Jurassic‐to‐present thermal history of the central High Atlas (Morocco) assessed by low‐temperature thermochronology

Abstract

Apatite fission track (AFT) and (U-Th)/He data from the High Atlas have been obtained for the first time to constrain the tectono-thermal evolution of the central part of the chain. Results from Palaeozoic basement massifs indicate long residence at low temperatures, consistently with their original location out of the deepest Mesozoic rift troughs and indicating minor exhumation. The best rocks for extracting the Alpine history of the Atlas Mountains are Jurassic intrusives, which yield AFT ages centred on c. 80 Ma; thermal models based on AFT data and constrained by (U-Th)/He suggest that these ages are included in a slow cooling trend from intrusion age to c. 50 Ma ago that we attribute to post-rift thermal relaxation. This is followed by a stability period of c. 30 Ma and then by a final exhumational cooling until present exposure. Eocene intrusives yield AFT ages similar to those of Rb-Sr and K-Ar suggesting rapid emplacement in the uppermost crust.

Post-Variscan evolution of the Anti-Atlas belt of Morocco constrained from low-temperature geochronology

“…That is a period of thermal relaxation of the lithosphere and subsequent thermal subsidence which probably affected the Anti-Atlas crust as well. The increase in subsidence toward the central domain of the Anti-Atlas mimics the evolution of the High Atlas trough, which Mesozoic depocenter was located in the central part of the rift system (Ellouz et al 2003;Barbero et al 2007;Gouiza et al 2010).…”

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

“…, 1988; Benammi and Jaeger, 2001; Tesón and Teixell, 2008). Moreover, a coeval phase of exhumation is also constrained by thermochronological data in the Central High Atlas (Barbero et al. , 2007).…”

Evidence for surface uplift of the Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleozoic basement)

“…2 and 6). Sample IM-16 in the Middelt area has been taken from Barbero et al (2007) spontaneous tracks measured parallel to the c-axis) are all very similar and average vary between 1.85 and 3.75 μm which points to compositions similar to the Durango apatite.…”