Carlos Galé

Age of the Cretaceous alkaline magmatism in northeast Iberia: implications for the Alpine cycle in the Pyrenees

Cretaceous magmatism in northeast Iberia is related to the opening of the Bay of Biscay and counterclockwise rotation of Iberia with respect to Europe and predates the collision between Iberia and Europe that resulted in the formation of the Pyrenees. To better constrain the age of this magmatism, we have undertaken a Ar/Ar study on samples from the Pyrenees and the Catalonian Coastal Ranges. In the Basque-Cantabrian Basin and the North Pyrenean Basins, we have obtained Albian ages (ca. 102 Ma). In the northern Catalonian Coastal Ranges, we have obtained Campanian ages (ca. 79 Ma). We integrate our data with a review of previously published ages and discuss our results in terms of their geodynamic significance. The Cretaceous magmatism in the Pyrenees is Albian-Santonian (mostly occurring between 105 to 85 Ma) and was emplaced in a tectonically unclear context after the opening of the Bay of Biscay and rotation of Iberia. The magmatism in the Catalonian Coastal Ranges is well constrained to ca. 79 Ma and could mark the onset of Alpine shortening in the Pyrenean realm in northeasternmost Iberia. Finally, we describe a Late Triassic (ca. 232 Ma)-Early Jurassic (ca. 180 Ma) phase of magmatism in the Central Pyrenees, previously considered to be Cretaceous, that widens temporally and geographically the extent of the rift-related alkaline magmatism in southwestern Europe at that time. Key Points New Ar/Ar data update the age of the Cretaceous magmatism in NE Iberia Magmatism in the Pyrenees postdates the rotation of Iberia Magmatism in the Catalonian Coastal Ranges could mark the onset of Alpine shortening

Magnetic fabric in folded sills and lava flows. A case study in the Permian basalts of the Anayet Massif (Pyrenean Axial Zone, Spain)

Abstract The shallow intrusive bodies and lava flows emplaced within the Permian upper red unit in the Anayet Massif, represent a magmatic episode that occurred about 255 Ma (Saxonian) in the Pyrenean Axial Zone (northern Spain). Anisotropy of magnetic susceptibility (AMS) measurements, in both igneous bodies and their host rocks, allow us to infer the existence of magnetic fabrics of tectonic origin linked to the main cleavage-related folding episode. The relationship between the susceptibility axes and the field structures is the criterion that permits to differentiate normal from inverse magnetic fabrics in the igneous samples. The structural interpretation of all AMS data taken from the igneous bodies and sedimentary host rocks, is in accordance with a folding model which include: (i) flattening associated with cleavage formation during fold amplification in incompetent layers (host pelites), responsible for a magnetic lineation at high angles with respect to the regional folding axis and (ii) buckling in competent (conglomerates and igneous bodies) levels, responsible for a magnetic lineation parallel to the regional fold axes.