Giang Anthony
Elemental Geochemistry of Tidal Marsh Sediment and Its Potential as an Indicator of Sea‐Level Change in Cascadia
Anthony, Giang; Pilarczyk, Jessica; Hong, Isabel; Riou, Louise; Huntley, David; MacLeod, Roger; Ward, Owen; Clague, John; Bobrowsky, Peter; Hawkes, Andrea; Engelhart, Simon; Horton, Benjamin
Authors
Jessica Pilarczyk
Isabel Hong
Louise Riou
David Huntley
Roger MacLeod
Owen Ward
John Clague
Peter Bobrowsky
Andrea Hawkes
Dr Simon Engelhart simon.e.engelhart@durham.ac.uk
Associate Professor
Benjamin Horton
Abstract
Holocene sea‐level reconstructions from tidal marshes are commonly derived from proxy indicators that have a consistent and quantifiable relationship with tidal elevation. While microfossils are most commonly employed, using multiple indicators leads to more robust reconstructions. We explore the utility of elemental geochemistry obtained through x‐ray fluorescence as a proxy indicator in tidal marshes at Port Alberni, British Columbia, Canada and Willapa Bay, Washington, United States. The elemental composition of bulk surface sediment collected from 141 stations along 10 transects was determined using an ITRAX Core Scanner. Partitioning Around Medoids cluster analysis on the elemental data distinguished between tidal flat, low marsh, and high marsh zones at both locations, similar to zones established from previously published microfossil (foraminifera, diatoms) data sets on the same samples. The elemental composition of low elevation samples from the tidal flat is dominated by lithogenic (Si, K, Ti, Fe) and biogenic (Sr) elements, whereas higher elevation samples have high proportions of organic content (Br, incoherent and coherent scattering ratio). Principal Component Analysis points to differences in organic versus inorganic content, a function of tidal elevation, as the main driver of geochemistry‐derived zones. Approximately 70% of the elemental variability within both marshes is controlled by the inorganic content, as indicated by lithogenic and biogenic elements versus organic content. The elemental composition of bulk surface sediment from two regions spaced ∼300 km apart shows a promising relationship with tidal elevation over a wider spatial scale and highlights the potential of this proxy for use in sea‐level reconstructions.
Citation
Anthony, G., Pilarczyk, J., Hong, I., Riou, L., Huntley, D., MacLeod, R., Ward, O., Clague, J., Bobrowsky, P., Hawkes, A., Engelhart, S., & Horton, B. (2025). Elemental Geochemistry of Tidal Marsh Sediment and Its Potential as an Indicator of Sea‐Level Change in Cascadia. Geochemistry, Geophysics, Geosystems, 26(5), Article e2024GC012129. https://doi.org/10.1029/2024GC012129
Journal Article Type | Article |
---|---|
Acceptance Date | Apr 18, 2025 |
Online Publication Date | May 8, 2025 |
Publication Date | May 1, 2025 |
Deposit Date | May 9, 2025 |
Publicly Available Date | May 14, 2025 |
Journal | Geochemistry, Geophysics, Geosystems |
Electronic ISSN | 1525-2027 |
Publisher | American Geophysical Union |
Peer Reviewed | Peer Reviewed |
Volume | 26 |
Issue | 5 |
Article Number | e2024GC012129 |
DOI | https://doi.org/10.1029/2024GC012129 |
Keywords | Cascadia, X‐ray fluorescence, tidal marsh, sea‐level change, surface transect, micropaleontology |
Public URL | https://durham-repository.worktribe.com/output/3936286 |
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Publisher Licence URL
http://creativecommons.org/licenses/by-nc-nd/4.0/
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