Stratigraphic succession, facies and depositional environment of Emsian reefal carbonates in the Ossa-Morena Zone (SW Spain)

Abstract

The Devonian succession between the Guadiana and Guadalquivir valleys in the Obejo- Valsequillo Domain comprises more than 600 m of shale and sandstone with some interbedded limestone and marl. The most complete reefal sequences of the region are exposed in the Guadámez-2 section, which is located on the western bank of the Guadámez River, near Zalamea de la Serena. It consists mainly of shale and calcareous shale in its lower part and shaly, skeletal and reefal limestone in its upper part. Conodont and brachiopod data indicate that this section spans the interval from the Lochkovian to at least the upper Emsian. Eight microfacies types have been identified in the calcareous facies: A, brachiopod-echinoderm wackestone/packstone; B1, echinoderm grainstone; B2, echinoderm-bryozoan grainstone/packstone; C, echinoderm packstone; D, tabulate coral rudstone; E, brachiopod wackestone/packstone; F, brachiopod grainstone/packstone; and G, stromatoporoid and tabulate coral boundstone/rudstone. Microfacies A, B1, C, E and F represent a sequence of environments from middle platform (A) to tidal flat (F), including shoals (B1) and shallow platform facies. Microfacies B2, D and G represent the development of patch-reefs super - imposed on the shoals.