High pressure experimental study of natural antigorite dehydration reactions Juliette Maurice To cite this version: Juliette Maurice. High pressure experimental study of natural antigorite dehydration reactions. Earth Sciences. Université Clermont Auvergne, 2017. English. NNT : 2017CLFAC099. tel-02918062 HAL Id: tel-02918062 https://tel.archives-ouvertes.fr/tel-02918062 Submitted on 20 Aug 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. UNIVERSITE BLAISE PASCAL U.F.R Sciences et Technologies ECOLE DOCTORALE DES SCIENCES FONDAMENTALES THESE Présentée pour obtenir le grade de DOCTEUR D’UNIVERSITE Spécialité : Pétrologie Par Juliette MAURICE Titulaire du Master 2 Recherche : « Magmas et Volcans » Étude expérimentale des réactions de déshydratation de l’antigorite naturelle à haute pression Soutenue publiquement le 17 mars 2017 devant la commission d'examen composée de: Jörg Hermann Professeur, Universität Bern Rapporteur Bruno Reynard Directeur de Recherches, ENS Lyon Rapporteur Patrizia Fumagalli Professeur, Università Degli Studi di Milano Examinateur Damien Guillaume Professeur, LMV Saint-Etienne Examinateur Nathalie Bolfan-Casanova Directrice de Recherches, LMV Directeur de thèse Tahar Hammouda Maître de Conférence, LMV Directeur de thèse Contents Remerciements ......................................................................................................................... 9 Résumé .................................................................................................................................... 13 Abstract ................................................................................................................................... 15 Résumé détaillé ....................................................................................................................... 17 Introduction ............................................................................................................................ 37 Background .......................................................................................................................... 37 Aims of this study ................................................................................................................ 39 Organization of the thesis ..................................................................................................... 40 Chapter I - Subduction zone and water ............................................................................... 43 I The Earth deep water cycle ................................................................................................ 44 II Hydratation of the volcanic floor ...................................................................................... 47 III Oceanic subduction processes ......................................................................................... 50 III.1 Thermal structure and dynamism of the subduction zone ................................................................... 51 III.2 Models of the thermal structure of the slab ......................................................................................... 53 III.3 Seismicity .............................................................................................................................................. 54 III.4 Arc magmatism .................................................................................................................................... 55 Chapter II - Hydrous Minerals and water budget in the subduction zone ....................... 57 I The crust ............................................................................................................................. 58 II The Mantle ........................................................................................................................ 61 II.1 Low pressure minerals ........................................................................................................................... 62 II.2 Serpentine and chlorite minerals ........................................................................................................... 65 II.3 Minerals stable beyond antigorite (and chlorite) stability ..................................................................... 78 II.4 High pressure and DHMS ....................................................................................................................... 86 Chapter III - Experimental and analytical methods ........................................................... 95 I Experimental methods ....................................................................................................... 96 I.1 Starting material ..................................................................................................................................... 96 I.2 Multi-anvil experiments ........................................................................................................................ 106 I.3 Experiment procedure........................................................................................................................... 112 I.4 About the choice of using multi-anvil at 3 GPa instead of piston-cylinder ........................................... 119 I.5 Kinetics of antigorite dehydration and run duration at 3 GPa .............................................................. 121 II Analytical methods ......................................................................................................... 121 II.1 Sample preparation for characterization ............................................................................................. 121 II.2 Sample characterization ...................................................................................................................... 123 Chapter IV - The intrinsic nature of natural serpentinite dehydration at 3 GPa: Implications for the oxygen fugacity conditions of slab dehydration .............................. 137 I Abstract ............................................................................................................................ 138 II Introduction .................................................................................................................... 139 III Methods ......................................................................................................................... 142 III.1 Natural antigorite sample .................................................................................................................. 142 III.2 Experimental methods ........................................................................................................................ 146 III.3 Characterization of run products ........................................................................................................ 147 IV Results ........................................................................................................................... 149 IV.1 Phase assemblages ............................................................................................................................. 149 IV.2 Textural and chemical evolution during dehydration ......................................................................... 150 V Discussion ...................................................................................................................... 164 V.1 Comparison with natural specimens ................................................................................................... 164 V.2 Comparison with antigorite stability from previous experimental studies .......................................... 164 V.3 Ferric iron redistribution in secondary phases ..................................................................................... 165 V.4 Influence of the redox environment on the formation of hematite during serpentinite dehydration . 167 V.5 Implications of high fO2 ....................................................................................................................... 170 VI Conclusion .................................................................................................................... 171 Chapter V - Antigorite phase relations for a natural system up to 11 GPa and 850 °C: Implications for slab related water transfer to the deep mantle ...................................... 177 I The role of post antigorite minerals in deep water transfer ............................................. 179 II Experimental procedure .................................................................................................. 180 III Shreinemakers analysis ................................................................................................. 181 III.1 The phase rule: generalities ................................................................................................................ 181 III.2 Definition of the system .....................................................................................................................