Abstract
Annual resolution sediment layers, known as varves, can provide continuous and high-resolution chronologies of sedimentary sequences. In addition, varve counting is not burdened with the high laboratory costs of geochronological analyses. Despite a more than 100-year history of use, many existing varve counting techniques are time consuming and difficult to reproduce. We present countMYvarves, a varve counting toolbox which uses sliding-window autocorrelation to count the number of repeated patterns in core scans or outcrop photos. The toolbox is used to build an annually-resolved record of sedimentation rates, which are depth-integrated to provide ages. We validate the model with repeated manual counts of a high sedimentation rate lake with biogenic varves (Herd Lake, USA) and a low sedimentation rate glacial lake (Lago Argentino, Argentina). In both cases, countMYvarves is consistent with manual counts and provides additional sedimentation rate data. The toolbox performs multiple simultaneous varve counts, enabling uncertainty to be quantified and propagated into the resulting age-depth model. The toolbox also includes modules to automatically exclude non-varved portions of sediment and interpolate over missing or disrupted sediment. CountMYvarves is open source, runs through a graphical user interface, and is available online for download for use on Windows, macOS or Linux at https://doi.org/10.5281/zenodo.4031811.
Original language | English (US) |
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Pages (from-to) | 89-100 |
Number of pages | 12 |
Journal | Quaternary Research |
Volume | 104 |
DOIs | |
State | Published - Nov 13 2021 |
Bibliographical note
Funding Information:This work is supported by the National Science Foundation under Grant No. EAR-1714614, coordinated by Lead PI Maria Beatrice Magnani.
Funding Information:
Maximillian Van Wyk de Vries was supported by a University of Minnesota College of Science and Engineering fellowship. We acknowledge the critical role played by the logistical and design expertise of Ryan O'Grady and Anders Noren of the Continental Scientific Drilling Facility (CSDF) in all 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 CSDF. We thank Matias Romero, Anastasia Fedotova, Cristina San Martín, Guillermo Tamburini-Beliveau, Alexander Schmies and Shanti Penprase for their help with core recovery or processing, and all Spanish-speaking team members for their critical contribution of language skills. We particularly thank capitán Alejandro Jaimes for his expert ship handling under challenging conditions, and for sharing his incisive knowledge of Lago Argentino during the coring cruise. Finally, we would like to thank editor Peter Langdon and reviewers Jack Ridge and Arndt Schimmelmann for insightful comments and suggestions.
Publisher Copyright:
Copyright © University of Washington. Published by Cambridge University Press, 2021.
Keywords
- Varves
- Sedimentation rate
- Patagonia
- Core chronology
- Image analysis
- Autocorrelation
- countMYvarves
- Paleolimnology
- Sedimentology
- Lakes
Continental Scientific Drilling Facility tags
- GCO
- HERD