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02/17/2021

Tectono-sedimentary Cenozoic evolution of the El Habt and Ouezzane Tectonic Units (External Rif, Morocco)

Filed under: geodynamic evolution,Morocco — Tags: , , — messinianalicante @ 7:41 AM

An interdisciplinary study based on lithostratigraphic, biostratigraphic, petrographic and mineralogical analyses has been performed in order to stablish the Cenozoic tectono-sedimentary evolution of the El Habt and Ouezzane Tectonic Units (Intrarif Subzone, External Rif, Morocco). The reconstructed record allowed identification of the depositional architecture and related sedimentary processes of the considered units. The Cenozoic successions were bio-chronologically defined allowing, at the same time, identification of unconformities and associated stratigraphic gaps.

Stratigraphic architecture of the Cenozoic of the El Habt and Ouezzane Units. The arrangement of the studied Logs and correlation with the timetable reflects the supposed paleogeographic position from proximal to distal. In addition, depositional sequences, unconformities, gaps (erosive and depositional), sedimentary realms and tectonic phases are shown.

The presence of five unconformities allowed to define the main stratigraphic units arranged in a regressive trend: (1) lower Paleocene interval (Danian p.p.) assigned to a deep basin; (2) Eocene interval (lower Ypresian-lower Bartonian p.p.) from a deep basin to an external carbonate-siliceous platform; (3) lower Rupelian-upper Chattian p.p. interval deposited on unstable slope with turbidite channels passing upward to an external siliciclastic platform; (4) Burdigalian p.p. interval from a slope; (5) Langhian-Serravallian p.p. interval from slope to external platform realms. The petrography of the arenites and calcarenites allowed to identify supplies derived from erosion of a recycled orogen (transitional and quartzose sub-types).

 

Qm/F/Lt + CE ternary diagram indicating a discrimination of the sandstones’ provenance. Qm: monocrystalline quartz; F: feldspars (plagioclase and K-feldspars); Lt + CE: lithic fragments including carbonate extrabasinal clasts.

 

The clay-mineralogy analysis indicates an unroofing (first erosion of Cretaceous terrains followed by upper Jurassic rocks) always accomplished by erosion of Cenozoic terrains. Several tectofacies checked in some stratigraphic intervals seems to indicate the beginning of deformation of the basement generating gentle folds and first activation of blind thrusts, mainly during the Paleogene. A pre-orogenic tectonic framework is considered as risponse to the generalized tectonic inversion (from extension to compression) as frequently registered in the central-western peri-Mediterranean areas. The large volumes of reworked terrigeneous supply during the latest Oligocene-Miocene p.p. indicates the beginnigs of the syn-orogenic sedimentation (foredeep stage of the basins) controlled by active tectonics.

Cites as: Martín-Martín, M., Guerrera, F., Hlila, R., Maaté, A., Maaté, S., Tramontana, M., Serrano, F., Cañaveras, J.C., Alcalá, F.J., Paton, D., 2020. Tectono-Sedimentary Cenozoic Evolution of the El Habt and Ouezzane Tectonic Units (External Rif, Morocco). Geosciences. 2020; 10(12):487.. https://doi.org/10.3390/geosciences10120487

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