17 Feb 2023
 | 17 Feb 2023
Status: this preprint is currently under review for the journal GChron.

Spatial variability of the modern radiocarbon reservoir effect in the high-altitude lake Laguna del Peinado (Southern Puna Plateau, Argentina)

Paula Andrea Vignoni, Francisco Elizalde Córdoba, Rik Tjallingii, Carla Santamans, Liliana Concepción Lupo, and Achim Brauer

Abstract. The high-altitude lakes of the Altiplano-Puna Plateau in the Central Andes often have large radiocarbon reservoir effects. This combined with the general scarcity of terrestrial organic matter makes obtaining a reliable and accurate chronological model based on radiocarbon ages a challenge. As a result, age-depth models based on radiocarbon dating are often constructed by correcting for the modern reservoir effect, however, commonly without consideration of spatial variations of reservoir ages within the lake and across the basin. In order to get a better constrain on the spatial variability of the radiocarbon reservoir effects, we analyse 14C ages of modern terrestrial and aquatic plants from the El Peinado basin in the Southern Puna Plateau, which hosts the Laguna del Peinado lake fed by hydrothermal springs. The oldest 14C ages of modern samples (> 18,000 and > 26,000 BP) were found in hot springs discharging into the lake likely resulting from the input of 14C-depleted carbon from old groundwater and 14C-free magmatic CO2. In the littoral and central part of Laguna del Peinado, modern samples 14C ages were several thousand years lower (> 13,000 and > 12,000 BP) compared to the inflowing waters as a result of CO2 exchange with the atmosphere. Altogether, our findings reveal a spatial variability of up to 14,000 14C years of the modern reservoir effect between the hot springs and the lake in the El Peinado basin. This study has implications for high-precision dating and accurate 14C-based chronologies in paleoclimate studies in the Altiplano-Puna Plateau and similar settings. Our results highlight the need to consider spatial and likely also temporal variations in the reservoir effects when constructing age-depth models.

Paula Andrea Vignoni et al.

Status: open (until 25 Apr 2023)

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  • RC1: 'Comment on gchron-2023-3', Anonymous Referee #1, 27 Mar 2023 reply

Paula Andrea Vignoni et al.

Paula Andrea Vignoni et al.


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Short summary
Radiocarbon dating is a widely used tool to establish chronologies for sediment records. We show that modern aquatic plants in the Laguna del Peinado lake system (Altiplano-Puna Plateau) give too old ages caused by reservoir effects from the input of old groundwater and volcanic CO2. Our results reveal a spatial variability of the modern reservoir effect within the lake basin, which has implications for radiocarbon-based chronologies in paleoclimate studies in this region and similar settings.