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Tan Tan Formation
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Tan Tan Fm base reconstruction

Tan Tan Fm

Period: 
Cretaceous

Age Interval: 
Berriasian – Aptian


Province: 
Tarfaya Basin

Type Locality and Naming

Record of EA-1 and CHBK-1 wells (Choubert et al., 1966; LeRoy & Piqué, 2001).

Synonym: Tan Tan Sands

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

During the major MDU (Mature Drift Unconformity) of Wenke (2014), the Jurassic platform was exposed and clastic sediments crossed the former shelf to form the Tarfaya and other offshore fans. A progressive transgression led to a thick sequence (1400 m to 4000 m) of fluvial to deltaic sandstones and shales on the Tarfaya margin (El Jorfi et al., 2015). In the inner shelf, the basal part is dominated by sandstones and conglomerates of the fluvial plain and contain high amounts of cross-stratification. Progressing to the top of the sequence, the succession features a proximal deepening trend of brackish/marine ingression including silty to sandy deposits containing high amounts of less diversified shells that indicate a base level rise (Wenke, 2011). This brief summary doesn't adequately give the lateral and upward complexity of this "Tan Tan" interval.


Lithology Pattern: 
Sandstone


Relationships and Distribution

Lower contact

It unconformably overlies the Puerto Cansado Fm. This is the major MDU (Mature Drift Unconformity) of Wenke (2014); and onset of the Tan Tan Fm unit is delayed to mid-Valanginian in the inner shelf region.

Upper contact

It is unconformably overlain by the Aguidir Fm. This is the PSU - Peak Spreading Unconformity of Wenke (2014)

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 

Extent of basal unconformity depends on location from minor at seaward (ca. mid-Berriasian) to major at landward (ca. mid-Valanginian) location (Wenke, 2014; table 6, p. 110). Generalized here as base-Valanginian. Compensation for the end-Albian PSU.

Age Span: 

    Beginning stage: 
Valanginian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
137.70

    Ending stage: 
Albian

    Fraction up in the ending stage: 
0.9

    Ending date (Ma):  
101.77

Depositional setting

The basin at this time included two depositional environments: deltaic facies dominated the northern area and prograded to the NNE, whereas the northwestern and southern areas encountered outer shelf carbonates to fine-grained clastic deposits (Ghassal et al., 2016).


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.