Quantitative palaeoclimate estimates for Early Miocene southern New Zealand: Evidence from Foulden Maar

Abstract

A rich and diverse plant macrofossil assemblage from an earliest Miocene diatomite deposit in southern New Zealand provides a detailed record of mid-latitude, Southern Hemisphere terrestrial climate in an oceanic setting. Quantitative palaeoclimate estimates for temperature and precipitation variables were obtained using the Climate Leaf Analysis Multivariate Program (CLAMP) and the Bioclimatic Analysis approach. In addition, the surface area of fossil Podocarpus travisiae leaves preserved at the site was used as a proxy for mean annual temperature. CLAMP and Bioclimatic analysis both estimated mean annual temperatures at ~18.5–19.5°C, with a moderate seasonal temperature range between summer and winter of ~10°C and leaf size in Podocarpus suggested a MAT of about 21°C. Precipitation rates were high at around 1700–2000mm per year. CLAMP analysis suggested a ~600mm difference between the dry and wet season, whereas Bioclimatic Analysis indicated a ~200–250mm difference between summer and winter. When compared to CLAMP analysis on modern vegetation on subtropical oceanic islands, it would seem that CLAMP overestimates seasonal precipitation differences.