A new Ar-40/Ar-39 study has been conducted on variably deformed rocks from the Cap de Creus massif in the Eastern Pyrenees with a focus on NW-SE crosscutting low-grade shear zones. Outside the shear zones, in the unsheared low pressure - high temperature Variscan metamorphic rocks (P similar to 3,5 kbar, T similar to 635 degrees C), mica porphyroblasts yield partially reset Ar-40/Ar-39 ages of 240 Ma to 150 Ma. In shear zones (P similar to 5-5,3 kbar, T similar to 435-505 degrees C) from the Northern Shear Belt, synkinematic fine-grained muscovite provides a crystallization age of 44-42 Ma while inherited clastic muscovite has ages between 175 and 100 Ma depending on grain size. In the Southern Shear Belt, magmatic biotite from granodioritic protomylonites preserves small amount of inherited argon while synkinematic newly crystallized metamorphic micas from mylonites and ultramylonites have crystallization ages between 44 and 38 Ma. Therefore, this step-heating and in situ laser probe Ar-40/Ar-39 study of micas from unsheared Variscan rocks and mylonitic to ultramylonitic rocks show a conspicuous relationship between the deformation gradient, the amount of syntectonic (re)crystallization, the change in mineral composition, the resetting of Variscan mica chronometers and the record of Eocene crystallization ages by newly formed synkinematic micas. It is suggested that low-grade shear zones in the poly-orogenic Cap de Creus massif were active during the main period of Eocene convergence of the Iberian and European plates and emplacement of the south-verging crustal nappes. We propose that such NW-SE mylonitic structures developed as R '-Riedel faults within a huge system of NE-SW trending crustal faults and that they may represent onshore precursors of offshore transfer faults related to the early opening of the Gulf of Lion.

In orogenic settings, fault networks accommodate crustal deformation during the evolution of mountain ranges. Fault zones exhibit multiphase ductile and brittle activity, complicating their interpretation. Dating deformation in orogenic basement remains a challenge. In this study, we conducted structural and microstructural observations, coupled with 40Ar/39Ar dating on encapsulated mineral fractions and chlorite thermometry, on major fault zones in the Eastern Pyrenees. To overcome the presence of K-feldspar within fault gouge, a major issue for fault gouge argon dating, we present a method to estimate the contribution of two mixed K-rich phases from 40Ar/39Ar step heating. This method provides limit or maximum age for the deformation recorded by fault gouges in which illite polytypes are mixed with K-feldspar. Our results reveal a ductile-to-brittle transition between 40 and 35 Ma (Priabonian-Bartonian), characterized by 2M1 muscovite and evidence of strike-slip movement along the Py NE-SW fault and NW-SE secondary faults. The Py fault gouge contains muscovite formed at temperatures exceeding 200-250 degrees C. In the Tet NE-SW fault gouge, the coexistence of 2M1 and 1M illite polytypes suggests late-stage crystallization of 1M illite at 22.1 +/- 1.4 Ma, at temperatures between 100 and 150 degrees C, as determined by chlorite thermometry. These findings confirm significant normal faulting activity on the Tet fault during the Oligo-Miocene, consistent with published low-temperature thermochronology data indicating early exhumation of the Canigou massif relative to the Caran & ccedil;a massif, facilitated by normal displacement along the Py fault, and a later exhumation of both massifs in relation to the Tet normal fault activity.

Revealing the environment and timing of clay formation in the geosphere is of major importance to understand and model the evolution of geological systems at the surface or near-surface of the continents, such as weathering covers, sedimentary basins or hydrothermal systems. Dating clay minerals by electron paramagnetic resonance spectroscopy (EPR) is a promising method that relies on the measurement of stable radiation-induced defects (RIDs) accumulating in their structure over time due to natural radioactivity. This approach has not yet been challenged by the inter-comparison with other geochronological methods, mostly because clay minerals accurately dated with methods independent from the EPR approach and also suitable for the EPR dating remain scarce in the geological record. Herein, an up-to-date protocol for the EPR dating and benchmarking are provided and developed by analyzing selected clay samples. The series includes a Mesoproterozoic illite (Thelon Basin, Canada), two paleosol kaolinites (Ukraine, Estonia) from at least late Ediacaran period, an Ypresian sedimentary kaolinite from the Aquitan Basin (France) and two Miocene and Pliocene kaolinites from lateritic duricrusts (Amazonia, Brazil). Despite some discussed uncertainties mainly related to the Th distribution in the samples, the time variation of dose rate and the thermal history of some clay samples, the EPR ages show a trend close to the 1/1 line with ages determined by other dating methods. These results bring promising support to the EPR dating methodology of clay minerals and extend its potential application field over a time-range spanning from Quaternary to Proterozoic.

Crustal deformation is characterized by brittle and ductile faults that accommodate at di fferent scales the strain imposed by plate tectonics. The aim of this contribution is to show with the help of di fferent examples how the in situ 40 Ar/ 39 Ar dating of synkinematic neocrystallized minerals in ductile shear zones and the step-heating 40 Ar/ 39 Ar dating of synkinematic authigenic clays in fault gouges can bring information on the timing of fault activity. However, due to their complex evolution, interpretation of the argon signature in fault zones requires consideration of several e ffects among which re- or neocrystallization, inheritance and fluid interaction processes are dominant.

Crustal deformation is characterized by brittle and ductile faults that accommodate at different scales the strain imposed by plate tectonics. The aim of this contribution is to show with the help of different examples how the in situ 40 Ar/ 39 Ar dating of synkinematic neocrystallized minerals in ductile shear zones and the step-heating 40 Ar/ 39 Ar dating of synkinematic authigenic clays in fault gouges can bring information on the timing of fault activity. However, due to their complex evolution, interpretation of the argon signature in fault zones requires consideration of several effects among which re- or neocrystallization, inheritance and fluid interaction processes are dominant.

Sedimentary provenance studies using detrital zircon U-Pb ages represent an important tool to investigate the evolution of orogenic basins and to suggest tectonic settings and paleogeography reconstructions when it comes to supercontinent modeling. Syn-orogenic basins worldwide are characterized by a large proportion of zircons with ages close to the maximum depositional period, reflecting the proximity of recently formed magmatic rocks. In this work, we combine field observations, detrital zircon U-Pb ages, whole-rock Sm-Nd and mica Ar-Ar isotopic analyses to constrain the final tectonic evolution of a restricted basin located in a poorly studied region at the easternmost limit of the Paraguay Belt in the Tocantins Province, central Brazil. The investigated area corresponds to the boundary sector of the Paraguay Belt and the Brasilia Belt and is also transected by the strikeslip fault system associated with the Transbrasiliano Lineament. This sector was previously mapped as part of the Cuiaba Group, internal zone of the Paraguay Belt. We provide 465 new detrital zircon U-Pb data with ages distributed from the early Cambrian to the Archean, with approximately 60% of the analyzed grains derived from Ediacaran-Cryogenian sources. The maximum depositional age of the basin is defined at ca. 590 Ma, constrained by the youngest age peak and an evident provenance shift in detrital input in the Paraguay Belt was demonstrated. The syn-orogenic character of the basin is inferred based on the main peak of the detrital zircon population age distribution around 600 Ma, which is very close to the maximum depositional period and points to a short time between erosion, deposition, and burial processes. The muscovite Ar-40/Ar-39 age of ca. 536-546 Ma obtained for muscovite schist metamorphosed under greenschist facies conditions indicates that the regional thermal regime was maintained up to the early-Cambrian in the area. The minimum fast cooling rate of 25 C-o/ Myr defined in the investigated area is constrained by the Ar-40/Ar-39 analysis of biotite (549.16 +/- 1.30 Ma) from a syn-to late-kinematic granodiorite intrusion. The very rapid magma emplacement occurred into relatively shallow crustal levels through the associated strike-slip faults. The Transbrasiliano Lineament would have facilitated the rapid unroofing of the study area and therefore the syn-orogenic deposition in a foreland domain at the final phase of West Gondwana amalgamation. The studied metasedimentary rocks represent a transition phase from the passive margin sedimentation (Cuiab ' a Group) to an orogenic phase, constraining an inversion event in the West Gondwana around ca. 590 Ma. The data provide evidence of a late orogenic basin that was formed contemporaneously with the evolution of an active margin between the Amazonian Craton and the eastern blocks/cratons (Sa similar to o Francisco-Congo and Rio de la Plata cratons and Paranapanema Block) close to Cambrian times. Our results support the existence of the younger Clymene Ocean and the subsequent final assembly of West Gondwana in the Cambrian.

Dating specific pressure–temperature–time–deformation–fluid (P–T–t–d–f) events is a major petrological issue, particularly for polymetamorphic assemblages. In order to better assess such events using mica populations, this study uses a combined in situ Rb–Sr and Ar–Ar dating approach coupled with chemical mapping, with application to an exhumed subduction complex (Schistes Lustrés, Western Alps). Geochronological investigation of the most Si-rich (Tschermak substitution) mica population allows us to investigate the (near-)peak burial ages of the various tectonometamorphic units of this high-pressure/low-temperature subduction complex. In the blueschist-facies units, a wide range of ages between ∼36 (younger than previously obtained peak ages) and ~ 52 Ma suggests a diachronous slicing of units with different initial paleogeography and/or a long residence time at near-peak conditions. The combined use of Ar–Ar and Rb–Sr isochron ages reveals the existence of some excess argon in the studied metamorphic rocks, interpreted as the result of (i) heterogeneous contamination from an argon-rich fluid in the higher grade eclogite-facies units and (ii) partial removal, during pseudomorphic recrystallization, of argon inherited from earlier stages of metamorphism in the lower grade blueschist-facies units.

Earth and Space Science Open Archive This work has been accepted for publication in Tectonics. Version of RecordESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary. Learn more about preprints. preprintOpen AccessYou are viewing the latest version by default [v1]Deciphering the Cenozoic exhumation history of the Eastern Pyrenees along a crustal-scale normal fault using low-temperature thermochronologyAuthorsGaétanMilesiiDPatrickMoniéiDRogerSolivaPhilippeMünchiDPierre G.VallaStéphanieBrichauiDMichaelBonnoCélineMartinMathieuBellangerSee all authors Gaétan MilesiiDCorresponding Author• Submitting AuthorChrono-environnementGéosciences MontpellieriDhttps://orcid.org/0000-0001-8658-9837view email addressThe email was not providedcopy email addressPatrick MoniéiDGéosciences MontpellieriDhttps://orcid.org/0000-0003-2448-6335view email addressThe email was not providedcopy email addressRoger SolivaGéosciences Montpellierview email addressThe email was not providedcopy email addressPhilippe MünchiDUniversité de MontpellieriDhttps://orcid.org/0000-0003-4616-8039view email addressThe email was not providedcopy email addressPierre G. VallaUniversity of Grenoble Alpes, University of Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerreview email addressThe email was not providedcopy email addressStéphanie BrichauiDInstitut de recherche pour le développementiDhttps://orcid.org/0000-0002-8073-7103view email addressThe email was not providedcopy email addressMichael BonnoGéosciences Montpellierview email addressThe email was not providedcopy email addressCéline MartinGéosciences Montpellierview email addressThe email was not providedcopy email addressMathieu BellangerTLS-GEOTHERMICSview email addressThe email was not providedcopy email address

A leucogranite sill in the footwall of the extensional Pilat shear zone (PSZ) Eastern French Massif Central was emplaced and sheared in a short time interval, between 301.8 +/- 3.1 and 303.0 +/- 1.6 Ma (zircon U-Pb and mica 40Ar/39Ar ages, respectively). Extension ended at 298.5 +/- 1.5 Ma (40Ar/39Ar on mica) as shown by a non deformed dike cross cutting the sheared zone. On the hanging wall of the fault, the opening of the St. Etienne Basin filled by coarse clastic sedimentation confirms the existence of a relief south of the PSZ. U-Pb dating of a lithic-rich ignimbrite at the bottom of the basin and of a volcanic layer at the top delivered ages of 310.5 +/- 3.4 Ma and 299.3 +/- 1.3 Ma, respectively. Close U-Pb and 40Ar/39Ar ages from syn-to post-tectonic granites indicate very fast cooling (similar to 150 degrees C/Myr) and exhumation rate (6 mm/yr) corresponding to the emplacement of granites in the middle crust immediately followed by their fast tectonic exhumation and cooling into the upper crust. The development of the Pilat fault in the thermally softened crust is responsible for the rapid exhumation of the Velay dome, a Metamorphic Core Complex localized in the footwall of the sheared zone. Here we propose that its rapid exhumation was due to localized sub crustal lithospheric mantle dripping. These new data show that there was only one extensional phase in the PSZ coeval with the opening of the St. Etienne coal Basin. Finally, the new chronology obtained in this study is challenging previous ages suggesting 20 Ma activity for the Pilat shear zone. Published by Elsevier B.V. on behalf of International Association for Gondwana Research.

The Sistan orogen (Eastern Iran) separates the Afghan and Lut continental blocks and stretches along-700 km from north to south, at a high angle with respect to other, dominantly E-W trending Alpine Himalayan orogens. This study reappraises the tectono-metamorphic evolution of the northern part of the orogen, as well as its significance within the Neotethyan realm. Detailed inspection of the Sistan ophiolite indicates that the Sistan Ocean was of a slow-spreading type and that, given its structural patterns, petrological characteristics and age, it opened in a transtensional setting-125 Ma ago. Closure of the Sistan Ocean took place through a major NE-dipping subduction zone, formed no later than 90 Ma, as shown by the location and age of bimodal juvenile arc magmatism, the SW vergence of the orogen and the location and age of subducted fragments. The discovery of a metamorphic sole at the base of the ophiolite (-750 degrees C-0.65 GPa) argues for the onset of an additional intra-oceanic thrust/subduction zone around 74-72 Ma, which resulted in the south-westward obduction and preservation of the ophiolite onto the continental Lut block. The Sistan Ocean therefore appears to have recorded two major geodynamic events that accompanied the closure of the Neotethys, i.e. the major change in kinematics at-105 +/- 5 Ma and the northward migration of India from-75 to 70 Ma onwards. Subsequent collision, likely started during the Paleocene and mostly completed by the Oligocene, was accompanied by a drastic change of the Eocene sedimentation yet by only moderate shortening (-30-50 km in total). Since the Late Miocene onwards, post-collisional deformation is dominated by far-field stresses related to the Zagros collision.(c) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The Passa Três granite is a 5 km2 intrusion in southern Brazil with an NNE–SSW-elongated shape, hosting gold-bearing quartz veins with fluorite, carbonates, sulphides (pyrite, chalcopyrite, aikinite, molybdenite) and native gold. Orebodies are hosted by the pluton roof zone, which is marked by various textures indicating magmatic–hydrothermal transition processes. Mineralisation formed between 613 and 608 Ma in extensional pull-apart structures controlled by two conjugated N–S and E–W fault systems. We report results from petrography, quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), scanning electron microscopy (SEM), electron probe microanalyses (EPMA), X-ray fluorescence (XRF), trace element analyses of pyrite by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), sulphur isotope (δ34S) analyses, and fluid inclusion microthermometry. Hydrothermal alteration is dominantly developed as phengite–quartz–carbonate and sericite–carbonate–chlorite assemblages along mineralised structures. Fluid inclusion study indicates mineralising fluids with H2O-CO2-NaCl composition, low to moderate salinity (0.2–12.84 wt % NaCl eq.), and temperatures from 400 to 150 °C. The sulphur isotopic composition of pyrite (−0.1 to 1.1‰) suggests magmatic origin. These data, in conjunction with structurally controlled mineralisation enriched in Au-Bi minerals shortly post-dating the granite emplacement, appoint towards similarities between the Passa Três deposit and intrusion-related gold systems. The specific location of the mineralisation in the core (and in the roof zone, regarding its vertical position) of the Passa Três granitic intrusion defines it as “granite-hosted” thus, it is representative of a specific model that can be used for exploration of other intrusion-related/hosted gold deposits near the studied area or in other locations.

The construction of ocean island basaltic volcanoes consists of a succession of eruptions, intrusions, and metamorphism. These events are often temporally ill‐constrained because the most widely used radiometric dating methods applicable to mafic volcanic rocks (K‐Ar or 40 Ar/ 39 Ar on whole rock or groundmass) are prone to inaccuracy when applied to slowly cooled, altered, or vesicular and aphyric products. Here, we adopt a multitechnique geochronology approach (including zircon U‐Pb, phlogopite 40 Ar/ 39 Ar, zircon and apatite (U‐Th)/He, and zircon double‐dating) to demonstrate its efficacy when applied to basaltic volcanoes. Taking the main volcano of Réunion Island (Piton des Neiges) as a case study, we establish the time of the major plutonic, metamorphic, and explosive events that had resisted previous dating attempts. We document four stages of pluton emplacement and metamorphism at 2,200–2,000 ka, 1,414 ± 8 ka, 665 ± 78 ka, and 150–110 ka, all coinciding with volcanism revival after quiescent intervals. We also date a major Plinian eruption at 188.2 ± 10.4 ka, coeval with the formation age of a large caldera, and, finally, we constrain the last eruption of Piton des Neiges to 27 ka, revising a previous estimate of 12 ka. By resolving several conundrums of Réunion's geological history, our multitechnique geochronology approach reveals that endogenous growth of a volcanic island proceeds as pulses at the beginning of renewed volcanism. We also demonstrate that crosschecking eruptions ages by diversified dating techniques is important to better assess the timing and recurrence of basaltic volcanic activity, with implications for hazard prediction.

A petro-structural and geochronological study has been conducted in the Agly Variscan Massif located in the Northern Pyrenean Zone (France). The Lower Gneiss Unit (LGU) displays highly ductile deformation with a NNE-SSW oriented stretching lineation and opposite senses of shear in the directions top-to-the-NNE and top-to-the-SSW. Field observations and thin section analysis show that these two senses of shear are coeval with bulk coaxial vertical shortening and horizontal lengthening. Focusing on syntectonic minerals located within shear bands, Th-U/Pb monazite and 40 Ar/ 39 Ar mica dating yield a 94–127 Ma age bracket for the mylonitic deformation. The principal conclusion from these results is that the main ductile strain ( i.e. , stretching lineations and kinematic indicators) in the LGU should be ascribed to the Cretaceous rifting. A PTt path for the LGU is proposed showing the diachronism between the Cretaceous metamorphic evolution in the Agly Massif (peak temperature at 127 Ma) and the sedimentary basins (peak temperature at 95 Ma) bordering it to the north and south. Finally, a north-south crustal scale evolution of the whole area is put forward to explain this diachronism.

Newly-formed clay minerals in fault zones can provide crucial information about conditions, mechanisms, and timing of deformation at low-grade metamorphism. The present study focuses on the major Lakora thrust in the west-central Pyrenees, that exposes an assemblage of Paleozoic-Upper Cretaceous rocks of the North Pyrenean Zone in the hanging wall and Campanian-Maastrichtian turbidites of the Axial Zone cover in the footwall. Detailed structural, petrological, mineralogical, and chemical investigations were performed on fault rock samples from the Lakora thrust footwall to unravel the deformation conditions related to thrusting. In addition, an attempt to date the thrust activity was made through direct 40Ar/39Ar step-heating on different fractions of muscovite/illite. The structural and petrographic observations suggest a brittle-ductile deformation in two stages along the fault zone: a first stage of bedding-parallel extension and bedding-perpendicular shortening that is marked by boudinage associated with a bedding-parallel cleavage (S0-S1) and a second stage of oblique shearing as marked by reverse faults, folds and oblique cleavage (S2). Pressure-solution and dissolution-recrystallization in the presence of fluids are the main deformation mechanisms that enhanced the neoformation of chlorite and illite associated with cleavage development during the two stages of deformation. The crystallinity, polytypism, and chemistry of illite show that the synkinematic clay minerals with the S2-stage formed under upper anchizone conditions (-250-300 degrees C). Such thermal conditions are higher than those expected from the inferred maximal burial (-6 km), thus arguing for a possible circulation of hot fluids along the thrust footwall. 40Ar/39Ar step -heating results confirm that the newly-formed illite is more abundant in the finer fractions of the most deformed sample, with a total gas age of c. 61.7 +/- 0.5 Ma in the finest <0.2 mu m fraction. This age is older than the early-mid Eocene age expected from structural constraints for the emplacement of the Lakora thrust sheet due to the mixing of newly-formed illites with small amounts of inherited micas and/or contamination by excess argon carried by fluids.

The brittle deformation of internal zones of the Rif chain, corresponding to the southern margin of the West Alboran Basin, is not or poorly dated because of the lack of stratigraphic constraints. We provide for the first time a direct dating of brittle deformation of internal zones of the Rif chain, in the Ceuta peninsula located in the westernmost part of the Gibraltar arc. 40Ar/39Ar illite ages from fault gouges in the footwall and hanging wall of the Ceuta Shear Zone range from 11.9 +/- 2.5 Ma to 15.7 +/- 1.7 Ma and from 14.7 +/- 0.1 Ma to 18.9 +/- 0.8 Ma, respectively. In addition, (U-Th)/He apatite ages from both units have been measured. They are younger in the hangingwall (similar to 20-21 Ma) than in the footwall (14-19 Ma), which highlights slightly different cooling histories. Thus, we interpret the illite ages to date growth of authigenic illite (1M polytype) during exhumation through the top few kilometers of the earth's surface. This study of brittle deformation within the internal zones of the Rif chain reveals that an E-W directed extension occurred between similar to 18-15 Ma during the low temperature exhumation of Sebtide-Alpujarride units. From 15 to 11 Ma, the direction of extension shifted to NNW-SSE and only minor steep normal faults occurred. Brittle normal faulting occurred during a stage of slow cooling (similar to 1-2 degrees C/myr) starting at similar to 19 Ma and coeval with exhumation processes within the uppermost levels of the continental crust. These new data emphasize a continuum of extensional deformation during the Burdigalian-Serravalian interval with an early E-W directed phase and then a NNW-SSE directed phase that match well the main subsidence pulses identified offshore in the neighboring West Alboran Basin. The brittle deformation of internal zones of the Rif chain, corresponding to the southern margin of the West Alboran Basin, is not or poorly dated because of the lack of stratigraphic constraints. We provide for the first time a direct dating of brittle deformation of internal zones of the Rif chain, in the Ceuta peninsula located in the westernmost part of the Gibraltar arc. 40Ar/39Ar illite ages from fault gouges in the footwall and hanging wall of the Ceuta Shear Zone range from 11.9 +/- 2.5 Ma to 15.7 +/- 1.7 Ma and from 14.7 +/- 0.1 Ma to 18.9 +/- 0.8 Ma, respectively. In addition, (U-Th)/He apatite ages from both units have been measured. They are younger in the hangingwall (similar to 20-21 Ma) than in the footwall (14-19 Ma), which highlights slightly different cooling histories. Thus, we interpret the illite ages to date growth of authigenic illite (1M polytype) during exhumation through the top few kilometers of the earth's surface. This study of brittle deformation within the internal zones of the Rif chain reveals that an E-W directed extension occurred between similar to 18-15 Ma during the low temperature exhumation of Sebtide-Alpujarride units. From 15 to 11 Ma, the direction of extension shifted to NNW-SSE and only minor steep normal faults occurred. Brittle normal faulting occurred during a stage of slow cooling (similar to 1-2 degrees C/myr) starting at similar to 19 Ma and coeval with exhumation processes within the uppermost levels of the continental crust. These new data emphasize a continuum of extensional deformation during the Burdigalian-Serravalian interval with an early E-W directed phase and then a NNW-SSE directed phase that match well the main subsidence pulses identified offshore in the neighboring West Alboran Basin.

The variety of temporal and structural constraints on the Alpine tectonometamorphic signature of the metamorphic core of the Betic‐Rif orogen (Alboran Domain) has supported a long‐lasting debate regarding the Alpine tectonic and geodynamic evolution of the Western Mediterranean region. Uncertainty still exists on the timing and tectonic significance of (a) the Alpine orogenic construction; (b) exhumation of the deep roots of the orogen; and (c) transition from orogenic shortening to crustal extension. In this study, we address these major geological issues by focusing on the lower‐grade units of the Alboran Domain (Upper Sebtides and Ghomarides) exposed in the Rif belt of northern Morocco. Through a multidisciplinary approach that integrates mesostructural and microstructural investigations with X‐ray diffraction, quantitative mineral chemistry, and 40 Ar/ 39 Ar geochronology, a 20 Ma long tectonic history is reconstructed, which involves burial of the tectonic units at depth (late Eocene) and postorogenic exhumation under brittle conditions in the upper crust (early Miocene). We document a Priabonian (∼37‐34 Ma) D 1 /M 1 progressive compressional deformation, during the formation of a SW‐verging orogenic wedge (present coordinates), accreted toward the Africa plate. Brittle extensional detachment tectonics operated during the Burdigalian (∼18‐17 Ma), controlling the thinning of the previously structured Alboran Domain nappe stack and the final exhumation of the Alpine orogenic units. We propose that transition from orogenic build‐up to collapse in the hinterland of the Betic‐Rif orogen occurred when the retreat of the Apennine‐Maghrebian subduction was efficient to drive transition from shortening to extension in the back‐arc domain of the western termination of the Apennine‐Maghrebian subduction zone.