Stratigraphy and vegetation signals from an upland, landslide-dammed, paleolake during the Last Glacial-Interglacial Transition, Waipaoa Sedimentary System, Hikurangi Margin, eastern North Island, New Zealand

ABSTRACT

A recently discovered upland paleolake (Redpath Lake) provides evidence of the expansion of lowland podocarp temperate forest to higher elevations within the tectonically active Waipaoa Sedimentary System (WSS), eastern North Island, New Zealand, during the Last Glacial-Holocene Transition. Interpreted as a localised landslide-dammed lake, lithofacies analyses indicate deposition and preservation in a low energy, sub-aqueous, lacustrine environment. Robust Bayesian-derived age-depth models constrained by key tephra fall beds and independent ¹⁴C dating (n = 7) indicate storm-bed frequency of c. 226 yrs on average. The absence of extensive soft-sediment deformation or lake-bed tilting implies that seismic shaking was insignificant during the Lake’s c. 12 ka yr (17.3–5.5 cal ka BP) existence. Pollen spectra extracted from lacustrine deposits include a mix of montane shrubland and lowland podocarp species spanning a well-dated c. 2200-year (c. 16.3–14.1 cal ka BP) period coeval with a phase of significant climate amelioration (late NZCe–5/NZce-4 mild episode), based on biotic proxies during the latter part of the climatically variable Last Glacial-Interglacial Transition (LGIT) (c. 18.2–11.8 cal ka BP). These pollen spectra represent the first New Zealand record of replacement of montane shrublands in terrestrial uplands of the WSS were replaced by lowland podocarp forest.

KEYWORDS:

• Landslide-dam
• paleolake sediments
• vegetation change
• LGIT
• WSS
• tephrochronology

Acknowledgements

We acknowledge the support of Landcare Research NZ Ltd staff members including Nic Faville and Cissy Pan for their assistance with the drafting of figures, Anne Austin for editorial support and Anne Sutherland for GIS support. Thanks also to the three external reviewers for their valuable comment.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Supporting information for Appendices A1 to A4 can be accessed at https://libguides.csun.edu/DMP/after.

Data supporting Appendix A5 is available on request to Mike Marden, and for Appendix 6, on request to Matt Ryan.

Notes

1 INTegration of Ice-core, MArine, and TErrestrial records; a core programme of the Palaeoclimate Commission of the International Union for Quaternary Research (INQUA).

Additional information

Funding

This work was funded in part by Manaaki Whenua Landcare Research Strategic Science Investment Fund (SSIF), the Massey University Research Fund (2008 round), and a grant from the U.S. National Science Foundation (GEO-0503609).