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Zoned Magma Chamber | John Seach
Zoned Magma Chamber
Zonation of magma chambers is considered a common phenomenon. Zonation consists of systematic changes in bulk major, and trace element chemistry, and in the compositions of phenocryst phases in the erupted products.
Smaller volume systems show more zonation than larger systems. The process which produces different liquids at the top of a magma chamber are not completely known.
The upward accumulation of differential liquid in a magma chamber occurs by a "filling-box" mechanism. The properties of the boundary layer depend upon the Lewis number, and the ratio of thermally-induced to compositionally-induced density differences across the boundary layer.