A current challenge of biodiversity and conservation is the estimation of the spatial extent of habitat types across broad territories. In the absence of fine‐resolution maps, predictive modelling ...helps in assessing the spatial distribution of vegetation cover. However, such approaches are still uncommon in regional planning and management. Here, we present a framework for mapping the area of occupancy (AOO) of habitat types that allows highly suitable estimates at different scales.
We model the potential AOO with abiotic variables related to topography and climate, resulting in broad AOO estimates that are subsequently downscaled to the local AOO with remote sensing. The combination of individual local AOO estimates allows the defining of the realized AOO, comprising locations with a high suitability and low uncertainty for each habitat. We applied this framework to mapping 24 protected habitat types of Natura 2000 sites in northern Spain.
Local and realized AOO were highly accurate, with a 70% overall accuracy for the realized AOO. Remote sensing data, and especially LiDAR, were the most important predictors in habitat types related to forests and shrubs, followed by rock outcrops and pastures. Environmental variables were also relevant for specific habitats subject to abiotic constraints.
The combination of ecological modelling with remote sensing offers multiple advantages over traditional field surveys and image interpretation, allowing the harmonization of habitat maps across large regions and through time. This is particularly useful for implementing conservation actions under Natura 2000 principles or assessing IUCN criteria for ecosystems.
The Schmidt hammer, widely used in Engineering Geology, has also been used in Structural Geology as a tool to quantify the mechanical properties of rocks affected by different structures and the ...damage caused to rocks by fracturing. However, how the impact resistance of rocks (rebound) varies in layers located in different positions of a fold has never been tested. Here, the Schmidt hammer is used to quantify this parameter in a syncline involving a Carboniferous carbonate sequence located in the Cantabrian Zone, the foreland fold-and-thrust belt of the Variscan orogen in western Iberia. The variations in the Schmidt-hammer rebound value along a folded layer are consistent with other indicators such as variations of dip and thickness. These findings have also implications on obtaining representative rebound values of stratigraphic units, and on deriving parameters such as the uniaxial compressive strength and the Young modulus from the Schmidt-hammer rebound values applied to folded regions.
•Schmidt-hammer rebound values depend on the structural position of a layer within a fold.•Schmidt-hammer rebound values may be different for beds with apparently the same lithologies.•Young moduli derived from Schmidt hammer values in folded regions must be taken with caution.
Key Points
The crustal model proposed by Pedrera et al. (2017) is not supported by the available deep seismic data set
The gravity model is built upon inaccurately retrieved residual gravity ...anomalies and uses inappropriate density values
The sequential restoration shows geometric‐structural inconsistencies, mechanical difficulties, and problematic isostatic and kinematic implications
The dimensions, the geographical position and the complex geological history of the Iberian Peninsula makes it a unique and singular target to study its crustal and upper mantle structure and ...geodynamical evolution using geophysical methods. The lithospheric structure beneath Iberia has been investigated since the 1970’s using deep multichannel seismic reflection and refraction/wide-angle reflection profiling. Gravimetric and magnetic data were acquired following the deployment of permanent and temporary stations, mostly during the 1990’s. Beginning in the late 1990’s, the progressive use of Global Navigation Satellite Systems (GNSS) instruments contributed to monitor the present-day motions. During the last decades, numerous geological and geophysical surveys have investigated the Iberian lithosphere and upper mantle in the onshore and offshore regions, the most recent ones related to the TopoIberia project. The approach developed in this contribution is twofold. Firstly, we summarize the available geophysical information over Iberia, from focusing on the upper crust to the lithosphere-asthenosphere boundary and the transition zone marking the bottom of the upper mantle. Results of GNSS data, potential fields, controlled source seismic profiles, magnetotelluric data, body and surface wave tomography, receiver functions and 2D and 3D lithospheric modeling are reviewed and compared. Secondly, we focus on the areas of greater geodynamic interest and the regions where inconsistencies within the geophysical results, or contradictions in their tectonic interpretation exist, identifying the major questions that are still under debate. Besides shedding light to the state of knowledge and pointing out present-day research challenges, this review provides a tool for the integration of the diverse geophysical datasets with the surface geology and geodynamical processes that are interpreted to have built the complex geology of the Iberian Peninsula.
Coupled structural and paleomagnetic analyses have shown that the northern Iberian bend of the Variscan orogen, referred to as the Cantabrian Orocline, developed by vertical axis rotation of an ...originally linear orogen. However, palinspastic restoration of the orocline has proven difficult owing to (1) an unusually great orogenic width of over 700km and (2) exposure of shallow water strata of the Gondwanan margin in the northern and southern portions of the orogen. We present paleocurrent data from Lower Ordovician shallow marine clastic sedimentary rocks across the Variscan of northern and central Iberia collected to constrain palinspastic restoration of the orogen. Paleocurrent data were collected from over 50 sites, and include cross bed foresets, ripple crests and casts, as well as rare ball and pillow structures, syn-sedimentary slump folds, and incised channels. Paleocurrent directions fan around the Cantabrian Orocline, are consistently oriented at a high angle to structural strike, and yield a consistent offshore direction outward from the oroclinal core. Similarly, changes in structural strike and paleocurrent direction across central Iberia imply the presence of a second more southerly orocline, the Central Iberian Orocline, that is continuous with, but convex in the opposite direction of the Cantabrian Orocline. Together, the Cantabrian and Central Iberian oroclines define an S-shaped pair of continental-scale buckle folds. Palinspastic restoration of the oroclines yields a linear continental margin >1500km long characterized by consistent offshore paleoflow to the west, defining a westerly oceanic domain (presumably the Rheic Ocean) and an easterly landward direction (presumably Gondwana). Recognition of the southern orocline explains the unusual width of the orogen, the geometry of aeromagnetic anomalies attributable to Variscan rocks, and is consistent with available structural data, paleomagnetic declination data, and the distribution of correlative Paleozoic and older rock sequences including shallow water strata of the Gondwanan margin. The S-geometry of the oroclines is similar to the Z-geometry of the Alaskan oroclines of the North America Cordillera, suggesting that as in the Cordillera, the Iberian oroclines may record a significant, margin-parallel translation event.
► We conduct paleocurrent analysis of pre-Variscan sediments of the Iberian Massif. ► Patterns of paleoflow and structural trend reveal a Central Iberian Orocline. ► Cantabrian and Central Iberian oroclines define S-geometry continental-scale pair. ► Iberian oroclines restore to linear continental margin >1500km in length. ► Scale and geometry of Iberian oroclinal pair mirror that of Alaskan oroclinal pair.
A N-S crustal transect of the whole Iberian Plate is presented. The displacement transfer during the Alpine deformation from the border ranges (Cantabrian and Betic chains) toward the interior ones ...was analyzed by means of balanced crustal sections. Inconsistencies in shortening values between upper and middle-lower crust in the Cantabrian Mountains (Basque–Cantabrian Zone) imply a mid-crustal detachment transferring orogenic shortening southward toward the Spanish Central System. Depending on the shortening value attributed to the Central System, this mid-crustal detachment could involve the entire Iberian Plate, connecting the Cantabrian Mountains and the Betic Chain. The very small crustal root in the Central System can be explained as a result of the tectonic load caused by the upper crustal shortening that was transferred from the border ranges. We conclude that a simple shear model, rather than a pure shear with lithospheric folding, better explains the whole Iberia deformation. Finally, the total Alpine shortening of the Iberian Plate is estimated between 267 and 292km.
•N-S crustal transect across the Iberian Plate•Extensional and contractional structure of the Basque–Cantabrian Zone•Mid-crustal displacement transfer during intraplate deformation of Iberia•Tectonic shortening in the upper and middle-lower crust in different ranges of Iberia•The Alpine shortening of the Iberian Plate is estimated between 267 and 292km
The Alpine Pyrenean‐Cantabrian orogen developed along the plate boundary between Iberia and Europe, involving the inversion of Mesozoic hyperextended basins along the southern Biscay margin. Thus, ...this margin represents a natural laboratory to analyze the control of structural rift inheritance on the compressional reactivation of a continental margin. With the aim to identify former rift domains and investigate their role during the subsequent compression, we performed a structural analysis of the central and western North Iberian margin, based on the interpretation of seismic reflection profiles and local constraints from drill‐hole data. Seismic interpretations and published seismic velocity models enabled the development of crustal thickness maps that helped to constrain further the offshore and onshore segmentation. Based on all these constraints, we present a rift domain map across the central and western North Iberian margin, as far as the adjacent western Cantabrian Mountains. Furthermore, we provide a first‐order description of the margin segmentation resulting from its polyphase tectonic evolution. The most striking result is the presence of a hyperthinned domain (e.g., Asturian Basin) along the central continental platform that is bounded to the north by the Le Danois High, interpreted as a rift‐related continental block separating two distinctive hyperextended domains. From the analysis of the rift domain map and the distribution of reactivation structures, we conclude that the landward limit of the necking domain and the hyperextended domains, respectively, guide and localize the compressional overprint. The Le Danois block acted as a local buttress, conditioning the inversion of the Asturian Basin.
Key Points
We define rift domains and their boundaries in the western and central North Iberian margin using geological and geophysical data
The North Iberian margin shows structural variability resulting from polyphase rifting and subsequent compressional reactivation
Rift domains controlled the subsequent inversion conditioning the current structure of the North Iberian margin and the Cantabrian Mountains
No study is currently available on the parasitofauna of the population of brown bears (Ursus arctos) inhabiting the Cantabrian Mountains in Spain. The aim of the present study was to obtain novel ...information on diversity and prevalence of gastrointestinal parasites in these individuals. During August 2016 and from May to July 2017, 14 fecal samples were collected from the western Cantabrian bear subpopulation, in the Somiedo Natural Park, in the Spanish province of Asturias. The prevalence of parasites detected was 71% and two genera were identified: Dicrocoelium sp. and Trichuris sp. Since the impact that pathogens such as endoparasites can have on the health of bears, together with other stressors, is still poorly understood, research efforts that include disease surveillance are critical to the successful protection of this emblematic species. Our preliminary findings require further investigations, with a wider sampling effort, and bring awareness for the need of carrying further studies on this area as a part of a proactive species management plan.
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•No information is available regarding the parasitofauna of the Cantabrian brown bear population, in Spain.•Fourteen fecal samples were collected from the western sub-population of the Cantabrian bear.•The prevalence of endoparasites detected on the samples was 71%.•Disease surveillance programs are critical to maintain human, domestic and wildlife health.
Crustal thickness maps at regional scales are typically compiled using estimations inferred from different geophysical datasets providing a variable coverage of the investigated area. Consequently, ...spurious effects related to changes in data resolution or artifacts in grid interpolation may affect significant zones of those maps. The TopoIberia-IberArray broad-band seismic network, covering the Iberian Peninsula and Northern Morocco with stations distributed on a regular 60×60km grid provides a unique opportunity to avoid such technical problems and to obtain a crustal thickness map derived from a same method sampling evenly all the region. Data from more than 340 stations has been gathered and analyzed using the P-to-S conversion phases at the Moho discontinuity (receiver functions). The crustal thickness has been inferred applying the classical H–κ stacking technique, though in regions of complex crustal structure, we have preferred to estimate the thickness directly from the arrival time of the converted phase at some sites.
The topography of the Moho discontinuity is strongly correlated with tectonic processes. The investigated area, extending from the Sahara platform to the Bay of Biscay, has a great geodynamic diversity, including, North to South, crustal imbrication in the Pyrenean and Cantabrian range, a large and relatively undisturbed Variscan Massif in the center of Iberia and areas of complex and still not completely understood geodynamics in the Alboran crust domain and the Atlas range. The crustal thickness map reflects this diversity, showing variations reaching 30km between the thickest and thinnest zones of continental crust. The final map has an overall similarity with previous estimations of the crustal thickness using independent data, as those coming from more sparse deep seismic sounding profiles, but provides further constraints at regional scale.
•New crustal thickness map of the westernmost Mediterranean from RF analysis.•The topography of the Moho discontinuity is strongly correlated with tectonic processes.•The crustal thickness map shows variations reaching 30km.•New RF data confirms the presence of a thick crust beneath the Rif domain.
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