2019
DOI: 10.1029/2018gc007697
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Dating Clinopyroxene Phenocrysts in Submarine Basalts Using 40Ar/39Ar Geochronology

Abstract: Dating submarine basalts using 40 Ar/ 39 Ar geochronology is often hindered by a lack of potassium-bearing phenocrystic phases and severe alteration in the groundmass. Clinopyroxene is a common phenocrystic phase in seafloor basalts and is highly resistive to low-temperature alteration. Here we show that clinopyroxene phenocrysts separated from marine basalts are a viable phase for 40 Ar/ 39 Ar incremental heating age determinations. We provide results from a pilot study comprising 16 age experiments from nine… Show more

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Cited by 9 publications
(3 citation statements)
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“…2). Moreover, analyses of low-K phases such as latest Pleistocene plagioclase phenocrysts (e.g., Carrasco-Nuñez et al, 2018) and Cenozoic pyroxene (e.g., Ware and Jourdan, 2018;Konrad et al, 2019) are now feasible. Higher precision on smaller and younger detrital grains is improving our understanding of progressive, grain size-specific detrital signal dilution in rivers, and our ability to provide robust provenance signals obtained for sediments located many hundreds of kilometers away from their source rocks (e.g., Blewett et al, 2019;Gemignani et al, 2019;Hereford et al, 2016).…”
Section: Modern Magnetic Sector Mass Spectrometrymentioning
confidence: 99%
See 1 more Smart Citation
“…2). Moreover, analyses of low-K phases such as latest Pleistocene plagioclase phenocrysts (e.g., Carrasco-Nuñez et al, 2018) and Cenozoic pyroxene (e.g., Ware and Jourdan, 2018;Konrad et al, 2019) are now feasible. Higher precision on smaller and younger detrital grains is improving our understanding of progressive, grain size-specific detrital signal dilution in rivers, and our ability to provide robust provenance signals obtained for sediments located many hundreds of kilometers away from their source rocks (e.g., Blewett et al, 2019;Gemignani et al, 2019;Hereford et al, 2016).…”
Section: Modern Magnetic Sector Mass Spectrometrymentioning
confidence: 99%
“…(5) 40 Ar/ 39 Ar analysis of nontraditional phases: Recent advances in our understanding of 40 Ar diffusion in minerals not traditionally used in 40 Ar/ 39 Ar chronometry, coupled with analytical advances that permit analysis of minerals that are poor in potassium, are rapidly expanding the spectrum of geologic questions that can be addressed. For example, 40 Ar diffusion data for pyroxenes (Cassata et al, 2011) provide new opportunities to use these minerals for the 40 Ar/ 39 Ar dating of mafic and ultramafic rocks (Ware and Jourdan, 2018;Konrad et al, 2019;Zi et al, 2019) and may provide more robust indications of the crystallization ages for weakly metamorphosed or hydrothermally altered samples than more familiar 40 Ar/ 39 Ar chronometers. The 40 Ar/ 39 Ar analyses of K-rich metasomatic and hydrothermal alteration phases (e.g., alunite, jarosite; Vasconcelos et al, 1994;Ren and Vasconcelos, 2019b) and 40 Ar/ 39 Ar dating of fluid inclusions via mechanical crushing (e.g., Xiao et al 2019) have become more commonplace.…”
Section: Remaining Challenges and Future Directions In 40 Ar/ 39 Ar Gmentioning
confidence: 99%
“…Using the trapped 40 Ar/ 36 Ar composition from the inverse isochron, a slightly more precise plateau age of 77.63 ± 0.30 Ma (1; MSWD = 0.89) was calculated for the same steps. The supra-atmospheric 40 Ar/ 36 Ar initial ratios in low-K minerals such as pyroxene have been related to the incorporation of fluids, melts, or minerals at the time of crystallization (e.g., Kelley, 2002;Konrad et al, 2019). In the analyzed sample, this seems to be supported by the increase in Ca/K ratios that yield older apparent ages in lowtemperature steps and in intermediate to high-temperature steps of the age spectrum (Supplementary File 5).…”
Section: Ar-ar Geochronology In Pyroxene From Leucogabbro Pva 19-2mentioning
confidence: 88%