Search Results (3)

The convergence zone of the Eurasian (EURA) and North Africa plate (NUBIA) is primarily marked by the activity between the Betics in south of Spain and the Rif and Atlas in Morocco. This area, where the diffuse tectonics between these plates are currently converging in a NW-SE direction, presents several continuous fault zones, such as the Betic–Alboran–Rif shear zone. The Royal Institute and Observatory of the Spanish Navy (ROA) currently operates geodetic stations in various parts of North Africa, some in particularly interesting locations, such as the Alhucemas (ALHU) rock, and also in more stable areas within the Nubian plate, such as Tiouine (TIOU). For the first time, the displacement velocities of the ROA CGNSS stations have been estimated to provide additional geodynamic information in an area with few stations. The obtained velocities have been compared with other recent studies in this field that included data older than 10 years or episodic campaigns without continuous stations. PRIDE (3.1.2) and SARI (February, 2025) software were used for processing, and the velocities were obtained by the ROA for international stations (RABT, SFER, MALA, HUEL, LAGO, TARI, and ALME). These initial results confirm the convergence trend between Eurasia and Nubia of approximately 4 mm/year in the NW-SE direction. It is also evident that there is independent behavior among the Atlas stations and those in the Moroccan Meseta compared to those located in the Rif mountain range, which could indicate the separation of smaller tectonic domains within the continental plate convergence zone. Along the Rif coast in Al Hoceima Bay, the faults are being approached; additionally, there is a slight clockwise displacement towards Melilla, which has also been demonstrated by stations in the Middle Atlas, such as TAZA. As for the stations in the Strait of Gibraltar, they exhibit a similar behavior until reaching the diffuse zone of the Guadalquivir basin where the diffuse convergence zone may exist. This may explain why stations to the north of the basin, such as LIJA or HUEL, change their behavior compared to nearby ones like SFER in the south. Furthermore, Alboran seems to follow the same displacement in direction and velocity as the other stations in North Africa and southern Spain. Full article

The Rif Cordillera, an Alpine orogen in the Western Mediterranean, was developed by the interaction of Eurasian and African (Nubia) plates. Neotectonic deformations of the Rif foreland influence the relief, especially in post-nappe basins and their boundaries with Jurassic and Cretaceous carbonate mountain massifs, and they contribute to highlighting the recent evolution of the Cordillera. The topographic and hydrological lineaments of these basins were characterised on the basis of multi-scale morphostructural data analysis, supported by digital mapping and GIS. They were correlated with geological structures, essentially with fractures. The outcrops of the Upper Tortonian and Messinian deposits depict well-defined geometric shapes with roughly rectilinear boundaries, as defined by their contacts with the massive and rigid rocks of the Jurassic and Cretaceous series. Upper Tortonian deposits evidence major regional N70°E and N40°E lineaments, which are obliquely intersected by late structures. Messinian N120°E and N25°E lineaments, associated with N140°E lineaments, are also recognised. The interpretation of these lineaments as faults indicates the activity of two systems of transtensive sinistral and then dextral brittle shearing that correspond to two episodes of neotectonic deformation that played a decisive role in shaping the reliefs of the Eastern Rif. These deformations are particularly relevant to isolate basins and likely have a key role during the closure of the South Rifian corridor during the Mediterranean Messinian Salinity crisis. Full article

The northwest-southeast convergence of the Eurasian and Nubian (African) plates in the western Mediterranean region propagates inside the Nubian plate and affects the Moroccan Meseta and the neighboring Atlasic belt. Five continuous Global Positioning System (cGPS) stations were installed in this area in 2009 and provide significant new data, despite a certain degree of errors (between 0.5 and 1.2 mm year⁻¹, 95% confidence) due to slow rates. The cGPS network reveals 1 mm year⁻¹ North/South shortening accommodated within the High Atlas Mountains, and unexpected 2 mm year⁻¹ north-northwest/south-southeast extensional-to-transtensional tectonics within the Meseta and the Middle Atlas, which have been quantified for the first time. Moreover, the Alpine Rif Cordillera drifts towards the south-southeast against its Prerifian foreland basins and the Meseta. In this context, the geological extension foreseen in the Moroccan Meseta and Middle Atlas agrees with a crustal thinning due to the combined effect of the anomalous mantle beneath both the Meseta and Middle-High Atlasic system, from which Quaternary basalts were sourced, and the roll-back tectonics in the Rif Cordillera. Overall, the new cGPS data provide reliable support for understanding the geodynamic mechanism that built the prominent Atlasic Cordillera, and reveal the heterogeneous present-day behavior of the Eurasia-Nubia collisional boundary. Full article