Geocronologia Rb-Sr de los leucogranitos del complejo plutonico de Burguìllos del Cerro (Badajoz)

Abstract

A Rb-Sr whole-rock array corresponding to an age of circa 330M. a. has been obtained for the slightly to moderately peraluminous leucogranites of the Burguillos del Cerro Massif. The samples were collected from several different leucogranite bodies and the data demostrate that the Sr-isotope composition was not homogeneous at the time of intrusion. It reveals the absence of isotopic homogenity of the original magmas. However two samples from the same body yield a tie line age of 330±9 M.a. i.e. tower Carboniferous. Furthermore, Rb-Sr isotopic evidence suggests that the alterations of the albititic type (a/bite + quartz), that are found within these granites, probably took place soon after the crystallization of the magmas. Fluid inclusion evidence supports this interpretation