Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs
Abstract The 2015 VESPA voyage (Volcanic Evolution of South Pacific Arcs) was a seismic and rock dredging expedition to the Loyalty and Three Kings Ridges and South Fiji Basin. In this paper we present 33 40Ar/39Ar, 22 micropaleontological, and two U/Pb ages for igneous and sedimentary rocks from 33...
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| Format: | Article |
| Language: | English |
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Wiley
2023-02-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2022GC010670 |
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| author | P. B. Gans N. Mortimer M. Patriat R. E. Turnbull M. P. Crundwell A. Agranier A. T. Calvert G. Seward S. Etienne P. M. J. Durance H. J. Campbell J. Collot |
| author_facet | P. B. Gans N. Mortimer M. Patriat R. E. Turnbull M. P. Crundwell A. Agranier A. T. Calvert G. Seward S. Etienne P. M. J. Durance H. J. Campbell J. Collot |
| author_sort | P. B. Gans |
| collection | DOAJ |
| description | Abstract The 2015 VESPA voyage (Volcanic Evolution of South Pacific Arcs) was a seismic and rock dredging expedition to the Loyalty and Three Kings Ridges and South Fiji Basin. In this paper we present 33 40Ar/39Ar, 22 micropaleontological, and two U/Pb ages for igneous and sedimentary rocks from 33 dredge sites in this little‐studied part of the southwest Pacific Ocean. Igneous rocks include basalts, dolerites, basaltic andesites, trachyandesites, and a granite. Successful Ar/Ar dating of altered and/or low‐K basalts was achieved through careful sample selection and processing, detailed petrographic and element mapping of groundmass, and incremental heating experiments on both phenocryst and groundmass separates to interpret the complex spectra produced by samples having multiple K reservoirs. The 40Ar/39Ar ages of most of the sampled lavas, irrespective of composition, are latest Oligocene to earliest Miocene (25–22 Ma); two are Eocene (39–36 Ma). The granite has a U/Pb zircon age of 23.6 ± 0.3 Ma. 40Ar/39Ar lava ages are corroborated by microfossil ages from associated sedimentary rocks. The VESPA lavas are part of a >3,000 km long disrupted belt of Eocene to Miocene subduction‐related volcanic rocks. The belt includes arc rocks in Northland New Zealand, Northland Plateau, Three Kings Ridge, and Loyalty Ridge and, speculatively, D’Entrecasteaux Ridge. This belt is the product of superimposed Eocene and Oligocene‐Miocene remnant volcanic arcs that were stranded along and near the edge of Zealandia while still‐active arc belts migrated east with the Pacific trench. |
| first_indexed | 2024-03-11T12:58:16Z |
| format | Article |
| id | doaj.art-2b5f939c99254d0e8e08d22bfbc5424f |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:58:16Z |
| publishDate | 2023-02-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-2b5f939c99254d0e8e08d22bfbc5424f2023-11-03T16:55:39ZengWileyGeochemistry, Geophysics, Geosystems1525-20272023-02-01242n/an/a10.1029/2022GC010670Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic ArcsP. B. Gans0N. Mortimer1M. Patriat2R. E. Turnbull3M. P. Crundwell4A. Agranier5A. T. Calvert6G. Seward7S. Etienne8P. M. J. Durance9H. J. Campbell10J. Collot11University of California Santa Barbara CA USAGNS Science Dunedin New ZealandCNRS Ifremer Geo‐Ocean University of Brest Plouzané FranceGNS Science Dunedin New ZealandGNS Science Lower Hutt New ZealandCNRS Ifremer Geo‐Ocean University of Brest Plouzané FranceU.S. Geological Survey Menlo Park CA USAUniversity of California Santa Barbara CA USAService Géologique de Nouvelle Calédonie Nouméa New CaledoniaGNS Science Lower Hutt New ZealandGNS Science Lower Hutt New ZealandService Géologique de Nouvelle Calédonie Nouméa New CaledoniaAbstract The 2015 VESPA voyage (Volcanic Evolution of South Pacific Arcs) was a seismic and rock dredging expedition to the Loyalty and Three Kings Ridges and South Fiji Basin. In this paper we present 33 40Ar/39Ar, 22 micropaleontological, and two U/Pb ages for igneous and sedimentary rocks from 33 dredge sites in this little‐studied part of the southwest Pacific Ocean. Igneous rocks include basalts, dolerites, basaltic andesites, trachyandesites, and a granite. Successful Ar/Ar dating of altered and/or low‐K basalts was achieved through careful sample selection and processing, detailed petrographic and element mapping of groundmass, and incremental heating experiments on both phenocryst and groundmass separates to interpret the complex spectra produced by samples having multiple K reservoirs. The 40Ar/39Ar ages of most of the sampled lavas, irrespective of composition, are latest Oligocene to earliest Miocene (25–22 Ma); two are Eocene (39–36 Ma). The granite has a U/Pb zircon age of 23.6 ± 0.3 Ma. 40Ar/39Ar lava ages are corroborated by microfossil ages from associated sedimentary rocks. The VESPA lavas are part of a >3,000 km long disrupted belt of Eocene to Miocene subduction‐related volcanic rocks. The belt includes arc rocks in Northland New Zealand, Northland Plateau, Three Kings Ridge, and Loyalty Ridge and, speculatively, D’Entrecasteaux Ridge. This belt is the product of superimposed Eocene and Oligocene‐Miocene remnant volcanic arcs that were stranded along and near the edge of Zealandia while still‐active arc belts migrated east with the Pacific trench.https://doi.org/10.1029/2022GC010670SW Pacifictectonicsgeochronologysubductionvolcanic arcsCenozoic |
| spellingShingle | P. B. Gans N. Mortimer M. Patriat R. E. Turnbull M. P. Crundwell A. Agranier A. T. Calvert G. Seward S. Etienne P. M. J. Durance H. J. Campbell J. Collot Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs Geochemistry, Geophysics, Geosystems SW Pacific tectonics geochronology subduction volcanic arcs Cenozoic |
| title | Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs |
| title_full | Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs |
| title_fullStr | Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs |
| title_full_unstemmed | Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs |
| title_short | Detailed 40Ar/39Ar Geochronology of the Loyalty and Three Kings Ridges Clarifies the Extent and Sequential Development of Eocene to Miocene Southwest Pacific Remnant Volcanic Arcs |
| title_sort | detailed 40ar 39ar geochronology of the loyalty and three kings ridges clarifies the extent and sequential development of eocene to miocene southwest pacific remnant volcanic arcs |
| topic | SW Pacific tectonics geochronology subduction volcanic arcs Cenozoic |
| url | https://doi.org/10.1029/2022GC010670 |
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