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This paper presents a sequentially restored cross-section of the Organyà and Montsec minibasins based on geological mapping, new field observations and available borehole data. The main objective was to describe the geometry and evolution of both basins in terms of salt tectonics and minibasin mobility. To this end, a comprehensive palaeomagnetic database has been used to constrain vertical-axis rotations potentially related to minibasin translation and pivoting. The Organyà minibasin constitutes an asymmetric depocentre formed during the Upper Jurassic-Lower Cretaceous by translation above a southerly inclined salt layer. Salt evacuation and minibasin touchdown induced salt accumulation on the northern side of the basin that culminated in the development of the major Santa Fe unconformity during the late Albian--early Cenomanian. Indicative of salt quiescence is the following isopachous Cenomanian to lower Santonian sequence Salt tectonics resumed during the late Santonian--Palaeocene, with the Montsec minibasin downbuilding coinciding with the onset of Pyrenean convergence. Changes of the base-salt topography reflects regional-scale geodynamic processes. The acceleration of crustal thinning in the North Pyrenean zone during the late Albian-early Cenomanian favoured uplift in the Axial Zone, increasing slope and triggering salt mobilization in the Southern Pyrenees. Likewise, the onset of contraction renewed the downslope gliding of the Organyà and Montsec minbasins, and supports the idea that the early stages of basin inversion were governed by gravity tectonics. The kinematic reconstruction suggests that the more that 30° counterclockwise vertical axis rotation records pivoting during the suprasalt translation of the Organyà minibasin rather than solely the Iberian microplate rotation. [ABSTRACT FROM AUTHOR]

Many works in the last decades underline the role of evaporites, not just as a conditioning factor but as the engine for subsidence and eventually basin inversion. The western Mediterranean alpine ranges are being investigated in this regard because of the presence of discontinuous units of Permian to Triassic evaporites, deposited in the western Tethys basins. This work presents a thorough analysis of two particular structures (Cañada Vellida and Miravete anticlines) in the intraplate Maestrazgo basin (eastern Iberian Chain, Spain) in which evidence to support their reinterpretation as salt‐driven structures have been recently reported. Our analysis includes (i) a comprehensive stratigraphic and structural study of the folds along their entire trace, (ii) the compilation of thickness and distribution of evaporite–bearing and supraevaporite units, paying special attention to changes in the thickness of units in relation to anticlines, and (iii) the study of fault patterns, sometimes in relation to the mechanical stratigraphy. All three aspects are also documented and discussed on a regional scale. The new data and interpretations reported here reinforce the extensional origin of the Late Jurassic–Early Cretaceous basins, and the role of regional extensional tectonics as the responsible for the development of first‐order syn‐sedimentary normal fault zones driving the formation and evolution of sub‐basins. These basins were subsequently inverted and deformed, including the formation of complex, box‐geometry anticlines that, in their turn, controlled deposition in Cenozoic basins. The review of the arguments that support the alternative of salt tectonics for the origin of such anticlines has allowed us to delve into the sedimentary and tectonic evolution of the inverted extensional basins and to propose a specific model for the development of these faulted anticlines. The role of salt levels and other interlayered detachments in the structuring of sedimentary basins and their inversion is also pondered. The observations in the eastern Iberian Chain reported here have implications to assess ongoing reinterpretations in terms of salt tectonics in other alpine basins and ranges of the western Mediterranean. [ABSTRACT FROM AUTHOR]

The propagation of the deformation front in foreland systems is typically accompanied by the incorporation of parts of the basin into wedge‐top piggy‐back basins, this process is likely producing considerable changes to sedimentation rates (SR). Here we investigate the spatial‐temporal evolution of SR for the Tremp–Jaca Basin in the Southern Pyrenees during its evolution from a wedge‐top, foreredeep, forebulge configuration to a wedge‐top stage. SR were controlled by a series of tectonic structures that influenced subsidence distribution and modified the sediment dispersal patterns. We compare the decompacted SR calculated from 12 magnetostratigraphic sections located throughout the Tremp–Jaca Basin represent the full range of depositional environment and times. While the derived long‐term SR range between 9.0 and 84.5 cm/kyr, compiled data at the scale of magnetozones (0.1–2.5 Myr) yield SR that range from 3.0 to 170 cm/kyr. From this analysis, three main types of depocenter are recognized: a regional depocenter in the foredeep depozone; depocenters related to both regional subsidence and salt tectonics in the wedge‐top depozone; and a depocenter related to clastic shelf building showing transgressive and regressive trends with graded and non‐graded episodes. From the evolution of SR we distinguish two stages. The Lutetian Stage (from 49.1–41.2 Ma) portrays a compartmentalized basin characterized by variable SR in dominantly underfilled accommodation areas. The markedly different advance of the deformation front between the Central and Western Pyrenees resulted in a complex distribution of the foreland depozones during this stage. The Bartonian–Priabonian Stage (41.2–36.9 Ma) represents the integration of the whole basin into the wedge‐top, showing a generalized reduction of SR in a mostly overfilled relatively uniform basin. The stacking of basement units in the hinterland during the whole period produced unusually high SR in the wedge‐top depozone. [ABSTRACT FROM AUTHOR]

• Uplifted landforms support diapir growth. • Impact of diapirism on drainage network diversion and truncation. • Episodic salt flow enhanced by erosional unloading. • Long term rates of diapiric uplift. This work analyses the Quaternary landforms, geomorphic changes and stratigraphic evidences of evaporite dissolution and halokinesis in the Estella salt diapir (Basque-Cantabrian Basin). The mapping of Quaternary deposits demonstrates that karstic subsidence and diapirism happen at the same time. The diapir geometry is characterised by a prominent 4.5 km-long fault scarp attributed to the uplift of the diapir and a fluvial gypsum escarpment along the northern and eastern diapir edges. The dissolution of the gypsiferous caprock is responsible for the development of a large number of collapse sinkholes, the local thickening of terrace deposits and a network of endokarstic conduits connected to saline springs that cause a notable increase in the salinity of the Ega river across the diapir (70% electrical conductivity increase). The 40 m vertical displacement of T4 terrace and P5 pediment deposits, the anomalous longitudinal profile of the old terraces, the deflection of infilled-valleys at the base of the fault scarp, the occurrence of wind gaps and the continuous lateral migration of the Ega river away from the diapir support salt upwelling since 644 ± 81 ka ago at a long-term, average uplift rate of 0.05–0.07 mm/yr. The 12 m offset of T8 terrace, the steepening of the Ega river floodplain and the tilting of the upper level and the antigravitative erosion genesis of the Longinos cave point to a faster diapir rising rate of 0.23–0.57 mm/yr in the last 36 ± 15 ka coinciding with a period of increasing river incision. The lack of tectonic activity in the region suggests that diapirism is enhanced by erosional unloading related to fluvial entrenchment. The thickening of pediment P5 supports the north-northeast flow of salt towards the river valley. [ABSTRACT FROM AUTHOR]

The structural and stratigraphic geological features associated with salt structures have received extensive attention from geologists. However, there is limited work on the geomorphic and Quaternary record of diapiric activity despite its practical implications (e.g., salt and hydrocarbon extraction, geostorage activities). This work analyses the Quaternary geomorphic and stratigraphic evidence of diapiric activity in the Navarrés salt wall (SE Spain), developed along the axis of a Neogene graben. This salt system is located in a region characterized by a peculiar network of orthogonal grabens that control the configuration and evolution of the drainage network. The protruding salt walls are spatially associated with the erosionally unloaded and deeply entrenched graben sections situated close to the regional base level. Evidence of recent/current activity in the Navarrés salt wall include: (1) internally drained areas in a marginal withdrawal basin with long-sustained aggradation; (2) distorted drainage network (defeated and deflected streams, wind gaps, knickpoints, changes in fluvial style), which changed from an initial axial longitudinal pattern to a longitudinal marginal distribution at the flanks of the salt wall; (3) development of diapiric fault scarps at the edge of the salt wall; (4) tilted fluvial terraces dipping away from the salt wall and with localized sediment thickening. The available data indicate along-strike variability in deformation style and long-term vertical deformation rates. These range from ≤0.09 mm/yr, to significantly higher values (>0.2–0.4 mm/yr) in the section where the salt wall displays a more prominent relief and is affected by deep fluvial entrenchment. The regional analysis and the characterization of the Navarrés salt wall suggest that Quaternary diapirism in the region is enhanced by erosional unloading related to fluvial entrenchment, which expands from the regional base level through the upstream propagation of an incision wave. • Geomorphic record of diapiric activity (diapiric geomorphology) • Salt flow enhanced by erosional unloading • Impact of active diapirism on drainage network development • Long-term rates of diapiric uplift [ABSTRACT FROM AUTHOR]

In this paper we present and discuss Cretaceous extensional folds of the eastern Basque-Cantabrian Basin (Northern Spain). Geometry and kinematics of folds is constrained by means of structural and sedimentological fieldwork integrated with geological mapping, revealing an intimate link between coeval folding, extensional faulting, and salt mobilization. In detail, the Mesozoic succession of the northwestern and southern borders of the Palaeozoic Bortziriak-Cinco Villas massif (eastern margin of the BCB) host late Albian–early Cenomanian syn-rift forced folds. The studied forced fold axes trend parallel and are located above main and inferred Cretaceous syn-sedimentary basement faults. Structural data indicate that these folds formed during the late Albian − early Cenomanian interval. The presence of Upper Triassic clay and evaporite outcrops along and/or close to the axes of folds and their stratigraphic relationship with Upper Cretaceous strata indicate their halokinetic origin and extrusion during folding. The trigger of salt tectonics is attributed to a basement extensional pulse during the Bay of Biscay – Pyrenean rifting. Related high subsidence-rates allowed salt to flow towards faults, forming salt walls and causing the inflation and folding of the overburden. [ABSTRACT FROM AUTHOR]

This paper presents a geological map and cross-sections of the Cotiella thrust sheet at 1:25,000 and 1:50,000 scale, respectively. The map covers an area of 225 km2in the southern Pyrenees. The structure of the studied area is dominated by an upper Santonian – lower Miocene thrust system, which transported a middle Coniacian-lower Santonian extensional basin, the Cotiella Basin, 10 s of kilometres southwards during the Pyrenean orogeny. The map focuses on the internal structure of the Cotiella Basin, its partially inverted extensional faults and its up to 6.5 km of upper Albian – lower Santonian sediments that unconformably overlie Upper Triassic salts. The map and cross-sections, together with outcrop-scale observations, have led us to interpret the rising of passive diapirs in the area. This newly recognized salt tectonic event in the Cotiella Basin is important because of the insights it can provide for the paleogeographic reconstruction of the Upper Cretaceous paleomargin of the northern parts of the Iberian Peninsula. [ABSTRACT FROM AUTHOR]

To assess the influence of growing salt structures on facies distribution, stratal pattern, and thickness trends, this paper provides the tectonostratigraphic framework of the outstandingly exposed Cotiella minibasins (South-Central Pyrenees, Spain). Based on detailed analysis of field cross-sections, our results showcase the syn-halokinetic upper Coniacian-lower Santonian Cotiella minibasins infill (1.5–3 km thick) records four shallow-marine depositional sequences, made of mixed siliciclastic-carbonate stratigraphic sequences. This infill is subdivided in three tectonostratigraphic units, identified by using large and small-scale halokinetic structures (i.e. wedges, megaflaps) and variations in facies associations, thicknesses, stratal patterns from the salt wall flanks to the central part of the minibasins. The first unit records the onset of salt movement with overlying laterally continuous sheet-like sedimentary layers and progressive facies transitions over distances of kms. The influence of halokinesis on sedimentation patterns was minor, and only impacted thickness trends and depocenters localization. The second unit records salt evacuation at the surface with the presence of salt-wall derived detritus, the rapid downbuilding and a increase of sand-rich facies proportions. The stratal pattern is characterized by sheet like layers, laterally discontinuous over distances of 300–600 m downdip to the salt wall. Topographically elevated salt walls likely amplified tidal currents, implying sand-rich facies accumulation along the salt wall margin. The halokinesis influence on sedimentation, thickness trends and depocenter localization was significant. The third unit records the end of the salt evacuation stage, marking a brutal decrease of sand-rich facies, likely controlled by regional controls such as eustacy and tectonics. The influence of halokinesis on sedimentation patterns, thickness trends, large-scale geometries and depocenter localization was significant. Our work indicates that distinguishing these large-scale tectonostratigraphic units and their characteristics is of prime importance to understand the archetypal facies distribution, thickness and stratal patterns along salt structures margins. • Cotiella Basin exposes exceptionally preserved seismic-scale minibasins and the salt-walls flanking strata. • Distinguishing minibasins tectonostratigraphic units is of prime importance. • Tectonostratigraphic units display different archetypal facies distribution, thickness trends and halokinetic structures. • High salt wall topography amplify tidal currents, implying sandy-rich facies accumulation along the salt wall margin. [ABSTRACT FROM AUTHOR]

• The Plataforma Burgalesa of northern Spain is not the hanging wall of a low-dipping ramp rooted in the middle/lower crust. • We list 13 critical problems concerning the Mesozoic and Cenozoic framework proposed by Ramos et al. • We criticize a model that neither honors data on the thrust system nor incorporates concepts on salt-bearing rifted margins. [ABSTRACT FROM AUTHOR]

The combined analysis of the Bicorb-Quesa diapir internal structure and the surrounding Mesozoic cover allows to recognize the main characteristics of the Eastern Prebetics as well as to make a new and unique evolutionary model of a squeezed and later reactivated diapir. Specifically, this work points out: 1) the Bicorb-Quesa diapir was generated during the Early Miocene due to the movement of a basement normal fault ENE-WSW oriented and dipping towards the NNW, 2) the diapir was squeezed during the Serravalian due to the displacement towards the NNW of the Jurassic-Cretaceous cover located in the footwall of the basement fault, and 3) the diapir was reactivated cutting the faults and thrusts previously generated. [ABSTRACT FROM AUTHOR]

The halite-bearing Barbastro Formation crops out in the core of the Barbastro Anticline (Ebro Tertiary Basin). This anticline is traversed perpendicularly by some of the most important Pyrenean drainages such as the Cinca and Noguera-Ribagorzana Rivers. The terrace sequences of these fluvial systems have been used as markers to identify and assess dissolution-induced subsidence and salt tectonics. In the limbs of the anticline, terrace deposits underlain by detrital bedrock do not show any evidence of deformation and have a consistent thickness of less than 10 m. The deposits of certain terrace levels of the Noguera-Ribagorzana River and its tributary, the Lo Reguer Creek, are locally thickened filling basins generated by dissolution-induced synsedimentary subsidence up to several kilometers long and more than 100 m deep. Conversely, terraces of the Cinca River do not show anomalously high thicknesses, but local uplifts related to differential upward flow of the halite-bearing bedrock. Locally, a minimum uplift rate of 0.3 mm/year has been estimated from a 64-ka terrace tilted away from the valley. The subsidence hazards occur chiefly in areas where the ground receives artificial water recharge. Serviceability of some canals has been notoriously affected by evaporite karstification. The problem has been mitigated to acceptable levels by grouting. Numerous buildings of Ivars de Noguera are severely damaged by dissolution subsidence, and possibly, by hydrocompaction of gypsiferous silts. The pipe network has been replaced to ameliorate the subsidence risk. In the Cinca River valley, cavities with a total volume of about 180,500 m3 have been created by solution mining at depths greater than 500 m. No investigation methods are applied in the brine field to monitor the distribution and evolution of artificial voids. Substantial increase in salinity of the Cinca River is another evidence of subjacent evaporite dissolution. [ABSTRACT FROM AUTHOR]

A new Coniacian-early Santonian extensional salt tectonics event has been identified in the Cotiella thrust sheet of the central Spanish Pyrenees. We present a new interpretation of the Cotiella thrust system and describe exceptional outcrop examples of postrift, gravity-driven extensional growth faults. The thrust sheet contains three, kilometer-scale extensional faults with as much as 5.5 km of Coniacian-lower Santonian growth strata in their hanging walls. These postrift listric growth faults detached on the prerift Triassic evaporites on the uplifted and eroded southern flanks of Early Cretaceous rift basins. Early Alpine (late Santonian-Maastrichtian) contractional deformation reactivated and reversed the displacement on both the Early Cretaceous rift faults and some of the postrift- salt detachment faults. Hanging walls of the listric growth faults deformed into major antiforms, but the original extensional geometries are well preserved. Continued Alpine shortening incorporated these reactivated extensional fault systems into the thin-skinned thrust sheets of the southern Pyrenees. These postrift extensional structures account for significant thickness variations in the postrift succession and for along-strike changes in the styles of the thrust structures. The Late Cretaceous extensional salt tectonics is interpreted to result from gravity-induced northward sliding on the Early Cretaceous rift margin, toward the axis of the rift basin. The listric growth faults are similar to those found on the Gulf of Mexico margin, in the southern North Sea, and the South Atlantic margins. [ABSTRACT FROM AUTHOR]

We investigated speleogenetical processes and the formation of unusual endo- and exokarstic features within carbonates rocks in the Sierra de Mollina mountain range (southern Spain), a sector affected by salt tectonics. Allochthonous Triassic evaporites partially overlie younger subsalt Jurassic limestones and dolostones. The carbonate beds show signs of karstification, including large collapse structures and a dense field of collapse sinkholes. We focus our study on the two deepest cavities (~100 m deep), namely Sima del Soldado and Órganos Cave, where significant secondary gypsum (CaSO 4 ·2H 2 O) and traces of mineralogical associations (alunite, jarosite, barite and others) have been reported. We analyzed the sulfur (δ34S) and oxygen (δ18O) of the gypsum sulfate and the δ18O and δD of its structural water. Our results suggest that reduction of sulfates from the Upper Triassic evaporites generated hydrogen sulfide (H 2 S). Subsequently, sulfuric acid (H 2 SO 4) was generated in oxic conditions, which triggered sulfuric acid speleogenesis (SAS). Our reconstruction of the isotopic composition of the paleo-aquifer using stable isotopes of gypsum hydration water (δ18O and δD) indicates that gypsum crystallized in a climatic setting colder than present. Gypsum precipitation included acid replacement of the carbonates and hydration of anhydrite (CaSO 4) generated in previous stages. The overlying Triassic evaporites provided the hydraulic gradient needed to drive sulfate-rich water towards the deeper, O 2 -depleted carbonate aquifer. Sulfate reduction in anoxic conditions generated H 2 S that later mixed with O 2 -enriched waters in the upper carbonate aquifer, creating the sulfuric acid necessary for SAS. The stable isotopes of gypsum from Órganos Cave reveal that the vadose zone was not connected to the surface, probably being confined beneath Triassic evaporitic rocks, while the Sima del Soldado underwent a partial connection with atmospheric O 2. [Display omitted] • Secondary gypsum and others minerals found in the caves are indicators of SAS. • The consequence of SAS is an unusual development of caves and sinkholes. • Isotopic analysis reveals that H 2 S in groundwater mostly derived from Triassic gypsum. • Isotopic composition of the AQW reveals gypsum formed in a colder climate period. • This study illustrates SAS operating in carbonate covered by allochthonous evaporites. [ABSTRACT FROM AUTHOR]

Salt depositional configuration exerted a fundamental control on both extensional and contractional deformation in the south-central Pyrenees. We divide the area into three domains and suggest that these domains are inherited from the original configuration of the Triassic Keuper salt basin. The Northern and Southern Domains are salt-diapir provinces with complex Mesozoic growth histories, whereas the Central Domain separating them has no diapirs and simpler Mesozoic isopachs. We use these patterns to interpret the Northern and Southern Domains as transported salt basins that were originally separated by the Central Horst, on which salt was thinner. During Dogger to mid-Cenomanian rifting, the Southern Salt Basin was an interior basin, isolated from deformation in the rift axis, whereas the Northern Salt Basin hosted an extensional breakaway at the updip end of the axial rift. During Pyrenean shortening, regions with preexisting salt structures were preferentially reactivated, whereas the stronger Central Horst remained relatively rigid. Eventually the sedimentary cover of the Southern Pyrenees was translated southwards and the connection with the original basement structure was lost. We tested our hypotheses using physical models. We confirmed that shortening a network of preexisting salt pillows could generate structures like the dome-and-basin pattern observed in the Southern Domain, and that it is possible to shorten salt basins on either side of a central horst while leaving sediments above the horst relatively undeformed. • The Southern Pyrenees can be divided into three domains based on salt tectonics. • The Southern Pyrenees comprises two salt basins separated by a horst with thin salt. • Diapirs in the salt basins were preferentially reactivated during shortening. • The Northern Salt Basin was part of a linked kinematic system during rifting. • The Southern Salt Basin was an interior basin, isolated from the continental margin. [ABSTRACT FROM AUTHOR]