Electronic Resource
Springer
Contributions to mineralogy and petrology
50 (1975), S. 145-155
ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Shock-melted rocks from the Fennoscandian shield commonly contain fragments of quartz which appear to represent paramorphs of quartz after lechatelierite and, therefore indicate very high melt temperatures, at or above 1700 °C. The presence of melt (glass) inclusions containing shrinkage bubbles in plagioclase microphenocrysts shows that the growth of this mineral took place in a fluid melt above the glass-transition temperature which in the glass from Dellen is estimated to approximately 900 °C. The morphology of plagioclase suggests that crystallization occurred at moderate degrees of supercooling and was similar to the crystallization history of melts derived by endogenous processes. Plagioclase growth in trapped melt inclusions resulted in reverse compositional zoning. Devitrification, i.e. crystallization below the glass-transition temperature, usually occurred by the formation of alkali feldspar spheralites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00373334
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