The discovery of scapolite marbles in the Biscay Synclinorium (Basque–Cantabrian basin, Western Pyrenees): geodynamic implications

Abstract

We report the presence of scapolite marbles in the Biscay Synclinorium of the Basque–Cantabrian basin, the link between the mainland Pyrenees and the North Iberian palaeomargin. From their microstructures and mineral assemblages these marbles are correlated with similar marbles formed during the Cretaceous metamorphism representative of the North Pyrenean Zone. Their setting in an area with northward‐verging structures leads us to propose a new location of the North Pyrenean Fault through the Basque–Cantabrian basin. Available geophysical information, gravity and magnetic anomalies, is better explained with this new proposal, which elucidates a major outstanding matter of Pyrenean geology.