Structural control on present-day topography of a basement massif : the Central and Eastern Anti-Atlas (Morocco)
Gimerà, Joan (Universitat de Barcelona. Departament de Geodinàmica i Geofísica)
Arboleya, María Luisa (Universitat Autònoma de Barcelona. Departament de Geologia)
Teixell Cácharo, Antonio (Universitat Autònoma de Barcelona. Departament de Geologia)

Data:	2011
Resum:	The Anti-Atlas basement massif extends South of the High Atlas, and, despite a very mild Cenozoic deformation, its altitude exceeds 1500m in large areas, reaching 3305m in Jbel Sirwa. Structural contours of the present elevation of a polygenic planation surface (the High Erosional surface) and of the base of Cretaceous and Neogene inliers have been performed to characterize the major tectonic structures. Gentle Cenozoic WSW-ENE- and N-Strending folds, of 60 to100km wavelength, reactivate Variscan structures, being the major contributors to the local topography of the Anti-Atlas. Reactivated thrusts of decakilometric to kilometric-scale and E-W trend involving the Neogene rocks exhibit a steep attitude and a small displacement, but they also produce a marked topographic expression. The resulting Cenozoic horizontal shortening along N-S sections across the Anti-Atlas is about 1%. The position of the major anticlinal hinges determines the location of the fluvial divides of the Warzazat basin and the Anti-Atlas, and a structural depression on one of these hinges (Jbel Saghro anticline) allowed the formerly endorheic Warzazat basin to drain southwards. The first Cenozoic structures generating local topography are of pre-mid Miocene age (postdated by 6. 7Ma volcanic rocks at the Jbel Saghro), whereas the youngest thrust movements postdate the Pliocene sedimentary and volcanic rocks (involving 2. 1Ma volcanic rocks at Jbel Sirwa). In addition to these features, the mean elevation of the Anti-Atlas at the regional scale is also the result of a mantle thermal anomaly reported in previous works for the entire Atlas system.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; Versió publicada
Matèria:	Cenozoic contraction ; Crustal folding ; Tectonic topography ; Anti-Atlas ; Morocco
Publicat a:	Geologica acta, Vol. 9, N. 1 (March 2011) , p. 55-65, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/240541
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001643
DOI: 10.1344/105.000001643

11 p, 7.8 MB

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