Results 241 to 250 of about 540,378 (271)
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Precision KRbSr isotopic analysis: Application to RbSr chronology
Chemical Geology, 1986Abstract A new ion-exchange separation procedure is described for the isolation of Sr from Ca. It has been designed to give reproducible results with only approximately known reagent concentrations. Evaporation during storage is not critical and may easily be checked with a common pH paper. The medium is buffered by pyridine in the range pH 5–6. The
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The statistical assessment of Rb-Sr isochrons
Journal of Geophysical Research, 1966The variance in isotope-dilution measurements of Rb87/Sr86in geological samples is shown to be proportional in general to (Rb87/Sr86)2, so that simple regression methods for estimating Rb-Sr isochrons are not formally valid. A new regression method which allows for known experimental error in both Sr87/Sr86 and Rb87/Sr86 and which weights the data to ...
G. A. McIntyre +3 more
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Li, K, Rb, Sr, Ba and rare-earth concentrations, and RbSr age of lunar rock 12013
Earth and Planetary Science Letters, 1970Abstract The light and dark-colored portions of 12013 are characterized by two distinct trace element patterns. The light-colored portions are lower in rare earths, slightly lower in Sr, the same in Li and higher in K, Rb and Ba when compared to the dark-colored portions.
C.C. Schnetzler +2 more
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1979
The Rb-Sr method is based on the β-decay of 8 7Rb which decays to 8 7Sr with a half life of 48.8 × 109 years. This half-life corresponds to the recommended decay constant (Steiger and Jager, 1977) of 1.42 × 10−11 /y. In the last years two different decay constants have been used.: λ(8 7Rb) = 1.39 × 10−11/y and λ(8 7Rb) = 1.47 × 10−11/y.
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The Rb-Sr method is based on the β-decay of 8 7Rb which decays to 8 7Sr with a half life of 48.8 × 109 years. This half-life corresponds to the recommended decay constant (Steiger and Jager, 1977) of 1.42 × 10−11 /y. In the last years two different decay constants have been used.: λ(8 7Rb) = 1.39 × 10−11/y and λ(8 7Rb) = 1.47 × 10−11/y.
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Nuclear reactions in Rb, Sr, Y, and Zr targets
Physical Review C, 1982Excitation functions of all stable or long-lived krypton isotopes were measured or estimated for incident protons and neutrons in Rb, Sr, Y, and Zr targets. Experimental data concern mostly Y and Zr targets bombarded with 0.059 to 24 GeV protons. The products /sup 78en-dash86/Kr, /sup 74/As, /sup 75/Se, /sup 83,84,86/Rb, /sup 85/Sr, /sup 88/Y, /sup 88 ...
Regnier, S. +3 more
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An Rb/Sr Age of the Småland Porphyries
Geologiska Föreningen i Stockholm Förhandlingar, 1972Abstract Rb/Sr whole-rock radiometric dating of 14 porphyries from Smaland, southeastern Sweden, yields an age of 1695 ± 20 million years (m. y.) (λ = 1.39 × 10−11 y.−1). The initial Sr87/Sr86 ratio is 0.7065 ± 0.0012. The relationship between the Smaland porphyries may be compared with that between the Dala porphyries, with respect both to relative ...
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Rb/Sr geochronology in the Eastern Alps
Contributions to Mineralogy and Petrology, 1976New Rb/Sr data on mineral and whole rock samples from in and around the south-east corner of the Tauern Window are presented. Pennine orthogeneisses yield an Rb/Sr whole rock age of 279±9 m.y., while orthogneiss samples from the Altkristallin Sheet near Innerkrems, Carinthia, yield an age of 381±30 m.y. by the same technique.
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The use of Rb/Sr ratios as a guide to mineralization
Journal of Geochemical Exploration, 1979Abstract Rb is incorporated in K minerals and Sr in Ca minerals and hence the Rb/Sr ratio amplifies any increase in K or loss of Ca in hydrothermal alteration zones. Submarine exhalative deposits, which have no recognizable alteration zones in the Broken Hill district and in southeastern New South Wales display an increase in the Rb/Sr ratio of the ...
I.R. Plimer, S.M. Elliott
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The Rb-Sr age of the Varberg charnockite, Sweden
Geologiska Föreningen i Stockholm Förhandlingar, 1978Abstract The Rb-Sr isochron age of the Varberg charnockite, south-western Sweden is 1450+53 Ma (λ = 1.39 × 10−11 a −1). The initial 87Sr/86Sr ratio is 0.7049±0.0006.
Eric Welin, Roland Gorbatschev
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A survey of Rb‐Sr systematics of eucrites
Meteoritics, 1993Abstract— This paper surveys the experimental material on the Rb‐Sr systematics of eucrites accumulated in the literature for the last two decades. Among the meteorites studied, those representatives have been chosen for which the absence of disturbances of isotope systems seems reliably fixed (according to evidence from Rb‐Sr, Sm‐Nd, and U‐Pb isotope ...
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