Reconstruction of the hydrological history of a shallow Patagonian steppe lake during the past 700 years, using chemical, geological, and biological proxies

COVIAGA, CORINA; RIZZO, ANDREA; PERÉZ, PATRICIA; DAGA, ROMINA; POIRÉ, DANIEL; CUSMINSKY, GABRIELA; RIBEIRO GUEVARA, SERGIO

QUATERNARY RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2017 vol. 87 p. 208 - 226

0033-5894

The limnological conditions during the past 700 years were reconstructed based on multi?proxy analysis of a short sedimentary sequence from El Toro Lake (~40ºS 70ºW).Mineralogical and geochemical features, and ostracods and chironomids, record Hydrologicalchanges in the El Toro Lake basin. The ostracod Limnocythere rionegroensis var. 1, a reliable indicator of high salinity, and Eucypris fontana, an eurihaline species with preferences for moderate salinity waters, are studied as paleolimnological proxies. The chironomid fauna indicates less saline conditions in the mid-20th century. These salinity changes are interpreted in terms of negative?positive hydrological balance. High lake level and low salinity between AD 1500 and 1700 match with the wetter and colder climate during the second pulse of the Little Ice Age in northern Patagonia. High salinity conditions occurred during late 19thcentury, corresponding to the driest period during the past 400 years in ortheasternPatagonia. An increase in the precipitation around middle of 20th century, opposite to the records in the Chilean side of the mountains, correlate with a positive phase of the Southern Annular Mode. This is associated, in turn, with a strengthening, poleward shift of the midlatitude westerlies, possibly enhancing easterly moist air flows into central-north Patagonia.