The shell accumulations in the La Meseta Formation (Eocene, Marambio Island) and their interpretation within a sequence stratigraphy framework

CASADIO, SILVIO; MARENSSI, SERGIO; SANTILLANA, SERGIO; GRIFFIN, MIGUEL

Buenos Aires

Simposio; VI Simposio Argentino y III Latinoamericano sobre investigaciones Antárticas; 2007

Instituto Antártico Argentino

The La Meseta Fm (Eocene) exposed in the northern third of Marambio (Seymour) Island and in a small sector of Cockburn Island, represents a sequence deposited in an incised valley. Sedimentation in this valley occurred in estuarine and wave-influenced tidal-shelf environments and contains an abundant and well preserved fauna of marine invertebrates and vertebrates, as well as terrestrial vertebrates and plants. The stratigraphic unit was subdivided into six allomembers, namely from bottom to top, Valle de las Focas, Acantilados, Campamento, Cucullaea I, Cucullaea II and Submeseta. The fossils lie mainly in remarkable accumulations dominated by mollusc shells. These fossils have been the subject of numerous systematic studies. However, very few of these deal with the nature and origin of the shell concentrations from a taphonomic and paleoecologic perspective. In this contribution we study and interpret the processes that originated the shell accumulations in the La Meseta Fm. This allows assessment of the significance of the concentrations within a sequence stratigraphy framework. In each shell beds, sedimentologic, palaeoecological, and taphonomic features were recorded...