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New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup

Mortimer, N; Hoernle, K; Hauff, F; Palin, J; Dunlap, William James; Werner, Roberto; Faure, K

Description

We present analytical results from four dredge locations across the eastern Zealandia continental margin and adjacent ocean crust. The 115 Ma dacites dredged from the West Wishbone Ridge (WWR) are isotopically primitive, weakly adakitic, slabderived lavas. The 97 Ma A-type granites and a basalt from the easternmost Chatham Rise enlarge the known area of postsubduction Gondwana magmatism. Amphibolite-grade schists from a fault block south of the Chatham Rise provide a critical bridge between the...[Show more]

dc.contributor.authorMortimer, N
dc.contributor.authorHoernle, K
dc.contributor.authorHauff, F
dc.contributor.authorPalin, J
dc.contributor.authorDunlap, William James
dc.contributor.authorWerner, Roberto
dc.contributor.authorFaure, K
dc.date.accessioned2015-12-07T22:28:09Z
dc.identifier.issn0091-7613
dc.identifier.urihttp://hdl.handle.net/1885/22254
dc.description.abstractWe present analytical results from four dredge locations across the eastern Zealandia continental margin and adjacent ocean crust. The 115 Ma dacites dredged from the West Wishbone Ridge (WWR) are isotopically primitive, weakly adakitic, slabderived lavas. The 97 Ma A-type granites and a basalt from the easternmost Chatham Rise enlarge the known area of postsubduction Gondwana magmatism. Amphibolite-grade schists from a fault block south of the Chatham Rise provide a critical bridge between the Zealandia and West Antarctica belts of Jurassic-Cretaceous accretionary prism rocks. The new recognition of the WWR as a remnant of a 115 Ma intraoceanic subduction system means that previous hypotheses of the WWR as a fracture zone or spreading ridge require modification. The dacite ages constrain the start of Osbourn Trough spreading, which caused breakup of the Hikurangi-Manihiki igneous plateau, to before 115 Ma. We speculate that, after 115 Ma, the WWR was rifted by an intraoceanic spreading center that developed along its southeast side. Impingement of this spreading center against the Gondwana margin led to widespread 95-100 Ma postsubduction magmatism, variable lithospheric stretching, and ultimately continental splitting of Zealandia and West Antarctica across basement trends.
dc.publisherGeological Society of America Inc
dc.sourceGeology
dc.subjectKeywords: Cretaceous; Gondwana; Microplates; Wishbone Ridge; Basalt; Geochemistry; Geochronology; Granite; Rocks; Tectonics; Structural geology; continental breakup; Cretaceous; Pacific Ocean Cretaceous; Dating; Geochemistry; Gondwana; Southwest Pacific; Tectonics
dc.titleNew constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume34
dc.date.issued2006
local.identifier.absfor040303 - Geochronology
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationu9503261xPUB20
local.type.statusPublished Version
local.contributor.affiliationMortimer, N, Institute of Geological and Nuclear Sciences
local.contributor.affiliationHoernle, K, Institute for Marine Sciences
local.contributor.affiliationHauff, F, Institute for Marine Sciences
local.contributor.affiliationPalin, J, University of Otago
local.contributor.affiliationDunlap, William James, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationWerner, Roberto, Tethys Geoconsulting
local.contributor.affiliationFaure, K, Institute of Geological and Nuclear Sciences
local.description.embargo2037-12-31
local.bibliographicCitation.issue3
local.bibliographicCitation.startpage185
local.bibliographicCitation.lastpage188
local.identifier.doi10.1130/G22168.1
dc.date.updated2015-12-07T10:01:27Z
local.identifier.scopusID2-s2.0-33645214934
CollectionsANU Research Publications

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