The Pennsylvanian microbial-dominated carbonate platform of the El Sueve massif: contribution to the reconstruction of the Variscan foreland basin of the Cantabrian Zone (N Spain)

Abstract

The Pennsylvanian carbonate systems of the Cantabrian Zone are characterized by microbial carbonates, and a flat-topped and steep-margined platform geometry. These systems have been exhaustively investigated from a sedimentological point of view in the Sierra del Cuera area and the Picos de Europa Province, but their NW prolongation in the El Sueve massif, has been overlooked so far. The main aim of this work is to study the El Sueve outcrops, applying the knowledge obtained in the previous studies. The main interest of the El Sueve outcrops concerns the depositional fabrics and facies of the microbial carbonates, the lateral extent and variability of microbial-dominated carbonate systems in the foreland basin of the Cantabrian Zone and the basin palaeogeography during Bashkirian times. The 925 m-thick studied succession shows the superposition of the three stratigraphic domains of a microbial-dominated carbonate platform: basin floor/toe of slope, depositional slope and platform top. This carbonate system was probably connected with other coeval carbonates (Valdeteja Fm.) exposed both to the West (Sobia and Aramo Units) and to the East (Cuera and Picos de Europa), forming a large scale calcareous domain defining a strong longitudinal (oriented N-S, parallel to the orogen) asymmetry of the Cantabrian foreland basin during the Bashkirian.