Microstructural map of a thin-section scale fold pair; implications for folding mechanism in a fine-grained garnet

• Autores: Dominicus G.A.M. Aerden, S. Aldaher, M. Bouybaouene, M. Sayab
• Localización: Trabajos de geología, ISSN 0474-9588, Nº 29, 2009, págs. 60-63
• Idioma: inglés
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• Resumen

  • etailed microstructural mapping of thin section-scale folds in a garnet bearing micaschist sample from the RIF Mountains (Morocco), including analysis of inclusion trails in 62 small garnets, reveals interesting details about the folding mechanism. A number of classic fold mechanisms capable of producing axial-plane cleavage are reviewed and shown to insufficiently explain the mapped microstructural patterns including cleavage fanning, wedge-shaped microlithons, and detailed crenulation geometries associated with different stages of compositional differentiation (S2). A new model is proposed in which crenulation cleavage evolves from initial conjugate kink bands to sets of closely spaced micro-shear zones with major shortening components.