eCite Digital Repository

Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level: a case study from Hungry Bay, Bermuda

Citation

Kemp, AC and Vane, CH and Khan, NS and Ellison, JC and Engelhart, SE and Horton, BP and Nikitina, D and Smith, SR and Rodrigues, LJ and Moyer, RP, 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 Article 1. ISSN 2055-298X (2019) [Refereed Article]


Preview
PDF
2Mb
  

Copyright Statement

Copyright 2019 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.5334/oq.49

Abstract

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.

Item Details

Item Type:Refereed Article
Keywords:Sargassum, Rock-Eval pyrolysis, mangrove, radiocarbon, δ13C
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Quaternary Environments
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Coastal and Estuarine Environments
UTAS Author:Ellison, JC (Associate Professor Joanna Ellison)
ID Code:130608
Year Published:2019
Deposited By:Geography and Spatial Science
Deposited On:2019-02-06
Last Modified:2019-05-02
Downloads:13 View Download Statistics

Repository Staff Only: item control page