87Sr/ 86Sr dating of coralline algal limestones and its implications for the tectono-stratigraphic evolution of the eastern Prebetic (Spain)

Abstract

The use of 87Sr/ 86Sr chronostratigraphy for dating marine carbonates is a powerful method in tectono-stratigraphic analysis of fold-and-thrust belts. In this paper, we present the results of 87Sr/ 86Sr dating of Early Miocene coralline algal limestones, which constrain the age of foreland folding in the eastern Prebetic Zone of the Betic Cordilleras (Spain). The first folding phase took place between 23.6 and 19.0 Ma, associated with erosion and the subsequent deposition of coralline algal limestones. Deposition of these limestones was terminated by drowning and subsequent folding between 21.5 and 17.2 Ma. Inferred regional variations in the ages of folds in the order of 1–2 m.y. are thought to reflect the sequential, and therefore intrinsically diachronous growth of fold belts. The depositional history was primarily controlled by these tectonic movements, even though eustasy may have contributed to the drowning of the algal carbonate platforms. The unconformities which bound the algal limestones probably formed in direct response to the thrust emplacement of the Betic nappe pile and reflect the northward migration of the peripheral bulge and foreland basin.