Progress of hydrothermal alternation in olivine–plagioclase system

Abstract

Hydrothermal experiments (230̊C, P_sat) were carried out in olivine–plagioclase (Pl)–H₂O system, as analogues of crust-mantle boundary. The mineralogy of the reaction products in the Ol-hosted region changed with increasing distance from the Ol–Pl boundary, from Al-lizardite to Al-free lizardite + brucite + magnetite. On the other hand, in Pl-hosted region, reaction products were not observed. The estimated element transport distance for Al and Si is 1.5 mm and 3.7 mm from Ol–Pl boundary, respectively. The total H₂O content is greater at the contact of Ol and Pl in Ol-hosted region than others.