Argon/Argon, micropaleontological and Uranium/Lead geochronological data for igneous and sedimentary rocks dredged during the VESPA scientific cruise

Date 2023-01-02
Author(s) Gans Phil BORCID1, Mortimer NickORCID2, Patriat MartinORCID3, Turnbull Rose E2, Crundwell MartinORCID4, Agranier Arnaud3, Calvert Andrew5, Seward Gareth1, Etienne SamuelORCID6, Durance Patricia Mj4, Campbell Hugh J4, Collot JulienORCID6
Affiliation(s) 1 : University of California, Santa Barbara, CA, USA
2 : GNS Science, Dunedin, New Zealand
3 : Univ Brest, CNRS, Ifremer, Geo-Ocean, F-29280 Plouzané, France
4 : GNS Science, Lower Hutt, New Zealand
5 : U.S. Geological Survey, Menlo Park, CA, USA
6 : Service Géologique de Nouvelle Calédonie, Nouméa, New Caledonia
DOI 10.17882/89740
Publisher SEANOE
Keyword(s) Southwest Pacific, New Zealand, New Caledonia, Igneous rocks, Sedimentary rocks, Ar/Ar geochronology, U/Pb geochronology, Micropaleontology, Geochemistry, Volcanic arc, Subduction, Tectonics, Cretaceous, Eocene, Oligocene, Miocene
Abstract

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 our 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 >3000 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.

Plain word summary: Samples of lava from the seabed between New Zealand and New Caledonia have been dated using atomic clocks and fossils. Most lavas erupted in a big pulse of volcanic activity between 25 and 22 million years ago. They are part of a belt of now-extinct undersea volcanoes that stretches for more than 3000 km between New Zealand and the Solomon Islands. These volcanoes were formed by subduction of the Pacific Plate under the Australian Plate.

Licence CC-BY
Data
File Size Format Processing Access
VESPA Dating Study Supp File 2: Thin section images of Ar/Ar dated samples 18 MB PDF Processed data Open access
VESPA Dating Study Supp File 3: Electron Microprobe Work 10 MB PDF Processed data Open access
VESPA Dating Study Supp File 8: Biostratigraphy Crundwell et al. (2016) 1 MB PDF Open access
VESPA Dating Study Supp File 0: Supplemental files header and general information 15 KB DOC, DOCX Open access
VESPA Dating Study Supp File 5: Petrography and Ar/Ar dating Summary 89 KB PDF Open access
VESPA Dating Study Supp File 6: Ar-Ar raw data 3 MB PDF Raw data Open access
VESPA Dating Study Supp File 4: Petrographic observations, photomicrographs, K and Ca element maps, mineral and K reservoir modes, argon spectra and interpretive comments for eight VESPA samples 3 MB PDF Quality controlled data Open access
VESPA Dating Study Supp File 0: Supplemental files header and general information 1 KB TEXTE Open access
VESPA Dating Study Supp File 7: Zircon cathodoluminescence images and U-Pb data 1000 KB XLS, XLSX Processed data Open access
VESPA Dating Study Supp File 1: Analytical Methods 137 KB PDF Open access
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How to cite 

Gans Phil B, Mortimer Nick, Patriat Martin, Turnbull Rose E, Crundwell Martin, Agranier Arnaud, Calvert Andrew, Seward Gareth, Etienne Samuel, Durance Patricia Mj, Campbell Hugh J, Collot Julien (2023). Argon/Argon, micropaleontological and Uranium/Lead geochronological data for igneous and sedimentary rocks dredged during the VESPA scientific cruise. SEANOE. https://doi.org/10.17882/89740