Effects of melt percolation on highly siderophile elements and Os isotopes in subcontinental lithospheric mantle: A study of the upper mantle profile beneath Central Europe
Abstract
This study is focused on effects of mantle percolation on HSE distribution and Re-Os isotopic systematics of upper mantle rocks brought to the surface during 5 Ma years old eruption of Kozákov volcano (Northern Bohemia). The Os-Ir-Ru-Pd distribution in these rocks shows significant depletions which are the result of the melt-rock interactions.
In contrast, Pt contents are commonly elevated and these enrichments are coupled with increasing melt/rock ratios. Osmium isotopic ratios are lower then chondrite meteorites and their strongly heterogeneous values reflect also melt-rock reactions.
All these results imply almost sulphide-breakdown in the lower sections of the mantle profile. On contrary, the middle and upper parts of the profile show only limited HSE removal.
Moreover, HSE were most likely even precipitated from percolating melt in some cases.