Mafické enklávy z granitoidů vystupujících v širším okolí Blanska

Petr Gadas, Miroslava Gregerová

Abstrakt

Mafic microgranular enclaves (MME) and associated host rocks occuring in the east granodiorite part of the Brno massif were studied petrologically and geochemically to establish their origin and to investigate the processes involved in their differentiation. Scarce enclaves display preserve narrow chilled margins. Many of enclaves show obvious similarities to their associated host rocks: they contain the identical mineral phases as their host rock, nevertheless the content of mafic minerals (biotite and hornblende) and opaque minerals is somewhat higher. Both types of rocks show some similar geochemical trends. Zoned plagioclase megacrysts in some enclaves contain anhedral cores jacketed by euhedral rim. These plagioclases could represent xenocrysts of early crystallised host rock phases mechanically accreted inward the liquid of enclaves. Acicular crystals of apatite and tiny lathy plagioclase in matrix are indicative of rapid crystallization of the enclaves liquid. Host rocks display intermediate to acid composition, while the enclaves are more basic. Macroscopic, microscopic and geochemical features indicate that the MME are products of mingling and incompletely mixing between a basic end member and host rocks of more acid composition.

Bibliografická citace

Gadas, P., & Gregerová, M. (2016). Mafické enklávy z granitoidů vystupujících v širším okolí Blanska. Geologické výzkumy na Moravě a ve Slezsku, 13. Získáno z https://journals.muni.cz/gvms/article/view/4866

Klíčová slova

granitoids; enclaves; petrology; geochemistry; xenocryst

Plný Text:

Reference

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