Data, images, and R programming language code for age-depth modeling a lake sediment record
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Date
2024-10-14
Authors
Gavin, Daniel G.
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Abstract
Langlois Lake in western Washington contains evidence of overbank flows (floods) onto an alluvial fan surface from the adjacent Tolt River. A six-meter sediment core from the lake, and a freeze core of the surface sediments, reveals the timing of these overbank flows as distinct silt units in the sediment. Radiocarbon dates and Pb-210 measurements provide a basis for aging these layers. However, due to the very different rates of sedimentation of the silt vs organic segments of the core, there is a complicated relationship between depth in the sediment and age of the sediment. Typical methods have simply removed the "slumps" of the rapidly-deposited material; this is a subjective step and difficult to apply for long cores with many such events. The method used here, originally used in two papers (Colombaroli and Gavin 2010, Colombaroli et al. 2018), uses an estimate of the fluvial silt component of sediment (from color or density) as a proxy for sedimentation rate. The R code (R programming language) and data sets here accompany an application of this method to Langlois Lake. We also provide image files of the sediment record which this method depends.
Colombaroli, D., & Gavin, D. G. (2010). Highly episodic fire and erosion regime over the past 2,000 y in the Siskiyou Mountains, Oregon. Proceedings of the National Academy of Sciences of the USA, 107(44), 18909–18914. https://doi.org/10.1073/pnas.1007692107
Colombaroli, D., Gavin, D. G., Morey, A. E., & Thorndycraft, V. R. (2018). High resolution lake sediment record reveals self-organized criticality in erosion processes regulated by internal feedbacks. Earth Surface Processes and Landforms, 43(10), 2181–2192. https://doi.org/10.1002/esp.4383)
Description
These files contain images of the sediment core, the derived color values, and the statistical analysis for developing the flood (silt deposition) chronology. Additional data files are in the Neotoma Paleoecology Database. A full description of the data is in the file readme.txt. The R code (R programming language) is accompanied by comments and designed to be applicable to other sites with little additional customization. The files also contain the input and output for the Pb-210 age depth model applied to the freeze-core sediments, using the package 'serac' in the R programming language.
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Citation
Daniel G. Gavin, William T. Struble and Mark A. Fonstad. Holocene Lake Sediments Reveal Alluvial Fan History with Links to Climate, Wildfire, and Earthquakes. Journal of Geophysical Research: Earth Surfaces.