Cenozoic

Mesozoic

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Miadol Formation

Miadol Fm

Period:

Neogene

Age Interval:

Middle Miocene

Province:
SouthSudan, Sudan S

Type Locality and Naming

Melut Basin (NE South Sudan - W Ethiopia), and the Rawat Basin (SE Sudan), which are the southeastern and the northwestern basins of the greater White Nile rift basin.

Reference: Dou et al., 2007; Dou et al., 2023 (Melut Basin); Mohammed et al, 2017 (Rawat Basin)

[Fig. 1: Simplified map of the West and Central African Rift System (WCARS) showing the major features discussed in the text and the location of the Melut Basin in South Sudan (modified from Genik, 1993)]

[Fig. 2: Comprehensive stratigraphic columns in the Melut Basin (from Dou et al., 2023)]

[Fig. 3: Rawat Basin- Block 25 in southern Sudan (after Ministry of Petroleum & Gas-OEPA, 2015, Extracted from Mohammed et al., 2017).]

[Fig. 4: Summary of Tectono-stratigraphy of the Rawat Basin (from Mohammed, 2016).]

Lithology and Thickness

In Melut Basin, it is about 292m of massive claystones interbedded with thin sandstones (Dou et al., 2007). In Rawat Basin, the formation is made up predominantly of claystone with occasional thin interbedded siltstone. The claystone is dusky yellowish green, greyish brown and light to dark grey and occasional moderately hard traces of carbonaceous material, and no calcareous material (Mohammed, 2016). Using wireline logs signature, Mohammed (2016) put the thickness at 119m at well M-1, and a total thickness of 538m in well M-2.

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

conformably rests on the Jimidi Fm

Upper contact

Daga Fm conformably rests on the Miadol Fm. In the Rawat Basin, the contact is an abrupt break in GR, Sonic, and Density logs (Hassan, 2016).

Regional extent

Melut Basin (NE South Sudan - W Ethiopia), and the Rawat Basin (SE Sudan), which are the southeastern and the northwestern basins of the greater White Nile rift basin.

GeoJSON

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Fossils

In Rawat Basin, it has Spores-Pollen (Praedapollis africanus, Cicatricosporites sp., Concavisporites triquetrus, Cyathides minor, Leiotriletes sp., Deltoidospora sp., Leiotriletes adriennis) (Mohammed et al., 2017)

Age

Middle Miocene (estimated Langhian-Serravallian in Melut Basin; mid-Burdgalian-Tortonian in Rawat Basin)NOTE: Age span as estimated for the Melut Basin used here for graphic and paleogeographic display purposes.

Age Span:

Beginning stage:

Langhian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

15.99

Ending stage:

Serravallian

Fraction up in the ending stage:

1.0

Ending date (Ma):

11.63

Depositional setting

Shallow lacustrine to fluvial environments (Dou et al., 2007). In Rawat Basin, it contains overbank/floodplain and/or shallow lacustrine shoreline environment (Mohammed, 2016).

Depositional pattern:

Additional Information

Compiler:

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

Dou L., Xiao K., Cheng D., Shi B., Li Z. (2007): Petroleum Geology of the Melut Basin and the Great Palogue Field, Sudan. Marine and Petroleum Geology, 24, pp.129-144

Dou L., Xiao K., Wang J. (2023): Petroleum Geology and Exploration of the Bongor Basin. Petroleum Industry Press.

Mohammed H. Z. A., Awad M. Z., Eisawi (2017): Upper Cretaceous to Neogene Palynology of the Rawat Basin, White Nile State, Sudan. Journal of Earth Science & Climatic Change. 08 (04)

Robertson Research International “RRI”, Geological Research Authority of Sudan “GRAS” (2016): The Geology and Petroleum Potential of Southern, Central, and Eastern Sudan. Unpublished Report. Vol. 1-4