Fold interference patterns in the Late Palaeozoic Anti‐Atlas belt of Morocco

Abstract

We document two phases of folding within the central part of the Late Palaeozoic Anti‐Atlas chain of Morocco. A first generation of SW–NE folds involve a horizontal shortening of 10–20%, accommodated by polyharmonic buckle folding of contrasting wavelengths in Ordovician Jbel Bani quartzites and Devonian Jbel Rich carbonates. A second generation of folds with similar style and wavelengths in an E–W direction lead to complex interference patterns. Dome and basins are developed within the Jbel Rich and within Lower Cambrian dolomites. Both folding phases are related to thick‐skinned uplift of Precambrian basement in a Laramide style. In contrast to the typical Rocky Mountain foreland style, however, cover deformation in the Anti‐Atlas is mostly decoupled from the undying basement along thick incompetent horizons such as the Lower Cambrian Lie‐de‐Vin and Silurian shales.

Structure de socle, sismostratigraphie et héritage structural au cours du rifting au niveau de la marge d'Ifni/Tan-Tan (Maroc sud-occidental)

“…Except for an opposite vergence, the structures of the lower group described from our sections show a similar style as that reported from the western Anti-Atlas Palaeozoic and Proterozoic outcrops [2,3,5,6,12,14,15,21,25,26,28,29]. These works indicate that the Bas-Draâ-Ifni onshore zone represents the foreland of the Hercynian Anti-Atlas folded belt, whose geological evolution underwent many phases resulting in present-day mostly NE-SW-trending southeastverging structures.…”

“…The stratigraphy of the Ifni/Tan-Tan margin is given by the Ifni-1, Tan-Tan-1, MO-4, Chebeika-1 and El Amra-1 wells (Fig. 1) and from neighbouring western Anti-Atlas outcrops and Tarfaya and Tindouf basins [2,3,[5][6][7]12,[14][15][16][17]21,[25][26][27][28][29] (Fig. 2).…”

“…The surface geology of the western Anti-Atlas is very well documented [2,3,5,6,12,14,15,21,25,26,28,29], whereas only few studies dealt with the Ifni/Tan-Tan margin itself and focused mainly on its Meso-Cenozoic seismo-stratigraphy [10,11,19]. In this paper we propose, thus, to shed some light on the structural style of the pre-Triassic basement of a segment of the margin located south of the South Atlas fault and to investigate the role of pre-existing fractures of this basement on the rifting processes.…”

Cenozoic mountain building and topographic evolution in Western Europe: impact of billions of years of lithosphere evolution and plate kinematics

“…It was then displaced relative to its Iberian counterpart by large transcurrent movement during the Late Carboniferous (Houari and Hoepffner, 2003;Mattauer et al, 1972) and Permian (Hoepffner et al, 2006;Michard et al, 2010) (Figure 6), which significance and age are greatly debated for Pangea reconstruction (Domeier et al, 2020). The Pan-African crust of Anti-Atlas was weakly overprinted by late-Variscan shortening (Burkhard et al, 2006;Helg et al, 2004;Séverine et al, 2004). Pan-African granitoids involved in the Variscan belt (Moroccan Meseta) (Figure 7) originally formed at the end of the Cadomian-Pan African orogeny.…”

Structural Analysis and Paleostress Evolution in the Imiter Silver Mining Region, Eastern Anti Atlas, Morocco: Implications for Mineral Exploration

“…The Ouarzazate Group of the late Ediacaran was para-conformably covered by Tata and Taroudant Groups deposits [24,51], marking the beginning of the long transgressive Paleozoic cycle [52][53][54]. At the end of the Carboniferous, Anti-Atlas suffered from moderately thick-skinned tectonics caused by the Pangean assembly during the Variscan orogeny [32,55,56]. During Late Triassic, the Anti-Atlas was influenced by Atlas-Alpine tectonics, first characterized by the NNW-SSE extension event relative to the central Atlantic opening [54,57].…”