Abstract
Ultramafic xenoliths of mantle origin occur in Hungarian Cretaceous lamprophyres. The aim of the present work was to determine the iron positions and their occupancy in phlogopites originated from ultramafic xenoliths by the help of Mossbauer spectroscopy. On the basis of the evaluation of the Mossbauer spectra FeM12+, FeM22+, FeM23+ and FeM13+ (or in some cases Fetet) octahedral and tetrahedral iron sites were identified in the samples. Quantitative analysis was performed for all of the iron sites. We have observed large differences between the Fe2+/Fe3+ ratio in samples originated from 120–150 km deepness, which phlogopites having been existed at different erosion circumstances. We have found a significantly higher Fe2+/Fe3+ ratio in phlogopites which had been solidified in 120–150 km depth from the surface of Earth 70–100 million years ago, than those had been crystallized in 60–80 km deepness.
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