Palynology of the early Miocene Foulden Maar, Otago, New Zealand: Diversity following destruction

Published Date
Review of Palaeobotany and Palynology
May 2014, Vol.204:27–42, doi:10.1016/j.revpalbo.2014.02.003

Research paper

• Author 

• Dallas C. Mildenhall ^a
• Elizabeth M. Kennedy ^a,,
• Daphne E. Lee ^b
• Uwe Kaulfuss ^b
• Jennifer M. Bannister ^c
• Bethany Fox ^b
• John G. Conran ^d

• aGNS Science, P.O. Box 30-368, Lower Hutt, New Zealand
• bDepartment of Geology, University of Otago, P.O. Box 56, Dunedin, New Zealand
• cDepartment of Botany, University of Otago, P.O. Box 56, Dunedin, New Zealand
• dAustralian Centre for Evolutionary Biology and Biodiversity & Sprigg Geobiology Centre, School of Earth and Environmental Sciences, Benham Bldg DX 650 312, The University of Adelaide, SA 5005, Australia

Received 10 May 2013. Revised 6 January 2014. Accepted 8 February 2014. Available online 26 February 2014. 

Highlights

• •
  New early Miocene palynological record from New Zealand.
• •
  Evidence of warm temperate to sub-tropical environments.
• •
  Highly diverse lake margin vegetation dominated by dicots.
• •
  Diverse regional lowland forest flora.

Abstract

Foulden Maar crater in Otago, southern New Zealand contains a thick sequence of earliest Miocene (~ 23 Ma) biogenic lacustrine sediments that have preserved a rich terrestrial biota. Diverse spores and pollen recovered from a 183 m core through these sediments provide evidence of warm temperate to subtropical environments with high rainfall and cloud cover. Charcoal and burnt and dark-coloured pollen are common in reworked tephra below the lacustrine diatomite. At this early post-eruptive depositional period a diverse regional podocarp/Casuarina/Brassospora lowland forest flora was present, with gleichenaceous ferns suggesting a locally acidic environment, possibly supporting a fire-induced fernland. The regional vegetation soon became dominated by Nothofagus (Brassospora), while a diverse subtropical forest with abundant Mallotus/Macaranga (Euphorbiaceae) developed on fertile volcanic soils around the maar. Evidence from palynomorphs combined with plant macrofossils represented in the lake sediments paints a picture of highly diverse lake margin vegetation that included rare ferns (Davallia), occasional conifers (Podocarpus and Prumnopitys), and a diverse array of monocots including at least one palm, two orchids, and species of Astelia, Cordyline, Freycinetia, Luzuriaga, Ripogonum and Typha. Overall, the vegetation close to the lake was dominated by a wide range of dicots, including Aquifoliaceae (Ilex), Araliaceae, Atherospermataceae (Laurelia), Chloranthaceae, Cunoniaceae, Elaeocarpaceae, Gyrostemonaceae (Gyrostemon), Lauraceae (Beilschmiedia, Cryptocarya, Litsea), Onagraceae (Fuchsia), Meliaceae (Dysoxylum), Monimiaceae (Hedycarya), Myrsinaceae, Myrtaceae, Rutaceae, Santalaceae, Sapindaceae (Cupania), Malvaceae, Strasburgeriaceae, Winteraceae and at least ten Proteaceae. Mistletoes, including several species of Loranthaceae were present. Pollens from bur reeds, bulrushes, flaxes, jointed rushes and sedges suggest that there were some swampy, shallow water edges to the generally steep-sided crater. Pollen evidence from alternate dark and light layers, regarded as being biogenic varves from sedimentology, shows no strong signal for differences in summer and winter pollen deposition. Based on palynology the age of the site is latest uppermost Rhoipites waimumuensis Zone to lower early Proteacidites isopogiformis Zone (New Zealand local stages, late Waitakian–early Otaian, ~ 23 Ma), agreeing with radiometric dates.

Keywords

New Zealand

Foulden Maar

early Miocene

palynology

paleoclimate

paleoenvironment

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Plate I.

Plate II.

Fig. 1.

Fig. 2.

Fig. 3.

 Table 1

Table 1.

 Table 2

Table 2.

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  Corresponding author. Tel.: + 64 4 570 4838; fax: + 64 4 570 4600.

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