El Mioceno marino entre las playas de L'Arrabassada y El Miracle (Tarragona): aspectos paleontológicos e implicaciones sedimentológicas
The Miocene deposits between L'Arrabassada and El Miracle beaches (Tarragona, Spain) have been studied in this paper. Two stratigraphic sequences (Garraf and Tarragona) previously defined by other authors in former papers have been recognized. The boundary between them is an omission surface with biogenic structures indicating some hardening of the sediment. This hardening was complete in one of the sections and allowed the development of a hardground with bioerosion structures, but it was partial in anothei- producing a firmground with well-bounded dwelling burrows. The Garraf Sequence outcrop is very small and overlies an erosional surface developped over the Jurassic substrate. On this surface, there is abundant bioerosion evidence that allows to recognize three different phases in its formation. The Tarragona Sequence is represented by the Ardenya Unit, with several different facies -conglomerates, lumachelles, bioclastic calcarenites, sandstones and marls-, including very abundant and diverse fossils -algae, corals, molluscs, briozoans, echinoids, vertebrate remains and trace fossils. The taphonomic and ichnologic study of these facies has permitted to recognize littoral to sublittoral sedimentary conditions, with a general tendency to increase the depth.