Oxygen isotope fractionation in SiO2 and Al2SiO5 polymorphs: effect of crystal structure
European Journal of Mineralogy Volume 5 Number 4 (1993), p. 651 - 658
published: Jul 22, 1993
manuscript accepted: Mar 29, 1993
manuscript received: Nov 9, 1992
ArtNo. ESP147050504013, Price: 29.00 €
Abstract Oxygen isotope fractionation factors for SiO2 and Al2SiO5 polymorphs have been calculated by means of the modified increment method. The results suggest that the 18O is depleted in the high pressure forms (i.e. the more dense phases). The effect of crystal structure on isotopic partitioning in polymorphic phases is important, because the cation-oxygen interatomic distances and coordination numbers can change due to compression or thermal expansion in geological processes.