HAL : hal-00077534, version 1

Fiche détaillée

Récupérer au format BibTeX - EndNote - TEI - RefWorks -

American mineralogist 84 (1999) 1336-1345

The effect of temperature and bulk composition on the solution mechanism of phosphorus in peraluminous haplogranitic magma.

B. O. Mysen 1, François Holtz 2, Michel Pichavant 2, Jean-Michel Bény 2, J.M. Montel 3

(1999)

Solution mechanisms of P in peraluminous glasses and melts in the system CaO-Na2O-K2O-Al2O3- SiO2-P2O5 have been examined with in-situ microRaman spectroscopy from ambient temperature to near 1200 °C. The principal aim was to examine the relative stabilities of phosphate complexes as functions of P content, peraluminosity, and temperature. Increasing peraluminosity was accomplished by increasing the proportions of Al3+ and Ca2+ of constant SiO2 content. The molar ratio Al2O3/ (CaO+Na2O+K2O) (A/CNK) ranged from ~1 to ~1.3. In all compositions, P5+ is bonded to Al3+ to form AlPO4 complexes. In addition, there is evidence for pyrophosphate complexing (P2O7). In melts with the highest (Ca+Na+K)/P, there is probably also a small fraction of orthophosphate complexes present. The relative importance of AlPO4-like complexes is correlated positively with peraluminosity (A/CNK), P2O5 content, and increasing temperature at temperatures above that of the glass transition. These structural relationships among phosphate complexes are coupled with decreasing polymerization of the aluminosilicate melts.

1 :	Geophysical Laboratory, Carnegie Institution of Washington
	Carnegie Institution of Washington
2 :	Institut des Sciences de la Terre d'Orléans (ISTO)
	CNRS : UMR6113 – INSU – Université d'Orléans
3 :	Laboratoire des Mécanismes et Transfert en Géologie (LMTG)
	CNRS : UMR5563 – Observatoire Midi-Pyrénées – Université Paul Sabatier [UPS] - Toulouse III – Institut de recherche pour le développement [IRD] : UMR154

domaine

:

Planète et Univers/Sciences de la Terre/Volcanologie

hal-00077534, version 1

http://hal-insu.archives-ouvertes.fr/hal-00077534

oai:hal-insu.archives-ouvertes.fr:hal-00077534

Contributeur : Nathalie Pothier <>

Soumis le : Mercredi 31 Mai 2006, 10:08:25

Dernière modification le : Vendredi 23 Juin 2006, 15:28:39