| Abstrakt: |
The present study aimed to extract a sea-level history from northern New Zealand salt-marsh sediments using a foraminiferal proxy, and to extend beyond the longest nearby tide-gauge record. Transects through high-tidal salt marsh at Puhinui, Manukau Harbour, Auckland, New Zealand, indicate a zonation of dominant foraminifera in the following order (with increasing elevation): Ammonia spp.-Elphidium excavatum, Ammotium fragile, Miliammina fusca, Haplophragmoides wilberti-Trochammina inflata, Trochamminita salsa-Miliammina obliqua. The transect sample faunas are used as a training set to generate a transfer function for estimating past tidal elevations in two short cores nearby. Heavy metal, [sup 210]Pb and [sup 137]Cs isotope analyses provide age models that indicate 35 cm of sediment accumulation since ~1890 AD. The first proxy-based 20th century rates of sea-level rise from New Zealand's North Island at 0.28 ± 0.05 cm year[sup -1] and 0.33 ± 0.07 cm year[sup -1] are estimated. These are faster than the nearby Auckland tide gauge for the same interval (0.17 ± 0.1 cm year[sup -1]), but comparable to a similar proxy record from southern New Zealand (0.28 ± 0.05 cm year[sup -1]) and to satellite-based observations of global sea-level rise since 1993 (0.31 ± 0.07 cm year[sup -1]). The sea-level history from New Zealand salt-marsh sediments was investigated using a foraminiferal proxy, Transect sample faunas were used as a training set to generate a transfer function for estimating past tidal elevations in two short cores nearby. The first proxy-based 20th century rates of sea-level rise from New Zealand's North Island at ~0.3 cm year[sup -1] are estimated. [ABSTRACT FROM AUTHOR] |
