Holocene raised beaches along the northern coast of the Beagle Channel, Tierra del Fuego, Argentina

Abstract

Raised beaches developed during Holocene times along the northern Beagle Channel coast. These deposits contain a rich marine fauna, especially shelled organisms such as mollusks. Four Holocene marine sites along the northern coast of the Beagle Channel have been analysed; from west to east they are: Bahía Ensenada, Playa Larga, Bahía Brown and Cutalátaca airfield. They were studied in relation to relative altitude, sediment type, faunal composition and radiocarbon dates. The area is characterized by several discontinuous terraces with elevations varying from about 1.5 to 10 m above sea level. Their possible origin (1) due to tectonic uplifting, in comparison with raised beaches of the northern part of Tierra del Fuego, and (2) resulting from glacio-isostatic recovery, taking into account the ice retreat, is discussed. Seventeen species of mollusks (eight bivalves, nine gastropods) were collected from the study sites. All of them are living species from the Beagle Channel and have been interpreted as representative of Holocene paleocommunities in this channel. These species show no evidence of substantial climatic changes during the Holocene, although minor temperature fluctuations cannot be ruled out yet.