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

Abstract

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 40Ar/39Ar 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.