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  • Author or Editor: Zuárd Ditrói-Puskás x
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The newly discovered crustal xenoliths from Miocene andesites in the Mátra Mts (Northeast Hungary) were classified into three petrographic types. Type 1 is a garnetiferous, plagioclase-rich cumulate rock, presumed to originate from the felsic portion of the nearby Szarvaskõ-Darnó mafic igneous complex. The almandine-rich garnet has been inferred to be of granulite facies origin. Garnet - orthopyroxene geothermobarometry on the orthopyroxene - plagioclase corona structure around it indicates a later high temperature (800-950 °C) low pressure (3-4 kbar) retrogression event. Type 2 is also plagioclase-rich cumulate rock with contact metamorphic assemblage containing spinel, corundum and andalusite, which crystallized in the course of dehydration reactions of biotite and/or smectite in hornblende hornfels to sanidinite facies conditions. Type 3 is microsyenite, which contains abundant anorthoclase and minor amount of Na- and K-rich kaersutitic-barkevikitic amphibole.

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Magnetic spherules from Pleistocene terrestrial sediments in southern Hungary were systematically collected and investigated. By means of chemical analysis, Fe, Fe(Mn), Fe(Ni) and glassy (silicate) spherules can be distinguished. Some of them have characteristic features suggesting an extraterrestrial origin: Ni-bearing crust, Ni-rich core and especially the platinum group nuggets with their unique chemical composition. They could have been formed by meteorite ablation process.

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