Mineral disequilibrium in lavas explained by convective self-mixing in open magma chambers
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Summary
This summary is machine-generated.Magma mixing in andesite and dacite lavas may not always indicate different origins. Convection within a single magma body, heated from below and cooled from above, can create similar crystal features.
Area Of Science
- Volcanology
- Petrology
- Geochemistry
Background
- Porphyritic andesite and dacite lavas often exhibit crystal disequilibrium features.
- These features are typically attributed to magma mixing events.
Purpose Of The Study
- To propose an alternative explanation for disequilibrium textures in lavas.
- To investigate the role of convective self-mixing in magma bodies.
Main Methods
- Petrological analysis of andesite lava from Soufrière Hills volcano, Montserrat.
- Experimental petrology on a representative groundmass composition.
- Thermodynamic modeling of mineral-melt interactions.
Main Results
- Observed features in Montserrat andesite suggest a heating event and crystal intermingling.
- Experimental data indicate high temperatures are required to explain plagioclase overgrowth compositions.
- Convective self-mixing can generate minerals with compositions that appear non-coexistent under equilibrium.
Conclusions
- Disequilibrium textures in lavas can arise from internal convective processes within a single magma body.
- Convective self-mixing provides a viable mechanism for generating complex mineral assemblages.
- This mechanism challenges the sole reliance on magma mixing to explain observed petrological features.