Paleoicnologia de depósitos turbidíticos: um estudo da formação Capdevila, Eoceno inferior, Cuba Ocidental

Abstract

Ichnological studies in Capdevila Formation (Los Palacios Basin, Lower Eocene) are scarce and there are few works in which the authors just identified the taxa of the trace fossils. The aims of this work are identify and study the ichnofossils from Capdevila Formation in order to realize a more accurate paleoecological interpretation of these deposits. Thus, samples from a fossil colection and from an outcrop of Capdevila Formation (Western Cuba) were studied. Trace fossils assigned to Bichordites and varied preservational morphologies of Scolicia were identified. Nine ichnofabrics (Asterosoma, Thalassinoides, Palaeophycus, Scolicia. Bichordites-Thalassinoides, Rhizocorallium, Scolicia-Thalassinoides, Ophiomorpha and Root traces) were recognized along the succession, preserved both in massive sandstone and sandstone with parallel lamination. This ichnofauna represents low ichnodiversity, dominance of sediment feeders, marine salinity conditions and a well-oxigenated substrate. The integrate sedimentological / ichnological analysis of the succession allowed to propose a depositional model of shallow slope, impacted by frequent gravity flows and / or high depositional rate. The recognized suites correspond to Glossifungites, Cruziana and Skolithos ichnofacies, being the latter two atypical when compared with their arquetipical counterparts, as a result of the stress caused by the predominance of high-energy conditions and / or high depositional rate. These suites indicate, for the studied succession, a shallowing phase of these deposits, including a period of subaerial exposure marked by a forced regression event, and the subsequent reestablishment of marine conditions, with the base level rise.