| 单词 | uranium lead |
| 释义 | > as lemmasuranium lead uranium lead n. (a) the isotope lead-206; = radium G n. at radium n. 1b; (b) attributive ( uranium-lead) designating a method of isotopic dating of rock based on measurement of the relative amounts of uranium-238 and -235 and of their ultimate decay products lead-206 and -207; (of dates, ages, etc.) obtained using this method. ΘΚΠ the world > matter > physics > atomic nucleus > radioactivity > [noun] > uranium uranium1790 uranium lead1914 the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [adjective] > using isotopic dating uranium lead1914 the world > matter > physics > atomic nucleus > radioactive isotope > specific isotopes > [noun] > radium radium A1904 radium B1904 radium C1904 radium D1904 radium E1904 radium F1904 radium G1904 uranium lead1914 1908 Bull. Geol. Soc. Amer. 19 135 It does not seem to me that geologists can possibly accept the ages of minerals as determined from the uranium-helium or the uranium-lead ratios, which do not seem consistent and are far longer than stratigraphers could admit.] 1914 London, Edinb., & Dublin Philos. Mag. 6th Ser. 28 825 The equation for the complete disintegration of uranium is U → 8He + Radium G (uranium lead). 1925 J. Joly Surface-hist. Earth ix. 153 If thorium-lead ratios are trustworthy we should divide the uranium-lead ages, as determined for very old rocks, by four. 1955 Bull. Geol. Soc. Amer. 66 1141/2 The analysis..demonstrates that small amounts of uranium lead and major amounts of thorium and thorium lead are very loosely bound, chemically. 1957 R. Casanova Illustr. Guide Fossil Collecting 43 Geological time has been calculated by a number of methods, of which the uranium-lead method is one of the best. 1977 A. Hallam Planet Earth 184/2 Rubidium-strontium and uranium-lead measurements conclusively show that all these rocks were formed between about 3700 and 3800 million years ago. 2006 D. H. Erwin Extinction iii. 92 So here we switch from argon years to uranium lead years. The lowermost volcanics of the Arydzhansky Suite date to 251.7 million years ago. < as lemmas |
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