Análisis sedimentológico de la Cuenca estefaniense de Tineoo (Asturias). Ejemplo de depósitos de carbón en abanicos aluviales

Abstract

A sedimentological analysis of the stephanian deposits of Tineo Basin is carried out. Three unities are established (Basal Breachs, Intermediate Unit and Conglomerate Unit) by means of lithological, mining and sedimentological criteria, which represent larger episodes in the filling of the basin. The first episode corresponds to the initial configuration of the basin, with coarse grained breccia deposits related to steep slopes (Basal Breccia). The second and more complex (Intermediate Unit), is represented by four larger sequences (stages from UI-l to UI-4, La Prohida Zone) which show secondary tectonic pulsations. At this moment the sedimentation is carried out in several subbasins separated by palaeoreliefs or thresholds. The third episode correspond to a strong reactivation of the northern edge of the basin, with deposition of the Conglomeratic Unit. The filling of the basin is assimilated to a pattern of alluvial fans in a tectonically-active basin, in which the coal deposition look place during calm (tranquil) periods when a large alluvial fan flanked by coalescent smaller sized fans developped alongs the northern margin of the basin.