| TAZ-TFG-2022-3382 |
Relaciones intrusivas y metamorfismo de contacto en el entorno del microgabro de Loscos (Teruel)
García Tricás, Eva
Arranz Yagüe, Enrique (dir.) ; Majarena Serrano, Urbez (dir.)
Universidad de Zaragoza,
CIEN,
2022
Departamento de Ciencias de la Tierra, Área de Petrología y Geoquímica
Graduado en Geología
Resumen: The Loscos microgabbro is the only phaneritic intrusive body of the Aragonese branch of the Iberian Range. It corresponds to a fine-grained, microgranular gabbroic intrusion with a calcoalkaline composition. Two absolute ages have been established for this intrusion (293 ± 3 Ma, 289 ± 1 Ma) that place it in the Cisuralian (Lower Permian). The emplacement of this intrusive body is related to the transtensive tectonics after the Variscan orogeny. The main outcrop of the intrusion is elongated in a SW-NE direction. Small outcrops are also observed to the west of the main intrusion, indicating that the extent of the Loscos microgabbro is greater that can be seen on the surface. Interaction with the host rock is observed, favouring the formation of contact metamorphism.
Three lithotypes are recognized in the Loscos microgabbro (gabbrorite, pyroxene-amphibole gabbro and amphibole gabbro) differentiated mainly by the dominant mafic minerals. Two pyroxenic andesitic dikes cut the microgabbro. These show warped contacts as the microgabbro was not fully consolidated during their emplacement. These confirm that the magmatic activity in the area has been multiepisodic.
Thanks to the study of different petrographic textures such as reaction rims in biotite and amphiboles or the plagioclase sieve texture, we can determine that there was a stagnation of the magma where the crystallization of some minerals began and, when the magma rose again, these minerals were destabilized and, in some cases, were overgrown at the emplacement level.
The host rocks correspond to Silurian and Devonian slates, limestones and quartzites. Different degrees of contact metamorphism are observed in the studied area, which mainly affect the Mariposas and El Castellar formations. Banded hornfelses and calcareous hornfelses are recognized, formed respectively, on rocks with alternating carbonates and slates and on pure limestone. From the study of the mineralogy and textures of a reaction aureole around a fingering of gabbro on pure limestone, it has been possible to approximate some conditions of the development of metamorphism.
Three lithotypes are recognized in the Loscos microgabbro (gabbrorite, pyroxene-amphibole gabbro and amphibole gabbro) differentiated mainly by the dominant mafic minerals. Two pyroxenic andesitic dikes cut the microgabbro. These show warped contacts as the microgabbro was not fully consolidated during their emplacement. These confirm that the magmatic activity in the area has been multiepisodic.
Thanks to the study of different petrographic textures such as reaction rims in biotite and amphiboles or the plagioclase sieve texture, we can determine that there was a stagnation of the magma where the crystallization of some minerals began and, when the magma rose again, these minerals were destabilized and, in some cases, were overgrown at the emplacement level.
The host rocks correspond to Silurian and Devonian slates, limestones and quartzites. Different degrees of contact metamorphism are observed in the studied area, which mainly affect the Mariposas and El Castellar formations. Banded hornfelses and calcareous hornfelses are recognized, formed respectively, on rocks with alternating carbonates and slates and on pure limestone. From the study of the mineralogy and textures of a reaction aureole around a fingering of gabbro on pure limestone, it has been possible to approximate some conditions of the development of metamorphism.
Tipo de Trabajo Académico: Trabajo Fin de Grado
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