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The Western Alpine Foreland Basin ("French Molasse Basin") is located along the Western Alps and is composed of Oligo-Miocene formations resulting, at least to some extent, from the erosion of the alpine range. The distribution of sedimentation area, drainage network and sedimentary sources have strongly varied during its development. Late Eocene and Miocene marine formations are well-constrained as longitudinal basins with some transverse sedimentary transfer: the Eocene turbiditic basin was fed from the South, whereas the Miocene molasse basin was flowing southward. The Oligocene time period corresponds to the beginning of continental collision and to the exhumation of internal crystalline massifs. The erosion of first Alpine landforms causes the transport of sedimentary materiel in the basin with the transition from flysch (underfilled) to molasse (overfilled) deposits. The paleoenvironment is mainly continental and sediments are preserved in both internal and external position, which attests of a complex drainage network. Oligocene is therefore an important period of reorganisation in the foreland basin but has been poorly studied at the scale of the whole Western Alps and remains under-documented, mainly because of scarce outcrops probably due to early deformation in the basin. Here, we provide a new tectono-sedimentary study of these deposits based on new field work, seismic and well data interpretations, palynological analyses and bibliographic synthesis. This work led us to propose an exhaustive synthesis of the Oligocene foreland basin (or sub-basins) with synthetic logs and detailed palaeoenvironmental maps. Our results show that the Oligocene Western Alpine Foreland Basin can be divided in two main sedimentation areas: (1) an internal area which is mainly influenced by the alpine range evolution and (2) the Rhône Valley which has been structured by both the European Rift and the Pyrenean orogeny ("Pyrenean-Provence phase") and receives autochthonous sediments but also erosional products from the Massif Central, the Pyrenean Chain and the Alps. Palaeoenvironments and nature of sedimentation have strongly changed during the entire Oligocene. The internal basins (i.e., in the footwall of the Penninic Frontal Thrust) are connected with the South Rhône Valley since the early Rupelian thanks to E-W transverses valleys possibly inherited from the Pyrenean orogeny. Sedimentary supply remains mixt (Massif Central/Alps) until the end of Oligocene. A final longitudinal system set up at the beginning of the Aquitanian in which all the Alpine material was flowing to the south and the Mediterranean Sea. Two episodes of marine incursion have been identified (Early Rupelian and Early Chattian) thanks to biostratigraphy in the Rhone Valley which was probably already connected to the Mediteranean Sea before the Miocene. To sum up, the West Alpine Foreland Basin experienced during Oligocene (and Early Miocene) times transient basin dynamics with sub-basins controlled by westward propagation of the wedge front due to frontal accretion, a complex transverse routing system along with global flow inversion from north to south.

International audience; The knowledge acquired on the exhumation of the Pyrenean chain and the evolution of the adjacent foreland basins makes this Alpine-type domain a good laboratory to better constrain a full sediment routing system in a compressive context and to apprehend the driving processes controlling the sediment routing in space and time. This integrated approach aims at enhancing our basin mastering approach as well as improving our predictions of reservoir properties. This Source-to-Sink study seeks to understand the evolution of sedimentary routing from the Source (orogenic relief, craton, basin recycling) through the transfer zone (peripheral or internal to the basin) to the final sink (flexural basin, deep turbiditic margin). Within this new cartography, we propose to compile the data over the entire peri-Pyrenean domain. We produced large scale quantitative and qualitative maps to better observe and interpret the tectonic, climatic and surface processes impacts of the SRS behavior. These maps include kinematic reconstructions of the Iberian-European-Mediterranean system, restored sequential cross-sections, history/magnitude of exhumation by thermochronology, source tracking, characterization of weathering and erosion surfaces, synthesis of the major structures activity, paleogeographic reconstructions, analysis of sedimentary geometries and transport directions as well as the quantification of volumes preserved in the basins. Their interpretation is combined with a time representation along the routing system, linking classical basin wheeler diagram representation to source erosion and lithologies to obtain a continuous view on the sediment journey. The time steps chosen for these 5 maps account for the different stages of tectono-sedimentary evolution of the peri-Pyrenean system at the early-, syn- and post-orogenic stages. The compilations carried out compare exhumed domains and sedimentation zones in terms of fluxes and volumes and make it possible to map the routing systems and point out the main drivers for the surface evolution during the construction/destruction cycle of an orogen. Research work financed and carried out as part of the BRGM-TOTAL Source-to-Sink program

The Western Alpine Foreland Basin ("French Molasse Basin") is located along the western Alps and is composed of Oligo-Miocene formations resulting from the erosion of the alpine range. Although the Miocene molasse basin have been widely described since the last decades, Oligocene basins lack documentation in terms of palaeoenvironmental evolution and source to sink approach. Most of these basins formed under both the Alpine influence and the European Cenozoic Rift System influence and developed in lacustrine environment with local sedimentation next to active normal faults. Several fluvial formations with exotic materials have been briefly described and could correspond to a transport from the internal parts of the Alps, where collision started at the Eocene/Oligocene boundary. Here, we propose a new tectono-sedimentary study of these fluvial deposits based on extensive fieldwork (facies analysis, sequence stratigraphy, palynological analysis) and reinterpretation of available subsurface data (seismic profile, well data). The goal is to provide a new palaeoenvironmental reconstitution of the Oligocene molasse basin(s) with regional correlations and to determine the evolution of early alpine drainage network. We focus on the entire Western Alpine Foreland Basin from the Rhone Valley (Bas-Dauphiné, Valréas, Mormoiron) to the Digne Thrust where Oligocene molasse is called « Red Molasse » (Dévoluy, Faucon-du-Caire, St-Geniez, Esclangon, Barrême). First results show that Red Molasse is composed of massive meandering deposits, which evolve to braided river and alluvial fan in a regressive continental sequence following the flysch formation. Transition from marine distal turbidites is often missing except in Dévoluy syncline where tidal and shoreface deposits precede fluvial molasse. Exotic material from the internal alps is very common and indicates high landforms nearby. In the Rhone Valley, a massive fluvial system has been identified on seismic and well log data in the Bas-Dauphiné and we documented a 900 m field section with two meandering formations with exotic minerals in the Mormoiron basin. Paleocurrents and channels direction indicate a major divide located east of Diois-Baronnies range with Dévoluy fluvial systems flowing to the north and other Red Molasse sites located south of the divide converging to St-Geniez system. On a regional scale, it may be possible that early salt tectonic which has been widely described caused this particular drainage network. South of the divide, converging fluvial formations may have flowed in an Est-West valley between Diois-Baronnies range and Ventoux-Lure Montain where tectonic and Eocene landforms link to the Pyreneo-Provençal orogen have been documented. These deposits where probably connected with Mormoiron and Bas-Dauphiné fluvial formations and formed a major drainage system located in the Rhone Valley.

The North Pyrenean foreland basin evolved from underfilled to overfilled during the Eocene time in mirror of the development of the Pyrenean orogeny. The resulted Eocene syn-orogenic conglomerate series, known as “Poudingues de Palassou”, recorded the evolution of the mountain belt and the draining system. Three units are classically differentiated in the eastern part: the first and third units deposited during the late Ypresian – Lutetian and Priabonian times respectively, contain clasts from the Meso-Cenozoic regional sedimentary cover. A second unit deposited during the Bartonian corresponds to clasts of magmatic and metamorphic origin (including granites). The objective of this study is to identify the sources of the sediments and to reconstruct the drainage evolution during the Eocene. To this end, U/Pb zircon dating was carried out on granite clasts from Unit 2 and on the conglomerate matrix of the three units using laser ablation-ICP-MS. These analyses are coupled with sedimentary characterization of depositional environments, paleocurrent directions measured in the fluvial deposits and Raman analyses performed on black flysch clasts from the Unit 1/Unit 2 transition. The zircon U/Pb results show a dominance of Variscan ages (290-360 Ma) in the upper part of the Unit 1 and for the matrix of Unit 2 conglomerates. Granite clasts of Unit 2 show mostly ages between 324±2 and 335±1 Ma. For Unit 3, the age spectrum is broader, ranging from Variscan to Cadomian (290 – 600 Ma). Sedimentary analysis of units 1 and 2, show an increase of the amount of sediments and a greater alluvial system during the deposition of the unit 2. The Raman analyses on the black flysch show temperature peaks ranging from 495 to 587°C, comparable to those obtained in the eastern part of the North Pyrenean Zone (NPZ) on black flysch deposits. Interpretation of the results shows that the deposits of Unit 1 are mainly derived from the erosion of the Meso-Cenozoic cover of the NPZ in the Late Ypresian and Lutetian, ending with black flysch of the NPZ, followed by erosion of the Variscan massifs. For Unit 2, the deposition is accompanied by a change in the nature of the clasts and a widening of the depositional zone reflecting wider drainage area including the Axial Zone (AZ). For Unit 3, the broad spectrum of ages obtained, as well as the nature of the clasts, suggest a fairly large catchment area drained from the AZ and significant recycling from the actively deformed foreland sedimentary cover during Priabonian. This research work was financed and carried out as part of the BRGM-TOTAL source-to-sink program.

Recently, the understanding of the role of salt dynamics in the evolution of fold-and-thrust belts and foreland basins has significantly improved with the development of high-resolution seismics. Understanding a salt-related structure in the field as a mini-basin requires a thorough understanding of the 3-D geometries of folds.In the western subalpine chain of Haute Provence, the Digne thrust area has undergone a complex tectonic history involving syn-sedimentary deformation, the migration of alpine front, late exhumation related to surface processes, and salt tectonics. In the front of the Digne thrust, the Vélodrome is an emblematic example of a complex fold displaying a 3D structure hardly explained by regional tectonics. The Vélodrome is an overturned syncline displaying a curved axis which direction changes from E-W in the north to N-S in the east and to E-W again in the south-eastern part. The Vélodrome is often interpreted as a growth fold with internal unconformities, but microstructural analyses (Fournier et al., 2008) have alternatively suggested a post-deposition folding. Moreover, recent studies (Graham et al., 2012; Celini, 2020) propose that the fold formed due to salt tectonics and interpret the Vélodrome as a mini-basin.Thus, the Vélodrome complex tectonic structure requires a thorough understanding of the 3-D geometries to understand its tectonostratigraphic evolution.This study aims at understanding the emplacement and the tectonic history of the Miocene Vélodrome series using in-situ field observations and drone field data to realize a 3-D geometrical model (GeoModeller - ©BRGM). More than 3000 structural data have been measured - both directly in the field and on 3D models obtained from drone image processing - and used in the GeoModeller to test the different hypotheses. The implicit approach offered by the GeoModeller and the field structural data-based approach bring an objective and new vision of 3-D geometries of the Vélodrome basin and confirm the Vélodrome as a syn-sedimentary fold. This study highlights several discontinuities inter- and intra-formations spatially localized. In the north of the Vélodrome, Aquitanian deposits do not present any unconformity, whereas internal unconformities can be observed in Burdigalian deposits. In the southeast of the fold, we observed internal unconformities both in the Aquitanian and Burdigalian deposits. This leads us to propose an early salt-related episode of deformation in the southeast part of the fold (Aquitanian) compared to the north, where deformation began only during the Burdigalian.

International audience

In the front of the Digne thrust, the deformed foreland basin, the well exposed tectonic window of Barles, is still not well understood. This region has undergone a complex tectonic history involving synsedimentary deformation, potential migration of alpine front, late exhumation related to surface processes and potential salt tectonics. Although the stratigraphy and the structural geology of the area is well known, the respective contributions of regional tectonics, salt tectonic and surface processes remain uncertain. The region displays still enigmatic objects emplaced at each step, from the rifting phase to the late exhumation, such as the overturned Liassic Barre de Chine or the overturned Miocene syncline of the Vélodrome. This study aims at understanding the evolution of the foreland Valensole basin from the deposition of first sediments 30Ma ago to late exhumation and relief formation. We focused our work on the emblematic Vélodrome syncline which is also the only place where a continuous sequence of the basin deposits is exposed. The molassic and conglomeratic layers of the Vélodrome form an overturned syncline with a curved axis of which direction changes from EW in the north to NS in the most south-eastern part. The Vélodrome has been studied for more than a century but its history is still debated. If the Vélodrome is often interpreted as a growth fold which explain the observation of progressive unconformities, microstructural analyses (Fournier et al., 2008) suggest that folding postdates sedimentation. Moreover, recent studies (Graham et al., 2012) propose that this spectacular fold formed as a result of salt tectonic. The obliquity of the regional shortening direction regarding the axis direction, the 3-D pattern of the overturned Miocene series and the origin of the progressive unconformities are issues still not resolved. Such a complex tectonic structure as the Vélodrome fold requires a thorough understanding of the 3-D geometries and their evolution through time. Based on field observations and 3-D geometrical modelling (GeoModeller - ©BRGM), we propose a preliminary model of the Vélodrome that brings new insights on this part of the Valensole basin. The implicit approach that offer the GeoModeller and the field structural data-based approach (here more than 2000 structural data) bring an objective and new vision of the geometries in 3-D of the Vélodrome basin and provide arguments to determine the contribution of each geological processes in the tectonostratigraphic evolution of the north margin of the Valensole basin and subsequent shortening at the western subalpine front.

National audience; La réinterprétation des données de sub-surface dans le bassin d’Aquitaine et les travaux menéssur les Corbières où affleurent le piémont pyrénéen permettent de reconstituer la déformationde ce retroforeland et l’évolution du système source to sink au cours de la période synorogénique,Eocène.Après une phase de quiescence paléocène, l’activité tectonique est marquée dans le bassin par(1) une reprise de subsidence à la fin du Thanétien, (2) la mise en place d’un bassin flexural(Yprésien- Lutétien), contemporain de l’augmentation de la taille de la chaine, et (3) lasegmentation de ce bassin par la réactivation d’accidents hérités à partir du Bartonien, quicorrespond à la collision sensu stricto. A ces trois phases, correspondent des systèmes source tosink différents, et permettent de préciser la compréhension des stades classiques (underfilled,filled, overfilled).1- Le Paléocène (quiescence) enregistre une sédimentation carbonatée qui évolue depuisdes systèmes récifaux vers des systèmes de rampes carbonatées. Durant le Thanétiensupérieur (début de la période syn-orogénique), se mettent en place des systèmesturbiditiques mixte terrigène-carbonaté, alimentés par le Massif Central etvraisemblablement par les premiers reliefs pyrénéens orientaux.2- L’Yprésien (orogenèse précoce) correspond à la croissance progressive des reliefspyrénéens, et une augmentation des apports pyrénéens. Un remplissage rapide duretroforeland par des dépôts deltaïques a lieu. Les influences respectives desévènements climatiques du début de l’Yprésien et de la déformation de l’avant-pays surles volumes érodés et les architectures sédimentaires seront discuses. Le comblementprogressif du bassin génère une large zone de transfert à partir du Lutétien.3- Le Bartonien (collision) correspond à une exhumation importante de la chaine. Dans lebassin d’Aquitaine, l’inversion des structures héritées génère la mise en place demultiples dépôt-centres plus ou moins déconnectés. Il en résulte une modificationmajeure du système source to sink, dans lequel l’augmentation des apportssédimentaires se traduit par un très faible export vers le bassin profond et uneaggradation importante des piémonts.

International audience; Collisional shortening in the external Western Alps was first accommodated by internal (distributed) deformation in the External Crystalline Massifs (ECM) and then on frontal crustal ramps (localized deformation). However, the timing of transition between these two periods is still under-constrained, mainly because the available dataset is incomplete in the Western Alps. We here provide new zircon and apatite fission-track (ZFT and AFT) and zircon (U-Th-Sm)/He (ZHe) data that constrain the early stages of cooling hence exhumation of the external Alpine wedge, as well as new Raman Spectroscopy of Carbonaceous Material (RSCM) data from the Belledonne massif. ZFT ages mainly range between 15 and 20 Ma, ZHe ages between 5 and 12 Ma, AFT ages between 2 and 10 Ma. Those data are integrated within HeFTy (inverse and forward) thermal models along with literature data to constrain the late Oligocene-Miocene cooling history and suggest that exhumation of the Belledonne and the Pelvoux massifs may have started as early as ca. 27 Ma. This early exhumation was rather slow (~ 50 m.Myrs−1 ± 2 m.Myrs−1) and may date the transition between the distributed and the localized mode of shortening, i.e., the initiation of the crustal ramps below these massifs. Further north, in the Mont Blanc and Aiguilles Rouges massifs, exhumation was active around 18 Ma, and started possibly earlier, around 20–25 Ma. From this time on (18 Ma), exhumation rates increased in all external massifs (~ 500 ± 40 m.Myrs−1, both North and South). This age most likely corresponds to the end of the transition period between distributed and localized shortening with localisation along the frontal crustal ramps and the rapid associated exhumation, then cooling of the hangingwall (even considering that cooling may start a few Myrs later than exhumation if isoterms are advected). This timing notably corresponds to a transition between the two molasse mega-sequences in the foreland basin (Lower Marine/Freshwater Molasse and Upper Marine/Freshwater Molasse).

International audience; The Altiplano and more specifically the Titicaca circum-lake sector have recorded several major landscape transformations. In particular, changes in the lake water level lead to a significant vulnerability and contributed to the development of flexible and diverse agropastoral activities of the pre-Columbian and current populations to climate change. The Tiwanaku River, particularly because of the presence of the pre-Columbian Tiwanaku site, has been the subject of several research studies aimed at characterizing the environment of the archaeological site. Here we propose a new synthesis of the geomorphology of the Tiwanaku River watershed based on an interdisciplinary approach (Historical geography and remote sensing, cross combined with field survey). Our results show that the general organization of the drainage system is influenced by lake level and climatic changes. However several watercourses of the Tiwanaku River might be related to pre-Columbian agricultural or protourban structures. Our work allowed to estimate the regressive pattern of the coastline of Lake Titicaca and to identify major changes of the terminal and medium watercourse of the Tiwanaku River over the last 70 years.

The axial fault-bounded depression of the South Kenya rift (SKR) locally displays anomalously wide sectors resulting from the presence of one (or many) elevated and offset block(s) on the flanks of the main trough. Very little attention has been paid so far to the nature of the driving mechanisms responsible for these atypical rift patterns. New insights are supplied by the Natron-Ol Doinyo Ogol rift segment at the southern extremity of the SKR, immediately north of the North Tanzanian Divergence (NTD). On the basis of interpreted SRTM-30 satellite imagery and Digital Elevation Models, our work allows us: i) to depict the highly-segmented arrangement of the ~7 Ma-lasted SKR system, ii) to establish a two-stage kinematic rift model that emphasizes the role of an inherited transverse discontinuity on the arrest, as well as lateral jump and off-axis development of anomalously-propagating rift structures, iii) to define the relative contribution of border vs inner fault networks to the total extension, which is estimated at 7–6 km (11.6–9.2%), and iv) to emphasize that inner faulting was not the dominant mode of strain accommodation during recent inward focussing of strain, and that no sharp transition exists from border fault- to intra-rift fault-dominated strain accommodation over time in the SKR immature rift system.

International audience; Bien moins connu que son équivalent sud du fait de la rareté des affleurements, le remplissage tertiaire du Bassin d’Aquitaine offre un bel exemple de remplissage d’un retroforeland qui peut être mis en relation avec la dynamique de l’orogène pyrénéen et celle du proforeland sud-pyrénéen. La synthèse des données de subsurface permet actuellement de reconstituer les principales phases de son évolution. L’Eocene correspond à la période syn-orogénique et à une décharge terrigène majeure en lien avec le début de l’exhumation des reliefs. Il se traduit par le comblement progressif d’est en ouest du bassin, tandis que le piedmont Est enregistre plusieurs séquences de mise en place de cônes alluviaux. L’objectif de ce travail est d’identifier les contraintes de premier ordre sur l’évolution du système source to sink au cours de cette période. Les dépôts carbonatés dominent largement durant le Paléogène. L’Yprésien est marqué par une progradation très rapide de dépôts deltaïques associée à (1) la première phase d’exhumation significative dans la chaîne, (2) au développement d’un bassin flexural de grande taille et (3) d’une contribution relativement importante de l’avant pays (4) dans un contexte climatique humide. Ce comblement a pour conséquence un très fort allongement de la zone de transfert entre pied- mont et sédimentation marine à partir du Lutétien, qui se marque par une modification importante du système source to sink. En effet, durant l’intervalle Lutétien moyen – Bartonien, la sédimentation marine est dominée par les dépôts carbonatés alors qu’une progradation majeure des cônes alluviaux est enregistrée dans le piedmont oriental, corrélée avec la phase majeure d’exhumation dans les Pyrénées. Cette situation suggère un fort tampon dans le transfert des sédiments. Nous montrerons que si une cause climatique peut expliquer une partie de la réduction d’apports vers le domaine marin, le tampon de la zone de transfert est en premier lieu dû à un contrôle tectonique marqué par une forte déformation dans l’avant pays qui a pour conséquence une forte segmentation du bassin et la génération de dépôts-centre isolés qui piègent une grande partie du sédiment. L’Eocène période s’achève par un ralentissement progressif de la subsidence à partir du Pri- abonien associé à une avancée importante de la sédimentation continentale et un comblement complet du bassin. Ces travaux de recherche ont été financés et réalisés dans le cadre du programme BRGM-TOTAL Source-to-Sink.

Reconstructing long-term drainage evolution in collisional setting is key to deciphering between the drivers controlling landscape and time scales of syn-orogenic sediment transfer processes. Provenance studies in orogenic systems often exploit the geochronological record of past magmatic events in sediments to infer their source rocks. However, detrital age distribution may be difficult to be directly related to a specific source rock because it depends on whole rock composition and a robust stratigraphic and sedimentologic framework. Description of the provenance signal over the orogenic cycle from rift basin to its inversion as an orogenic prism may therefore appear to be a very challenging task. Here, we take advantage of an extensive set of geochronological dates in combination with sedimentological data in well-dated stratigraphic units to resolve uncertainties on grain provenance. We focus on the Pyrenees Mountains that developed in response to the inversion of European and Iberian continental margins from the Late Cretaceous to the Miocene. Inversion of hyper-extended rift basins in the Northern Pyrenees is recorded by specific cooling histories contrasting with the Southern Pyrenees where crustal extension was minor. We review and compile all available detrital thermochronological and geochronological data sets and provide new U/Pb and (U-Th-Sm)/He analyses on detrital zircon grains. This new data set allows us to re-examine the evolution of the sediments routing in the Pyrenees from rift-related Mesozoic basin evolution to tectonic inversion during Cenozoic foreland development. Together with sedimentological and petrographical constraints from syn -rift Mesozoic and syn-orogenic Cenozoic sediments, and within the frame of quantitative kinematic plate reconstructions based on existing rotation data, and balanced cross-sections, we examine the temporal and spatial evolution of sediment routing in the entire Pyrenean realm from rift to collision. Our paleogeographic reconstructions of the sediment dispersal pattern are presented for four key time steps at ~ 100, 70, 55, and 40 Ma, accounting for Iberia's plate motion. Early Cretaceous extension on the European margin led to the formation of multiple and narrow basins that were fed locally. This contrasts with the larger-scale pattern of sediment dispersal on the southern Iberia margin. The differences in sediments dispersal are shown to reflect first-order N-S asymmetry of extension. The asymmetry is maintained during the earliest stages of convergence in Late-Cretaceous – Paleocene. The southern foreland basin exhibits large-scale longitudinal drainage patterns while sediments dispersal in the northern basin is controlled by inherited pre-orogenic E -W-striking basin architecture. In the Paleocene, the southwards migration of thrust sheets and underplating below the Axial Zone led to increasing exhumation at the origin of the emplacement of the first transverse drainage network in the Southern Pyrenees. Changes from dominant longitudinal to transverse drainage in the north occurred in the middle Eocene. Our study emphasizes the role played by the rifted margin on the syn -collisional sediment routing system. We anticipate that this main result could be transposed to other orogens that have resulted from rift basin inversion.

International audience; Sediments deposited after the peak of the Messinian Salinity Crisis (MSC) in the Apennine foredeep of Italy embody a topic debated on both chronostratigraphic and palaeoenvironmental grounds. We performed micropalaeontological (calcareous nannofossil and dinoflagellate cyst) analyses on four stratigraphic sections (Monticino, Civitella del Tronto, Fonte dei Pulcini, Fonte la Casa) and reused those from Maccarone. All sections belong to the p-ev 2 Formation that includes the Colombacci deposits, usually considered emblematic of the Lago Mare in the area. Marine microfossils recorded in previous studies have often been neglected or considered reworked and hence discarded. We propose the occurrence of at least four marine inflows between 5.36 and 5.33 Ma, the first of which is reflected in the Apennine foredeep by marine dinoflagellates that are then replaced by Paratethyan (brackish) ones. Paratethyan species occupied favourable environments during intervals separating marine inflows while the marine species survived elsewhere. From this perspective, the Apennine foredeep was an isolated perched basin during most of the peak of 2 the MSC (5.60–5.36 Ma), and was progressively and repeatedly invaded by marine waters overflowing a palaeo-sill before the beginning of the Zanclean (5.33 Ma) which itself reflects a continuing eustatic rise. The Gargano Peninsula and, offshore, the present-day Pelagosa sill may be regarded as the remnants of such a Messinian sill. This interpretation provides new possibilities for ecostratigraphically correlating the sections with Lago Mare biofacies, the deposition of which unquestionably started prior to the deposition of Colombacci sediments and continued just into the earliest Zanclean. The results of this study show that the Lago Mare facies cannot be restricted to a single brackish palaeoenvironment but included competing marine and brackish waters controlled by geographic and chronological factors. Deposits overlying the unconformity separating the regional p-ev 1 and p-ev 2 formations are considered to represent the first marine incursion into the Apennine foredeep. These results allow us to refine the palaeogeographic reconstruction of the Apennine foredeep during the peak of the MSC. Although this basin was deep, its history during the peak of the MSC did not parallel that of the central Mediterranean basins.

The Betics are a key area to study an orogenic landscape disrupted by late-orogenic extension. New low-temperature thermochronology (LTT) data (AHe and AFT) coupled with geomorphic constraints in the Sierra de Gador (Alpujarride complex) are used to reconstruct the cooling history and evolution of relief during the Neogene. We document three stages: (i) a fast cooling event between 23 and 16 Ma associated with the well-known extensive tectonic exhumation of the Alpujarride unit, (ii) a period of slow cooling between 16 and 7.2 Ma related to a planation event and (iii) a post-7.2 Ma surface uplift associated with the inversion of the Alboran domain undetected by LTT. The planation event followed by this late uplift can explain the occurrence of inherited low-relief surfaces overlain by Tortonian–Messinian platform deposits at the top of the range. Finally, we propose that the Sierra de Gador is a more transient landscape than the nearby Sierra Nevada. This article is protected by copyright. All rights reserved.

We reply to the comments of J. Philip regarding the structure of La Nerthe range (southern Provence, France) and the timing of the deformation. We first agree with J. Philip on the structural independence of La Nerthe and L’Etoile ranges. We then discuss the allochthonous and autochthonous models. The allochthonous model mainly relies on a reactivation of a N-verging thrust during the Oligocene. There are no evidences for a Middle Rupelian thrusting event and the interpretation of the Oligocene series in southern Provence area was entirely revised. J. Philip’s argumentation is solely based on the existence of steep dipping Rupelian limestones. However we demonstrate that they could be tilted along normal faults as it is the case in the Marseille basin. Recent works clearly show that the Oligocene Marseille and Saint-Pierre basins have a similar tectonic history resulting from two main extensional events. The last point debated by J. Philip is the age of the strike-slip faults. As it is pointed in our contribution the strike-slip fault planes cut folded strata and were reactivated during an extensional event. This strike-slip faulting event occurred between the latest stages of the main Bartonian compressional event and the beginning of the Early Rupelian extensional tectonics. As pointed by J. Philip the E-trending faults of Saint-Pierre basin acted as normal faults during the Oligocene. We however suggest that these faults were inherited from the Late Eocene strike-slip tectonics and reactivated during the Oligocene.

International audience; The Tertiary evolution of the Aquitaine basin (northern Pyrenean foreland) is closely linked tothe Pyrenean orogeny and its northern retrowedge. During the Middle Eocene maximum ofIberia- Eurasia collision (Ypresian- Bartonian) strong denudation of the mountain belt takesplace, partly compensated by the subsidence of the foreland. In the Aquitaine basin this periodis registered by the progressive transition from dominantly marine underfilled sedimentationto continental overfilled sedimentation. In the proximal part of this system, this overfillingleads to a massive, kilometer thick, conglomeratic sedimentation while deltaic sedimentationprogressively fills the basin from east to west.This study focuses on the proximal part of this system in order to characterize (1) the dynamicsof the piedmont sedimentation and its relation to tectonics, climate and denudation ofthe orogen, and (2) the transfer of sediments from the piedmont towards more distal areas, through the definition of types of sedimentary systems and identification of zones of trappingand bypass . Field study of the syn-orogenic Palassou conglomerates and molasses deCarcassonne from Mouthoumet massif to Lavelanet has been coupled with interpretation ofsubsurface (well logs and seismic profiles) in order to characterize the geometries and contentsof these deposits.The Ypresien – Late Bartonian system is organized along two main megasequences:- A continued progradation during Ypresian from deltaic to proximal braided streamand sheet flood deposits. Clasts are mainly composed of meso-cenozoic cover. This progradingtrend accompanies the onset of thrusting in the foreland. The following retrograding trendtakes place during Lutetian with the sedimentation of lacustrine and floodplain deposits withintercalated coarse sheet flood deposits.- The second megasequence displays a major progradation with proximal braidedstream to alluvial fan deposits which traduces uplift and incision of the piedmont. This sequenceregister the first input of material derived from the axial zone.These two sequences display significantly different geometries revealing strong differentcontrols by tectonics and sediment supply and evolving sediment routing. While the first -underfilled-sequence is strongly controlled by the deformation of the foreland, the second one is more widespread with limited control of the deformation and progressive sealing of the structures.Thermochronology as well as refined datations and correlations will complete this early resultsand help linking the dynamics of the Pyrenean orogeny and among all the relative influence oftectonics and climate with the input of sediment and their transfer toward sink areas.The characterization of the transfer of sediments during the syn-orogenic period will be studiedin the framework of the S2S project (a Total- BRGM collaboration). The current results havebeen collected during research programs RGF (BRGM) and Gaia (TIGF/BRGM/AEAG).

The morphology of the Pyrenees is characterized by the presence of high-elevation, low-relief surfaces. The origin of these Lower-Miocene surfaces is still debated. Two major interpretations have been proposed, both assuming that these surfaces are remnants of a single composite planation surface. The first interpretation proposes that this surface corresponds to a peneplain developed near sea level before the Late Miocene, subsequently uplifted and dissected. The present-day Pyrenees is therefore supposed to rise from the Late Miocene. In the second interpretation, the rise of the efficient base level of the chain induced the progressive inhibition of erosion and the smoothing of the relief before the Late Miocene, resulting in a highly elevated peneplain. According to this latter interpretation, the high elevation of the low-relief surfaces does not equate to post-orogenic uplift. We test these two interpretations by investigating, among other considerations, the relation between the elevation of the planation surface remnants and the deep structure of the chain. We find that (1) the isostatic compensation of the dissected Pyrenean planation surface by crustal thickening and (2) the absence of thinning of the lithosphere mantle below the chain favors the second interpretation., We are grateful to the BRGM (Bureau de recherches geologiques et minieres) for funding the Gemma V. Bosch PhD thesis (Project RGF, ‘‘Référentiel géologique de la France’’).

The Eocene shortening directions along the Southern Provence fold-and-thrust belt are commonly assumed to be N-S. We present here new observations and data that allow reinterpreting the structure of the La Nerthe range as a right-lateral transpressive flower structure. Structural data collected along the range argue for an Eocene N145o shortening event. The age of this shortening event is constrained by the fact that faulting and folding affect the Late Cretaceous-Paleocene continental deposits along the northern flank of the La Nerthe range and is sealed by the Miocene marine deposits. Moreover striated fault planes display both horizontal and vertical striae suggesting that they were reactivated during the Oligocene extensional event. We question here the shortening directions along the Southern Provence thrust belt. Structural data suggest both N-S and NNW-SSE shortening directions during the Eocene. During the Eocene the Provence area was in the foreland of a complex orogenic belt that extended from the Betic Cordillera to the Corsica-Sardinia block. This orogenic belt developed along the subduction linked to the convergence between Africa and Eurasia. Although the convergence vector was nearly N-S the NE-SW orientation of the trench may have led to a complex deformation pattern along the orogenic belt with NW-SE and N-S shortening directions that reflected both the along-trench compression and the regional convergence.

Situee dans les Chaines subalpines meridionales, la region du Devoluy-Bochaine offre une " discordance ante-senonienne " interpretee classiquement comme le resultat d'une phase de compression d'âge turonien. Nous presentons des arguments conduisant au contraire a interpreter cette discordance comme le resultat d'un glissement synsedimentaire majeur sur la pente de la paleomarge europeenne. Pendant l'intervalle Tithonique-Cretace superieur, le Devoluy-Bochaine etait situe sur la pente joignant la plate-forme du Vercors et le Bassin vocontien (partie profonde du bassin du Sud-Est), dans lequel s'accumulaient glissements en masse et depots resedimentes. Sous la discordance, le plissement du Devoluy affecte les series allant du Kimmeridgien au Cenomanien, detachees en " mega-collapse " sur les " Terres Noires " du Jurassique moyen-superieur. La troncature du toit de l'unite collapsee resulte de plusieurs facteurs, failles normales, fragmentation des couches encore peu consolidees et erosion par les courants de fond. On ne trouve dans l'interface de discordance ni depots continentaux ou paleosols, ni conglomerats de transgression, mais seulement des breches de pied d'escarpement de faille sous-marine. Les couches sus-jacentes, d'âge essentiellement coniacien-maastrichtien, sont des calci-turbidites chenalisees ou les slumpings sont encore frequents. En conclusion, les massifs du Devoluy-Bochaine offre le premier exemple, dans les Alpes externes, d'un collapse synsedimentaire majeur comparable aux cas decrits en offshore sur les marges du Niger ou d'Israel.

Rivers respond to a drop in their base level by incising the topography. The upstream propagation of an incision, as usually depicted by a knickpoint migration, is thought to depend on several parameters such as the drainage area, lithology, and the amplitude of the base level drop. We first investigate the case of the Messinian Salinity Crisis that was characterized by the extreme base level fall (1500 m) of the Mediterranean Sea at the end of the Miocene. The response of drainage areas of three orders of magnitude (10(3) to 10(6) km(2)) highlights the dominant role of the drainage area (with a square root relationship) in controlling the knickpoint migration after a base level fall. A compilation of mean rates of knickpoint propagation for time durations ranging from 10(2) to 10(7) years displays a similar relationship indicating that successive wave trains of knickpoint can migrate in a river: first, wave trains linked to the release of the alluvial cover and then, wave trains related to the bedrock incision, which correspond to the real time response of rivers. Wave trains with very low retreat rates (long lived knickpoints >1 My) rather correspond to the response time of regional landscape. (C) 2008 Elsevier B.V. All rights reserved.

We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high-resolution multibeam echo-sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate-boundary structures are a series of strike-slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre-existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike-slip regime. Along the most recent trace of the SOFZ, we measured a strike-slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS-derived motion of 9.8 ± 2 mm a−1 has remained stable during the entire Quaternary.

International audience; The oblique collision of Taiwan orogen led to a progressive southward uplift and emergence of a submarine accretionary wedge. The Hengchun Peninsula located at the southernmost tip of Taiwan island represents the most recently emerged landform of an antecedent submarine surface. In this study we examine the geomorphic evolution of this newly emerged and uplifted landscape. The extraction of geomorphic parameters (knickpoint distribution, steepness index of rivers) indicates a transient nature of the landscape but shows that a simple model of regressive erosion consecutive to sudden uplift is unsatisfactory. Knickpoint migration modeling shows that only the upstream Sizhong basin can be explained by this single process. On the other hand, the occurrence of a relict landscape (Mutan Ponds low relief) developed at low elevations and, today uplifted in the core of the peninsula, has strongly influenced the drainage evolution. Numerous knickpoints are linked to capture processes around the Mutan Ponds area, indicating a dynamic reorganization of the drainage system. We propose that the landscape of the Hengchun Peninsula is in a transient stage and results from a combination between rejuvenation and drainage rearrangement caused by the late stage of emergence of the south of Taiwan.

International audience; The growth of relief in active tectonic areas is mainly controlled by the interactions between tectonics and surface processes (erosion and sedimentation). The study of long-lived morphologic markers formed by these interactions can help in quantifying the competing effects of tectonics, erosion and sedimentation. In regions experiencing active extension, river-long profiles and faceted spurs (triangular facets) can help in un- derstanding the development of mountainous topography along normal fault scarps. In this study, we devel- oped analogue experiments that simulate the morphologic evolution of a mountain range bounded by a normal fault. This paper focuses on the effect of the fault slip rate on the morphologic evolution of the foot- wall by performing three analogue experiments with different fault slip rates under a constant rainfall rate. A morphometric analysis of the modelled catchments allows comparing with a natural case (Tunka half- graben, Siberia). After a certain amount of fault slip, the modelled footwall topographies of our models reaches a dynamic equilibrium (i.e., erosion balances tectonic uplift relative to the base level) close to the fault, whereas the topography farther from the fault is still being dissected due to regressive erosion. We show that the rates of vertical erosion in the area where dynamic equilibrium is reached and the rate of re- gressive erosion are linearly correlated with the fault throw rate. Facet morphology seems to depend on the fault slip rate except for the fastest experiment where faceted spurs are degraded due to mass wasting. A stream-power law is computed for the area wherein rivers reach a topographic equilibrium. We show that the erosional capacity of the system depends on the fault slip rate. Finally, our results demonstrate the pos- sibility of preserving convex river-long profiles on the long-term under steady external (tectonic uplift and rainfall) conditions.

Using industrial seismic data available in the French Southeast Basin in Provence, we put into evidence thin skinned processes that have dominated tectonics in this basin since the Oligocene. These interpretations are then replaced within the regional structural framework of SW France with geological maps and field work. A thick Mesozoic and Cenozoic sedimentary cover is detached on a main décollement frequently localized within the Triassic evaporites. The underlying basement is undeformed. The Mid-Durance fault, the Luberon, Trévaresse, and the Ventoux-Lure thrust zones and the Diois-Baronnies fold and thrust belt are produced by thin-skinned tectonics, the associated structures having no roots within the pre-Triassic basement. This thin-skinned deformation is interpreted as resulting from a regional southward gravity mass flow, induced by the westward Alps extrusion, followed in recent times by radial collapse of the Alps. The incipient stage of this gravity sliding occurred during the Late Oligocene in the Diois-Baronnies (the former Mesozoic Vocontian basin), and then rapidly progressed to the south across the Ventoux-Lure thrust zone in Provence during the Miocene. Southward, this gravity sliding vanishes approaching the E-W trending structural high of the Eocene Pyrénéo-Provençal orogenic belt in southern Provence.

We investigate the geodynamics of the Southeast Basin with the help of maps of the basement and of major sedimentary horizons based on available seismic reflection profiles and drill holes. We also present a study of the seismicity along the Middle Durance fault. The present seismic activity of the SE Basin cannot be attributed to the Africa/Eurasia shortening since spatial geodesy demonstrates that there is no significant motion of Corsica-Sardinia with respect to Eurasia and since gravitational collapse of the Alps has characterized the last few millions years. Our study demonstrates that the basement of this 140 by 200 km Triassic basin has been essentially undeformed since its formation, most probably because of the hardening of the cooling lithosphere after its 50% thinning during the Triassic distension. The regional geodynamics are thus dominated by the interaction of this rigid unit with the surrounding zones of active deformation. The 12 km thick Mesozoic sediment cover includes at its base an up to 4 km thick mostly evaporitic Triassic layer that is hot and consequently highly fluid. The sedimentary cover is thus decoupled from the basement. As a result, the sedimentary cover does not have enough strength to produce reliefs exceeding about 500 to 750 m. That the deformation and seismicity affecting the basin are the results of cover tectonics is confirmed by the fact that seismic activity in the basin only affects the sedimentary cover. Based on our mapping of the structure of the basin, we propose a simple mechanism accounting for the Neogene deformation of the sedimentary cover. The formation of the higher Alps has first resulted to the north in the shortening of the Diois-Baronnies sedimentary cover that elevated the top of Jurassic horizons by about 4 km with respect to surrounding areas to the south and west. There was thus passage from a brittle-ductile basement decollement within the higher Alps to an evaporitic decollement within the Diois-Baronnies. This shortening and consequent elevation finally induced the southward motion of the basin cover south of the Lure mountain during and after the Middle Miocene. This southward motion was absorbed by the formation of the Luberon and Trévaresse mountains to the south. To the east of the Durance fault, there is no large sediment cover. The seismicity there, is related to the absorption of the Alps collapse within the basement itself. To the west of the Salon-Cavaillon fault, on the other hand, gravity induces a NNE motion of the sedimentary cover with extension to the south and shortening to the north near Mont Ventoux. When considering the seismicity of this area, it is thus important to distinguish between the western Basin panel, west of the Salon-Cavaillon fault affected by very slow NNE gliding of the sedimentary cover, with extension to the south and shortening to the north; the central Basin panel west of the Durance fault with S gliding of the sedimentary cover and increasing shortening to the south; and finally the basement panel east of the Durance fault with intrabasement absorption of the Alps collapse through strike-slip and thrust faults.

[1] After a base level drop, rivers are the first components of the landscape to respond by incising into topography. A base level drop results in a knickpoint in the downstream part of river longitudinal profiles. Whether knickpoints are preserved or erased during the upstream propagation of incision is still debated. Preservation and erasure of knickpoints are two end-member processes that work in natural systems at different timescales, different length scales, and different places. The huge (1500 m) and fast (tens of kiloyears) sea level drop in the Mediterranean during the Messinian resulted in the fast propagation of incision far inland. This is especially the case in the Rhone Valley (southern France) where the knickpoint is 300 km from the Mediterranean coast. Numerical modeling of this event has been performed using the ros model, which simulates both erosional and depositional processes in rivers. The best fit between numerical results and geological data is obtained for a nonlinear relation between incision and drainage area and for a small transport length of sediment. This small transport length, at least 2 orders of magnitude lower than the length of the Rhone, suggests that the longitudinal profile relaxed in a diffusive way, so that the initial knickpoint was not preserved. Finally, after a base level fall, the propagation of fluvial incision is very fast at geological timescales (hundreds of kiloyears). Despite this, the diffusive response implies that the time required for restoration of an equilibrium profile is very long.

International audience; The connection of the Ebro basin via the Ebro River to the Mediterranean Sea is supposed to have played a major role in the rejuvenation of relief of northern Spain and especially of the South Pyrenees from the Neogene by lowering the initial base level of the Ebro internal drainage area down to sea level. However, the timing and causes of this connection are still debated. A fundamental issue is whether the Ebro basin became connected to the Mediterranean before or after the Messinian salinity crisis? Morphological analysis and numerical modeling of landscape evolution show that this connection did not exist before the Messinian salinity crisis but is effective from the Pliocene because of progressive regressive erosion.

International audience; Most interpretations of the Early Pliocene opening of the Strait of Gibraltar involve a tectonic process. However, no tectonic structure of this age has been unequivocally documented that could account for such a hypothesis. On the other hand, the sea-level drop of the Mediterranean during the Messinian Salinity Crisis has dramatically enhanced continental erosion and in particular regressive fluvial erosion. We show that such erosional process inevitably developed in the Gibraltar area. We finally propose that regressive fluvial erosion was at the origin of the opening of the Strait of Gibraltar.

The cause of the desiccation of the Mediterranean Sea during the Messinian Salinity Crisis has been widely debated, but its re-flooding remains poorly investigated. Interpretations generally involve tectonic collapse of the Strait of Gibraltar or global sea-level rise, or even a combination of both. The dramatic sea-level fall in the Mediterranean has induced deep fluvial incision all around the desiccated basin. We investigate erosion dynamics related to this base level drop by using the numerical simulator EROS. We show that intense regressive erosion develops inevitably in the Gibraltar area eventually inducing the piracy of the Atlantic waters by an eastward-flowing stream and the subsequent re-flooding of the Mediterranean.

New thermochronological data (AFT, ZHe, and ZFT) on the Belledonne and Grandes Rousses ECMs basement show a similar and relatively rapid exhumation dynamic around 18 Ma for all the External Cristalline Massifs. However, the exhumation of southern massifs (e.g., Oisans) could start earlier, from 25 Ma suggesting a diachronous exhumation along the Alpine Arc. This also suggests a progressive localization of deformations along the crustal ramps between ~25 and 18 Ma. Finally, the rapid exhumation starting at around 18 Ma seems to correspond to the limit of mega-sequences in the molassic basin. Field analysis, borehole data and seismic lines show that the basin was deformed as early as the Oligocene (25 Ma). This also allows the calculation of the sediment volumes preserved within the West Alpine Molassic Basin. Finally, a preliminary study of the source to sink in the West Alpine basins is approached from petro-detritic analyses, detrital thermochronology and calculation from the seismic lines. These results highlighted the progressive denudation of the Variscan crust of the upper plate whose detrital signal has been present since the Eo-Oligocene in the peri-alpine basins. The late Miocene appearance in the West Alpine Molassic basin of a tertiary thermochronological signal suggests a change in surface dynamics and/or a different sedimentary routing over time, but also significant differences compared to the basins located north of the Alps.; Les nouvelles données thermochronologiques (AFT, ZHe et ZFT) sur le socle des MCE de Belledonne et des Grandes Rousses mettent en évidence une dynamique d’exhumation similaire et assez rapide vers 18 Ma pour tous les Massifs Cristallins Externes. Cependant, l'exhumation des massifs du Sud (e.g., Oisans) pourraient commencer plus tôt, à partir de 25 Ma suggérant une exhumation diachrone le long de l’Arc Alpin. Cela suggère aussi une localisation progressive des déformations le long des rampes crustales entre ~25 et 18 Ma. Enfin, l'exhumation rapide vers 18 Ma semble correspondre à la limite de méga-séquences dans le bassin molassique. Les analyses de terrain, des données de forages ainsi que des lignes sismiques montrent notamment une déformation du bassin assez précoce, dès l'Oligocène (25 Ma). Elles permettent aussi le calcul des volumes de sédiments préservés dans le bassin molassique Ouest Alpin. Enfin, une étude préliminaire à l’approche source to sink dans les bassins ouest-alpins est abordée à partir d'analyses petro-détritiques, de thermochronologie détritique et de calcul des volumes à partir des lignes sismiques. Ces résultats ont permis de mettre en évidence la dénudation progressive de la croute varisque de la plaque supérieure dont le signal détritique est présent depuis l’Eo-Oligocène dans les bassins péri-alpins. L’apparition tardive au Miocène dans le bassin molassique Ouest Alpin d’un signal thermochronologique tertiaire suggère un changement de dynamique de surface et/ou un routage sédimentaire différents dans le temps, mais aussi des différences significatives avec les bassins au nord des Alpes.

Competing between internal and external processes controls the evolution of continental surfaces at geological time scale. The topography and associated drainage network of the Betics are transient (summit surfaces, knickpoints) implying that the erosional response of the geomorphic system hasn’t counterbalanced the last stages of uplift yet. Exhumation history of the internal zones shows a major planation event near sea level between ~ 18 and 7 Ma. Some of these surfaces are preserved from erosion at the summit of several sierras. Rivers in the eastern sierras show relatively mature incision pattern initiated since the Late Miocene inversion. At the regional scale the drainage network shows a more recent uplift related to dynamic topography. Post-Tortonian shortening in the Internal Zones is low (~5 km) whereas E-W tearing of the Iberian lithosphere since the Late Miocene has led to an important mantle support of the eastern topography. To the west, Iberian lithosphere is pulled by the slab and the mean topography above is deflected. These deep processes are responsible for an important non-isostatic component of the Betics topography. The tear geometry of the lithosphere beneath the Betics can explain the instability of the main divide (Atlantic/Mediterranean). Rejuvenation of the relief and the dynamic reorganization of the rivers suggest a brief and recent uplift (few Ma) related to a discontinuous tearing of the lithosphere.; La compétition entre les processus internes et externes contrôle l'évolution des surfaces continentales à l'échelle des temps géologiques. La topographie et le réseau de drainage actuels des Cordillères Bétiques apparaissent comme transitoires (surfaces aplanies sommitales, knickpoints) impliquant que la réponse érosive du système géomorphologique n'a pas encore contrebalancé les dernières étapes de surrection. L'exhumation des zones internes montre un épisode d'aplanissement majeur de la topographie à une altitude proche du niveau marin entre ~ 17 et 8 Ma. Certaines de ces surfaces sont préservées de l'érosion en altitude. Les rivières montrent une incision relativement mature dans les sierras orientales initiée lors de l'inversion tardi-miocène, et une surrection régionale plus récente reliée à de la topographie dynamique. Le raccourcissement post-tortonien dans les zones internes est faible (~ 5 km) tandis que la déchirure E-W de la lithosphère ibérique depuis la fin du Miocène entraîne un soutien mantellique permettant d'expliquer les hautes topographies orientales. A l'ouest, la lithosphère ibérique subit la traction du panneau plongeant impliquant une topographique moyenne plus basse. L'implication de ces processus engendre une forte composante non-isostatique de la topographie. La géométrie de la déchirure de la lithosphère ibérique permet d'expliquer l'instabilité de la ligne de partage des eaux séparant les versants atlantique et méditerranéen. Le rajeunissement du relief bétique et la réorganisation dynamique du réseau de drainage suggère une surrection brève et récente (quelques Ma) rattachée à un fonctionnement discontinu de la déchirure de la lithosphère.