Isotopic dating of the emplacement of the ultramafic masses in the Serrania de Ronda, Southern Spain

✍ Scribed by H. N. A. Priem; N. A. I. M. Boelrijk; E. H. Hebeda; I. S. Oen; E. A. Th. Verdurmen; R. H. Verschure

• Publisher: Springer
• Year: 1979
• Tongue: English
• Weight: 707 KB
• Volume: 70
• Category: Article
• ISSN: 0010-7999
• DOI: 10.1007/bf00371876

✦ Synopsis

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_+4Ma ()~= 1.42 • 10-in 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 ultramatics 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.