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A close relationship of the kinematics and timing between low‐angle extensional faulting and upright folding is established for the Miocene detachment systems in the hinterland of the Betics in southeastern Spain. Folding accompanied tectonic denudation developing elongated domes with fold axes both parallel and perpendicular to the direction of extension. The geometry, kinematics, and tectonic evolution of two major sequentially developed extensional fault systems have been characterized in several E‐W elongated mountain ranges of the central Betics on the basis of new cartographic and structural data and a comprehensive revision of other available geological and geophysical observations. The extensional systems have an average WSW direction of extension and led to exhumation of the two lower metamorphic complexes of the Betics, the Nevado‐Filabride and the Alpujarride, during the middle and upper Miocene (Serravallian to Tortonian). The extended domain contains a core complex, with distal and proximal antiformal hinges separated by around 60 km and with a fold amplitude of ∼6 km (measured parallel to the direction of extension). The total amount of extension across the core complex is about 109–116 km, corresponding to a stretching factor (β) of 3.5–3.9, estimated using the distance between fold axial surfaces and a geometrical model accomplishing footwall deformation during tectonic denudation via subvertical simple shear. The elongated domal and basinal geometry of the detachments and their respective footwalls is due to the interference between two sets of orthogonal large‐scale open folds, trending N‐S and E‐W. Longitudinal, N‐S trending folds are interpreted as isostatic folds, i.e., folds that developed in response to differential unloading of the extensional detachment footwalls inducing ductile flow in the middle crust. These folds formed in a rolling‐hinge anticline in which rotation migrates westward through the footwall as it is progressively unroofed. In contrast, E‐W trending folds, being subparallel to the direction of extension, have a contractional origin and progressively affect to the west the isostatically readjusted segments of the detachments once they are inactive. Orthogonal folding occurred since the Serravallian to lower Pliocene. Extension is still active from the rolling‐hinge anticline in Sierra Nevada to the west. The middle Miocene to Pliocene tectonic evolution of the Sierra Nevada elongated dome at the core of the Betic hinterland is another example of the coexistence of extension and contraction during continued overall convergence and mountain‐building.

Figure 1. Tectonic map of Betic-Rif arc. Internal Betics, Internal Rif, and floor of Alboran Sea constitute Alboran domain. Prebetic, Subbetic, and External Rif form external Betic-Rif arc. Line of section in Figure 2 is shown as dotted line. Inset: Alpine orogenic system in Mediterranean.

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Removal of lithosphere at depths significantly greater than 62.5 km cannot explain the combination of high temperatures reached by these rocks and the shallow depth at which they attained the maximum temperature. Only a combination of significant postcollisional radiogenic heating, then wholesale removal of lithospheric mantle below the orogenic crust, followed by rapid stretching can explain the observed PT path. These results appear to support some form of lithospheric delamination as the primary cause for the formation of the Alboran Sea basin.

Abstract. A three-dimensional gravity modeling combined with integrated heat flow and elevation modeling is conducted to map out the crustal and lithospheric mantle thickness in the Alboran Basin, in the westernmost Mediterranean. A "sediment"-corrected Bouguer anomaly has been derived using a depth-to-the-basement map and densities determined from well logs and seismic data. The gravity effect of the base of the lithosphere has been removed from the sediment-corrected Bouguer anomaly to obtain a "crustal" Bouguer anomaly, which has been inverted for crustal thickness. The resulting lithospheric structure is further constrained by elevation data under the assumption of local isostasy. The low residual elevation anomalies obtained (_+100 m in average) suggest that the area is in local isostasy, particularly the medium-and long-wavelength topography features.

A comprehensive interpretation of single and multichannel seismic reflection profiles integrated with biostratigraphical data and log information from nearby DSDP and ODP wells has been used to constrain the late Messinian to Quaternary basin evolution of the central part of the Alboran Sea Basin. We found that deformation is heterogeneously distributed in space and time and that three major shortening phases have affected the basin as a result of convergence between the Eurasian and African plates. During the Messinian salinity crisis, significant erosion and local subsidence resulted in the formation of small, isolated, basins with shallow marine and lacustrine sedimentation. The first shortening event occurred during the Early Pliocene (ca. 5.33–4.57 Ma) along the Alboran Ridge. This was followed by a major transgression that widened the basin and was accompanied by increased sediment accumulation rates. The second, and main, phase of shortening on the Alboran Ridge took place during the Late Pliocene (ca. 3.28–2.59 Ma) as a result of thrusting and folding which was accompanied by a change in the Eurasian/African plate convergence vector from NW‐SE to WNW‐ESE. This phase also caused uplift of the southern basins and right‐lateral transtension along the WNW‐ENE Yusuf fault zone. Deformation along the Yusuf and Alboran ridges continued during the early Pleistocene (ca. 1.81–1.19 Ma) and appears to continue at the present day together with the active NNE‐SSW trending Al‐Idrisi strike‐slip fault. The Alboran Sea Basin is a region of complex interplay between sediment supply from the surrounding Betic and Rif mountains and tectonics in a zone of transpression between the converging African and European plates. The partitioning of the deformation since the Pliocene, and the resulting subsidence and uplift in the basin was partially controlled by the inherited pre‐Messinian basin geometry.

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