International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Chemical composition of spinels from Mesozoic alkali basalts of the Western Carpathians: implications for sources of detrital spinels in flysch sediments

Pages: 447 - 460

Authors: TOMAS MIKUS, JAN SPISIAK, MILAN SYKORA, RASTISLAV DEMKO

Abstract: Cr-spinel is a relatively widespread accessory heavy mineral in Mesozoic alkali volcanic rocks in the Central Western Carpathians. According to their chemical composition, spinels from these rocks (basalts, submarine hyaloclastites) can be divided into several groups (volcanic — Cr-spinel and Fe-Ti spinel, and peridotitic spinel, altered). Volcanic spinels crystallized in the plumbing system, and peridotitic spinels ultimately originated from peridotitic xenoliths, entrapped and brought to the surface by magmas. Melt/silicate inclusions (clinopyroxenes, plagioclases, melt) were found only in Cr-spinels of volcanic origin. Alteration processes are similar in all studied samples (enrichment in Ti4+, Fe2+, Fe3+ and depletion in Mg2+ and Al3+). The chemical composition of Cr-spinels from Cretaceous alkali basalts from the Western Carpathians is different to those of detrital Cr-spinels of volcanic origin from the Albian Poruba flysch Fm. Mesozoic alkali volcanites were not important sources for widespread detrital spinels of volcanic origin in Cretaceous sediments (mainly in the Tatric and Fatric tectonic units).

Keywords: Cretaceous volcanism, Cr-spinel, silicate melt inclusions, clinopyroxene, alteration

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Volume 57 no. 6 / December 2006

Volume 57 no. 6