Affiliation:
1. Institute of Precambrian geology and geochronology RAS
2. Saint Petersburg State University
Abstract
Morphology and compositions of minerals in metamorphized Early Proterozoic gabbroids of the Northern Ladoga area were studied with the purpose to identify criteria of their magmatic or metamorphic origin. These rock-forming minerals of the Kaalamsky complex are stable in the wide range of temperatures and pressure. To solve the problem, together with comparison with minerals from non-metamorphized rocks of the Potudan intrusion (Volga-Don orogen), there were used the data of petrographic study in as well as the data of mineral compositions and thermodynamic modeling. It was concluded that it is possible to distinguish groups of magmatic and metamorphic rock-forming minerals with help of morphogenetic, geochemical, and thermobarometric criteria, as well as criteria based on revealing the concordance between observed and modeled mineral compositions. Combined application of these criteria has allowed determining that rocks of Kaalamsky complex contain olivine, clinopyroxenes, amphiboles, plagioclases of magmatic origin, and also their metamorphic analogues.
Publisher
The Russian Academy of Sciences
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