Offshore-onshore correlation of Pleistocene rhyolitic eruptions from New Zealand; implications for TVZ eruptive history and paleoenvironmental construction

Author(s): Alloway, Brent V.; Carter, Lionel; Westgate, John; Pillans, Brad; Naish, Tim
Author Affiliation(s): Primary:
Institute of Geology and Nuclear Sciences, Wairakei Research Centre, Taupo, New Zealand
National Institute of Water and Atmospheric Research, New Zealand
University of Toronto, Canada
Australian National University, Australia
Volume Title: XVI INQUA congress; shaping the Earth, a Quaternary perspective
Source: International Union for Quaternary Research [Congress of the International Union for Quaternary Research, Vol.16, p.204-205; XVI INQUA congress; shaping the Earth, a Quaternary perspective, Reno, NV, July 23-30, 2003. Publisher:], International
Note: In English
Summary: Deep-sea cores retrieved from Ocean Drilling Program sites 1123 and 1124, located east of New Zealand, have provided an unpreceded 12 m.y. record of major rhyolitic eruptions from the Coromandel (CVZ) and Taupo Volcanic Zones (TVZ). A total of 197 macroscopic tephras have been dated by a combination of magnetostratigraphy, orbitally tuned stable-isotope data and isothermal plateau fission track ages. The widespread occurrence of ash offshore to the east of New Zealand is favoured by the small size of New Zealand, the explosivity of the mainly plinian and ignimbritic eruptions and vigorous prevailing westerly winds. In cores 1124 and 1123, c. 100 tephra beds are recognised post-dating the Plio-Pleistocene boundary at 1.81 Ma. Though some tephras can be directly attributed to known TVZ eruptions, there are many more tephras represented with the ODP-cores that have yet to be recognised in near-source sequences. This can be attributed to proximal source area erosion and/or deep burial as well as the adverse effect of vapour phase alteration and devitrification within near-source welded ignimbrites. Despite these difficulties, a number of key deep-sea tephras can be reliably correlated to equivalent-aged tephra exposed in uplifted marine back arc successions of Wanganui Basin where an excellent chronology also exists based on magnetostratigraphy, orbitally tuned stable-isotope data and isothermal plateau fission track ages. Significant Pleistocene tephra markers include: Kawakawa, Rangitawa, Onepuhi, Kupe, Kaukatea, Potaka, Ridge, Pakihikura, Birdgrove, Ototoka, Table Flat and Vinegar Hill Tephras. The identification of these Pleistocene TVZ-sourced tephras within the ODP-cores, and their correlation to Wanganui Basin is a significant advance for two reasons. Firstly, it provides an even higher-resolution history of the TVZ than can be currently achieved from the near-source record and secondly, it yields a detailed and reliable tephrochronologic framework essential for future paleoenvironmental reconstructions.
Year of Publication: 2003
Research Program: ODP Ocean Drilling Program
Key Words: 05 Petrology, Igneous and Metamorphic; 24 Surficial Geology, Quaternary Geology; Australasia; Back-arc basins; Basins; Cenozoic; Cores; Coromandel Peninsula; Coromandel volcanic zone; Eruptions; Fission-track dating; Geochronology; Igneous rocks; Ignimbrite; Leg 181; Magnetostratigraphy; Marker beds; Miocene; Neogene; New Zealand; North Island; ODP Site 1123; ODP Site 1124; Ocean Drilling Program; Offshore; Onshore; Paleoenvironment; Paleogeography; Pleistocene; Plinian-type eruptions; Pyroclastics; Quaternary; Reconstruction; Relative age; Rhyolites; Rhyolitic composition; Stratigraphic units; Taupo volcanic zone; Tephrochronology; Tertiary; Volcanic ash; Volcanic rocks; Volcanism; Wanganui Basin
Coordinates: S414710 S414710 W1712956 W1712956
S392954 S392954 W1763154 W1763154
Record ID: 2007026872
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Desert Research Institute, Reno, NV, United States