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

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-e...

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Main Authors: Kemp, Andrew C., Vane, Christopher H., Khan, Nicole S., Ellison, Joanna C., Engelhart, Simon E., Horton, Benjamin Peter, Nikitina, Daria, Smith, Struan R., Rodrigues, Lisa J., Moyer, Ryan P.
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/142089
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spelling sg-ntu-dr.10356-1420892020-09-26T21:25:40Z Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda Kemp, Andrew C. Vane, Christopher H. Khan, Nicole S. Ellison, Joanna C. Engelhart, Simon E. Horton, Benjamin Peter Nikitina, Daria Smith, Struan R. Rodrigues, Lisa J. Moyer, Ryan P. Asian School of the Environment Earth Observatory of Singapore Science::Geology Sargassum Rock-Eval Pyrolysis 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. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version 2020-06-15T09:26:17Z 2020-06-15T09:26:17Z 2019 Journal Article Kemp, A. C., Vane, C. H., Khan, N. S., Ellison, J. C., Engelhart, S. E., Horton, B. P., . . . Moyer, R. 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(1), 1-17. doi:10.5334/oq.49 2055-298X https://hdl.handle.net/10356/142089 10.5334/oq.49 2-s2.0-85064751403 1 5 1 17 en Open Quaternary © 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/. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic Science::Geology
Sargassum
Rock-Eval Pyrolysis
spellingShingle Science::Geology
Sargassum
Rock-Eval Pyrolysis
Kemp, Andrew C.
Vane, Christopher H.
Khan, Nicole S.
Ellison, Joanna C.
Engelhart, Simon E.
Horton, Benjamin Peter
Nikitina, Daria
Smith, Struan R.
Rodrigues, Lisa J.
Moyer, Ryan P.
Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
description 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.
author2 Asian School of the Environment
author_facet Asian School of the Environment
Kemp, Andrew C.
Vane, Christopher H.
Khan, Nicole S.
Ellison, Joanna C.
Engelhart, Simon E.
Horton, Benjamin Peter
Nikitina, Daria
Smith, Struan R.
Rodrigues, Lisa J.
Moyer, Ryan P.
format Article
author Kemp, Andrew C.
Vane, Christopher H.
Khan, Nicole S.
Ellison, Joanna C.
Engelhart, Simon E.
Horton, Benjamin Peter
Nikitina, Daria
Smith, Struan R.
Rodrigues, Lisa J.
Moyer, Ryan P.
author_sort Kemp, Andrew C.
title Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
title_short Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
title_full Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
title_fullStr Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
title_full_unstemmed Testing the utility of geochemical proxies to reconstruct Holocene coastal environments and relative sea level : a case study from Hungry Bay, Bermuda
title_sort testing the utility of geochemical proxies to reconstruct holocene coastal environments and relative sea level : a case study from hungry bay, bermuda
publishDate 2020
url https://hdl.handle.net/10356/142089
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