第15回ジオダイナミクスセミナー
　　　Geodynamics　Seminar

要旨

　SUBSOLIDUS PHASE RELATIONSHIPS IN HYDROUS PERIDOTITES
　　　　　　 TO 7 GPa: AN EXPERIMENTAL STUDY

　　　　　　　　PATRIZIA FUMAGALLI STEFANO POLI
　Universita degli Studi di Milano, Dipartimento di Scienze della
　Terra, Via Botticelli 23, 20133 Milano; Stefano.Poli@unimi.it

Subduction zone dynamics is related to the transport and release of aqueous fluids from the slab and to their interaction with the mantle wedge where changes in phase assemblages and relationships occur. A variety of hydrous phases have been recognized as water carriers in both the mafic and ultramafic portion of the slab. Hydrous peridotites have been extensively modeled in the system MgO-SiO2-H2O (MSH), where antigorite is the major hydrous phase to 6 GPa. However, lacking of chemical and structural informations on other high pressure hydrous phases, including amphibole, chlorite and the 10A phase, requires further characterizations in order to predict their relevance in hydrous peridotites. Furthermore more complex systems, e.g. Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O are almost unexplored at subsolidus conditions. This experimental study focuses on phase relationships in different model systems for peridotites at subsolidus conditions and on their relevance in hydration-dehydration processes occurring at high-pressure conditions.