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

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 14 670 ± 750 yr 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.