Poitrasson Franck auteur aut IRD Zambardi T. auteur aut IRD text journalArticle eng text/pdf born digital access A comparison between terrestrial and lunar igneous rocks reveals that Si isotope compositions become slightly, though significantly enriched in heavy isotopes from basalts to granites and anorthosites as a function of the rock SiO2 concentration and/or tectosilicate content. This is interpreted as the result of a global igneous differentiation process that leads to an increased amount of tectosilicates in the rocks. This relationship of increasing degree of melt polymerization with increasingly heavy silicon isotope composition is particularly apparent in lunar rocks. The terrestrial trend, however, is more scattered. Given the sensitivity of Si isotopes to water-rock interactions, it is likely that the more erratic terrestrial trend reveals the involvement of water that does not occur on the Moon. Hence, Si isotopes appear to reflect the occurrence of low temperature water-rock interaction products, like clay minerals, in the source of peraluminous leucogranites. Conversely, the heavy silicon isotope composition of some andesites possibly trace the input of fluids involved in subduction zones and/or interaction of the oceanic crust with isotopically heavy seawater before subduction. specialized 066 064 167 301-312 2015 0016-7037 https://www.documentation.ird.fr/hor/fdi:010065271 10.1016/j.gca.2015.07.005 0016-7037 [F B010065271] https://www.documentation.ird.fr/hor/fdi:010065271 https://www.documentation.ird.fr/intranet/publi/2015/10/010065271.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-11-06 2017-08-23 fdi:010065271 fre