Subsurface stratigraphy, paleoenvironments, palynology, and depositional history of the late Neogene Tauranga Group at Ohinewai, Lower Waikato Lowland, South Auckland, New Zealand

Nelson, Campbell S.; Mildenhall, Dallas C.; Todd, Andrew; Pocknall, David T.

doi:10.1080/00288306.1988.10417808

Cited by 26 publications

(17 citation statements)

References 14 publications

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“…Other tree species common in these forests included casuarina and Myrtaceae (e.g., Metrosideros, Eucalyptus, Leptospermum/Kunzea). Late Miocene pollen assemblages from Taranaki (Mildenhall & Pocknall 1984) are similar to those described further north at Ohinewai (Nelson et al 1988), and suggest some uniformity in the forest cover of western North Island at that time.…”

Section: Analysis Of Pollen Assemblages From Various Sedimentary Sequsupporting

confidence: 49%

Petrified wood from the Miocene volcanic sequence of Coromandel Peninsula, northern New Zealand

Moore

Wallace

2000

Journal of the Royal Society of New Zealand

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Petrified (silicified) wood is found throughout the Miocene sub-aerial volcanic sequence of Coromandel Peninsula. The identification of 160 samples, mostly collected from geological formations of known age, shows that over the period from 18-6 Ma the majority of trees within local forests were angiosperms, particularly southern beech (Nothofagus spp.) and casuanna (Casuarinaceae). A species close to modern Weinmanma and Lauretta was also relatively common. Conifers, including kauri (Agathis), celery pine (Phyllocladus), and other podocarps (Podocarpaceae), were subordinate.Only the stems of larger forest tree species, with more durable heartwood, appear to have been preserved, and angiosperm species in general are poorly represented. This is attributed largely to the selective destruction of smaller, mainly angiosperm, trees by fire, decay, and abrasion during transportation within volcanic flows. Charred wood does not seem to have been silicified.Analysis of the wood assemblage suggests there were some significant changes in the relative abundance of certain tree species during the Miocene. Kauri apparently constituted 10-20% of the forest canopy around 13-15 Ma ago, but may have almost disappeared by latest Miocene time. Casuanna increased dramatically about 9-10 Ma ago, probably as a result of localised destruction of the existing forest by volcanic (pyroclastic) eruptions, and rapid colonisation of the devastated area. It had declined to low numbers by the end of the Miocene. In contrast, Phyllocladus was relatively common between 6 and 7 Ma ago, possibly indicating a change to cooler climatic conditions.The study has shown that various factors need to be taken into account in the interpretation of petrified wood assemblages, including sampling bias, selective preservation, the local derivation of wood (versus the more regional representation of pollen), and the influence of differing environmental conditions on forest composition.

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Section: Analysis Of Pollen Assemblages From Various Sedimentary Sequsupporting

confidence: 49%

Petrified wood from the Miocene volcanic sequence of Coromandel Peninsula, northern New Zealand

Moore

Wallace

2000

Journal of the Royal Society of New Zealand

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“…3) shows some discrepancies in abundance and distribution, mainly consisting of taxa with a last occurrence (LO) well short of their known LO from terrestrial sequences. For example, Cupanieidites orthoteichus (Sapindaceae), Monogemmites gemmatus, Parsonsidites psilatus (all of which have a solitary occurrence), Beaupreaidites elegansiformis, and Reevesiapollis reticulatus (two occurrences each), are frequent in late Pliocene to early Pleistocene terrestrial sediments (Nelson et al 1988;Mildenhall 1999Mildenhall , 2001a. They all have a LO of Opoitian in this sequence but are known to become extinct in the early Nukumaruan (Mildenhall 2001a).…”

Section: Biostratigraphymentioning

confidence: 99%

“…Nothofagaceae (subgenus Brassospora) pollen type found in four samples in the Waipipian and Mangapanian close to its known range in terrestrial sequences (Nelson et al 1988). Nothofagidites spinosus is far more common, becoming extinct in the early Pleistocene (Mildenhall & Pocknall 1989).…”

Section: Nothofagidites Longispinosus: This Is a Very Rarementioning

confidence: 99%

Deep‐sea record of Pliocene and Pleistocene terrestrial palynomorphs from offshore eastern New Zealand (ODP Site 1123, Leg 181)

Mildenhall

2003

New Zealand Journal of Geology and Geophysics

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Terrestrial palynomorph assemblages of Pliocene and Pleistocene age have been recovered from ODP Site 1123 (Leg 181), 1100 km offshore from eastern New Zealand and from a water depth of 3300 m. Palynomorphs occur in such significant numbers as to allow for a greatly enhanced correlation between the orbitally tuned marine record and climatically controlled changes in terrestrial vegetation, despite a long distance from shore and a great depth.Gradual changes in the dominant pollen types from more mesothermal taxa (Nothofagus subgenus Brassospora), in the Pliocene and early Pleistocene, to less mesothermal (Nothofagus subgenus Fuscospora and podocarp conifers) taxa in the middle and late Pleistocene reflect what have been detected in shorter onshore sections. Since assemblages are regional in origin, this suggests a gradual change from warm, humid, maybe cloudy conditions to a cooler, drier climate over time superimposed upon more intense glacial/interglacial cycles. The glacial periods in this marine setting have more Halocarpus, Phyllocladus, Nothofagus subgenus Fuscospora, and Coprosma pollen relative to the interglacials.Overall, the palynomorph assemblages are derived from regional podocarp/hardwood forest vegetation from the southern part of North Island, New Zealand, with pollen and spores from a range of terrestrial environments represented in all samples. Recycling has occurred but is difficult to quantify because of the great variation in the quality of preservation and the different sources and possible modes of transport of palynomorphs to the site of deposition.Angiosperm pollen are dominated by Nothofagus, but angiosperm pollen generally are relatively sparse, while robust spores such as Cyathea, and bisaccate pollen such as Podocarpus/Prumnopitys, with the ability to float great distances, are over-represented. This over-representation is the result of a constant supply of these taxa to the deposition site despite changes in the strength and direction of the wind and water currents over the depositional site, and changes in the vegetation, climate, and rates of erosion in source areas. A gradual decrease in the rate of extinction through the section occurs up to and within the Mid-Pleistocene Climate Transition with rare, probably recycled, extinct taxa appearing later than this. These extinctions provide a biostratigraphic link to the onshore terrestrial record, and the marine record has the potential to provide accurate dates for terrestrial extinctions.

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“…Similar fossil species from South Africa, described as P. parvus, also come from lowland subtropical forest situations quite unrelated to alpine or sub-alpine environments (Coetzee & Rogers 1982;Coetzee 1983;Coetzee & Muller 1983). In New Zealand, Podosporites species are regularly found in settings suggesting harsh paleoclimatic conditions (e.g., Mildenhall 1978;Mildenhall & Suggate 1982) but, again, are just as often associated with lowland beech/podocarp and hardwood/ podocarp forest pollen assemblages from the Miocene and Pliocene-Pleistocene (e.g., Nelson et al 1988;Mildenhall 2001a). Similarly, the combination of P. parvus in a lowland forest setting, along with Cupanieidites sp.…”

Section: Environmental Significancementioning

confidence: 99%

A redescription ofPodosporites parvus(Couper) Mildenhall emend. Mildenhall & Byrami from the Early Pleistocene, and late extinction of plant taxa in northern New Zealand

Mildenhall

Byrami

2003

New Zealand Journal of Botany

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Subsurface stratigraphy, paleoenvironments, palynology, and depositional history of the late Neogene Tauranga Group at Ohinewai, Lower Waikato Lowland, South Auckland, New Zealand

Abstract: At Ohinewai, South Auckland, New

Cited by 26 publications

References 14 publications

Petrified wood from the Miocene volcanic sequence of Coromandel Peninsula, northern New Zealand

Petrified wood from the Miocene volcanic sequence of Coromandel Peninsula, northern New Zealand

Deep‐sea record of Pliocene and Pleistocene terrestrial palynomorphs from offshore eastern New Zealand (ODP Site 1123, Leg 181)

A redescription ofPodosporites parvus(Couper) Mildenhall emend. Mildenhall & Byrami from the Early Pleistocene, and late extinction of plant taxa in northern New Zealand

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