Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand

Abstract

Research Article| September 01, 2014 Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand D.T. Downs; D.T. Downs † 1School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand †E-mail: d.downs@auckland.ac.nz. Search for other works by this author on: GSW Google Scholar C.J.N. Wilson; C.J.N. Wilson 2School of Geography, Environment, and Earth Sciences, Victoria University, P.O. Box 600, Wellington 6140, New Zealand Search for other works by this author on: GSW Google Scholar J.W. Cole; J.W. Cole 3Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand Search for other works by this author on: GSW Google Scholar J.V. Rowland; J.V. Rowland 1School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand Search for other works by this author on: GSW Google Scholar A.T. Calvert; A.T. Calvert 4U.S. Geological Survey, Volcano Science Center, 345 Middlefield Road, Menlo Park, California 94025, USA Search for other works by this author on: GSW Google Scholar G.S. Leonard; G.S. Leonard 5GNS Science, P.O. Box 30368, Lower Hutt 5035, New Zealand Search for other works by this author on: GSW Google Scholar J.M. Keall J.M. Keall 6First Australian Resources Limited, 530 Collins Street, Melbourne, Victoria 3000, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information D.T. Downs † 1School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand C.J.N. Wilson 2School of Geography, Environment, and Earth Sciences, Victoria University, P.O. Box 600, Wellington 6140, New Zealand J.W. Cole 3Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand J.V. Rowland 1School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand A.T. Calvert 4U.S. Geological Survey, Volcano Science Center, 345 Middlefield Road, Menlo Park, California 94025, USA G.S. Leonard 5GNS Science, P.O. Box 30368, Lower Hutt 5035, New Zealand J.M. Keall 6First Australian Resources Limited, 530 Collins Street, Melbourne, Victoria 3000, Australia †E-mail: d.downs@auckland.ac.nz. Publisher: Geological Society of America Received: 20 Mar 2013 Revision Received: 25 Feb 2014 Accepted: 13 Mar 2014 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2014 Geological Society of America GSA Bulletin (2014) 126 (9-10): 1131–1144. https://doi.org/10.1130/B30891.1 Article history Received: 20 Mar 2013 Revision Received: 25 Feb 2014 Accepted: 13 Mar 2014 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D.T. Downs, C.J.N. Wilson, J.W. Cole, J.V. Rowland, A.T. Calvert, G.S. Leonard, J.M. Keall; Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand. GSA Bulletin 2014;; 126 (9-10): 1131–1144. doi: https://doi.org/10.1130/B30891.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract We here explore the temporal and spatial relationships between the contrasting sources for two eruptive episodes that collectively represent the Whakamaru Group, the largest ignimbrite-forming sequence in the ∼2 m.y. history of the Taupo Volcanic Zone in New Zealand. At 349 ± 4 ka (weighted mean at 2σ), the >1500 km3 widespread Whakamaru Group ignimbrites and ∼700 km3 Rangitawa Tephra fallout were erupted in association with collapse of the 40 km long by 25 km wide rectilinear Whakamaru caldera. New 40Ar/39Ar age data presented here show that the co-magmatic >110 km3 Paeroa Subgroup ignimbrites, previously included as part of the Whakamaru Group, are slightly younger and were erupted at 339 ± 5 ka (weighted mean at 2σ). New field evidence also presented here demonstrates that the Paeroa Subgroup ignimbrites came from a source geographically separated from vents for the widespread Whakamaru Group ignimbrites. The presence of co-ignimbrite lag breccias, sizes of vent-derived lithic clasts, thicknesses of exposed and subsurface deposits, and morphologies of deposits imply that eruptions of the Paeroa Subgroup occurred from a linear source (the Paeroa linear vent zone), coinciding with the present-day northeast-striking Paeroa fault, and outside (northeast) of the earlier Whakamaru caldera collapse area. No separate caldera has been recognized, although three nearby areas may have undergone eruption-related subsidence. Residual magma from the Whakamaru or adjacent Kapenga caldera areas may have migrated toward the Paeroa linear vent zone during eruptive episodes, resulting in subsidence in either, or both, of these areas. Shallow plutons are also inferred to lie beneath near source fault blocks (Paeroa and Te Weta) on each side of the fault, and eruption-related subsidence may have been expressed as movement across the Paeroa fault and localized subsidence in the southern Paeroa fault block. Subsequent secular, rift-related displacement along the Paeroa fault has obscured the Paeroa linear vent zone. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.