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.

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We present the results of anisotropy of magnetic susceptibility (AMS)

We present new fission-track and (U–Th)/He data from apatite and zircon in order to reconstruct the exhumation of the Sierra de Cameros, in the northwestern part of Iberian Range, Spain. Zircon fission-track ages from samples from the depocentre of the basin were reset during the metamorphic peak at approximately 100 Ma. Detrital apatites from the uppermost sediments retain fission-track age information that is older than the sediment deposition age, indicating that these rocks have not exceeded 110 °C. Apatites from deeper in the stratigraphic sequence of the central part of the basin have fission-track ages of around 40 Ma, significantly younger than the stratigraphic age, recording the time of cooling after peak metamorphic conditions. Apatite (U–Th)/He ages in samples from these sediments are 31–40 Ma and record the last period of cooling during Alpine compression. The modelled thermal history derived from the uppermost sediments indicates that the thermal pulse associated with peak metamorphism was rapid, and that the region has cooled continuously to the present. The estimated palaeogeothermal gradient is around 86 °C km−1 and supports a tectonic model with a thick sedimentary fill (c. 8 km) and explains the origin of the low-grade metamorphism observed in the oldest sediments.

In this work, we explore by means of analogue models how different basin‐bounding fault geometries and thickness of a viscous layer within the otherwise brittle pre‐rift sequence influence the deformation and sedimentary patterns of basins related to extension. The experimental device consists of a rigid wooden basement in the footwall to simulate a listric fault. The hangingwall consists of a sequence of pre‐rift deposits, including the shallow interlayered viscous layer, and a syn‐rift sequence deposited at constant intervals during extension. Two different geometries exist of listric normal faults, dip at 30 and 60° at surface. This imposes different geometries in the hangingwall anticlines and their associated sedimentary basins. A strong contrast exists between models with and without a viscous layer. With a viscous décollement, areas near the main basement fault show a wide normal drag and the hangingwall basin is gently synclinal, with dips in the fault side progressively shallowing upwards. A secondary roll‐over structure appears in some of the models. Other structures are: (1) reverse faults dipping steeply towards the main fault, (2) antithetic faults in the footwall, appearing only in models with the 30° dipping fault and silicone‐level thicknesses of 1 and 1.5 cm and (3) listric normal faults linked to the termination of the detachment level opposite to the main fault, with significant thickness changes in the syn‐tectonic units. The experiments demonstrate the importance of detachment level in conditioning the geometry of extensional sedimentary basins and the possibility of syncline basin geometries associated with a main basement fault. Comparison with several basins with half‐graben geometries containing a mid‐level décollement supports the experimental results and constrains their interpretation.