Abstract
A quantitative analysis of migmatitic textures is used to describe the complex large-scale geometry of a Variscan migmatite terrain (Argentera massif, western Alps). Small-scale textural variations in migmatites, which can be observed in hand-sample and outcrop scale, closely resemble the overall structural style and kilometer-scale distribution of texturally distinct migmatites within the Argentera basement. Three-dimensional contouring of textural properties in this area suggests a strong influence of migmatization processes on the resulting seismic image of continental crust. A three-dimensional model which has been derived from the geologically reasonable extrapolation of field data shows that regional migmatization mainly results in the formation of “textural gradients”. Such gradients destroy pre-existing fabrics, lithological boundaries and layers of various acoustic impedances. Apart from the typical occurrence of granitic intrusions within the Variscan domain, the strong migmatization of basement gneisses is believed to be largely responsible for the observed seismic transparency in the mid- to upper crustal parts of the internal European Variscides.
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© 1996 Kluwer Academic Publishers
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Bierbrauer, K., Oncken, O. (1996). Large-Scale Geometry of Migmatites — Implications for the Seismic Properties of Continental Crust. In: Oncken, O., Janssen, C. (eds) Basement Tectonics 11 Europe and Other Regions. Proceedings of the International Conferences on Basement Tectonics, vol 5. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-1598-5_9
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DOI: https://doi.org/10.1007/978-94-009-1598-5_9
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