Cenozoic

Mesozoic

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Lau Formation

Lau Fm

Period:

Paleogene

Age Interval:

Oligocene (Melut Basin)

Province:
Sudan S

Type Locality and Naming

Melut Basin (NE South Sudan - W Ethiopia) which is the southeastern basin of the greater White Nile rift basin, BUT IS NOT in Rawat Basin (SE Sudan), which is the northwestern basin. Mainly encountered in the center of Melut 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

It is characterized by a fining-upward clastic cycle. The lower part is characterized by interbedding of equal-thickness sands and claystones, and the upper part by claystones (Dou et al., 2007). Toward the basin center, the thickness of the formation increases to 500m.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Lau Fm unconformably rests on the Adar Fm

Upper contact

Jimidi Fm rests unconformably Lau Fm

Regional extent

Only in the Melut Basin (NE South Sudan - W Ethiopia), which is the southeastern basin of the greater White Nile rift basin.

GeoJSON

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Fossils

Age

OligoceneNOTE: Age span as estimated for the Melut Basin used here for graphic and paleogeographic display purposes.

Age Span:

Beginning stage:

Rupelian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

33.90

Ending stage:

Chattian

Fraction up in the ending stage:

1.0

Ending date (Ma):

23.04

Depositional setting

deposited in shallow lacustrine to braided river environments (Dou et al., 2007).

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