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Exponential decay of concentration variance during magma mixing: Robustness of a volcanic chronometer and implications for the homogenization of chemical heterogeneities in magmatic systems
- Publication Year :
- 2017
-
Abstract
- The mixing of magmas is a fundamental process in the Earth system causing extreme compositional variations in igneous rocks. This process can develop with different intensities both in space and time, making the interpretation of compositional patterns in igneous rocks a petrological challenge. As a time-dependent process, magma mixing has been suggested to preserve information about the time elapsed between the injection of a new magma into sub-volcanic magma chambers and eruptions. This allowed the use of magma mixing as an additional volcanological tool to infer the mixing-to-eruption timescales. In spite of the potential of magma mixing processes to provide information about the timing of volcanic eruptions its statistical robustness is not yet established. This represents a prerequisite to apply reliably this conceptual model. Here, new chaotic magma mixing experiments were performed at different times using natural melts. The degree of reproducibility of experimental results was tested repeating one experiment at the same starting conditions and comparing the compositional variability. We further tested the robustness of the statistical analysis by randomly removing from the analysed dataset a progressively increasing number of samples. Results highlight the robustness of the method to derive empirical relationships linking the efficiency of chemical exchanges and mixing time. These empirical relationships remain valid by removing up to 80% of the analytical determinations. Experimental results were applied to constrain the homogenization time of chemical heterogeneities in natural magmatic system during mixing. The calculations show that, when the mixing dynamics generate millimetre thick filaments, homogenization timescales of the order of a few minutes are to be expected.
- Subjects :
- 010504 meteorology & atmospheric sciences
Homogenization time
Geochemistry
FOS: Physical sciences
Mineralogy
Chemical exchange
Magma chamber
010502 geochemistry & geophysics
01 natural sciences
Homogenization (chemistry)
Physics - Geophysics
Chemical exchanges
Geochemistry and Petrology
Exponential decay
Petrology
Mixing (physics)
Magma mixing, Chemical exchanges, Homogenization time, Volcanic chronometer
0105 earth and related environmental sciences
geography
geography.geographical_feature_category
Volcanic chronometer
Geology
Geophysics (physics.geo-ph)
Igneous rock
Volcano
Magma
Igneous differentiation
Magma mixing
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....70284b5df42f8fed7e51dea7411b5db7