Details
| Original language | English |
|---|---|
| Pages (from-to) | 209-223 |
| Number of pages | 15 |
| Journal | Chemical Geology |
| Volume | 174 |
| Issue number | 1-3 |
| Early online date | 23 Feb 2001 |
| Publication status | Published - 1 Apr 2001 |
Abstract
The 1-atm viscosities of hydrated synthetic iron-free phonolite and trachyte melts are reported between 108.4 and 101.3.1 Pa s for water contents between 0 and 5 wt.%. These show a very strong reduction with increasing water content, particularly at low contents. Empirical formulate are derived for the dependence of viscosity on temperature and water content. At magmatic temperatures of about 1100 K and water contents of 5 wt.%, viscosities are about 910 Pa s for the phonolite and 1120 Pa s for the trachyte. Comparisons with data on peralkaline rhyolites show that the effects of dissolved water are similar, even though the viscosities of the different compositions vary. This indicates that the mechanism by which water reduces the viscosities of partially depolymerized aluminosilicate liquids is independent of the alkali/alkaline earth element ratio. In addition, no major change in this pattern is observed whether water dissolves primarily as OH- or molecular H2O. This suggests that a third water-dissolution mechanism may be important in these compositions, in addition to Si-O-Si bond-breaking and dissolution of molecular water.
Keywords
- Hydrous, Magmas, Phonolites, Silicate melts, Trachytes, Viscosity
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Chemical Geology, Vol. 174, No. 1-3, 01.04.2001, p. 209-223.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The viscosity of hydrous phonolites and trachytes
AU - Whittington, Alan
AU - Richet, Pascal
AU - Linard, Yannick
AU - Holtz, François
N1 - Copyright: Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2001/4/1
Y1 - 2001/4/1
N2 - The 1-atm viscosities of hydrated synthetic iron-free phonolite and trachyte melts are reported between 108.4 and 101.3.1 Pa s for water contents between 0 and 5 wt.%. These show a very strong reduction with increasing water content, particularly at low contents. Empirical formulate are derived for the dependence of viscosity on temperature and water content. At magmatic temperatures of about 1100 K and water contents of 5 wt.%, viscosities are about 910 Pa s for the phonolite and 1120 Pa s for the trachyte. Comparisons with data on peralkaline rhyolites show that the effects of dissolved water are similar, even though the viscosities of the different compositions vary. This indicates that the mechanism by which water reduces the viscosities of partially depolymerized aluminosilicate liquids is independent of the alkali/alkaline earth element ratio. In addition, no major change in this pattern is observed whether water dissolves primarily as OH- or molecular H2O. This suggests that a third water-dissolution mechanism may be important in these compositions, in addition to Si-O-Si bond-breaking and dissolution of molecular water.
AB - The 1-atm viscosities of hydrated synthetic iron-free phonolite and trachyte melts are reported between 108.4 and 101.3.1 Pa s for water contents between 0 and 5 wt.%. These show a very strong reduction with increasing water content, particularly at low contents. Empirical formulate are derived for the dependence of viscosity on temperature and water content. At magmatic temperatures of about 1100 K and water contents of 5 wt.%, viscosities are about 910 Pa s for the phonolite and 1120 Pa s for the trachyte. Comparisons with data on peralkaline rhyolites show that the effects of dissolved water are similar, even though the viscosities of the different compositions vary. This indicates that the mechanism by which water reduces the viscosities of partially depolymerized aluminosilicate liquids is independent of the alkali/alkaline earth element ratio. In addition, no major change in this pattern is observed whether water dissolves primarily as OH- or molecular H2O. This suggests that a third water-dissolution mechanism may be important in these compositions, in addition to Si-O-Si bond-breaking and dissolution of molecular water.
KW - Hydrous
KW - Magmas
KW - Phonolites
KW - Silicate melts
KW - Trachytes
KW - Viscosity
UR - http://www.scopus.com/inward/record.url?scp=0035088941&partnerID=8YFLogxK
U2 - 10.1016/S0009-2541(00)00317-X
DO - 10.1016/S0009-2541(00)00317-X
M3 - Article
AN - SCOPUS:0035088941
VL - 174
SP - 209
EP - 223
JO - Chemical Geology
JF - Chemical Geology
SN - 0009-2541
IS - 1-3
ER -