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 sediment 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-derived major element composition. Secondly, we find that PxIs correlate with both austral summer temperatures and wind speeds, but not with precipitation. PxI timeseries reach the p<0.1 correlation significance threshold for use as a paleo-wind proxy in as many as 6 cores and a paleo-temperature proxy in up to 4 cores. 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 not suitable as a paleoclimatic proxy, 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 311-330 |
| Number of pages | 20 |
| Journal | Journal of Paleolimnology |
| Volume | 70 |
| Issue number | 4 |
| DOIs | |
| State | Published - Dec 2023 |
Bibliographical note
Funding Information:MV was supported by a University of Minnesota College of Science and Engineering Fellowship and a Doctoral Dissertation Fellowship. We acknowledge the critical role played by logistical and design expertise of Ryan O’Grady and Anders Noren of the CSD Facility in planning and field phases of this research. Kristina Brady Shannon, Jessica Heck, Alex Stone and Rob Brown seamlessly coordinated core processing and analytical activities at the CSD Facility. We thank Anastasia Fedotova, Cristina San Martín, Guillermo Tamburini-Beliveau, Alexander Schmies and Shanti Penprase for their help with core recovery and processing, and all Spanish-speaking team members for their critical contribution of language skills. Pedro Skvarca, Scientific Director of the Glaciarium Interpretive Center, provided important planning and logistical assistance during initial phases of work. We particularly thank Capitán Alejandro Jaimes for his expert handling of the MV Janet, and for sharing his incisive knowledge of Lago Argentino. We also acknowledge Robert Brown from the University of Minnesota Duluth for acquiring the XRF data. This material is based upon work supported by the National Science Foundation under Grant No. EAR-1714614, coordinated by Lead PI Maria Beatrice Magnani. Data on the LArg cores are available from the CSD Facility at https://cse.umn.edu/csd/projects. Full resolution core scans and stratigraphic information are available at 10.5281/zenodo.5815107. The code used to count laminations in the cores, countMYvarves, is freely available under a GPL3.0 license at doi.org/10.5281/zenodo.4031812. Finally, we thank editors Andrea Lami and Margarita Caballero and two anonymous reviewers for their comments which greatly improved this manuscript.
Funding Information:
MV was supported by a University of Minnesota College of Science and Engineering Fellowship and a Doctoral Dissertation Fellowship. We acknowledge the critical role played by logistical and design expertise of Ryan O’Grady and Anders Noren of the CSD Facility in planning and field phases of this research. Kristina Brady Shannon, Jessica Heck, Alex Stone and Rob Brown seamlessly coordinated core processing and analytical activities at the CSD Facility. We thank Anastasia Fedotova, Cristina San Martín, Guillermo Tamburini-Beliveau, Alexander Schmies and Shanti Penprase for their help with core recovery and processing, and all Spanish-speaking team members for their critical contribution of language skills. Pedro Skvarca, Scientific Director of the Glaciarium Interpretive Center, provided important planning and logistical assistance during initial phases of work. We particularly thank Capitán Alejandro Jaimes for his expert handling of the MV Janet, and for sharing his incisive knowledge of Lago Argentino. We also acknowledge Robert Brown from the University of Minnesota Duluth for acquiring the XRF data. This material is based upon work supported by the National Science Foundation under Grant No. EAR-1714614, coordinated by Lead PI Maria Beatrice Magnani. Data on the LArg cores are available from the CSD Facility at https://cse.umn.edu/csd/projects. Full resolution core scans and stratigraphic information are available at 10.5281/zenodo.5815107. The code used to count laminations in the cores, countMYvarves, is freely available under a GPL3.0 license at doi.org/10.5281/zenodo.4031812. Finally, we thank editors Andrea Lami and Margarita Caballero and two anonymous reviewers for their comments which greatly improved this manuscript.
Publisher Copyright:
© 2023, The Author(s).
Keywords
- Climate proxy
- Lake core
- Patagonia
- Physical limnology
- Sediment color
Continental Scientific Drilling Facility tags
- GCO