Cenozoic

Mesozoic

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Abu Gabra Formation

Abu Gabra Fm

Period:

Cretaceous

Age Interval:

Aptian

Province:
Sudan S

Type Locality and Naming

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

Synonym: Sharaf Fm and the overlying Abu Gebra Fm are often combined into a single Abu Gebra Fm (Lenhard et al., 2025)

Reference: Shuaib and Berguig, 2022; Lenhard et al., 2025

[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)]

Lithology and Thickness

Abu Gabra Formation is split into three parts: AG3 at the bottom, AG2 in the middle, and AG1 at the top. The AG1 member is composed of light grey sandstone and grey mudstone of delta facies. The grains are coarsening-upwards. The top is medium-coarse grained sandstone with medium to poor porosity, and good roundness (Shuaib and Berguig, 2022). The Abu Gabra Fm is estimated to be about 1800 m thick (Ramses, 1997).

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Conformably rests on the Sharaf Fm. Sandstone increases in frequency upwards from Sharaf Fm through the Abu Gebra Fm.

Upper contact

Bentiu Fm unconformably rests on the Abu Gabra Fm. The hiatus may encompass the early Albian.

Regional extent

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

GeoJSON

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Fossils

Age

Aptian (assuming upper half of Sharaf-AbuGabra merged interval in strat column of Lenhard et al., 2025)

Age Span:

Beginning stage:

Aptian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

121.40

Ending stage:

Aptian

Fraction up in the ending stage:

1.0

Ending date (Ma):

113.20

Depositional setting

Lacustrine deltaic environment (Ramses, 1997)

Depositional pattern:

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024) - Stratigraphic Lexicon compiled from the following books:

Dou D., Dingsheng C., Zhi L., Zhiwei Z., Jingchun W. (2013): Petroleum Geology of the Fula Sub-Basin, Muglad Basin, Sudan. Journal of Petroleum Geology, 36(1): pp.43-60

Jingyao W. (2015): The Study of Sequence Stratigraphy and Sedimentary System in Muglad Basin. IOSR Journal of Applied Geology and Geophysics (IOSR-JAGG), 3(6): pp.37-40

Makeen Y. M., Abdullah W. H., Hakimi M. H. (2013): Biological markers and organic petrology study of organic matter in the Lower Cretaceous Abu Gabra sediments (Muglad Basin, Sudan): origin, type and palaeoenvironmental conditions. Arabian Journal of Geosciences. DOI 10.1007/s12517-013-1203-z

Lenhardt, N., Omietimi, E. J., Edegbai, A. J., Schwark, L., Catuneanu, O., Fairhead, J. D., Gotz, A. E. (2025): Traversing the rift: A review of the evolution of the West and Central African Rift System and its economic potential. Earth-Science Reviews, 261: pp. 1-39