Tracking lithospheric delamination and surface processes across the Messinian salinity crisis

Abstract

Abstract Lithospheric delamination involves short-lived crustal and surface responses, alkaline magmatism, high heat flow and extension. In the Western Mediterranean, delamination is thought to have triggered uplift at the origin of the Messinian Salinity Crisis (MSC). This scenario is questioned by the insufficient temporal resolution relative to other proposed mechanisms that include crustal shortening and slab detachment. Here, we report new U-Pb ages and clumped isotope analyses from calcite veins formed in an intramontane basin of the eastern Betics. They reveal a short-lived fluid event from 8.5 to 5 Ma linked to extension and retreating delamination. The end of extension coincides with the onset of shortening and uplift at 4.5-3 Ma across the boundary between the Cabo de Gata arc basement and the Iberia margin. Our results reveal that the MSC was established before the onset of shortening while delamination was underway. The MSC is therefore the product of long-lived lithospheric thinning and evolution from calc-alkaline to high-alkaline magmatism during delamination. After the MSC, around 5 Ma, slab detachment triggered the formation of a new plate boundary fault and tectonic escape between Africa and Iberia.