https://vital.lib.tsu.ru/vital/access/manager/Index en-us 5 https://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000625384 40 and low Yb = 0.2–0.5 ppm. Their multi-element patterns show clear Nb-Ta negative anomalies. The low Nb/Ta ratios (7–15) and Zr (114–191 ppm) suggest a MORB-type protolith (amphibolite) with subchondritic Nb/Ta (8–17) and low Zr (1–72 ppm). The low contents of K and Rb suggest weak assimilation of the melts by island arc felsic crust. The subchondritic Nb/Ta ratios exclude their derivation by the melting of subducted/dehydrated MORB. We argue that the Char high-Al tonalites and plagiogranites formed by the melting of hydrated MORB at the base of the mafic lower crust at pressures of 10–15 kbar. The occurrences of the Char tonalites and plagiogranites inside the Visean serpentinite mélange overlapped by Serpukhovian conglomerates, their alignment parallel to deformation zones, and their geochemical features suggest their origin by the melting of mafic lower crust in relation to the collision of the Siberian and Kazakhstan continents.]]> Fri 11 May 2018 12:53:25 KRAT ]]>