Features of dike magmatism in the northern frame of the Pechenga structure

A comprehensive study of Paleoproterozoic dike complexes within North-Western part of the Kola region has been carried out. The research allows establish stages of their formation, correlate with thickness of volcanites and reconstruct the geodynamic conditions of introduction. The most common dikes are composed of quartz dolerites with U-Pb age 2304 ± 1 Ma, εNd = -1.12 and model Sm-Nd protolite age - 2838 Ma. Dikes from the Ambarnaya Bay area correlate to dike swarm of the village Liinakhamari. Rocks of both swarms are correlated with volcanogenic formations of andesibasalt composition, the lower part of Pechenga structure section. Small fluctuations MgO (4-7 wt.%), low Cr (10-50 ppm) and moderate Y, Zr, REE, weakly fractionated HREE with minor negative Eu anomaly and (La/Yb)n = 5.1-5.8 are typical for dolerites. Rocks are enriched by Rb, Ba, K, depleted by Nb, Ti, and have low Sr/Y = 11-13. Dikes of quartz dolerites break plagiogranites and granites of the Archean foundation...