Interaction between a mafic melt and host rocks during formation of the Kivakka layered intrusion,North Karelia

The study of interaction between mantle melts and crustal rocks is of great importance for deciphering the evolution of the Earth’s crust and for better understanding the composition of mantle sources, in particular, the degree of their compositional heterogeneity. This work presents the results of Rb-Sr and Sm-Nd isotopic studies of 37 samples taken from the Kivakka layered intrusion, host rocks, and rocks at the contact. The studies were aimed at verifying the hypothesis of possible crustal contamination of mafic melt during magma chamber crystallization. It was found that the section of the Kivakka layered massif is characterized by initial Sr and Nd isotopic heterogeneity, with negative correlation between initial Nd isotopic ratio and its content. The rocks of the massif have low ɛ_Nd(T) values.