Universals and the Diachronic Life Cycle of Languages

Hurford, James R.

doi:10.1093/acprof:oso/9780195305432.003.0003

Cited by 6 publications

(2 citation statements)

References 21 publications

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“…The regression line gives the intercept age of 28.07 ± 0.35 Ma (95% confi dence, MSWD = 3.7), which is 1.2% younger than that of the SHRIMP data. But the present age data are in good agreement with the 39 Ar-40 Ar age (27.8 ± 0.2 Ma; Hurford & Hammerschmidt, 1985 ). For the SL13 zircon, the 206 Pb/ 238 U and 207 Pb/ 206 Pb ratios were monitored for 15 spot analyses on a single grain.…”

Section: Fct and Sl13 Zirconssupporting

confidence: 86%

U‐Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd‐YAG (λ = 213 nm) Laser Ablation System: Comparison with LA‐ICP‐MS Zircon Analyses with a NIST Glass Reference Material

2008

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This paper evaluates the analytical precision, accuracy and long-term reliability of the U-Pb age data obtained using inductively coupled plasma -mass spectrometry (ICP-MS) with a frequency quintupled Nd-YAG ( = 213nm) laser ablation system. The U-Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 m d iameter. For 207 Pb/ 206 Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 ( n = 280, 95% confi dence), which agrees well with the published value of 0.9096. The time-profi le of Pb/U ratios during single spot ablation showed no signifi cant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength ( = 213 nm) laser ablation. But 206 Pb/ 238 U and 207 Pb/ 235 U ages obtained by this method for seven zircon standards are systematically younger than the published U-Pb ages obtained by both isotope dilution -thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion-microprobe (SHRIMP). Greater discrepancies (3 -4% younger ages) were found for the 206 Pb/ 238 U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation-transport processes of the sample aerosols cannot be neglected. When the 206 Pb/ 238 U (= 0.2302) newly defi ned in the present study is used, the measured 206 Pb/ 238 U and 207 Pb/ 235 U ages for the seven zircon standards are in good agreement with those from ID-TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP-MS with laser ablation sampling (LA-ICP-MS) zircon analysis, but it is necessary to determine the correction factor for 206 Pb/ 238 U by measuring several zircon standards in individual laboratories.

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Section: Fct and Sl13 Zirconssupporting

confidence: 86%

U‐Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd‐YAG (λ = 213 nm) Laser Ablation System: Comparison with LA‐ICP‐MS Zircon Analyses with a NIST Glass Reference Material

2008

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“…Third, it was agreed from the start that the calibration against age standards was an interim measure and that an independent calibration should be pursued in parallel (Hurford 1998). For example, the reported radiometric ages of the Fish Canyon Tuff, one of the age standards, vary between 27.4 Ma and 28.5 Ma depending on the dating method, or vary between laboratories even when the same method is used (Hurford & Hammerschmidt 1985;Lanphere & Baadsgaard 2001;Schmitz & Bowring 2001;Spell & McDougall 2003;Bachmann et al 2007). Which value should be adopted as the reference age in fission track dating?…”

Section: Introductionmentioning

confidence: 99%

A review of the present state of the absolute calibration for zircon fission track geochronometry using the external detector method

Danhara¹,

Iwano²

2013

Island Arc

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The authors have developed and demonstrated an independent calibration of zircon fission track dating with the external detector method. During the past two decades, investigations have continued concerning the issues of the absolute age calibration of fission track dating. The derivation of accurate fission track age equations has been made possible by taking into account the relationships between the latent and etched track lengths. Our dating exercise involving 10 zircon reference samples supports our claim that absolute age determinations can be carried out based on the following three parameters:(1) the 238 U spontaneous fission decay constant of 8.5 ¥ 10 -17 a -1 (l f ) which is recommended by the IUPAC; (2) thermal neutron fluence values based on pre-irradiated IRMM540 dosimeter glass, which is equivalent to the Au and Co metal activation monitors in the 1990 IUGS recommendation; and (3) a [GQR] correction value of 1.35 which has been experimentally determined for the combination of zircon external surfaces irradiated with mica external detectors. Independent measurements of uranium concentration by the fission track method were also tested. A new method of fission track dating that uses mass spectrometry for uranium measurements was simulated with success using our zircon data. We propose that the Fission Track Community reassesses the situation and formulates a new recommendation, in which the established independent method is placed on at least an equal footing with the standard-based method.

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Plank¹

2015

Studies in Language Companion Series

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Universals and the Diachronic Life Cycle of Languages

Cited by 6 publications

References 21 publications

U‐Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd‐YAG (λ = 213 nm) Laser Ablation System: Comparison with LA‐ICP‐MS Zircon Analyses with a NIST Glass Reference Material

U‐Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd‐YAG (λ = 213 nm) Laser Ablation System: Comparison with LA‐ICP‐MS Zircon Analyses with a NIST Glass Reference Material

A review of the present state of the absolute calibration for zircon fission track geochronometry using the external detector method

Time for change

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