New Zealand Journal of Geology and Geophysics abstracts

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Holocene and late Last Glaciation pollen record from drillholes at Miramar and Lambton Harbour, Wellington, New Zealand

D. C. MILDENHALL

Institute of Geological and Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand.

Abstract Pollen and spores obtained from condensed late Last Glaciation sequences of carbonaceous silts, with occasional gravel and peat horizons, from drillholes at Miramar and Lambton Harbour, Wellington, indicate a bleak, windswept, grassland/shrubland environment dominated by Poaceae. The dominant tree pollen type is Phyllocladus, probably P. alpinus. The 50.7 m thick Miramar sequence contains the Kawakawa Tephra at 24.5 m below ground level; this tephra was also identified in the field 16-17 m below ground level in two of the Lambton Harbour drillholes, the deepest of which went to 40 m. A disconformity exists between the late Last Glaciation sediments deposited immediately after deposition of the Kawakawa Tephra and the onset of Holocene sedimentation. This disconformity occurs in most sequences of this age in the Wellington area and is caused by unstable climatic and depositional conditions at the time. Recycling of spores, pollen, and dinoflagellates from Late Cretaceous and Cenozoic sediments occurs at both localities. It is inferred that sediments of this age were being locally eroded during the deposition of both Last Glaciation and Holocene sediments. No sediments of corresponding age range crop out close to Wellington today.
Holocene spores and pollen at Miramar indicate warm, moist, frost-free conditions during which time podocarp forest dominated by Podocarpus, Prumnopitys, and Dacrydium cupressinum existed. The spores Bryosporis problematicus (Couper) and B. anisopolaris Mildenhall & Bussell occur at Miramar in the Holocene and are now regarded as fossil representatives of two modern species of an unidentified bryophyte.

Keywords pollen analysis; pollen diagrams; radiocarbon dates; Pleistocene; Holocene; Last Glaciation; Kawakawa Tephra; Miramar; Lambton Harbour; Wellington; Sheet R27; paleoclimate; paleoenvironments; recycled palynomorphs

Received 26 November 1992; published 14 September 1993
New Zealand Journal of Geology & Geophysics, 1991, Vol. 36: 349—356
0028Ð8306/06/3603—0349 ©The Royal Society of New Zealand 1991

PDF file of entire paper: medium quality (859K); (scanned from paper original: notes about this process). Digitisation of this article from the printed journal was kindly facilitated by the Geological Society of New Zealand

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