Basalts and dolerites of the Middle Timan: new data

Basalts of the Vezhayu-Vorykva nappe (D3vl) and dolerites of dikes of the Kanin-Timan complex (D2-3kt) of the Middle Timan have been studied. The paper highlights new mineralogical-petrographic, petrogeochemical, geochronological (40Ar/39ArPl), and isotopic-geochemical (Sm-Nd, Rb-Sr) data. No significant differences have been found in the mineralogical-petrographic and petrogeochemical composition of the rocks. Basalts and dolerites are composed of a single complex of minerals; differences arise in structure, contrasting compositions of mineral zones and particularities of ore and accessory minerals. The chemical composition of the rocks is homogeneous and typical of basic volcanic rocks of the normal-alkaline suborder. The age of dolerites of the Kanin-Timan complex, which fill dike bodies feeding channels for basalts that make up the Vezhayu-Vorykva nappe, is 392±7 Ma. By characteristics, the rocks correspond to intraplate formations. The mantle source (ɛNd(t)-+3.8-+4.1, Th/Nb (0.22–0.29)) was affected by the crustal component (negative anomalies for Nb and Ta, low Ce/Pb values (2.3–9.15), high Th/Ce values (0.07–0.08) and 87Sr/86Sr (0.708–0.710).