Cenozoic

Mesozoic

Information provided by geoscience team at Ahmadu Bello University, Zaria, Nigeria --see About

Nayil Formation

Nayil Fm

Period:

Paleogene

Age Interval:

Eocene-Oligocene

Province:
Sudan S

Type Locality and Naming

Muglad Basin -- SW Sudan and the northwestern part of South Sudan. Basal formation of the Kordofan Gr.

Reference section: Makeen et al., 2013, Jingyao, 2015; Ahmed and Ozumba, 2017

[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

The Nayil Formation is mostly shaly and has an estimated thickness of 850m (Makeen et al., 2013, Jingyao, 2015)

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

Overlain below unconformably by the Amal Fm

Upper contact

Overlain on top conformably by the Tendi Fm

Regional extent

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

GeoJSON

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Fossils

Pollen (Striatopollis spp)

Age

Eocene-Oligocene

Age Span:

Beginning stage:

Ypresian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

56.00

Ending stage:

Chattian

Fraction up in the ending stage:

1.0

Ending date (Ma):

23.04

Depositional setting

lacustrine as well as fluvial overbank depositional setting (Ahmed and Ozumba, 2017).

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