Cartografía geológica submarina del oeste de la costa de Bizkaia

Resumen

With the widespread of multibeam echosounder technology (MBES) and bathymetric LIDAR in the last decades, ship- borne multibeam bathymetric surveys have provided detailed digital terrain models. These remote sensing techniques offer high-quality data that can deliver geological information. In this work, a geological cartography of the Biscay continental shelf off the Nervion estuary, from -10 to -100 m, is presented. Although the study area is partially covered by quaternary sediments, the extensive rocky outcrops allow a structural and stratigraphic interpretation of the data. The obtained infor- mation together with the existing onshore cartography at 1:25.000 and 1:100.000 (EVE, multiple authors, 1991 & 1995) and field data from the coast have been integrated in an offshore geological map at 1:25.000 scale. The study area is located in Basque-Cantabrian Basin (BCB), the western termination of the Pyrenean Alpine orogenic system, within the so-called Basque Arc (Feuillée y Rat, 1971). The Basque Arc is the most deformed area in the BCB and exhibits a complex structure characterized by the arched shape of a number of NE-verging folds and thrusts. The Biscay Syn- clinorium stands out as one of the most relevant structures; its axial trace continues for more than 80 km inland and deforms Cretaceous and Paleogene sedimentary rocks. The interpretation of the MBES data has allowed the offshore north-westwards extension of the onshore sedimentary formations and the identification of new ones. For example, the Biscay Synclinorium axial trace is recognized at seafloor for more than 13 km.