Articles | Volume 9, issue 6
Research article
10 Dec 2018
Research article |  | 10 Dec 2018

Myrmekite and strain weakening in granitoid mylonites

Alberto Ceccato, Luca Menegon, Giorgio Pennacchioni, and Luiz Fernando Grafulha Morales

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Cited articles

Abart, R., Heuser, D., and Habler, G.: Mechanisms of myrmekite formation: case study from the Weinsberg granite, Moldanubian zone, Upper Austria, Contrib. Mineral. Petr., 168, 1074, 2014.
Becke, F.: Über myrmekite, Mineralogie und Pétrographie Mitteilungen 27, 377–390, 1908.
Behrmann, J. H. and Mainprice, D.: Deformation mechanisms in a high-temperature quartz-feldspar mylonite: evidence for superplastic flow in the lower continental crust, Tectonophysics, 140, 297–305, 1987.
Bellieni, G.: Caratteri geochimici del massiccio granodioritico tonalitico delle Vedrette di Ries (Rieserferner) – Alto Adige Orientale, Rendiconti della Società Italiana di Mineralogia e Petrologia 34, 527–548, 1978.
Berger, A., Herwegh, M., Schwarz, J. O., and Putlitz, B.: Quantitative analysis of crystal/grain sizes and their distributions in 2D and 3D, J. Struct. Geol., 33, 1751–1763, 2011.
Short summary
Metamorphic fine-grained reaction products make continental crust rocks weaker. Microstructural processes related to the transformation of strong K-feldspar into weak aggregates of plagioclase and quartz during crustal deformation have been investigated through electron microscopy. Rheological calculations show that the occurrence of even small amounts of weak aggregates, whose deformation is mainly diffusion-assisted, would lead to a decrease in rock viscosity of several orders of magnitude.