New Zealand Journal of Geology and Geophysics abstracts

---

Holocene vegetation, environment, and tephra recorded from Lake Pupuke, Auckland, New Zealand

Mark Horrocks^1,2
Paul Augustinus^2,3
Yanbin Deng⁴
Phil Shane³
Sofia Andersson⁵

¹ Microfossil Research Ltd
31 Mont Le Grand Rd, Mt Eden
Auckland, New Zealand

²School of Geography & Environmental Science
University of Auckland
Private Bag 92 019
Auckland, New Zealand

³ Department of Geology
University of Auckland

⁴ School of Biological Sciences
University of Auckland

⁵ Earth Sciences Centre
Göteborg University
S-405 30
Göteborg, Sweden

Abstract  Lake Pupuke provides a near-complete, high-resolution environmental record of the Holocene from northern New Zealand. Tephra beds constrain the timing of a range of proxy indicators of environmental change, and demonstrate errors in a radiocarbon chronology. Agathis australis forest progressively increases from c. 7000 yr BP and, in conjunction with indicators of reduced biomass productivity, support a model of long-term climate change to drier conditions over the Holocene. However, except for Agathis, conifer-hardwood forest dominated mainly by Dacrydium cupressinum shows little change throughout the pre-human Holocene, suggesting environmental stability. Dramatic vegetation change occurred only within the last millennium as a result of large-scale Polynesian deforestation by fire. This happened a short time before the local eruption of c. 638 cal. yr BP Rangitoto Tephra. The identification of two eruptions of tephra from Rangitoto volcano has implications for future hazard planning in the Auckland region, because the volcanoes were previously considered single event centres. Changes in atmospheric circulation since the Late Glacial, possibly causing lower frequency of distal ashfall in Auckland during the Holocene, complicates the use of long-term records in hazard frequency assessment.

Keywords  palynology; tephrochronology; geochemistry; ¹⁴C dating; Holocene; Lake Pupuke; New Zealand

G04004; Received 16 January 2004; accepted 27 April 2004; Online publication date 23 March 2005
New Zealand Journal of Geology & Geophysics, 2005, Vol. 48: 85–94
0028–8306/05/4801–0085 © The Royal Society of New Zealand 2005

PDF file of entire paper: Print-quality (2044K) | screen-quality (470K)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page