Preprints
https://doi.org/10.5194/cp-2022-29
https://doi.org/10.5194/cp-2022-29
 
20 Apr 2022
20 Apr 2022
Status: this preprint is currently under review for the journal CP.

Paleoclimatic value of sediment pixel intensity time series from Lago Argentino, Patagonia

Maximillian Van Wyk de Vries1,2, Emi Ito1,3, Mark Shapley3, Matias Romero4,5, and Guido Brignone4 Maximillian Van Wyk de Vries et al.
  • 1Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA
  • 2Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55455, USA
  • 3Continental Scientific Drilling Facility, Dept. of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA
  • 4Facultad de Ciencias Exactas, Físicas y Naturales (FCEFyN), Universidad Nacional de Córdoba, Av. Haya de la Torre, Córdoba, X5000HUA, Argentina
  • 5Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Córdoba, X5000IND, Argentina

Abstract. The quantity and characteristics of sediment deposited in lakes are affected by climate to varying extents. As sediment is deposited, it provides a record of past climatic or environmental conditions. However, determining a direct relationship between specific climatic variables and measurable sediment properties, for instance between temperature and sediment optical reflectance, is complex. In this study, we investigate the suitability of sediment reflectance, recorded as digital pixel intensity (PxI), as a paleoclimate proxy at a large ice-contact lake in southern Patagonia, Lago Argentino. We also evaluate whether sediment PxI can be used to investigate the present-day climatic drivers of sedimentation across Lago Argentino. First, we show that sediment PxIs relate to underlying sediment composition, and are significantly correlated with XRF major element compositional data. Secondly, we find that PxIs correlate with both austral summer temperatures and austral summer wind speeds, but not with precipitation. PxI timeseries reach the correlation significance threshold for use as paleo-temperature or paleo-wind speed proxies. However, high spatial variability and the non-unique relationship between PxI and both temperature and wind speed challenges the necessary assumption of stationarity at Lago Argentino. While we do not find it suitable for use as a paleoclimatic proxy, significant correlations between PxI and instrumental climate data do chronicle current climatic controls on sediment deposition at Lago Argentino: high summer temperatures enhance settling of coarse, optically dark grains across the lake basin by promoting ice melt and lake stratification, while high wind speeds reduce the settling of fine, optically bright grains in the ice-proximal regions by transporting sediment-rich waters away from the glacier fronts. The assumptions required for quantitative paleoclimatic reconstruction must be carefully evaluated in complex lacustrine environments, but records unsuitable for use as proxies might nevertheless yield valuable information about the drivers of modern sedimentary transport and deposition.

Maximillian Van Wyk de Vries et al.

Status: open (until 25 Jun 2022)

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  • RC1: 'Comment on cp-2022-29', Anonymous Referee #1, 20 Apr 2022 reply

Maximillian Van Wyk de Vries et al.

Maximillian Van Wyk de Vries et al.

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Short summary
In some situations, the color of sediment records information about the climatic conditions under which it was deposited. We show that sediment color and climate are linked at Lago Argentino, the world's largest ice-contact lake, but that this relationship is too complex to be used for reconstructing past climate. We instead use this sediment color-climate relationship to show that temperature and wind speed affect sediment deposition in the summer, but not in the winter.