Pluton accommodation at high strain rates in the upper continental crust. The example of the Central Extremadura batholith,Spain |
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| Affiliation: | 1. Institut für Mineralogie und Kristallographie, Universität Wien, A - 1090 Wien, Austria;2. Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk 664033, Russia;3. Department of Imaging and Applied Physics, Curtin University of Technology, Perth, WA 6102, Australia;1. Institute of Earth Sciences Jaume Almera–CSIC, c/Lluis Solé Sabarís s/n, 08028 Barcelona, Spain;2. Geodynamics Department, Faculty of Geological Sciences of Granada University, Campus de Fuentenueva s/n, 18071 Granada, Spain;3. Geological Department, Faculty of Geology, Oviedo University, Arias de Velasco s/n 33005 Oviedo, Spain;1. ISPRA, National Institute for Environmental Protection and Research, Via Vitaliano Brancati 60, 00144 Rome, Italy;2. Università di Cagliari, Department of Chemical and Geological Sciences, Via Trentino 51, 09127 Cagliari, Italy |
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| Abstract: | Emplacement in the tensional bridge of a stepped dextral shear zone system is proposed for the Central Extremadura batholith (Spain). The country rocks show a pervasive anisotropy that conditioned the style of the structures developed as a consequence of the transference of displacement from the stepped shear zones to the releasing area. The kinematic evolution of the resulting megakink fold provided the volume increase necessary for the granite emplacement. Thermal and kinematic models suggest that the growth of individual plutons took place in periods of no more than several hundred to a few thousand years. Fast strain rates (10−10–10−11 s−1) must concentrate in local structures (e.g. initiation of kink folds) even in zones deforming as a whole under typical strain rates (10−14±1 s−1). Granite plutons might be used as strain-rate gauges for syn-plutonic structures. |
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