The age and significance of in-situ sinter at the Te Kopia thermal area, Taupo Volcanic Zone, New Zealand

One hundred pollen grains and spores, recovered from a single sample of in situ silica sinter from the Te Kopia geothermal field, include some from a podocarp forest that grew in a temperate, frost-free climate, unlike that o f today, as indicated by the presence of Ascarina. Also present are pollen From taxa introduced within the last 100 years. Ascarina has been absent fr om the area since at least 1800 B.P. and its presence in the sinter indicat es that alkali chloride waters discharged at the surface of Te Kopia before 1800 B.P., and possibly before 3500 B.P. Although palynology is a powerful tool to place age limits on fluctuations in the shallow hydrology of geoth ermal fields, interpretation must be moderated by considering the present f lora and also changes in both local and regional flora, habitat and climate . (C) 2000 CNR. Published by Elsevier Science Ltd. All rights reserved.