TY - JOUR
T1 - Magma zonation
T2 - Effects of chemical buoyancy and diffusion
AU - Spera, Frank J.
AU - Oldenburg, Curtis M.
AU - Yuen, David A.
PY - 1989/12
Y1 - 1989/12
N2 - Numerical simulations and scale analysis are used to assess the viability of the marginal box‐filling mechanism for producing compositional zonation in magma bodies. Scale analysis and two‐dimensional numerical experiments both show that box‐filling occurs provided a critical ratio of compositional to thermal buoyancy (Rρcrit) is exceeded. This critical ratio depends on the ratio of thermal to chemical diffusivity (Le). For box‐filling to occur in the simplified dike‐like model system, Rρ > 2/9 Le2/3. Application of this result to magma bodies suggests that box‐filling may occur for components with relatively high chemical diffusivities such as water. However, box‐filling will not produce significant zonation for components with small chemical diffusivities such as silica, unless diffusive coupling increases silica diffusivity.
AB - Numerical simulations and scale analysis are used to assess the viability of the marginal box‐filling mechanism for producing compositional zonation in magma bodies. Scale analysis and two‐dimensional numerical experiments both show that box‐filling occurs provided a critical ratio of compositional to thermal buoyancy (Rρcrit) is exceeded. This critical ratio depends on the ratio of thermal to chemical diffusivity (Le). For box‐filling to occur in the simplified dike‐like model system, Rρ > 2/9 Le2/3. Application of this result to magma bodies suggests that box‐filling may occur for components with relatively high chemical diffusivities such as water. However, box‐filling will not produce significant zonation for components with small chemical diffusivities such as silica, unless diffusive coupling increases silica diffusivity.
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U2 - 10.1029/GL016i012p01387
DO - 10.1029/GL016i012p01387
M3 - Article
AN - SCOPUS:0024879904
SN - 0094-8276
VL - 16
SP - 1387
EP - 1390
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 12
ER -