Results 231 to 240 of about 51,712 (271)

Precision KRbSr isotopic analysis: Application to RbSr chronology

Chemical Geology, 1986
Abstract 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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Li, K, Rb, Sr, Ba and rare-earth concentrations, and RbSr age of lunar rock 12013

Earth and Planetary Science Letters, 1970
Abstract 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, J.A. Philpotts, M.L. Bottino   +2 more
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Rb-Sr mantle isochrons from oceanic regions

Earth and Planetary Science Letters, 1976
Existing data for87Sr/86Sr and Rb/Sr ratios of basalts from oceanic islands and mid-ocean spreading ridges show significant positive correlations on a Rb-Sr isochron diagram (when data are averaged by island group). Furthermore, tholeiites and alkali basalts occupy distinct non-overlapping fields on this plot.
C. Brooks, S.R. Hart, A. Hofmann, D.E. James   +3 more
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Rb-Sr age of stony meteorites

Geochimica et Cosmochimica Acta, 1965
Abstract A suite of samples of stony meteorites with a spread in Rb 87 Sr 86 ratios from about 0.02 to 3.0 has been analysed for Rb and Sr contents and Sr isotopic compositions. These whole-meteorite analyses all coincide within experimental error with a single isochron.
W.H Pinson, C.C Schnetzler, E Beiser, H.W Fairbairn, P.M Hurley   +4 more
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The statistical assessment of Rb-Sr isochrons

Journal of Geophysical Research, 1966
The 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, C. Brooks, W. Compston, A. Turek   +3 more
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Nuclear reactions in Rb, Sr, Y, and Zr targets

Physical Review C, 1982
Excitation 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., Lavielle, B., Simonoff, M., Simonoff, G.N.   +3 more
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RB–SR AGE DETERMINATIONS ON SOUTH AFRICAN KIMBERLITE PIPES

Physics and Chemistry of the Earth, 1975
Abstract A study has been made to establish to what extent reliable age-measurements can be obtained by the RbSr isochron method on phlogopite micas from kimberlite and its associated inclusions. Essentially linear isochrons were usually obtained for the micas when grouped according to their source.
H.L. Allsopp, D.R. Barrett
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Rb-Sr ages and elemental abundances of K, Rb, Sr, and Ba in samples from the Ocean of Storms

Geochimica et Cosmochimica Acta, 1971
Abstract Rb-Sr internal isochron ages for three basaltic crystalline rocks from the Ocean of Storms are 300–600 m.y. younger than the ages of basaltic rocks from the Sea of Tranquillity. Rock 12063 has an age of 3.34 ± 0.10AE and [ 87 Sr 86 Sr ]I of 0.69914 ± 3. Internal isochron ages of two separate samples of rock 12004 yield ages of
V.Rama Murthy, N.M Evensen, Bor-Ming Jahn, M.R Coscio   +3 more
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Rb-Sr geochronology of Graham Land, Antarctica

Journal of the Geological Society, 1982
Thirty-five new Rb-Sr whole-rock and mineral isochrons are reported for igneous rocks from Graham Land. Magmatism was essentially continuous but peaks of activity occurred in early Jurassic, early Cretaceous, late Cretaceous and Eocene times. The oldest dated granite is Triassic (209 ± 3 Ma).
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A Rb-Sr ISOCHRON FOR THE SHAP GRANITE

Proceedings of the Yorkshire Geological Society, 1978
SUMMARY A Rb-Sr age of 394 ± 3 Ma has been determined from a 21–point isochron for the Shap Granite, which was probably emplaced in lower Devonian times. The determination provides a minimum age for the base of the Gedinnian Stage. K-Ar measurements on biotites and U-Pb measurements on zircons from the granite give similar ages.
A. J. WADGE, N. H. GALE, R. D. BECKINSALE, C. C. RUNDLE   +3 more
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