Holocene costal longitudinal sand dunes in the westernmost end of Isla de los Estados (Staaten Island), Tierra del Fuego, Southernmost South America

PONCE, J. F.; MARTINEZ, O.; RABASSA, J.

Mar Chiquita, Cordoba.

Otro; Holocene enviromental catastrophes in South America: From the lowlands to the Andes; 2005

Universidad Nacional de Cordoba

A small group of longitudinal sand dunes has been identified in the westernmost end of Isla de los Estados (Staaten Island), at the inland extreme of Caleta Lacroix (Bahía Franklin), within a depression connected towards the northeast with the extended peat-bogs which dominate that sector of the island. The group is composed by 12-13 sand dunes which cover a surface slightly above 2 km2, with an estimated sand volume of 2.5 millions m3. Neither of the sand dunes is longer than 1.5 km and their height and basal wide dimensions are 15-20 m and 50 m respectively. The linear sand dunes are oriented N 65°-70°, the same orientation of the present prevailing winds. The morphology of the dunes is very well preserved and a dense cover of Subantarctic forest over the sand ridges and grassland and peat-bogs in the interdune zone indicate that the aeolian processes which formed the sand dunes are less significant at the present than in the recent past. The dune sands are poorly sorted and show clear compositional affinity with the neighbouring coastal-deltaic deposits. The development of these longitudinal sand dunes field is, tentatively, correlated with dryer palaeoclimatic conditions and/or with a larger availability of sand, probably related with a relative drop of sea level, at the local or global scale. Since these dunes have developed over a glacial landscape, they are assumed to be of Holocene age, although 14C dates and dendrochronological studies on the trunks and wood fragments found into an organic layer underlying these aeolian deposits will certainly allow to propose a most refined chronology and their correlation with global or regional events. At the same time, palynological studies are being carried on from two interdune peat-bog cores and from 8 superficial samples of the Bahía Franklin area.