Evolution of the Late Mesozoic Magmatism of the Omulevka Terrane of the North Part of the Verkhoyansk–Kolyma Orogenic Region

This article presents the results of a study Late Mesozoic intrusive formations Omulevka terrane Verkhoyansk–Kolyma orogenic region. The research area covers Selennyakh block and territory adjacent to south. compositions rock-forming, accessory restitic minerals geochemical features rocks are considered. methods optical microscopy, microprobe, silicate spectral analyses were used. There following several stages in evolution magmatism: (1) Jurassic supra-subduction (gabbro, dolerites), (2) beginning Early Cretaceous-transitional from marginal-continental (gabbro-diorites, diorites, granodiorites), (3) Cretaceous active continental margin (granodiorites, granites), (4) postorogenic or continental-riftogenic (alkali-feldspar granites A-type), (5) riftogenic (subalkaline gabbroids basaltoids). In process stage one four, there was an increase silicic acid content, total alkalinity ferruginousity with movement magmogeneration levels higher horizons lithosphere (calculated pressure 1.6–1.4 GPa 0.6–0.9 GPa). At same time, preservation high temperatures (1000–1150 °C) crystallization implies supply additional heat external (deep) source during formation granitoid melts. magmatic activity is completed by intrusion subalkaline derivatives deep hearth, formed metasomatized lherzolites. All studied igneous either direct mantle fusions, bear signs participation matter generation parent melts crustal substrates: presence tschermakite gabbroids, nonequilibrium structures, composition early generations biotites corresponding crust-mantle derivatives, pyroxenes characteristic magmas granitoids. diagram Al-Na-K-2Ca–Fe + Ti Mg, points tend mixing trend. general, suggest that magmatism specific rock caused interaction as result rise diapirs crust long-existing hearth main melt.