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| Titel |
The interaction of migrating grain boundaries and fluid inclusions in naturally deformed quartz |
| VerfasserIn |
Joyce Schmatz, Janos L. Urai |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056175
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| Zusammenfassung |
| We studied the microstructure of a folded and partly recrystallized quartz vein from the Hunsrück Slates
in Germany, focusing on the morphology and distribution of fluid inclusions in the old and new grains
and along the different types of grain boundaries. Blocky vein quartz grains show undulose extinction
and develop subgrains. New grains form by subgrain rotation and grain boundary migration, with
a bimodal size distribution.
The old, deformed grains contain numerous, complex, H2O-CO2-graphite inclusions, with significant
differences in fluid inclusion setting along subgrain boundaries. The new grains have a lower content of
H2O-rich inclusions than the old grains and do not contain graphite, and there is a significant difference
in volume and density of fluid inclusions between the large and small new grains. Grain boundaries
between old and new grains are irregular, containing similar fluid inclusions as the old grains, but no
enrichment in graphite, while grain boundaries between new grains are smooth and can be inclusion free
or contain arrays of fluid inclusions.
We interpret these structures to have formed by a series of complex interactions between grain
boundaries migrating at different velocity and the fluid inclusions. Differences in mobility and grain
boundary velocity can result in different variations of drag and drop- interaction, while chemical
differences lead to phase separation during grain boundary-fluid interaction. Migration of grain
boundaries into the old grains was accompanied by significant redistribution of fluids and graphite along
the grain boundary together with oxidation of graphitic inclusions to CO2. |
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