Discerning Permian orogenic metamorphism from other tectonothermal events (Mesoproterozoic to Alpine, contact to orogenic or extensional) in the concealed basement of the Basque-Cantabrian Basin (northern Spain)
| Autor: | F. Sarrionandia, Luis M. Agirrezabala, Benito Ábalos, P. Puelles, M. Carracedo-Sánchez, José Ignacio Gil-Ibarguchi |
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| Rok vydání: | 2017 |
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| Zdroj: | Lithosphere. 9:441-452 |
| ISSN: | 1947-4253 1941-8264 |
| DOI: | 10.1130/l619.1 |
| Popis: | Recently discovered Albian submarine diatremes sample tectonites from the Basque-Cantabrian Basin concealed basement. Garnet-sillimanite gneiss xenoliths provide petrologic, petrofabric, and radiometric evidence on a so-far unidentified early Permian (ca. 280–275 Ma) high-grade regional metamorphism. It is interpreted as a syntectonic event recorded at middle to lower crustal settings and related to the Variscan orogeny. This metamorphism is 25–30 m.y. younger than the Variscan high-grade regional metamorphism preserved in the axial zone of the Pyrenees and 15–30 m.y. younger than low-pressure plutonometamorphism documented in the core of the Ibero-Armorican arc. By contrast, it is 15–20 m.y. older than Variscan regional and contact metamorphism unraveled in basement outcrops around the Basque-Cantabrian Basin; it can be thoroughly discriminated from Proterozoic high-grade metamorphism preserved in lower crustal segments of the submerged north Iberian continental margin, and from low-pressure metamorphism related to mid-Cretaceous hyperextension predating the Alpine orogeny. The early Permian metamorphism reveals protracted and diachronic Variscan tectonomagmatic activity in the core of the Ibero-Armorican arc due to orocline buckling processes triggering lithosphere delamination, asthenosphere upwelling, and eventually heat and mass transfer through the continental crust. |
| Databáze: | OpenAIRE |
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