Geology, Geochemistry and Mineralogy of the Gneissic Trondhjemites, Tonalities, Granodiorites and Related Rocks within the Proterozoic Idzhek-Nuiam and Tyrkanda Faults of the Aldan Shield (North Asian Craton)

Abstract

Researched magmatic rocks, which undergone the process of polymetamorphism in granulite, amphibolite and greenschist facies, earlier by some geologist was defined as paragneisses and (or) intrusive rocks. In this paper based on geological and geochemical data argue the magmatic nature of rocks and identity to the calc-alkaline series. The series consists of gabbros, diorites, quartz diorites, granodiorites, tonalites and trondhjemites. Contents of the rock-forming oxides and rare earth elements in these rocks are close to the widely known early Proterozoic gabbro-diorite-tonalite-trondhjemite series of the South-West Finland. These features indicate the probability of formation of the researched rocks with the participation of the subduction. As a results of studies established what in M complex possible inclusion of rocks and bodyes from other sites such as Ust-Timpton, Idzhek-Seym and Upper-Gonam pluton. The features of the MS include the linkage with the long-lived faults and associated dynamometamorphic changes of the bodies, polymetamorphism, superimposed chemical changes in the composition of primary rocks, as well as rarely preserved migmatite veinlets in the host rocks. Geochemical similarity of trondhjemite-, tonalites, granodiorites Mariin series and associated rocks with well-known early Proterozoic differentiated series of southwest Finland typical for the Proterozoic and Paleozoic continental margins suggests that the plutons of the Mariin series formed in an active continental margin setting.