La discontinuidad del Campaniense basal en el Prebético: ¿inicio de la convergencia alpina en la Margen Bética?

Abstract

In the platforms of the Mesozoic southeastern continental margin of the Iberian plate (the Betic Margin), a major stratigraphic unconformity developed at -83 Ma (earliest Campanian), which is interpreted -on the basis of regional stratigraphic analysis and interregional correlation- to mark the onset of the transition of the Betic passive margin into a convergent one. The unconformity was induced by a tectonic event that caused: (1) total restructuring of the platform, (2) changes in tectonic subsidence patterns, (3) rejuvenation of siliciclastic source areas, and (4) substantial modifications in fossil assemblages, some of them with biogeographic implications. Correlation with other paleogeographic domains of Iberia (Pyrenean basin, Cantabrian margin, Iberian Seaway) allows to propose a supraregional control for that tectonic event now recognized in the betic Margin: it coincides in time with initiation of convergence in Pyrenees, with the end of sea-floor spreading in Bay of Biscay, and with a generalized uplift in central Iberia and the Iberian basin. Rapid transmission of intraplate stresses within the Iberian block in relation with the onset of the african - european convergence makes that tectonic pulse to be registered isochronously (at a geologic scale) in a variety of geodynamic settings (passive margins, intraplate basins, etc.) separated hundreds of kilometers away.