Devonian basalts and dolerites of the Timan and the Kanin Peninsula: petrography, mineralogy, geochemistry, isotopy

The paper presents general information on the petrographic, mineralogical and isotope-geochemical features of the Devonian basaltoids of the Kanin Peninsula, the Northern, Middle and Southern Timan. The main rock-forming minerals are clinopyroxenes and plagioclases represented by both phenocrysts and crystals of the groundmass. Among ore minerals, there are titanomagnetite, rarely ilmenite, pyrite, chalcopyrite, and galena. Accessory minerals are apatite and potassium feldspar. The rocks are mainly normal-alkaline basalts and correspond to the tholeiitic series. Total concentrations of rare-earth elements have wide variations: Kanin Peninsula = 36.5–81.27 ppm, Northern Timan = 35.6–64.2 ppm, Middle Timan = 62.0–88.6 ppm, Southern Timan = 44.82–52.41 ppm. The rocks are characterized by geochemical features typical of igneous rocks of basic composition, formed in a continental intraplate geodynamic setting. The mantle source, which gave rise to the melts, was enriched by the crustal component. The least differentiated melts, most closely corresponding to the primary magmas from which the basaltoids of Timan and the Kanin Peninsula were formed, were formed by spinel lherzolite melting with a melting degree from 10 to 30 %.