Cenozoic evolution of the Alboran Domain: A review of the tectonomagmatic models

Abstract

The Alboran Domain is constituted by the Betic-Rif orogenic system and the Alboran Sea between southwestern Europe and northwestern Africa. In this realm, the Mesozoic-Cenozoic transition represents the climax of the Alpine convergence events between Africa and Eurasia. During the rest of the Cenozoic, widespread extensional collapse and transtensional disruption occurred, which caused the generation of a wide spectrum of magmatic rocks (tholeiites, calc-alkaline to ultrapotassic series, and alkali basalts) with unusual geochemical characteristics. In the last two decades, this small spot on Earth has become a strategic site for geoscientists, inspiring more interpretations than any other comparable region of the world. The geological and volcanological complexity of the Alboran Domain has triggered a multitude of tectonomagmatic models that are often contradictory and lack the integration of all the available data. These models might be subdivided into six major groups (subduction, compression, extension, transtension, detached lithospheric roots, and mantle upwelling), plus a series of mixed scenarios.

In the first section of this paper, we describe these tectonomagmatic models and then undertake a generalized review of these scenarios, in particular, the subduction schemes involving Neogene to present active subduction slabs. Then, we will suggest a tectonomagmatic model that integrates the more diagnostic geological, geophysical, and geochemical data of this domain during the Cenozoic. This unifying model involves three main stages: (1) Oligocene to early Miocene localized synorogenic extension in southern Spain involving tholeiitic dike swarms; (2) Miocene widespread postorogenic extension resulting from the convective removal of a lithospheric root, characterized by predominant calc-alkaline to ultrapotassic series (with minor tholeiitic volcanism); and (3) late Miocene to present transtension associated with a huge sinistral shear zone that spans from the Canary Islands to the North Sea which allows the extrusion of alkaline basalts.