On the relationships between the 40Ar-39Ar dating results and the conditions of basaltic samples.

Iwata, Naoyoshi; Kaneoka, Ichiro

doi:10.2343/geochemj.34.271

Cited by 18 publications

(2 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Accordingly, Ar-Ar methods for dating petit-spot volcanics were only successful for the holocrystalline rocks at Site A. This approach was also supported by Iwata and Kaneoka (2000), who concluded that fresh, holocrystalline rocks should be analyzed for precise Ar-Ar dating.…”

Section: Age Determinationsmentioning

confidence: 85%

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

Hirano

2011

Geochem. J.

View full text Add to dashboard Cite

Section: Age Determinationsmentioning

confidence: 85%

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

Hirano

2011

Geochem. J.

View full text Add to dashboard Cite

“…A review paper by Schaen et al (2021) addressed technical matters of irradiation, standards, monitors, and statistical treatment of data, but paid less attention to sample selection strategies, screening and sample preparation, and interpretation of "disturbed" age spectra. Many studies have noted that incremental heating 40 Ar/ 39 Ar analyses from whole rock or groundmass separates of fine-grained mafic rocks often do not yield straightforward plateaus (e.g., Fleck et al, 2014;Gans, 1997;Iwata & Kaneoka, 2000). While plausible explanations and recommendations for interpreting these "disturbed" spectra have been offered, rarely is a rigorous assessment made as to how potassium is actually distributed between various primary and secondary groundmass phases and how this might influence the resultant age interpretation.…”

Section: General Considerationsmentioning

confidence: 99%

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

Gans

Mortimer

Patriat

et al. 2023

Geochem Geophys Geosyst

View full text Add to dashboard Cite

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 >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.Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. Key Points► A major pulse of 25-22 Ma volcanism is documented on the Loyalty and Three Kings Ridges, southwest Pacific Ocean ► The ridges are part of a more than 3000 km long belt of Eocene to Miocene remnant volcanic arcs, stranded along the edge of Zealandia ► With care in sample selection, and petrological work, meaningful Ar/Ar ages can be obtained from altered and/or very low-K submarine basalts Plain Language SummarySamples 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.

show abstract

Polychronous (Early Cretaceous to Palaeogene) emplacement of the Mundwara alkaline complex, Rajasthan, India: 40Ar/39Ar geochronology, petrochemistry and geodynamics

Pande

Cucciniello

Sheth

et al. 2016

Int J Earth Sci (Geol Rundsch)

View full text Add to dashboard Cite

The Mundwara alkaline plutonic complex (Rajasthan, north-western India) is considered a part of the Late Cretaceous–Palaeogene Deccan Traps flood basalt province, based on geochronological data (mainly 40Ar/39Ar, on whole rocks, biotite and hornblende). We have studied the petrology and mineral chemistry of some Mundwara mafic rocks containing mica and amphibole. Geothermobarometry indicates emplacement of the complex at middle to upper crustal levels. We have obtained new 40Ar/39Ar ages of 80–84 Ma on biotite separates from mafic rocks and 102–110 Ma on whole-rock nepheline syenites. There is no evidence for excess 40Ar. The combined results show that some of the constituent intrusions of the Mundwara complex are of Deccan age, but others are older and unrelated to the Deccan Traps. The Mundwara alkaline complex is thus polychronous and similar to many alkaline complexes around the world that show recurrent magmatism, sometimes over hundreds of millions of years. The primary biotite and amphibole in Mundwara mafic rocks indicate hydrous parental magmas, derived from hydrated mantle peridotite at relatively low temperatures, thus ruling out a mantle plume. This hydration and metasomatism of the Rajasthan lithospheric mantle may have occurred during Jurassic subduction under Gondwanaland, or Precambrian subduction events. Low-degree decompression melting of this old, enriched lithospheric mantle, due to periodic diffuse lithospheric extension, gradually built the Mundwara complex from the Early Cretaceous to Palaeogene time

show abstract

On the relationships between the 40Ar-39Ar dating results and the conditions of basaltic samples.

Cited by 18 publications

References 11 publications

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

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

Polychronous (Early Cretaceous to Palaeogene) emplacement of the Mundwara alkaline complex, Rajasthan, India: 40Ar/39Ar geochronology, petrochemistry and geodynamics

Contact Info

Product

Resources

About

On the relationships between the 40Ar-39Ar dating results and the conditions of basaltic samples.

Cited by 18 publications

References 11 publications

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

Petit-spot volcanism: A new type of volcanic zone discovered near a trench

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

Polychronous (Early Cretaceous to Palaeogene) emplacement of the Mundwara alkaline complex, Rajasthan, India: 40Ar/39Ar geochronology, petrochemistry and geodynamics

Contact Info

Product

Resources

About

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