Late-pleistocene wedge structures along the patagonian coast (argentina): Chronological constraints and palaeo-environmental implications

• Published in: Geografiska Annaler: Series A, Physical Geography
• Main Authors: Ribolini, A, Bini, M, Consoloni, I, Isola, I, Pappalardo, M, Zanchetta, G, Fucks, E, Terrasi, F., PANZERI, LAURA, MARTINI, MARCO
• Other Authors: Panzeri, L, Martini, M, Terrasi, F
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Ltd 2014
• Subjects: Geology; Geography; Planning and Development; Antarctic; Argentina; Patagonia; The Antarctic; Antarc*; permafrost; wedge*
• Online Access: http://hdl.handle.net/10281/84101; https://doi.org/10.1111/geoa.12038; http://www.blackwellpublishing.com/aims.asp?ref=0435-3676

This paper investigates several wedge structures formed in continental deposits covering marine sediments deposited during MIS 5 along the central Patagonian coast of Argentina. The size and surface microtexture characteristics of the infilling sediments are consistent with a depositional environment dominated by aeolian transport. Fragments of Andean volcanic rocks (glass shards) in the wedge-fill suggest long-distance transport via a westerly component of wind direction. The wedges are interpreted as products of deep seasonal frost action in frozen ground, which produced open cracks that filled rapidly with partially non-local aeolian sediments. Many wedges cross cut carbonate crusts that formed under permafrost conditions in coastal Patagonia. The radiocarbon dating of carbonate crusts yielded an age of 25-27 kyr bp, while wedge-fill sediments are OSL dated to 14670±750yr bp. This indicates that ground wedge formation occurred during a cold event (the Antarctic Cold Reversal period) that interrupted the permafrost degradation following the Last Glacial Maximum. © 2014 Swedish Society for Anthropology and Geography.