Resolving uncertainties in foraminifera-based relative sea-level reconstruction: a case study from southern New Zealand

Garrett, E.; Brain, M.J.; Hayward, B.W.; Newnham, R.; Morey, C.J.; Gehrels, W.R.

Abstract

Since the pioneering work of David Scott and others in the 1970s and 1980s, foraminifera have been used to develop precise sea-level reconstructions from salt marshes around the world. In New Zealand, reconstructions feature rapid rates of sea-level rise during the early to mid 20th century. Here, we test whether infaunality, taphonomy, and sediment compaction influence these reconstructions. We find that surface (0 – 1 cm) and subsurface (3 – 4 cm) foraminiferal assemblages show a high degree of similarity. A landward shift in assemblage zones is consistent with recent sea-level rise and transgression. Changes associated with infaunality and taphonomy do not affect transfer function-based sea-level reconstructions. Applying a geotechnical modelling approach to the core from which sea-level changes were reconstructed, we demonstrate compaction is also negligible, resulting in maximum post-depositional lowering of 2.5 mm. We conclude that salt-marsh foraminifera are indeed highly accurate and precise indicators of past sea levels.

Citation

Garrett, E., Brain, M., Hayward, B., Newnham, R., Morey, C., & Gehrels, W. (2023). Resolving uncertainties in foraminifera-based relative sea-level reconstruction: a case study from southern New Zealand. Journal of foraminiferal research, 53(1), 78-89. https://doi.org/10.2113/gsjfr.53.1.78

• Journal Article Type: Article
• Acceptance Date: Nov 3, 2022
• Publication Date: 2023-01
• Deposit Date: Nov 4, 2022
• Publicly Available Date: Nov 9, 2022
• Journal: Journal of Foraminiferal Research
• Print ISSN: 0096-1191
• Electronic ISSN: 1943-264X
• Publisher: Cushman Foundation for Foraminiferal Research
• Peer Reviewed: Peer Reviewed
• Volume: 53
• Issue: 1
• Pages: 78-89
• DOI: https://doi.org/10.2113/gsjfr.53.1.78
• Publisher URL: https://doi.org/10.2113/gsjfr.53.1.78