Illite crystallinity patterns in the Anti-Atlas of Morocco

The low-grade metamorphism of the sedimentary cover of the Moroccan Anti-Atlas is investigated using Illite crystallinity (IC) method. More than 200 samples from three key areas (southwestern, central and eastern Anti-Atlas) have been taken from a maximum of different stratigraphic levels and have been analysed. The metamorphism is of low to very low degree throughout the southern flank of the Anti-Atlas. It increases from northeast to southwest. Whereas in the eastern Anti-Atlas diagenetic and anchizonal IC-values are predominant, in the western and central Anti-Atlas also epizonal IC-values are found. In every respective area the IC improves with stratigraphic age. At the scale of the entire Palaeozoic Anti-Atlas basin the IC correlates best with estimated paleo-overburden. However, burial metamorphism cannot be the cause even though considering missing sedimentary pile of Late Carboniferous age. The ‘abnormal' paleo-geothermal gradient of 43-35 °C/km we evidenced for the Carboniferous is a true one, and has to be related to a basement sequence enriched in heat producing elements such as series of the West African Crato

Tectonics of the Anti-Atlas of Morocco

Tectonique de l'Anti-Atlas marocain. L'Anti-Atlas est revu et examiné sous l'angle de sa signification géodynamique comme bassin paléozoïque et comme chaîne plissée paléozoïque. Le raccourcissement est accommodé par le plissement polyharmonique de la couverture, avec une nette implication du socle. Aucun système significatif de chevauchement ni duplex ne s'est développé. L'Anti-Atlas est un bassin intracratonique fortement inversé plutôt qu'une partie de la marge passive de la Paléotéthys. L'inversion doit dater du Carbonifère tardif/Permien précoce. La direction du raccourcissement a changé au cours du temps depuis une direction NW–SE vers une direction nord–sud et peut-être même NE–SW, ce qui conduit à la formation de figures d'interférences de plis en dômes et bassins aux échelles allant de 100 m à 10 km.The Anti-Atlas is reviewed and examined in the light of its geodynamic significance as a Palaeozoic basin and fold belt. Shortening is accommodated by polyharmonic buckle folding of the cover in a thick-skinned fashion without the development of any significant thrust/duplex systems. The Anti-Atlas is heavily inverted deep intracratonic basin, rather than a former passive margin of the Palaeo-Tethys Ocean. Inversion took place in Late Carboniferous to Early Permian times. Main shortening directions changed from NW–SE to north–south and maybe NE–SW through time, leading to the development of dome and basin patterns on scales from 100 m to 10 km

which should be used for any reference to this work 1 Tectonics of the Anti-Atlas of Morocco

Written on invitation of the Editorial Board The Anti-Atlas is reviewed and examined in the light of its geodynamic significance as a Palaeozoic basin and fold belt. Shortening is accommodated by polyharmonic buckle folding of the cover in a thick-skinned fashion without the development of any significant thrust/duplex systems. The Anti-Atlas is heavily inverted deep intracratonic basin, rather than a former passive margin of the Palaeo-Tethys Ocean. Inversion took place in Late Carboniferous to Early Permian times. Main shortening directions changed from NW–SE to north–south and maybe NE–SW through time, leading to the development of dome and basin patterns on scales from100mto10km.To cite this article: M. Burkhard et al., C. R. Geoscience 338 (2006). Résumé Tectonique de l’Anti-Atlas marocain. L’Anti-Atlas est revu et examiné sous l’angle de sa signification géodynamique comme bassin paléozoïque et comme chaîne plissée paléozoïque. Le raccourcissement est accommodé par le plissement polyharmonique de la couverture, avec une nette implication du socle. Aucun système significatif de chevauchement ni duplex ne s’est développé. L’Anti-Atlas est un bassin intracratonique fortement inversé plutôt qu’une partie de la marge passive de la Paléotéthys. L’inversion doit dater du Carbonifère tardif/Permien précoce. La direction du raccourcissement a changé au cours du temps depuis une direction NW–SE vers une direction nord–sud et peut-être même NE–SW, ce qui conduit à la formation de figures d’interférences de plis e