Emplacement, structural and P-T evolution of the ˜346 Ma Miretin Pluton (eastern Tepla-Barrandian Zone, Bohemian Massif): implications for regional transpressional tectonics
2012
* �Correspondingauthor The calc-alkaline Miřetin Pluton (newly dated at 346 Ma ± 5 Ma; an U-Pb age obtained by laser-ablation ICP MS me- thod on zircons) is a NNE-SSW elongated intrusive body emplaced into the upper- to mid- crustal rocks of the Policka Unit (eastern Tepla-Barrandian Zone; Bohemian Massif). Its composition reveals similarities to other calc-alkaline granitoids, which are mostly interpreted as products of magma mixing between the basic magmas derived from mantle wedge above a subduction zone with crustally-derived acid melts. The conditions of magma crystallization estimated at 653-681 °C and 0.29-0.43 GPa roughly correspond to peak metamorphic evolution of the host volcano-sedimentary rocks of the northwestern part of the Policka and Hlinsko units. The Miřetin Pluton was emplaced into a NNE-SSW oriented transpressional domain, well recognized on a regional scale along the eastern margin of the Tepla-Barrandian Zone. During, or shortly after the magma emplacement, the Miřetin Pluton was affected by pervasive submagmatic to high-T solid-state deformation, reflecting an additional strain increment of regional transpression in a narrow zone of thermal softening. Sharply superimposed low-T solid-state fabric preserved along the western part of the Pluton was connected with normal shearing between the Policka Unit at the bottom and the overlying Hlinsko Unit after 335 Ma.
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