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Experimental Study of Partial Melting of Mantle Peridotite—A Discussion about the Genesis of Silica‐rich Fluids (Melts)
Author(s) -
Jianping LI,
JACQUES Kornprobst
Publication year - 1999
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.1999.tb00848.x
Subject(s) - peridotite , partial melting , mantle (geology) , silicate , metasomatism , geology , xenolith , geochemistry , mineralogy , chemistry , organic chemistry
Experiments on partial melting of mantle lherzolite have been realized at 0.6 and 1.0 GPa and the chemical compositional variations of melts during different melting stages have been first discussed. The results show that the trends of variations in SiO 2 , CaO, Al 2 O 3 , Na 2 O and TiO 2 are different at different melting stages. The melts produced at lower pressure are richer in SiO 2 than those at higher pressure. The mantle‐derived silica‐rich fluids (silicate melts) are polygenetic, but the basic and intermediate‐acid silicate melts in mantle peridotite xenoliths from the same host rocks, which have equivalent contents of volatile and alkali components and different contents of other components, should result from in‐situ (low‐degree) partial melting of mantle peridotite under different conditions (e.g. at different depths, with introduction of C‐O‐H fluids or in the presence of metasomatic minerals). The intermediate‐acid melts may be the result of partial melting (at lower pressure) Opx + Sp + K‐Na‐rich fluid ± (Amphi) ± (Phlog) = Ol + melt. But the intermediate‐acid magmas cannot be produced from the partial melting of normal mantle peridotite unless the crustal materials are introduced to some extent.