TY - JOUR
T1 - Dynamic mixing in magma bodies
T2 - theory, simulations, and implications
AU - Oldenburg, C. M.
AU - Spera, F. J.
AU - Yuen, D. A.
AU - Sewell, G.
PY - 1989
Y1 - 1989
N2 - Considerable geochemical and petrographic evidence suggests that magma mixing phenomena are important in producing the chemical heterogeneity commonly observed in plutonic and volcanic rocks on a variety of scales in both space and time. Simulations of time-dependent, variable viscosity, double-diffusive convection have been carried out to quantitatively investigate the mixing dynamics of magma in melt-dominated magma bodies. Mixing times are at a minimum for equant bodies, while for sill-like bodies, mixing is inhibited by the formation of multiple cells of different composition in the horizontal. Assimilation and fractional crystallization geochemical models that assume "well-mixed' magma bodies may be grossly misleading. A viscous (ie crystal laden), large (d~5km) magma body heated weakly from below and initially strongly chemically stratified will remain unmixed for several Ma. A large-volume, thermally well-connected basaltic body will mix rapidly (103-104yr). Because flow reversals may occur in dynamic mixing (Rr>0), crystal distributions within convecting magma bodies will be different from those predicted assuming steady state velocity fields. -from Authors
AB - Considerable geochemical and petrographic evidence suggests that magma mixing phenomena are important in producing the chemical heterogeneity commonly observed in plutonic and volcanic rocks on a variety of scales in both space and time. Simulations of time-dependent, variable viscosity, double-diffusive convection have been carried out to quantitatively investigate the mixing dynamics of magma in melt-dominated magma bodies. Mixing times are at a minimum for equant bodies, while for sill-like bodies, mixing is inhibited by the formation of multiple cells of different composition in the horizontal. Assimilation and fractional crystallization geochemical models that assume "well-mixed' magma bodies may be grossly misleading. A viscous (ie crystal laden), large (d~5km) magma body heated weakly from below and initially strongly chemically stratified will remain unmixed for several Ma. A large-volume, thermally well-connected basaltic body will mix rapidly (103-104yr). Because flow reversals may occur in dynamic mixing (Rr>0), crystal distributions within convecting magma bodies will be different from those predicted assuming steady state velocity fields. -from Authors
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U2 - 10.1029/JB094iB07p09215
DO - 10.1029/JB094iB07p09215
M3 - Article
AN - SCOPUS:0024940266
SN - 0148-0227
VL - 94
SP - 9215
EP - 9236
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - B7
ER -