New Zealand Journal of Geology and Geophysics abstracts

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Late Quaternary evolution of the Rotoaira Basin, northern Tongariro ring plain, New Zealand

Jérôme A. Lecointre*
Vincent E. Neall
R. Cleland Wallace

Soil and Earth Sciences - Institute of Natural Resources
Massey University - Turitea Campus PN 432
Private Bag 11 222
Palmerston North, New Zealand
*email: J.A.Lecointre@massey.ac.nz

Mike B. Elliot

Whangarei Boys’ High School
P.O. 5034 - Regent
Whangarei, New Zealand

Rodger Sparks

Rafter Radiocarbon Laboratory
Institute of Geological & Nuclear Sciences
P.O. Box 31 312
Lower Hutt, New Zealand

Abstract  The last 100 000 yr record of volcaniclastic sedimentation in the Rotoaira Basin reflects the critical role played by tectonic and eruptive activity that led to: (1) the catastrophic emplacement of Te Whaiau Formation (60-55 ka); (2) major episodes of effusive activity (c. 30 ka and c. 15 ka); and (3) syn- and post-eruptive lahar aggradation on the shores of Lake Rotoaira. Stratigraphic unconformities, fluvial and aeolian reworking, and subsequent volcanogenic sedimentation indicate that climate change driven periods of erosion contributed significantly to the evolution of the landscape during the late Quaternary.

Waters that accumulated in a newly expanded graben formed Lake Rotoaira. An attempt to core through the sediments on the lake’s floor revealed a >6.5 m thick mantling of Taupo ignimbrite, restricting chronostratigraphic sampling to the last 1.85 ka. Lake Rotoaira pollen profiles record: (1) the destruction of the indigenous forest by the Taupo ignimbrite eruption; (2) the following period of vegetation recovery (c. 300 yr); and (3) periods of human occupation of the lakeshores (bracken spores and Pinus pollen) in the younger sediments. Coarse sand generated by the 1995-96 tephra-producing Ruapehu eruptions also contributed to the recent lake sedimentation.

Keywords  Rotoaira; Tongariro ring plain; volcaniclastic sedimentation; Quaternary; New Zealand

G03036; Received 25 January 2003; accepted 22 August 2003; Online publication date 7 September 2004
New Zealand Journal of Geology & Geophysics, 2004, Vol. 47: 549-565
0028-8306/04/4703-0549 © The Royal Society of New Zealand 2004

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