The fossil record of jaw-bearing polychaetes from South America is scarce, and only a few occurrences of Ordovician scolecodonts have been reported so far. Here, we document a monospecific jawed polychaete assemblage from the Darriwilian Lenodus crassus conodont zone of the San José Formation in the eastern Cordillera of Peru. The single species, Protarabellites luztejadae sp. nov., represents the oldest record of the family Ramphoprionidae worldwide and may point to the biogeographic origin of this group in Gondwana. The reconstructed jaw apparatus of P. luztejadae bears primitive characters such as the slightly enclosed myocoele, distinguishing it from the younger members of the family and providing insights into the evolutionary relationships with other labidognath families. The described assemblage is the first record of Ordovician scolecodonts from Peru, as well as from the northern part of the Central Andean Basin, and one of very few cases from where apparatus-based classification has been applied. However, the Palaeozoic scolecodonts in South America appear to be more common than generally thought. A review of poorly known regional literature shows that scolecodonts have been mentioned in various sites from Ordovician, Silurian, Devonian, and Carboniferous–Permian strata of Argentina, Bolivia, Brazil, Colombia, Peru, and Uruguay. This highlights the potential for future scolecodont studies in South America.
The Garraf Mountain Range (GMR), located in Catalonia, NE Spain, is a calcareous karstic region subjected to intense anthropogenic influence, primarily due to the presence of numerous urban areas and extractive activities. Utilizing a new 2x2 m LIDAR-derived Digital Elevation Model (DEM), we updated the doline inventory, increasing the count from 710 collapse dolines to 968. The main objective of this study was to provide a preliminary characterization of the spatial distribution of the updated doline dataset across the entire GMR relative to hydrological issues and geological hazards. Factors that influence karst development like lithology, regional lineaments, and drainage network, along with slope, and altimetry were reviewed. Altogether, these aspects facilitated the delimitation of four distinct geomorphological blocks for GMR: Calafell, Ordal-Vilanova i la Geltru, Central, and Pallej & agrave;-Gava. No direct proximity relationship with structural lineaments traces was observed over doline occurrence. Dolines were more frequently associated with proximity to river streams and areas of high drainage density which do show structural control in their trend. These two facts aid in the definition of preferential directional paths for water running/infiltration that are important for quantifications of karst capture in water balance evaluations for GMR watersheds. Also, high concentrations of dolines near urban zones, landfills, and quarries were observed in the northeastern and southeastern sectors of the GMR, particularly in the municipalities of Vallirana and eastern Sitges, respectively. The updated inventory can be used in improving accuracy in water balance and karst hazard evaluations.
Landform recognition and surface analysis are critical in geomorphological and morphotectonic studies. In particular, the detailed study of the surface expression of active faults is essential for their characterization as seismic sources in fault-based seismic hazard models. However, increasing anthropogenic action has profoundly altered the natural landscape, degrading or erasing tectonic landforms, and limiting the accurate characterization of active faults in many regions worldwide. A paradigmatic example is the southeastern Iberian Peninsula, where extensive agricultural development over last decades has completely transformed the natural landscape. To address this limitation, we produced three historical Digital Surface Models (DSMs) using historical aerial imagery across two active faults in the Betic Cordillera: the Palomares and Llano del & Aacute;guila faults. Two DSMs were generated for the Palomares Fault (one from the American B-series Flight, 1956-1957, and one from the Interministerial Flight, 1973-1986), and one DSM was generated for the Llano del & Aacute;guila Fault from the Interministerial Flight, all with a spatial resolution of 2 & times; 2 m. We introduce Surface Roughness as a new diagnostic metric to assess quality and to identify model artifacts, while DEM of Difference analyses were used to quantify elevation changes and assess the consistency of the reconstructed surfaces. Rather than focusing solely on absolute geolocation accuracy, our approach emphasizes evaluating the reliability of the historical surface reconstruction. This methodology highlights the potential of historical aerial imagery to enhance active fault characterization and near-fault morphotectonic analyses in landscapes heavily modified by anthropogenic activity.
In a pioneer study, the electrical conductivity structure is determined beneath a fixed location on the Martian surface: the InSight landing site. The dataset used to attain this goal is the magnetic data recorded by InSight, from which are calculated the magnetic field variations in both high and low frequency, by spectral analysis. These variations are used to determine the surface ratios of vertical to horizontal magnetic field components, which are considered as the observed data that must be described/satisfied by some electrical conductivity models proposed. These models are the expression of the electrical conductivity structure of Mars, beneath the InSight landing site, and they should be recalculated when the data provided by future missions will be available (e.g. the Exobiology on Mars (ExoMars) Mission).
The Sant Corneli Anticline is an asymmetric, westward-plunging structure at the termination of the Boixols Thrust (Tremp Basin, Spanish Pyrenees), which was emplaced in the Late Cretaceous and generated an elongated, westward-deepening foredeep basin. A stratigraphic and paleontological study of inoceramid bivalves in the southern flank of the Sant Corneli Anticline has provided refined constraints on the timing and lateral distribution of the synorogenic carbonate-marly units (growth strata) predating the emplacement of the mixed depositional systems during anticline uplift.Two stratigraphic units were identified and dated via inoceramid biostratigraphy: the upper Podega Member (marly limestone with slumps), and the Montesquiu Member (limestone alternating with marls). The upper Podega Member unit can be traced laterally southwest of the Sant Corneli Anticline, decreasing in thickness from 230 m in the west to 170 m in the east. Meter- to decemeter-scale soft-sediment deformation structures and syn-sedimentary faults attest to the occurrence of gravitational collapses. This unit spans the upper Santonian through the basal upper Campanian (in the European bipartite stage subdivision). In turn, the Montesquiu Member laterally decreases in thickness from 226 m in the west to 150 m in the east, and exhibits frequent intraformational unconformities and meter- to decemeter-scale soft-sediment deformation, indicative of active tectonism. This unit, placed in the middle- upper Campanian based on inoceramid biostratigraphy, precedes the sedimentation of shallower mixed depositional environments which are marginally affected by soft-sediment deformation features.
