Sequence of thrusting and syntectonic sedimentation in the eastern Sub-Atlas thrust belt (Dadès and Mgoun valleys, Morocco)

Abstract

A series of balanced cross-sections across the Sub-Atlas thrust belt and the northern Ouarzazate basin are used to illustrate the structural geometry and the timing of deformation at the southern front of the High Atlas Mountains of Morocco. The selected area is among the best sedimentary records of mountain building of the entire orogenic system. The study of the relationships between thrusts and synorogenic continental formations enables the unraveling of kinematic sequences and the proposal of a relative chronology of deformation. Active thrusting in the area occurred in a rather continuous fashion from the Oligocene to the Pliocene, punctuated by a major erosional phase imprecisely placed in late Oligocene to early Miocene times. Detrital sedimentary facies indicate that uplift in the hinterland of the High Atlas, to the north of the Sub-Atlas belt, was taking place already by mid Eocene times, although it might have commenced locally even earlier. Within the Sub-Atlas zone, the exposed faults did not propagate in a simple piggyback fashion but show evidence of a complex, synchronous sequence with events of fault reactivation and out-of-sequence thrusting.

The Agoudal (High Atlas Mountains, Morocco) shatter cone conundrum: A recent meteorite fall onto the remnant of an impact site

“…; Frizon de Lamotte et al. ; Tesón and Teixell ). Exhumation rates of 80–100 m Ma −1 have been inferred from apatite fission‐track thermochronology for the Neogene, whereas average denudation rates of 80 m Ma −1 (0.08 mm yr −1 ) have been estimated for the Anti‐Atlas region (Ruiz et al.…”

Neogene exhumation of the Marrakech High Atlas (Morocco) recorded by apatite fission‐track analysis

“…, 1988; El Harfi et al. , 1996, 2001, 2006; Tesón and Teixell, 2008), but these sedimentary records do not constrain the timing of uplift (see for example the discussion in Massironi et al. , 2007).…”

The Atlas System

“…In front of it, smaller structures developed using the décollement level located within Upper Triassic-Lower Liassic evaporites (Fig. 4.35D Teson & Teixell (2006). Notice the occurrence of coarse conglomerates in Oligocene?-Early Miocene and Pliocene-Pleistocene series, following the two main tectonic episodes.…”

“…For the Siroua shelf (between the Souss and Ouarzazate Basins), a recent reference is Missenard et al (2007). Due to spectacular tectonic structures and the presence of a well-developed Cretaceous-Eocene series, the Ouarzazate Basin is somewhat over-studied (Laville et al, 1977;Fraissinet et al, 1988;Görler et al (1988), Zylka (1988), Jossen & Filali-Moutei, 1992;Gheerbrant et al, 1993;Herbig & Trappe (1994); Errarhaoui, 1998;El Harfi et al, 2001;Benammi et al, 2001;Tabuce et al, 2005;Teson & Teixell, 2006). .…”

“…These conglomerates are sourced from the raising High Atlas. The Hadida-El Arbi red sands and pebbles, first considered as sourced in the Anti-Atlas (Görler et al, 1988), are more likely recycled Lower Cretaceous material from the uplifted High Atlas (Teson & Teixell, 2006) The propagation of Cenozoic deformation south of the South Atlas Front, i.e. in the Anti-Atlas domain, has been recognized (see Chap.…”