CICTERRA   20351
CENTRO DE INVESTIGACIONES EN CIENCIAS DE LA TIERRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The 20th century hydroclimatic changes in central Argentina recorded in the sedimentary deposits of Laguna Melincué
Autor/es:
GUERRA, L; PALAMEDI, S; PIOVANO, E
Reunión:
Congreso; 18ISC - Sedimentology at the foot of the Andes; 2010
Resumen:
Understanding the role played by the middle latitudes of Southeastern South America (SESA) during climate
change situations has become a topic of growing interest among the scientific community. In this sense, the sedimentary
record of Laguna Melincué (33°S-61°W), an alkaline shallow lake located in the Argentinean Pampean
region, provides the opportunity to disentangle past and present hydroclimate variability across the subtropics of
SESA. The instrumental and historical records of Laguna Melincué show important surface and water level fluctuations
throughout the 20th century. Changing P-E ratios in this portion of SESA are ruled by the variability of
the South America Monsoon like atmospheric circulation system. The high sensitivity and rapid response of La -
guna Melincué in front of recent hydrological balance variability highlight the significance of its sedimentary record
to analyze Holocene paleoeoclimates in SESA. The multiproxy analyses of sedimentary cores allow the recognition
of alternating high lake-level facies (organic matter- rich), deposited during positive hydrological balances
and low lake-level facies (carbonate-rich), indicative of negative balances. The hydrological reconstruction
suggests an initial arid period during the first decades of the 20th century, followed by alternating humid and dry
phases. A dramatic shift to wetter conditions (registered on both, sedimentary and instrumental records) started
during the decade of 1970 and it is still present. When the last 100 years record of hydrological variability in
Melincué is compared to other lacustrine records across the Pampean region (e.g. Mar Chiquita, Lagunas Encadenadas)
synchronous water level fluctuations are recognized. The observed in-phase hydrological behavior
across the Pampas points toward the influence of the South America Monsoon on the last 100 years of hydrological
changes and supports the hypothesis of this mechanism controlling Holocene hydroclimate variability in
SESA.
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