Quantitative palaeoclimate estimates from Late Cretaceous and Paleocene leaf floras in the northwest of the South Island, New Zealand

Three new plant macrofossil assemblages were collected from Late Cretaceous and Paleocene fluvio-lacustrine sediments of the Pakawau and Kapuni groups in the northwest of the South Island, New Zealand. Palaeoenvironmental interpretations were made from each locality and palaeoclimate was deduced from the dicotyledonous angiosperm leaf component of each flora. A latest Cretaceous (Pakawau Bush Road locality) flora yielded 58 different dicotyledonous leaf forms; the two Paleocene collections, Ian’s Tip and Pillar Point Track, included 23 and 28 dicotyledonous leaf forms respectively. Quantitative palaeoclimate estimates were obtained using both Leaf Margin Analysis (LMA) and the Climate Leaf Analysis Multivariate Program (CLAMP). Temperature estimates suggest that there was a slight cooling from the latest Cretaceous into the early Paleocene in the northwest Nelson region of New Zealand, supporting similar Southern Hemisphere palaeoclimate findings from Antarctic data. Consistency in temperature estimates using different methods, including LMA, multivariate leaf morphological analysis (CLAMP), oxygen isotope data, regional versus local studies and global palaeoclimate models, suggests that the mean annual temperature for the Pakawau region in the latest Cretaceous was between 12 and 15°C. LMA produced temperature estimates between 6.5 and 8°C for the two Paleocene assemblages whereas CLAMP-produced estimates were slightly higher between 9 and 12.5°C