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Lebtaina Formation
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Lebtaina Fm base reconstruction

Lebtaina Fm

Period: 
Cretaceous

Age Interval: 
Turonian-Maastrichtian


Province: 
Tarfaya Basin

Type Locality and Naming

Recorded at drill sites EA-1 and CHBK-1 wells (Choubert et al., 1966; LeRoy & Piqué, 2001) and 100km east of Laâyoune (Wenke, 2014).

Synonym: Labtaina al Talliya (Wenke, 2011).

References: Wenke, 2014

[Fig. 1. Regional crustal framework of the Moroccan Atlantic rifted-passive margin showing its three, major rifted-passive margin segments that are conjugate with eastern Canada: 1) Northern Central Atlantic; 2) Georges Bank- Tarfaya Central Atlantic, and; 3) Southern Central Atlantic (three zones modified from Nemcok et al., 2005). (Galhom, 2020).]

[Fig. 2. Schematic chrono-lithology chart from the basin to inner shelf settings of the Tarfaya Basin. (Table 6, page 110, in Wenke, 2014)

[Fig. 3. Summary chart for the Tarfaya Dakhla basin showing geologic time scale, lithostratigraphy, controlling tectonic events, and interpreted horizons (Galhom, 2020).]

[Fig. 4. Lithostratigraphy and log characteristics of the Triassic to Miocene succession at well W10, offshore Tarfaya Basin (El Jorfi et al., 2015).]


Lithology and Thickness

The succession of Labtaina al Talliya is split in a southern shallowing-upward succession from marine sandstones to beach facies containing cross stratified sandstones and microconglomerates and a northern lagoonal facies mainly consisting of clay to siltstones with interbedded evaporites. Wenke (2014) cross-section indicates that above the basal black shale (OAE-3) is marl (claystones with some limestone layers) and the OAE-3 black shale in late SantonianThe mudstones contain a high amount of flint. The whole Coniacian to Maastrichtian of the Tarfaya-Laâyoune Basins is dominated by the deposition of fine clastic material, often heavily weathered and overprinted by silex in the outcrops (Wenke, 2014).


Lithology Pattern: 
Pelagic marl


Relationships and Distribution

Lower contact

It conformably overlies the Aguidir Fm

Upper contact

It is unconformably overlain by the Salmat Fm. This is the IAU (Initial Atlasian Unconformity) of the beginning of Atlas uplifts.

Regional extent

The Dhakla, Laayoune and Tarfaya Basins (TB) extend along the southern Moroccan continental shelf approximately to the town of Sidi Ifni, where a gradual transition to the Souss-Basin (SB) in the north takes place (Wenke et al., 2010).


GeoJSON

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Fossils


Age 

Turonian through Maastrichtian, but with an adjustment for the end-Cretaceous IAU unconformity. (Wenke, 2014; table 6, p. 110)

Age Span: 

    Beginning stage: 
Turonian

    Fraction up in beginning stage: 
0.00

    Beginning date (Ma): 
93.90

    Ending stage: 
Maastrichtian

    Fraction up in the ending stage: 
0.9

    Ending date (Ma):  
66.65

Depositional setting

Inner shelf low-energy and middle-outer shelf lagoonal environments (Wenke, 2014). During the Lebtaina Fm, the coastline retrograded and a coastal facies developed 120km east of the present day coastline or 100km east of Laâyoune.


Depositional pattern:  


Additional Information


Compiler:  

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

El Jorfi L., Süss M.P., Aigner T., and Mhammdi N. (2015): Triassic – Quaternary Sequence Stratigraphy of the Tarfaya Basin (Moroccan Atlantic): Structural Evolution, Eustasy and Sedimentation. Journal of Petroleum Geology, 38(1), pp. 77-98.

Ghassal B.I., Littke R., Sachse V., Sindern S., Schwarzbauer J. (2016): Depositional environment and source rock potential of Cenomanian and Turonian sedimentary rocks of the Tarfaya Basin, Southwest Morocco. Geologica Acta, 14(4), pp. 419-441.

Wenke A. A. O. (2014): Sequence stratigraphy and basin analysis of the Meso- to Cenozoic Tarfaya- Laâyoune Basins, on- and offshore Morocco. PhD Thesis at Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht-Karls-Universität Heidelberg.