The effect of temperature and bulk composition on the solution mechanism of phosphorus in peraluminous haplogranitic magma. - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles American Mineralogist Year : 1999

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

Abstract

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.

Domains

Volcanology
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Dates and versions

hal-00077534 , version 1 (31-05-2006)

Identifiers

  • HAL Id : hal-00077534 , version 1

Cite

B. O. Mysen, François Holtz, Michel Pichavant, Jean-Michel Bény, J.M. Montel. The effect of temperature and bulk composition on the solution mechanism of phosphorus in peraluminous haplogranitic magma.. American Mineralogist, 1999, 84, pp.1336-1345. ⟨hal-00077534⟩
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