Publication Date:
2020-10-29
Description:
We present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite,
trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry
measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements,
combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized
melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D.
B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the
viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of
natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity
considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental
data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in
viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the
compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully
controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the
excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative
error (e.g., RMSE of 0.45 logunits).
Description:
Published
Description:
42–56
Description:
reserved
Keywords:
Viscosity
;
Model
;
Silicate melts
;
Metaluminous
;
Peraluminous
;
Peralkaline
;
04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology
;
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
717294 bytes
Format:
application/pdf
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