A 700-year multiproxy reconstruction on the Argentinian Pampas inferred from the sediments of Laguna Blanca Grande

CHARO LOPEZ-BLANCO; GLORIA ALEJANDRA RODRÍGUEZ-ABAUNZA; CARINA SEITZ; LAURA PEREZ; CAROLINA CUÑA-RODRIGUEZ; SONIA FONTANA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2020

0895-9811

The Pampean region is a crucial area to obtain sensitive paleoclimatic lacustrinearchives due to the presence of shallow environments in a territory non impacted byhumans until the last centuries. In this study, we provide a paleoecologicalreconstruction for the last ca. 700 years based on a multiproxy lacustrine record fromLaguna Blanca Grande, in Olavarría (Buenos Aires, Argentina). Our inferences, whichwere based on sedimentary properties, diatom, cladoceran and ostracod assemblages,offered interesting information about hydroclimatic variability and nutrient increase.Changes in relative abundances on diatoms, specifically on Aulacoseira granulataand Aulacoseira granulata var. angustissima and fragilariods, were used to infershifts in nutrient conditions. The remainder proxies together indicated small lake levelchanges. Reconstructed hydroclimatic conditions in Laguna Blanca Grande areconsistent with previous paleoecological inferences indicating a humid phase aroundca. AD 1450 and progressive drier conditions ca. AD 1530-1900. A flood gateconstruction and an increase of nutrient in the lake revealed a higher human pressuredue to population increase and land-use changes during the last century. Furtherstudies on taxonomy and autecology of microcrustaceans are needed to effectivelyunlock the information contained in biological proxies from Sudamerican records.