INVESTIGADORES
ROMERO Maria Virginia
congresos y reuniones científicas
Título:
Concentraciones sedimentológicas de ostras en la Formación Roca (Daniano) en Casa de Piedra, La Pampa (Argentina): Implicancias paleoambientales
Autor/es:
M.V. ROMERO, S.S. BREZINA Y E. SAGUAS
Reunión:
Congreso; X Congreso Argentino de Paleontología y Bioestratigrafía y VII Congreso Latinoamericano de Paleontología; 2010
Resumen:
Carbonatic facies from the Daniano, belonging to the Roca Formation outcrop in the locality of Casa de Piedra, which is situated in the western boundary of La Pampa. In these facies, sedimentary oysters-dominated shell concentrations are remarkable that reveal the existence of ecosystems with high biodiversity. The most abundant oyster species is Pycnodonte (Phygraea) sarmientoi Casadío, 1998. The presence of valves with a high degree of incrustation and bioerosion and of Thalassinoides isp. suggests moderate to relatively low energy conditions in an environment oxygenated with low rate of sedimentation. The poor selection of bioclasts together with its chaotic arrangement would indicate that the sedimentary environment was calm and that they would have stayed enough time on the bottom to suffer from disarticulation. Taphonomic characteristics of oysters in the base of the section reveal the presence of events of storms that would have favoured the disarticulation, reorientation and accumulation of the valves, allowing the shells to form parautochthonous and allochthonous concentrations. The analysis of facies and the taphonomic evidence suggest the development of a subtidal to intertidal environment of oxygenated waters, with low content of sediments in suspension. Finally, favourable environmental conditions together with the existence of valves of Pycnodonte (Phygraea) sarmientoi were crucial for the setting and development of encrusting and boring organisms communities. High diversity of epibionts recorded on Pycnodonte (Phygraea) sarmientoi allows to infer that these oysters were ecosystem engineers of shallow environments during the late Daniano.