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| Titel: |
Basic data on the age of the boundaries between certain geological systems and epochs |
| Auteur: |
Afanas'yev, G. D. Bagdasaryan, G. P. Garris, M. A. Khramrabayev, I. Kh. |
| Verschenen in: |
International geology review |
| Paginering: | Jaargang 7 (1965) nr. 11 pagina's 1928-1948 |
| Jaar: |
1965-11 |
| Inhoud: |
Many K-Ar ages have been accumulated in the world's geochronologidal laboratories but, as different decay constants are used in various countries for calculation of the formulae, it is difficult to compare the figures. Data from parallel K-Ar determinations on the one hand and from Rb-Sr and U-Pb figures often compare more favorably with the K-Ar ages calculated from the constants used in the Soviet Union. (λk - 0.557•10-10/year; λβ = 4.72•10-10/year). There follows a review of reference points in post-Precambrian time. A comparison of ages of individual geological boundaries with Kulp's 1961 scale is given. The Jurassic-Cretaceous and Triassic-Jurassic boundaries are identical in age on the basis of our new data and on Kulp's scale. The base of the Triassic cannot be older than 230-240 million years, and its duration is 40 m. y., which is more likely than the 50 m. y. suggested by Kul.P. We retain Kulp' s age of 280 m. y. for the Carboniferous- Permian boundary. The suggested age of the Devonian-Carboniferous boundary is 15 m. y. younger than Kulp's. The Silurian-Devonian boundary has been fixed on a single figure of 405 m. y. Kulp assesses the duration of the Silurian at 20 m. y., but we propose 25 m. y. The Proterozoic-Cambrian boundary cannot be older than 560 m. y. The 70 m. y. duration of the Cambrian is more realistic than Kulp's estimate which approaches 100 m. y. — J. E. Haun. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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