Upper Quaternary evolution of the dune field of the Bolsón de Fiambalá, Catamarca: Sand dispersal at the Andes piedmonts

摘要: Abstract The South American Arid Diagonal extends in Argentina from Puna to Patagonia regions. Several dune fields are scattered between the Andes and Pampas ranges, covering plains plateaus. One of northernmost is occupying tectonic valley known as Bolson de Fiambala (27°S; 67°W) White transverse dunes extend west east, climbing Range. Some outcrops surrounding area allow understand evolution this field. At Chaschuil valley, a profile composed 4 m stratified sands gravels were sampled at Las Lozas site. Epiphytes benthic diatom assemblages suggest shallow lake located 3700 m altitude. Many these brackish/freshwater aerophilous taxa tolerate desiccation periods salt concentration. dominated by Nitzschia frustulum, linearis, Achnanthes thermalis var. rumrichorum, Epithemia adnata, Pinnularia viridis y capitellata. Limestones outcrop dated on 32,000 ± 520 29,380 ± 410 14C years BP (Garleff et al., 1993), suggesting Marine Isotopic Stage 3. Holocene Interglacial recorded either Abaucan rivers valleys. Lake deposits 3000 m altitude gave ages 6175 ± 70 2990 ± 70 1993). sand field northern part was supplied fanglomerates west, Medanitos. There also significant supply pumicite, derived Cerro Blanco volcanic dome. An aridity increase have been previously archaeological data confirmed discharge records River during 1919–1957 interval. Although with high content glass clearly Andes, other central deactivation Desaguadero-Curaco system.