Glacial isostatic adjustment near the center of the former Patagonian Ice Sheet (48 degrees S) during the last 16.5 kyr

• Published in: Quaternary Science Reviews
• Main Authors: Troch, Matthias, Bertrand, Sebastien, Lange, Carina B., Cardenas, Paola, Arz, Helge, Pantoja-Gutierrez, Silvio, De Pol-Holz, Ricardo, Kilian, Rolf
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Earth and Environmental Sciences; Patagonia; Isolation basin; Sea level; Salinity indicators; Late glacial; Holocene; SEA-LEVEL RISE; CHILEAN PATAGONIA; SOUTH-AMERICA; LATE-HOLOCENE; FJORD SYSTEM; FLUCTUATIONS; SEDIMENTS; EVOLUTION; ICEFIELD; ANDES; Ice Sheet
• Online Access: https://biblio.ugent.be/publication/8752631; http://hdl.handle.net/1854/LU-8752631; https://doi.org/10.1016/j.quascirev.2021.107346; https://biblio.ugent.be/publication/8752631/file/8752633

Our understanding of glacial isostatic rebound across Patagonia is highly limited, despite its importance to constrain past ice volume estimates and better comprehend relative sea-level variations. With this in mind, our research objective is to reconstruct the magnitude and rate of Late Glacial and Holocene glacial isostatic adjustment near the center of the former Patagonian Ice Sheet. We focus on Larenas Bay (48 degrees S; 1.26 km(2)), which is connected to Baker Channel through a shallow (7.4 m) and narrow (ca. 150 m across) inlet, and hence has the potential to record periods of basin isolation and marine ingression. The paleoenvironmental evolution of the bay was investigated through a sedimentological analysis of a 9.2 m long radiocarbon-dated sediment core covering the last 16.8 kyr. Salinity indicators, including diatom paleoecology, alkenone concentrations and CaCO3 content, were used to reconstruct the bay's connectivity to the fjord. Results indicate that Larenas Bay was a marine environment before 16.5 cal kyr BP and after 9.1 cal kyr BP, but that it was disconnected from Baker Channel in-between. We infer that the postglacial rebound started before 16.5 cal kyr BP and that it outpaced global sea-level rise until slightly before 9.1 cal kyr BP. During the Late Glacial and early Holocene, the center of the former Patagonian Ice Sheet experienced an absolute uplift of ca. 96 m, at an average rate of 1.3 cm/yr. During the remainder of the Holocene, glacial isostatic adjustment continued (ca. 20 m), but at a slower average pace of 0.2 cm/yr. Comparisons between multi-millennial variations in the salinity indicators and existing records of global sea-level rise suggest that the glacial isostatic adjustment rate also fluctuated within these time intervals, likely in response to glacier dynamics. More specifically, most of the glacial isostatic adjustment registered between 16.5 - 9.1 cal kyr BP seems to have occurred before meltwater pulse 1A (14.5 - 14.0 kyr BP). Likewise, it appears that the highest ...