Eclogitization of basites in early proterozoic shear zones in the area of the village of Gridino, western Belomorie |
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| Authors: | V V Travin N E Kozlova |
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| Institution: | 1. Institute of Geology, Karelian Research Center, Russian Academy of Sciences, ul. Pushkinskaya 11, Petrozavodsk, 185910, Russia
2. Geological Institute, Kola Research Center, Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk oblast, 184209, Russia
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| Abstract: | The considered part of ductile shear zones, which are widespread in the area of the village of Gridino in the central part
of the Belomorian Mobile Belt, is accompanied by the high-temperature eclogitization of basites. The paper reports examples
of eclogitization in rocks of various age, mostly in rocks of the Early Proterozoic lherzolite-gabbronorite and coronite gabbro
complexes. The degrees of structural and mineralogical transformations in unequally deformed bodies of gabbronorites and olivine
gabbronorites of the lherzolite-gabbronorite complex are correlated with the degrees of deformations of these rocks and their
fluid recycling. The relatively weakly deformed rocks have massive and apomagmatic textures with garnet and omphacite reaction
rims at boundaries between grains of magmatic plagioclase and pyroxenes. These rims are typical of the domainal equilibrium
stage, which is an intermediate eclogitization stage between a magmatic rock and completely equilibrated eclogite. The enhancement
of rock deformation results in the development of equilibrium eclogite with anisotropic metamorphic textures and structures.
Textural transformations simultaneous with intense deformations are manifested involved the recrystallization of magmatic
minerals and the development of linear fine-grained mineral aggregates of the Pl-Opx-Grt-Omp eclogite mineral assemblage and the systematically oriented growth of much larger mineral neoblasts in amphibole eclogite
assemblages. |
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