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Rheometry of a dacitic melt: Experimental results and tests of empirical models for viscosity estimation
Author(s) -
Stein Daniel J.,
Spera Frank J.
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl01878
Subject(s) - rheometry , viscosity , thermodynamics , empirical modelling , rheology , mineralogy , shear rate , silicate , geology , materials science , chemistry , physics , computer science , simulation , organic chemistry
Empirical models have long been available for estimating the Newtonian viscosity of single‐phase silicate melts from composition in terms of oxide components [ Bottinga and Weill , 1972; Shaw , 1972]. These models are used regularly to estimate or parametrize viscosity in field studies and fluid dynamical calculations of magmatic transport. However, few independent viscosity measurements on multi‐component melts of natural composition have been made to test the accuracy of the empirical estimation models. A series of experimental measurements of viscosity has been performed on a dacitic melt, using the technique of concentric cylinder rheometry. In the ranges of temperature and shear rate examined (1000 to 1150° C and 0.013 to 7.43 s −1 , respectively), the melt viscosity is found to be independent of shear rate. When the viscomentric results from the present study and those on a rhyolitic composition [ Hochella and Brown , 1984] are compared with the results from the empirical models, the model of Shaw [1972] is found to represent both sets of experimental data better than that of Bottinga and Weill [1972]. This is presumably due to differences in the ranges of temperature and composition represented in the data used to construct the respective models.