Variscan tectonics in the Malaguide Complex (Betc Cordillera, southern Spain): stratigraphic and structiural constraints from the Ardales area (Province of Malaga). Part I: Stratigraphy.

In the Betic Cordillera, the pre-Alpine deformation in the Paleozoic basements is rather poorly known. At Ardales, several classic sections of the Malaguide Complex belong to two distinct, superposed Alpine tectonic units including both Paleozoic basement and Mesozoic-Tertiary cover rocks. Within the Alpine footwall unit, new stratigraphic studies allow the documentation of Upper Ordovician, Silurian, and Lower and Middle Devonian conodont associations. In particular, Silurian-Lower Devonian limestones rest on a Devonian-Lower Carboniferous succession by means of a tectonic contact, the latter sealed by unconformable Triassic redbeds. Consequently, the tectonic superposition of the studied Paleozoic successions is interpreted as the result of a Variscan thrust. The conodont color alteration index shows average values around 5-5.5, independent of the conodont association and age and the tectonic position of the studied samples. This indicates that the Malaguide Paleozoic successions were affected by a low-temperature and low-pressure Variscan metamorphism. This study provides the first solid stratigraphic evidence that documents thrust tectonics related to pre-Alpine orogeny in the Betic Cordillera. The Paleozoic stratigraphy and tectonic evolution of the Malaguide Complex are quite different from those of other Variscan regions of southern Spain and confirm its paleogeographic provenance from Paleotethyan domains located far to the east and close to the Alps, whereas most Spanish Variscan regions were connected to the Rheic Ocean, which opened to the west of Iberia and closed earlier than the Paleotethys.