Distribución de facies y evolución de un margen de plataforma carbonatada pensilvaniense en el Sector Lois-Ciguera de la Cuenca Carbonífera Central Asturiana (Zona Cantábrica)

Abstract

This study focuses on the sedimentology, depositional architecture and evolution of a pennsylvanian carbonate shelf margin (Bachende Limestones, Lena Group, Podolskian). The evolution can be subdivided into 5 stages. Stage 1 is formed by an oncolitic transgresive level. Stages 2 and 3 represent the main development of the platform, showing a lower clinoformal succession and an upper agradational package. Prograding clinoforms are formed by microbial boundstones, that show basinward stratal thinning and change laterally into argillaceous cherty and bioclastic limestones. Stage 4 is formed by shales and sandstones that thicks basinward and overlie an irregular erosive surface. Finally, stage 5 consits of a new transgressive carbonate unit, formed by micritic limestones and boundstones of dasicladacean algae, calcareous sponges and corals. Platform geometry and development reflects the interaction of variations on avaible accommodation space (mostly controlled by sea level glacioeustatic fluctuations and changes in flexural subsidence) and siliciclastic influx