A redetermination of the isotopic abundances of atmospheric Ar

Jeeyon, Lee; Marti, K.; Severinghaus, Jeffrey P.; Kawamura, Kenji; Yoo, Hyun-jung; Lee, Jin Bok; Kim, Jin Seog

doi:10.1016/j.gca.2006.06.1563

Cited by 1,061 publications

(671 citation statements)

References 11 publications

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“…Discrimination is monitored by analysing splits of atmospheric Ar from a reservoir attached to the extraction line and for these samples D1amu ¼ 1.007504±0.000279. All isotopic ratios are mass discrimination corrected using 40 35) is more precise, but acceptance is controversial and that ratio has no impact on this study because normalizing to a different value does not change the age 36 . Typical system blanks including mass spectrometer backgrounds were 1.5 Â 10 À 18 mol of m/z 36, 9 Â 10 À 17 mol of m/z 37, 3 Â 10 À 18 mol of m/z 39 and 1.5 Â 10 À 16 mol of m/z 40, where m/z is mass/ charge ratio.…”

Section: Methodsmentioning

confidence: 99%

Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology

et al. 2013

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As continental rift zones mature the tectonic and volcanic processes associated with crustal extension become confined to narrow magmatic rift zones, reminiscent of oceanic spreading ridges. The formation of these rift zones and the development of ocean-ridge type topography is a significant milestone in rift evolution as it signifies the localization of crustal extension and rift-related volcanism. Here we show that lavas, which erupted since B200 ka along part of the on-land Red Sea rift system in Afar, Ethiopia, have a consistent age-progression from the rift axis outwards, indicating that axial dyke intrusion has been the primary mechanism of segment growth and that focused magmatic accretion and extension in the crust have remained stable here over this period. Our results suggest that as this rift segment has formed, in thinned and intruded continental crust, the time-averaged surface opening rate has closely approximated the total extension rate between Africa and Arabia.

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Section: Methodsmentioning

confidence: 99%

Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology

et al. 2013

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“…Ratios listed in Table 2 were calculated under the assumption that the atmospheric 36 Ar/ 38 Ar = 5.305 (Lee et al, 2006). Interestingly, Genesis SW-Ar analyses agree better among themselves than the measurements of atmospheric 36 Ar/ 38 Ar (Mark et al, 2011 and Refs.…”

Section: Argonmentioning

confidence: 96%

“…Table 3 Argon released from PAC solar wind collector in 23-step UV laser ablation combined with subsequent pyrolysis of the laser-ablated area. Atmospheric contamination and blank were removed assuming both have isotopic composition of atmospheric argon (Lee et al, 2006). "R" indicates repeated extraction with the same laser power.…”

Section: Fig 10mentioning

confidence: 99%

Heavy noble gases in solar wind delivered by Genesis mission

Meshik

Hohenberg

Pravdivtseva

et al. 2014

Geochimica et Cosmochimica Acta

100

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One of the major goals of the Genesis Mission was to refine our knowledge of the isotopic composition of the heavy noble gases in solar wind and, by inference, the Sun, which represents the initial composition of the solar system. This has now been achieved with permil precision: 36 124 Xe/ 132 Xe = .00491 ± .00007 (error-weighted averages of all published data). The Kr and Xe ratios measured in the Genesis solar wind collectors generally agree with the less precise values obtained from lunar soils and breccias, which have accumulated solar wind over hundreds of millions of years, suggesting little if any temporal variability of the isotopic composition of solar wind krypton and xenon. The higher precision for the initial composition of the heavy noble gases in the solar system allows (1) to confirm that, exept 136 Xe and 134 Xe, the mathematically derived U-Xe is equivalent to Solar Wind Xe and (2) to provide an opportunity for better understanding the relationship between the starting composition and Xe-Q (and Q-Kr), the dominant current "planetary" component, and its host, the mysterious phase-Q.

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“…"Atm." indicates modern-day atmosphere (Lee et al, 2006). Uncertainties are two-sigma, and include the uncertainty in J and decay constants.…”

Section: Discussionmentioning

confidence: 99%

“…All data regression was undertaken in MassSpec version 8.131. Mass spectrometer discrimination was calculated per AMU using the power law, the average 40 Ar/ 36 Ar value from all air pipette analyses ( 40 Ar/ 36 Ar of 296.89 ± 0.99, 1 standard deviation, n = 85), and an atmospheric 40 Ar/ 36 Ar value of 298.56 ± 0.31 (Lee et al, 2006) which has been independently confirmed by Mark et al (2011). We have used the Alder Creek sanidine age of 1.1891 ± 0.0008 Ma (1σ uncertainty) (Niespolo et al, in press) and the potassium decay constants reported by Renne et al (2011).…”

Section: Methodsmentioning

confidence: 99%

Holocene-Neogene volcanism in northeastern Australia: Chronology and eruption history

Cohen

Mark

Fallon

et al. 2017

Quaternary Geochronology

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Quaternary and late Neogene volcanism is widespread in northeastern Australia, producing at least 397 eruptions covering more than 20,000 km 2 , including at least 20 flows over 50 km long. Despite this abundance of young volcanism, before this study numerous eruptions had tentative ages or were undated, and the area requires a comprehensive evaluation of eruption patterns through time. To help address these issues we applied multi-collector ARGUS-V 40 Ar/ 39 Ar geochronology to determine the age of four of the younger extensive flows: Undara (160 km long, 189 ± 4/4 ka; 2σ, with full analytical/external uncertainties), Murronga (40 km long, 153 ± 5/5 ka), Toomba (120 km long, 21 ± 3/3 ka), and Kinrara (55 km long, 7 ± 2/2 ka). Verbal traditions of the Gugu Badhun Aboriginal people contain features that may potentially describe the eruption of Kinrara. If the traditions do record this eruption, they would have been passed down for 230 ± 70 generations -a period of time exceeding the earliest written historical records. To further examine north Queensland volcanism through time we compiled a database of 337 ages, including 179 previously unpublished K-Ar and radiocarbon results. The compiled ages demonstrate that volcanic activity has occurred without major time breaks since at least 9 Ma. The greatest frequency of eruptions occurred in the last 2 Ma, with an average recurrence interval of <10-22 ka between eruptions. Activity was at at times likely more frequent than these calculations indicate, as the geochronologic dataset is incomplete, with undated eruptions, and intraplate volcanism is often episodic. The duration, frequency, and youthfulness of activity indicate that north Queensland volcanism should be considered as potentially still active, and there are now two confirmed areas of Holocene volcanism in eastern Australia -one at each end of the continent. More broadly, our data provides another example of 40 Ar/ 39 Ar geochronology applied to Holocene and latest Pleistocene mafic eruptions, further demonstrating that this method has the ability to examine eruptions and hazards at the youngest volcanoes on Earth.

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A redetermination of the isotopic abundances of atmospheric Ar

Cited by 1,061 publications

References 11 publications

Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology

Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology

Heavy noble gases in solar wind delivered by Genesis mission

Holocene-Neogene volcanism in northeastern Australia: Chronology and eruption history

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