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

Eolian depositional phases during the past 50 ka and inferred climate variability for the Pampean Sand Sea, western Pampas, Argentina

“…These results, combined with prior observations (Tripaldi and Forman, 2007;Tripaldi et al, 2013;Forman et al, 2014), yield a basis for identifying six eolian depositional phases, formed by successive eolian strata interposed with paleosols and/or bounded by erosive surfaces. Age control was provided by optically stimulated luminescence (OSL) dating of small aliquots of quartz grains from eolian stratigraphic units and this approach has yielded previously a consistent chronology (Tripaldi and Forman, 2007;Tripaldi et al, 2013;Forman et al, 2014). This paper provides new insight into the nature and the timing of eolian depositional phases for the past ca.…”

“…These studies have documented pervasive sand sheet deposits near Villa Mercedes in San Luis Province that reflect nearly continuous eolian deposition from ca. 12 ka to 1 ka (Forman et al, 2014). This aggradational eolian system was associated with Monte-type vegetation (shrub steppe) with an inferred mean annual precipitation between 100 and 450 mm and a weakened influence of the South American Monsoon system (SAMS) (Forman et al, 2014).…”

“…Extensive, late Quaternary deposits of loess and eolian sand occur across central Argentina and are important archives of hydrologic variability, distal to seasonal effects of the South American Monsoon (Clapperton, 1993;Iriondo and Kr€ ohling, 1995;Z arate, 2003Rutter et al, 2012;Forman et al, 2014). These presently stabilized eolian landscapes grade texturally from loess and loess-like deposits in the eastern and northern Pampas to sand in the central and western Pampas and the Andean piedmont (Fig.…”

“…This aggradational eolian system was associated with Monte-type vegetation (shrub steppe) with an inferred mean annual precipitation between 100 and 450 mm and a weakened influence of the South American Monsoon system (SAMS) (Forman et al, 2014). In contrast, the few late Pleistocene records studied, spanning from 40 to 15 ka are characterized by multiple paleosols intercalated with eolian sand reflecting heightened precipitation variability compared to the Holocene (Tripaldi and Forman, 2007;Forman et al, 2014). Previous studies of moraine records for valley glaciers and lake records from the tropical and subtropical Andes inferred significantly wetter, millennial-scale intervals between ca.…”

Intermontane eolian sand sheet development, Upper Tulum Valley, central-western Argentina

“…The geomorphology and chronology of dune fields are well established in western areas of San Luis, La Rioja, and San Juan's provinces (Tripaldi & Forman 2007). Presently stabilized and active dune fields are common across the Argentinian Pampas to the Andean Piedmont (Zárate & Tripaldi 2012) and sand sheet deposits appear to form a continuously succession that span most of the Holocene in the San Luis paleodune field (Forman et al 2014). In the Upper Tulum Valley, Suvires (2004) described the influence of eolian sediments as parent materials for soil formation, and Basilici and Dal' Bó (2014) recognized the influence of subaqueous deposition on the construction and accumulation of the eolian sand sheet.…”