| Autor: |
Priem, H. N. A., Boelrijk, N. A. I. M., Hebeda, E. H., Oen, I. S., Verdurmen, E. A. Th., Verschure, R. H. |
| Zdroj: |
Contributions to Mineralogy and Petrology; March 1979, Vol. 70 Issue: 1 p103-109, 7p |
| Abstrakt: |
A Rb-Sr analysis of suites of samples from a small intrusion of cordierite-bearing alkali granite into the peridotite of the Sierra Bermeja (Serrania de Ronda) yields an age of 22± 4 Ma (? = 1.42×10-11 a-1): Late Oligocene/Early Miocene. It is believed that the intrusion was derived from contact-anatectic melts produced along the hot ultramafic mass during and/or directly following its tangential, tectonic dislocation from a mantle diapir. Its age can thus be taken as dating the termination of the hot emplacement of the ultramafic masses. K-Ar dates of biotites and Rb-Sr dates of biotite/whole-rock pairs in contact-metamorphic wall rocks along the ultramafics mostly lie between 19.5 and 18.5 Ma. This probably indicates that about 19 Ma ago the contact-zones of the ultramafic masses had cooled down to the blocking temperature of biotite to Rb-Sr and K-Ar. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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