Wiek izotopowy a wiek paleomagnetyczny ryodacytów z Zalasu ko³o Krakowa (S Polska)

Jerzy Nawrocki, Anna Lewandowska, Mark Fanning


Isotope and paleomagnetic ages of the Zalas rhyodacites (S Poland).
S u m m a r y . The single-grain U-Pb dating of most zircon grains separated from the Zalas rhyodacites gave mean age of the magma emplacement 294.2 ± 2.1 Ma. Some zircons, however, displayed younger ages (268.7± 3.4 Ma), probably related to metasomatic alterations of these rocks. The paleomagnetic ages of the Zalas intrusion and its metasomatosis are slightly younger. It is probably connected with a certain error of time calibration of the reference apparent polar wander path used for paleomagnetic dating.

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