Details
| Original language | English |
|---|---|
| Pages (from-to) | 1155-1165 |
| Number of pages | 11 |
| Journal | American Mineralogist |
| Volume | 81 |
| Issue number | 9-10 |
| Publication status | Published - 1 Oct 1996 |
Abstract
The viscosity η of dry and hydrous haplogranitic melts (anhydrous normative composition: Qz28Ab34Or38) has been determined between 3 and IO kbar and 800 and 1400 °C using the falling-sphere method. The H2O content of the melt ranged from 0.03 to 8.21 wt%. Experiments were performed in internally heated pressure vessels (T = 900-1400 °C) and cold-seal pressure vessels (T = 800 °C). The viscosity decreases with increasing H2O content of the melt. The strongest decrease is observed at low H2O concentrations. The effect of H2O is smaller at high H2O concentrations in the melt, with an almost linear behavior between log η and H2O content expressed as weight percent H2O (decrease of 0.26 log units per weight percent H2O for H2O contents ≥4 wt% H2O). No pressure effect could be observed between 3 and 10 kbar at 900 °C for a melt containing 5.90 wt% H2O. In the investigated range the activation energy of the viscous flow decreases from 195 to 133 kJ/mol for melts with 1.05 to 8.21 wt% H2O. The effect of T and H2O content of the melt on viscosity can be calculated with a precision of ±0.2 log units with the use of the following expression: log η = -1.57 + [23.398 - 13.197(cH2O)0.11] × 103 (1/T). Viscosities calculated using the model of Shaw (1972) show that, for the investigated composition, the model underestimates the influence of H2O for low H2O concentrations (≤4 wt% H2O, difference up to two orders of magnitude at 800 °C) and overestimates slightly the influence of H2O for high H2O concentrations (≥5 wt% H2O). In comparison with the model of Persikov et al. (1990), which takes into account the OH and molecular H2O proportions, the experimental data at 800 °C are in good agreement with the calculated viscosities (deviation ≤ 1 log unit) assuming that the proportions of OH- groups and molecular H2O are those found in an in situ spectroscopic investigation of the melt. However, at higher temperatures (1000-1300 °C) the viscosity is overestimated for the OH- and H2O proportions recalculated for the appropriate temperatures.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: American Mineralogist, Vol. 81, No. 9-10, 01.10.1996, p. 1155-1165.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The influence of H2O on the viscosity of a haplogranitic melt
AU - Schulze, Frank
AU - Behrens, Harald
AU - Holtz, François
AU - Roux, Jacques
AU - Johannes, Wilhelm
N1 - Copyright: Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1996/10/1
Y1 - 1996/10/1
N2 - The viscosity η of dry and hydrous haplogranitic melts (anhydrous normative composition: Qz28Ab34Or38) has been determined between 3 and IO kbar and 800 and 1400 °C using the falling-sphere method. The H2O content of the melt ranged from 0.03 to 8.21 wt%. Experiments were performed in internally heated pressure vessels (T = 900-1400 °C) and cold-seal pressure vessels (T = 800 °C). The viscosity decreases with increasing H2O content of the melt. The strongest decrease is observed at low H2O concentrations. The effect of H2O is smaller at high H2O concentrations in the melt, with an almost linear behavior between log η and H2O content expressed as weight percent H2O (decrease of 0.26 log units per weight percent H2O for H2O contents ≥4 wt% H2O). No pressure effect could be observed between 3 and 10 kbar at 900 °C for a melt containing 5.90 wt% H2O. In the investigated range the activation energy of the viscous flow decreases from 195 to 133 kJ/mol for melts with 1.05 to 8.21 wt% H2O. The effect of T and H2O content of the melt on viscosity can be calculated with a precision of ±0.2 log units with the use of the following expression: log η = -1.57 + [23.398 - 13.197(cH2O)0.11] × 103 (1/T). Viscosities calculated using the model of Shaw (1972) show that, for the investigated composition, the model underestimates the influence of H2O for low H2O concentrations (≤4 wt% H2O, difference up to two orders of magnitude at 800 °C) and overestimates slightly the influence of H2O for high H2O concentrations (≥5 wt% H2O). In comparison with the model of Persikov et al. (1990), which takes into account the OH and molecular H2O proportions, the experimental data at 800 °C are in good agreement with the calculated viscosities (deviation ≤ 1 log unit) assuming that the proportions of OH- groups and molecular H2O are those found in an in situ spectroscopic investigation of the melt. However, at higher temperatures (1000-1300 °C) the viscosity is overestimated for the OH- and H2O proportions recalculated for the appropriate temperatures.
AB - The viscosity η of dry and hydrous haplogranitic melts (anhydrous normative composition: Qz28Ab34Or38) has been determined between 3 and IO kbar and 800 and 1400 °C using the falling-sphere method. The H2O content of the melt ranged from 0.03 to 8.21 wt%. Experiments were performed in internally heated pressure vessels (T = 900-1400 °C) and cold-seal pressure vessels (T = 800 °C). The viscosity decreases with increasing H2O content of the melt. The strongest decrease is observed at low H2O concentrations. The effect of H2O is smaller at high H2O concentrations in the melt, with an almost linear behavior between log η and H2O content expressed as weight percent H2O (decrease of 0.26 log units per weight percent H2O for H2O contents ≥4 wt% H2O). No pressure effect could be observed between 3 and 10 kbar at 900 °C for a melt containing 5.90 wt% H2O. In the investigated range the activation energy of the viscous flow decreases from 195 to 133 kJ/mol for melts with 1.05 to 8.21 wt% H2O. The effect of T and H2O content of the melt on viscosity can be calculated with a precision of ±0.2 log units with the use of the following expression: log η = -1.57 + [23.398 - 13.197(cH2O)0.11] × 103 (1/T). Viscosities calculated using the model of Shaw (1972) show that, for the investigated composition, the model underestimates the influence of H2O for low H2O concentrations (≤4 wt% H2O, difference up to two orders of magnitude at 800 °C) and overestimates slightly the influence of H2O for high H2O concentrations (≥5 wt% H2O). In comparison with the model of Persikov et al. (1990), which takes into account the OH and molecular H2O proportions, the experimental data at 800 °C are in good agreement with the calculated viscosities (deviation ≤ 1 log unit) assuming that the proportions of OH- groups and molecular H2O are those found in an in situ spectroscopic investigation of the melt. However, at higher temperatures (1000-1300 °C) the viscosity is overestimated for the OH- and H2O proportions recalculated for the appropriate temperatures.
UR - http://www.scopus.com/inward/record.url?scp=0030430385&partnerID=8YFLogxK
U2 - 10.2138/am-1996-9-1014
DO - 10.2138/am-1996-9-1014
M3 - Article
AN - SCOPUS:0030430385
VL - 81
SP - 1155
EP - 1165
JO - American Mineralogist
JF - American Mineralogist
SN - 0003-004X
IS - 9-10
ER -