Microbiofacies de algas y corales del Kasimoviense del norte de los Picos de Europa, N de España

Abstract

Dentro de los sedimentos carbonáticos del Kasimoviense del norte de los Picos de Europa se han distinguido tres litologías distintas, asociadas cada una de ellas a microbiofacies muy características: - Calizas masivas con algas tubulares y corales solitarios de pequeño tamaño. - Calizas tableadas y margocalizas bioclásticas con corales solitarios con disepimentos. - Margas con diversidad de algas y corales solitarios sin disepimentos. Se analizan e interpretan las diferentes facies y su distribución en el área estudiada.

Carbonate sediments with algae and corals are abundant in the Kasimovian sequence from Northern Picos de Europa. The lithology is very variable and it is possible to find conglomerate, sandstone, marl, limestone, etc. Within the carbonates we distinguish three different facies with algae and corals: - Massive limestone with abundant tubular algae which construct tabular frameworks. They are associated to little horn corals, bryozoans, brachiopods, and foraminifera. - Stratified and marly limestone with abundant corals (Geyeronaotia, Bothrophyllum), oncoids and fragments of bryozoans, brachiopods, fusulinids, echinoderms, and pelecypods, frequently encrusted by Girvanella filaments. - Marl with a rich coral fauna (Asserculinia, Lophophyllidiurn, Lophocarinophyllum, Bradyphyllum, etc.), abundant (Donetzella, Epimastopora, Hikococodium. Archaeolithophyllum, etc.). Bryozoans, brachiopods, gastropods, pelecypods and foraminifera are common too. These facies are irregularly distributed in the different studied outcrops. In Covadonga dominate the stratified limestones and massive lirnestones. In Gamonedo dominate marls and it is possible to find marly limestones too. In Berodia, Arenas and Oceño marly limestones abound; marls and massive limestones are not rare. In Puentellés the stratigraphical succession is almost totally composed by massive limestones. This evidence suggests that the paleogeography (and tectonic was very complicated in the studied area during the Kasimovian. There was a double control of facies: Tectonic and geographic. During the tarios con disepimentos. Lower Kasimovian the tectonic movement were stronger than in the Middle and Upper Kasimovian. In addition the stratigraphic sequence mentos. suggests that the coast was in Gamonedo, Berodia, Arenas and Oceño nearer than in Puentellés and Covadonga.