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Late Holocene sea-level changes and vertical land movements in New Zealand

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journal contribution
posted on 25.08.2021, 02:59 by Daniel KingDaniel King, RM Newnham, WR Gehrels, KJ Clark
Coasts in tectonically active regions face varying threat levels as land subsides or uplifts relative to rising sea levels. We review the processes influencing relative sea-level change in New Zealand, and the geological context behind ongoing land movements, focussing on major population centres. Whilst Holocene sea levels have been reconstructed using a variety of techniques, recent work uses salt-marsh microfossil assemblages to reconstruct relative sea-level changes over the past few centuries. For the twentieth century, these proxy-based studies often show enhanced rates of sea-level rise relative to tide-gauge observations. The effects of tectonic subsidence must be considered, alongside vertical and dating uncertainties in the sea-level reconstructions. Global Positioning Systems (GPS) observations for the past few decades show that vertical land movement (VLM) may be influencing rates of relative sea-level rise. However, the short period of GPS observations, during which trends and rates have varied at some localities, raises questions over the longer-term contribution of VLM to sea-level change over the past few centuries and for future projections. We argue that high-resolution palaeo-sea-level reconstructions from salt-marsh sedimentary sequences can help to answer these questions regarding the interplay between sea-level change and VLM at key locations.

History

Preferred citation

King, D. J., Newnham, R. M., Gehrels, W. R. & Clark, K. J. (2021). Late Holocene sea-level changes and vertical land movements in New Zealand. New Zealand Journal of Geology and Geophysics, 64(1), 21-36. https://doi.org/10.1080/00288306.2020.1761839

Journal title

New Zealand Journal of Geology and Geophysics

Volume

64

Issue

1

Publication date

01/01/2021

Pagination

21-36

Publisher

Informa UK Limited

Publication status

Published

Online publication date

18/05/2020

ISSN

0028-8306

eISSN

1175-8791

Language

en