Resumo

COLOMBO, F. et al. First absolute ages for holoceno lacustrine deposits of the Jáchal River, Precordillera of San Juan. Rev. Asoc. Geol. Argent. [online]. 2005, vol.60, n.3, pp.605-608. ISSN 0004-4822.

In this paper are discussed the first absolute ages obtained for Holocene lacustrine deposits found in the upper reach of the Jáchal River. The Quaternary record has been divided in three informal alloformations, each one of them characterizing different stages in the evolution of the intramontane quaternary fill. Lacustrine sediments belonging to the alloformation 2 and fluvial terraces corresponding to the alloformation 3 were dated in this contribution. According to the obtained ages the lacustrine episode would have begun in the Early Holocene (8930 ± 50 AP) and continued at least by 2400 years (until 6,497 ± 45 AP). As a consequence of the damming break took place a large hiatus until the formation of the fluvial terraces corresponding to the alloformation 3 which were dated in 978 ± 20 AP and 525 ± 32 AP.

Palavras-chave : Holoceno; Lacustrine; Precordillera.

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