New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup
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...
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Online Access: | http://hdl.handle.net/1885/22254 https://doi.org/10.1130/G22168.1 https://openresearch-repository.anu.edu.au/bitstream/1885/22254/5/Mortimer%2BGSA%2Bet%2Bal.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/22254/7/01_Mortimer_New_constraints_on_the_age_and_2006.pdf.jpg |
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/22254 2024-01-14T10:02:16+01:00 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 http://hdl.handle.net/1885/22254 https://doi.org/10.1130/G22168.1 https://openresearch-repository.anu.edu.au/bitstream/1885/22254/5/Mortimer%2BGSA%2Bet%2Bal.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/22254/7/01_Mortimer_New_constraints_on_the_age_and_2006.pdf.jpg unknown Geological Society of America Inc 0091-7613 http://hdl.handle.net/1885/22254 doi:10.1130/G22168.1 https://openresearch-repository.anu.edu.au/bitstream/1885/22254/5/Mortimer%2BGSA%2Bet%2Bal.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/22254/7/01_Mortimer_New_constraints_on_the_age_and_2006.pdf.jpg Geology Keywords: Cretaceous Gondwana Microplates Wishbone Ridge Basalt Geochemistry Geochronology Granite Rocks Tectonics Structural geology continental breakup Cretaceous Pacific Ocean Cretaceous Dating Southwest Pacific Journal article ftanucanberra https://doi.org/10.1130/G22168.1 2023-12-15T09:38:21Z 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 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. Article in Journal/Newspaper Antarc* Antarctica West Antarctica Australian National University: ANU Digital Collections West Antarctica Pacific Wishbone Ridge ENVELOPE(-166.933,-166.933,-84.933,-84.933) Geology 34 3 185 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: Cretaceous Gondwana Microplates Wishbone Ridge Basalt Geochemistry Geochronology Granite Rocks Tectonics Structural geology continental breakup Cretaceous Pacific Ocean Cretaceous Dating Southwest Pacific |
spellingShingle |
Keywords: Cretaceous Gondwana Microplates Wishbone Ridge Basalt Geochemistry Geochronology Granite Rocks Tectonics Structural geology continental breakup Cretaceous Pacific Ocean Cretaceous Dating Southwest Pacific Mortimer, N Hoernle, K Hauff, F Palin, J Dunlap, William James Werner, Roberto Faure, K New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
topic_facet |
Keywords: Cretaceous Gondwana Microplates Wishbone Ridge Basalt Geochemistry Geochronology Granite Rocks Tectonics Structural geology continental breakup Cretaceous Pacific Ocean Cretaceous Dating Southwest Pacific |
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 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. |
format |
Article in Journal/Newspaper |
author |
Mortimer, N Hoernle, K Hauff, F Palin, J Dunlap, William James Werner, Roberto Faure, K |
author_facet |
Mortimer, N Hoernle, K Hauff, F Palin, J Dunlap, William James Werner, Roberto Faure, K |
author_sort |
Mortimer, N |
title |
New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
title_short |
New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
title_full |
New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
title_fullStr |
New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
title_full_unstemmed |
New constraints on the age and evolution of the Wishbone Ridge, southwest Pacific Cretaceous microplates, and Zealandia-West Antarctica breakup |
title_sort |
new constraints on the age and evolution of the wishbone ridge, southwest pacific cretaceous microplates, and zealandia-west antarctica breakup |
publisher |
Geological Society of America Inc |
url |
http://hdl.handle.net/1885/22254 https://doi.org/10.1130/G22168.1 https://openresearch-repository.anu.edu.au/bitstream/1885/22254/5/Mortimer%2BGSA%2Bet%2Bal.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/22254/7/01_Mortimer_New_constraints_on_the_age_and_2006.pdf.jpg |
long_lat |
ENVELOPE(-166.933,-166.933,-84.933,-84.933) |
geographic |
West Antarctica Pacific Wishbone Ridge |
geographic_facet |
West Antarctica Pacific Wishbone Ridge |
genre |
Antarc* Antarctica West Antarctica |
genre_facet |
Antarc* Antarctica West Antarctica |
op_source |
Geology |
op_relation |
0091-7613 http://hdl.handle.net/1885/22254 doi:10.1130/G22168.1 https://openresearch-repository.anu.edu.au/bitstream/1885/22254/5/Mortimer%2BGSA%2Bet%2Bal.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/22254/7/01_Mortimer_New_constraints_on_the_age_and_2006.pdf.jpg |
op_doi |
https://doi.org/10.1130/G22168.1 |
container_title |
Geology |
container_volume |
34 |
container_issue |
3 |
container_start_page |
185 |
_version_ |
1788057192370274304 |