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Aguidir Formation
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Aguidir Fm base reconstruction

Aguidir Fm

Period: 
Cretaceous

Age Interval: 
Aptian-Turonian


Province: 
Tarfaya Basin

Type Locality and Naming

Recorded at sites EA-1 and CHBK-1 wells (Choubert et al., 1966; LeRoy & Piqué, 2001) and exposed in the Foum Aquidir WSW of Akhfennir in the Puerto Cansado anticline (Wenke, 2014).

Synonym: Aguidir Limestones, Calcaire d’Aquidir

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

Several oxygen minimum zones led to the development of black shales during the Albian to Santonian (Kuhnt et al., 2009). At Oued Chebeika, it consists of carbonatic mudstones alternating with silty claystones of dark and light greyish colors at the base with the latter exhibiting bioturbation that represents cycles of anoxic to oxic environmental changes. The upper Aguidir section of Cenomanian/Turonian age includes a 70m thick transgressive-regressive cycle consisting mostly of limestones alternating with silty clay/mudstones that in turn are covered by fine grained sandstones (Wenke, 2014). Cross-section of Wndki (2014; table 6, p. 110) generalizes as an Albian of black shales (OAE-1c, OAE-1d) and limestone; and Cenomanian of claystone with lesser limestone.


Lithology Pattern: 
Clayey limestone


Relationships and Distribution

Lower contact

It unconformably overlies the Tan Tan Fm. This is the PSU - Peak Spreading Unconformity of Wenke (2014)

Upper contact

It is conformably overlain by the Lebtaina Fm

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 

Albian-Cenomanian, but with an adjustment for the base-Albian PSU unconformity. (Wenke, 2014; table 6, p. 110)

Age Span: 

    Beginning stage: 
Albian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
110.66

    Ending stage: 
Cenomanian

    Fraction up in the ending stage: 
1.00

    Ending date (Ma):  
93.90

Depositional setting

Inner shelf low-energy and middle-outer shelf lagoonal environments (Wenke, 2014).


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.