ANALYSIS OF MANTLE SOURCES FOR MAFIC ASSOCIATIONS ON THE BASIS OF GEOCHEMICAL AND Nd ISOTOPIC DATA
The (La/Nb)pm, (Th/La)pm, (La/Sm)pm, (Nb/Y)pm ratios 1 corresponds to an undepleted/enriched source. (La/Nb)pm does not change during melting of mantle peridotites, so the Nd minimum is a characteristic feature of the lithospheric mantle metasomatized by fluid/melt. According to the isotopic Nd composition, there are two mantle sources: (1) depleted (+eNd), which corresponds to the asthenospheric and/or lithospheric mantle of restite origin, (2) enriched (-eNd) lithospheric, having a lowered Sm/Nd due to metasomatism. Estimates of the characteristics of the mantle sources of mafic rocks based on their trace element-and isotopic composition can either correlate with each other or differ.