Relict sand wedges in southern Patagonia and their stratigraphic and paleo-environmental significance

• Published in: Quaternary Science Reviews
• Main Authors: Bockheim, J., Coronato, Andrea Maria Josefa, Rabassa, Jorge Oscar, Ercolano, Bettina, Ponce, Juan Federico
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd
• Subjects: RELICT SAND WEDGES; SOUTHERN PATAGONIA; MIDDLE PLEISTOCENE; PERIGLACIAL ENVIRONMENTS; https://purl.org/becyt/ford/1.5; https://purl.org/becyt/ford/1; Argentina; Austral; Bockheim; Patagonia; permafrost; wedge*
• Online Access: http://hdl.handle.net/11336/133223

Relict sand wedges are ubiquitous in southern Patagonia. At six sites we conducted detailed investigations of stratigraphy, soils, and wedge frequency and characteristics. Some sections contain four or more buried horizons with casts. The cryogenic features are dominantly relict sand wedges with an average depth, maximum apparent width, minimum apparent width, and H/W of 78, 39, 3.8, and 2.9 cm, respectively. The host materials are fine-textured (silt loam, silty clay loam, clay loam) till and the infillings are aeolian sand. The soils are primarily Calciargidic Argixerolls that bear a legacy of climate change. Whereas the sand wedges formed during very cold (-4 to -8 °C or colder) and dry (ca. ≤100 mm precipitation/yr) glacial periods, petrocalcic horizons from calcium carbonate contributed by dustfall formed during warmer (7 °C or warmer) and moister (≥250 mm/yr) interglacial periods. The paleo-argillic (Bt) horizons reflect unusually moist interglacial events where the mean annual precipitation may have been 400 mm/yr. Permafrost was nearly continuous in southern Patagonia during the Illinoian glacial stage (ca. 200 ka), the early to mid-Pleistocene (ca. 800-500 ka), and on two occasions during the early Pleistocene (ca. 1.0-1.1 Ma). Fil: Bockheim, J. University of Wisconsin; Estados Unidos Fil: Coronato, Andrea Maria Josefa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Rabassa, Jorge Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Ercolano, Bettina. Universidad Austral; Argentina Fil: Ponce, Juan Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina