Growth mechanism of snowball garnets from the Lukmanier Pass area (Central Alps, Switzerland): a combined μCT/EPMA/EBSD study
- Robyr, Martin Institute of Mineralogy and Geochemistry, University of Lausanne, Switzerland
- Vonlanthen, Pierre Department of Geosciences, University of Fribourg, Switzerland
- Baumgartner, Lukas P. Institute of Mineralogy and Geochemistry, University of Lausanne, Switzerland
- Grobéty, Bernard Department of Geosciences, University of Fribourg, Switzerland
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21.07.2007
Published in:
- Terra Nova. - 2007, vol. 19, no. 4, p. 240-244
English
For two decades, considerable efforts have been made to explain the formation of snowball garnets by either the rotational or non-rotational models. On the basis of morphological, chemical and crystallographic evidence, this paper presents new data on snowball garnets showing that the formation of these microstructures can be explained by the combination of the two previously proposed mechanisms operating consecutively during garnet growth. The crystallization sequence of garnet revealed by Mn contouring and the distribution of crystallographic orientations within the spiral indicate that the final stages of garnet growth are controlled by post-kinematic crystallization. However, some microstructural arguments plead for a rotational contribution during the first stages of growth. In this view, the overall spiral geometry is thought to overestimate the true amount of rotation experienced by the garnets. Results also reveal the existence of complex snowball garnets consisting of several grains formed from distinct nucleation sites.
- Faculty
- Faculté des sciences et de médecine
- Department
- Département de Géosciences
- Language
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- English
- Classification
- Mineralogy
- License
- License undefined
- Identifiers
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- RERO DOC 8665
- DOI 10.1111/j.1365-3121.2007.00741.x
- Persistent URL
- https://folia.unifr.ch/unifr/documents/300501
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