CONICET | Buscador de Institutos y Recursos Humanos

Six areas of the Patagonian coast, Argentina, were investigated in order to determine the number. characteristics, geomor- phology and development of Quaternary littoral zones. It became apparent that utilizing D/L ratios of aspartic acid and leu- -_ cine of various molluscan species would be the most useful in correlation, relative age dating and estimating the ages of these zones. The oldest littoral zone is found at elevations between 24 and 41 m above mean sea level and is judged to be older than Oxygen Isotope Substage 5e in age based on relatively high amino acid ratios and extrapolated from non-linear kinetic models. L d An intermediate aged littoral zone may be present at some locations based upon beach ridges or platforms varying in elevation between 16 and 28 m above mean sea level. D/L ratios are generally lower than those for the oldest zone but show a greater variation. This zone may represent the Substage 5e sea level stand. Well defined young beach ridges &12 m above mean sea level are found in most locations and have been 14C dated, and verified hy amino acid ratios, as being Holocene. The presence of Quaternary aged emerged littoral zones at roughly the same elevation suggest that the glacio-eustatic contribution is the primary cause of the high sea level stands whereas secondary variations are attributed to other factors.

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