TY - JOUR

T1 - Water solubility in phonolite melts

T2 - Influence of melt composition and temperature

AU - Schmidt, Burkhard C.

AU - Behrens, Harald

N1 - Funding Information: This research was supported by the German Science Foundation (DFG grant SCHM 1622/2). The authors would like to thank G. Raschke for the synthesis of some of the starting glasses, A. Kronz for assistance with electron microprobe analysis and U. Köhler for the manganometric measurements. The manuscript benefited from the constructive comments of three anonymous reviewers. We also thank D. Dingwell for the editorial handling.

PY - 2008/11/15

Y1 - 2008/11/15

N2 - The water solubility in various phonolite melts was determined experimentally at pressures between 50 and 395 MPa and at temperatures between 850 and 1200 °C. The aim of this study was to elucidate to which extent chemical and physical parameters such as relative amounts of alkali and alkaline earth elements or temperature affect the water solubility. For this purpose a total of 10 different phonolite glasses were prepared. For a series of four glasses, the Na/(Na + K) ratio was varied from 0.2 to 0.8, for another series of four glasses, the (Na + K)/(Ca + Mg) ratio was varied from 2.8 to 10.1, while keeping Na/(Na + K) constant at 0.4. For these two series water solubility experiments were performed at 1200 °C and pressures between 50 and 395 MPa in an internally heated pressure vessel. The data show that both chemical variables have rather small effects on the water solubility. For instance, at 2 kbar and 1200 °C an increase in Na/(Na + K) ratio from 0.2 to 0.8 leads to an increase in water solubility of about 0.4 wt.% (5.58 to 5.94 wt.%), while increasing the (Na + K)/(Ca + Mg) ratio from 2.8 to 10.1 leads to an increase of about 0.2 wt.% water. The effect of temperature was investigated for two phonolite compositions, representative of Montaña Blanca, Tenerife, Spain and the Laacher See volcanic complex, East Eifel, Germany at pressures of 50, 100, 150, 200, 250 and 300 MPa, and temperatures between 850 and 1200 °C. At these conditions both melts exhibit negative temperature dependence ranging from about - 0.1 to - 0.24 wt.% water per 100 °C. The strongest temperature dependence (most negative values) occurs at 150 to 200 MPa and seems to approach zero slightly above 300 MPa.

AB - The water solubility in various phonolite melts was determined experimentally at pressures between 50 and 395 MPa and at temperatures between 850 and 1200 °C. The aim of this study was to elucidate to which extent chemical and physical parameters such as relative amounts of alkali and alkaline earth elements or temperature affect the water solubility. For this purpose a total of 10 different phonolite glasses were prepared. For a series of four glasses, the Na/(Na + K) ratio was varied from 0.2 to 0.8, for another series of four glasses, the (Na + K)/(Ca + Mg) ratio was varied from 2.8 to 10.1, while keeping Na/(Na + K) constant at 0.4. For these two series water solubility experiments were performed at 1200 °C and pressures between 50 and 395 MPa in an internally heated pressure vessel. The data show that both chemical variables have rather small effects on the water solubility. For instance, at 2 kbar and 1200 °C an increase in Na/(Na + K) ratio from 0.2 to 0.8 leads to an increase in water solubility of about 0.4 wt.% (5.58 to 5.94 wt.%), while increasing the (Na + K)/(Ca + Mg) ratio from 2.8 to 10.1 leads to an increase of about 0.2 wt.% water. The effect of temperature was investigated for two phonolite compositions, representative of Montaña Blanca, Tenerife, Spain and the Laacher See volcanic complex, East Eifel, Germany at pressures of 50, 100, 150, 200, 250 and 300 MPa, and temperatures between 850 and 1200 °C. At these conditions both melts exhibit negative temperature dependence ranging from about - 0.1 to - 0.24 wt.% water per 100 °C. The strongest temperature dependence (most negative values) occurs at 150 to 200 MPa and seems to approach zero slightly above 300 MPa.

KW - Phonolite melt

KW - Temperature dependence

KW - Water solubility

UR - http://www.scopus.com/inward/record.url?scp=54149110527&partnerID=8YFLogxK

U2 - 10.1016/j.chemgeo.2008.06.043

DO - 10.1016/j.chemgeo.2008.06.043

M3 - Article

AN - SCOPUS:54149110527

VL - 256

SP - 259

EP - 268

JO - Chemical geology

JF - Chemical geology

SN - 0009-2541

IS - 3-4

ER -