Eolian sand sheet deposition in the San Luis paleodune field, western Argentina as an indicator of a semi-arid environment through the Holocene

• Autores: Forman, Steven L.; Tripaldi, Alfonsina; Ciccioli, Patricia Lucia
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Eolian Sand Sheet; Holocene; Western Pampas; Semi-Arid Paleoenvironment
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Eolian deposits are common in the western Pampas of Argentina, and most are assumed to be associated with glacial conditions. Stratigraphic and sedimentologic studies coupled with OSL dating in San Luis Province document for the first time a nearly continuous sequence of eolian sand sheet deposits that span most of the Holocene. Petrology and geochemical analyses indicate that the source of the sand is from pre-existing Pleistocene eolian sediments. Sand sheet deposition between ca. 12 and 1 ka is associated with sparse, Monte-type vegetation that occurs with drier conditions (MAP 450–100 mm) than the late 20th century (~ 700 mm). This paleoenvironmental inference is consistent with nearby pollen and lake level records. A persistent semi-arid environment in western Argentina during the Holocene may reflect sustained warm SSTs in the western equatorial Atlantic Ocean, which may have suppressed the pressure gradient between the South Atlantic Anticyclone and Chaco Low and thus, the flux of summer moisture to western Argentina. There appears to be a paleoclimatic “dipole” response between a dry western Argentina and a wet southeastern Brazil, which is consistent with the increasing strength of the South American Monsoon through the Holocene. Sand sheet accretion appears to cease by 800 to 200 years ago with wetter conditions and succession to Espinal vegetation prior to European contact.
Fil: Forman, Steven L.. Baylor University; Estados Unidos
Fil: Tripaldi, Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentina
Fil: Ciccioli, Patricia Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentina