Kemp, Andrew C. and Vane, Christopher H. and Khan, Nicole S. and Ellison, Joanna C. and Engelhart, Simon E. and Horton, Benjamin P. and Nikitina, Daria and Smith, Struan R. and Rodrigues, Lisa J. and Moyer, Ryan P. (2019) 'Testing the utility of geochemical proxies to reconstruct holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda.', Open quaternary., 5 . pp. 1-18.
On low-lying, tropical and sub-tropical coastlines freshwater marshes may be replaced by salt-tolerant mangroves in response to relative sea-level rise. Pollen analysis of radiocarbon-dated sediment cores showed that such a change occurred in Hungry Bay, Bermuda during the late Holocene. This well-established paleoenvironmental trajectory provides an opportunity to explore if geochemical proxies (bulk-sediment δ13C and Rock-Eval pyrolysis) can reconstruct known environmental changes and relative sea level. We characterized surface sediment from depositional environments in Bermuda (freshwater wetlands, saline mangroves, and wrack composed of Sargassum natans macroalgae) using geochemical measurements and demonstrate that a multi-proxy approach can objectively distinguish among these environments. However, application of these techniques to the transgressive sediment succession beneath Hungry Bay suggests that freshwater peat and mangrove peat cannot be reliably distinguished in the sedimentary record, possibly because of post-depositional convergence of geochemical characteristics on decadal to multi-century timescales and/or the relatively small number of modern samples analyzed. Sediment that includes substantial contributions from Sargassum is readily identified by geochemistry, but has a limited spatial extent. Radiocarbon dating indicates that beginning at –700 CE, episodic marine incursions into Hungry Bay (e.g., during storms) carried Sargassum that accumulated as wrack and thickened through repeated depositional events until ~300 CE. It took a further ~550 years for a peat-forming mangrove community to colonize Hungry Bay, which then accumulated sediment rapidly, but likely out of equilibrium with regional relative sea-level rise.
|Full text:||(VoR) Version of Record|
Available under License - Creative Commons Attribution.
Download PDF (1083Kb)
|Publisher Web site:||https://doi.org/10.5334/oq.49|
|Publisher statement:||Copyright: © 2019 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/|
|Date accepted:||14 January 2019|
|Date deposited:||21 January 2020|
|Date of first online publication:||05 February 2019|
|Date first made open access:||21 January 2020|
Save or Share this output
|Look up in GoogleScholar|