title: Radioactive secular equilibrium in ²³⁸U and ²³²Th series in granitoids from Greece.
abstract: Granitoid rocks belonging to plutons of Greece, covering a wide range of compositions and rock-types, have been studied for their specific activity (Bq/kg) of (238)U and (226)Ra from (238)U radioactive series and (228)Ra and (228)Th from (232)Th radioactive series by using gamma-ray spectroscopy. Results on the radioactive secular equilibrium of both (238)U and (232)Th radioactive series are presented by studying the (226)Ra/(238)U and (228)Ra/(228)Th ratios. The majority of the samples are in radioactive secular equilibrium for (226)Ra/(238)U ± 1σ. However, several samples exhibit (226)Ra/(238)U ratios significantly different from 1. The distortion of the secular equilibrium in the (226)Ra-(238)U isotopic system of those samples has occurred over the last 1 Ma, and can be associated with post-magmatic processes, mainly rock-water interactions. All studied samples have (228)Ra/(228)Th ratios equal to unity ±1σ. Consequently, they can be considered to be in secular equilibrium for the last 40 a.
authors.affiliation: Department of Mineralogy, Petrology and Economic Geology, School of Geology, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece. argpapad@geo.auth.gr
authors.forename: A
authors.initials: A
authors.lastname: Papadopoulos
authors.forename: G
authors.initials: G
authors.lastname: Christofides
authors.forename: A
authors.initials: A
authors.lastname: Koroneos
authors.forename: S
authors.initials: S
authors.lastname: Stoulos
authors.forename: C
authors.initials: C
authors.lastname: Papastefanou