A marine to freshwater sediment succession from Kowhai Beach wetland, Northland: Implications for Holocene sea level

An infilled wetland located behind coastal dunes in north-east Northland is used to reconstruct a local history of environmental change spanning early Holocene (c. 7000 yr BP) to modern time. Proxy indicators (sediment texture, diatoms and pollen) provide evidence for a transition from marginal mari...

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Bibliographic Details
Published in:Journal of the Royal Society of New Zealand 2007-09, Vol.37 (3), p.91-107
Main Authors: Hicks, Helen, Nichol, Scott L.
Format: Article
Language:English
Subjects:
Bacillariophyceae
C dating
diatoms
highstand
palynology
sea level
sediments
stratigraphy
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Summary:An infilled wetland located behind coastal dunes in north-east Northland is used to reconstruct a local history of environmental change spanning early Holocene (c. 7000 yr BP) to modern time. Proxy indicators (sediment texture, diatoms and pollen) provide evidence for a transition from marginal marine- to brackish- to freshwater-conditions in the wetland. Radiocarbon ages constrain the chronology of this succession to 7880-7430 cal. yr BP for the early period of marine conditions, 3570-3210 cal. yr BP for the latter brackish phase and 1060-800 cal. yr BP for the change to freshwater conditions. Within this succession, the diatom record preserves a strong brackish signal at core depths above the limit of the modern tidal range. This is presented as preliminary evidence for a mid-Holocene sea level highstand for northern New Zealand of approximately 1.2 m above present mean sea level.
ISSN:0303-6758
1175-8899
DOI:10.1080/03014220709510539