schull 1988; Dou Lirong et al. 2013 – extracted from Makeen et al., 2013)]

[Fig. 5: Location map of the Fula sub-basin in the Muglad basin including oilfields (study area) (after Dou Lirong et al. 2013 – extracted from Makeen et al., 2013)]

The Amal Formation is largely made up of coarse-grained sandstone and has an estimated thickness of 650m (Makeen et al., 2013; Jingyao, 2015). This formation is primarily massive, mostly coarse to very coarse-grained, frequently pebbly and conglomeratic sands with subangular to subrounded clasts. Thin beds of clay, grey to brown claystone, siltstone, and grey, brown and black lignite also occur. Trace amounts of pyrite are seen throughout the interval (Babikir, 1997). The Amal Fm is characterized by sequences rich in quartz. The high sandstone to shale ratio, coarse grain size and poor to moderate sorting indicate rapid deposition in a high energy regime such as is found in fluviatile environments. Thin lignite beds have been deposited within this interval (Babikir, 1997).

Pollens (Mauritiidites crassiexinus–Echimonocolpites rarispinosus)

Paleocene

This formation was deposited as successive fining upwards sand cycles separated by a few thin beds of silty claystones that are generally oxidized or weakly reduced (Babikir, 1997).