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Quantitative analysis and scaling of sheared granitic magmas
Author(s) -
Koenders M. A.,
Petford Nick
Publication year - 2000
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 - 10.1029/1999gl011118
Subject(s) - dilatant , geology , biot number , scaling , rheology , magma , buoyancy , shear (geology) , strain rate , petrology , mechanics , mineralogy , geotechnical engineering , geochemistry , thermodynamics , physics , volcano , geometry , mathematics
We present a quantitative treatment of the macroscopic behaviour of a sheared granitic magma using Biot's theory [ Biot, 1941] and a shear‐dilatancy sensitive material model for the solids. The calculations are relevant to a magma in the solidosity range 0.55–0.7. The resulting excess pore pressure distribution is a function of the position and the time. Results are presented in graphical form. A scaling emerges that enables the results to be presented in non‐dimensional form. A sensitivity study is carried out of the parameters describing the rheology of the solid matrix (including permeability features). The model enables the estimate of pressure and flow rates, thus opening a way of understanding the features in the granite crystal mush that are caused by upflowing magma. At high strain rates (10 −10 S −1 ) flow rates due to shear far exceed melt movement due to buoyancy effects.