Chemical Modification of Lherzolite Xenoliths Due to Interaction with Host Basanite Melt: Evidence from Tumusun Volcano, Baikal Rift Zone

To investigate the process and chemistry of mineral reaction zone formation, we conducted detailed petrographic observations chemical analysis rocks minerals spinel lherzolite xenoliths from basanites Tumusun volcano (Baikal Rift Zone). The zones gradually disappear contact toward center xenoliths. influence basanite melt on major trace element composition secondary is notable only at a distance up to 100–200 μm contact. At 0.3–1.0 mm contact, clinopyroxenes orthopyroxene indicates their formation formed by dissolution influenced diffusion melt. Inside xenoliths, have Mg# values equal or higher than primary minerals, inherit depleted enriched REE pattern pyroxenes. compositional variations in testify heterogeneity. Clinopyroxene rims slightly LILE similar abundances other elements compared clinopyroxene cores. This consistent with model developed experimental studies: due interaction basanite, incongruent occurs form which circulates leads pyroxenes dissolution. Diffusion results enrichment K, Na, Rb, Ba, La, Ce, are incorporated feldspars as well feldspar veinlets. Non-dissolved cores homogenous without rims.