Upper Crust structural evolution of the Alpine orogeny in an intracontinental belt: Western High Atlas (WHA) Mountains, Morocco
- 1Geology and Sustainable Mining Institute, University Mohammed VI Polytechnic, Benguerir, Morocco (salih.amarir@um6p.ma)
- 2School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide, Australia
- 3Laboratory of Structural Geology and Thematic Mapping, Faculty of Sciences, Ibn Zohr University, Agadir, Morocco
The Atlas system is an intracontinental chain established upon a Paleozoic substratum by the inversion of Triassic basins starting in the late Mesozoic-early Cenozoic. The inversion of the chain is related to the Atlas rift system that was influenced by the opening of the Central Atlantic in the West and the Tethys in the north. This was coeval with a regional exhumation following the Alpine shortening responsible for the continuous uplifting of the chain since Late Cretaceous. The structural history and chronology of events are still matter of debates. To contribute to this, we focus on the Western High Atlas (WHA) aiming a retro enactment of the paleo-stresses states, by analyzing deformation structures at various scales. The geological data were collected at different stratigraphic levels: from the contact Paleozoic basement/Mesozoic cover interface to the Triassic detrital formations of the Argana corridor in the east, to the Jurassic-Cretaceous and Cenozoic plateaus in the west. Preliminary results highlight two major tectonic events: (1)- a first extensive event, with sub-horizontal minimal principal stress σ3 oriented NW-SE, that is linked to the Central Atlantic basin opening. This event is characterized by pull apart basins structured into horsts and grabens. (2)- a second compressive event, marked by NE-SW to NNE-SSW shortening. The later is subdivided into two episodes: i- an early post-rift episode (Middle-Late Jurassic to Early Cretaceous), marked by stylolites and meso-structures that occurred at the beginning of the main uplifting stage. ii- a late compression episode, characterized by a maximum principal stress σ1 mainly oriented NNE-SSW to NNW-SSE, starting at the late Cretaceous and accelerating during the Tertiary, simultaneously with the Africa-Europe collision.
Keywords: Paleo-stress, Structural analysis, Atlas rift system, Tectonic inversion, Western High Atlas Morocco, Alpine orogeny.
How to cite: Amarir, S., Amrouch, K., Belfoul, M. A., and Skikra, H.: Upper Crust structural evolution of the Alpine orogeny in an intracontinental belt: Western High Atlas (WHA) Mountains, Morocco, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2858, https://doi.org/10.5194/egusphere-egu23-2858, 2023.
