Nd isotopic heterogeneity in late-Hercynian granitic plutons from Central Spain

Abstract

Some Hercynian granitic plutons from Central Spain show variation in initial Nd isotopic ratios defining different trends with increasing silica content. There is a decoupling between the Sr and Nd isotopic systems as these plutons present homogeneous initial Sr ratios. Magmatic processes could explain this Nd isotopic disequilibrium; it is suggested that Nd-bearing restitic or early precipitating accesory phases could control the Nd isotopic heterogeneity of the granites.