Trabajos de Geología

Prologue to the special volume of the journal Trabajos de Geología on the geology of the Pyrenean Axial Zone

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Sin resumen

The structure of the Palaeozoic rocks in the Soulcem valley (Axial Zone, French Pyrenees): the western termination of the Merens Fault

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The aim of this study is the structural analysis, at all scales, of the western termination of the northern branch of the Merens Fault. In this area, the Soulcem granite intrudes pre-Caradocian quartzites and slates. In the northern part of this zone, Variscan recumbent folds are dominant with the associated S1 foliation, developed under medium-grade metamorphic conditions. To the south, upright and E-W trending Variscan folds are predominant, developed under low-grade metamorphism. Both domains are separated by the Merens Fault, which is interpreted as a Variscan structure with little Alpine displacement.

Variscan deformation of the Tor-Casamanya and Llavorsí Synclines in the Pyrenean Axial Zone (Central Pyrenees)

2023-05-10T08:09:43+02:00

The geological mapping and a structural analysis of the Tor-Casamanya and Llavorsí Synclines, in the central part of the Pyrenean Axial Zone allowed us to find structures and foliations related to two deformation events of the Variscan Orogeny, D1, characterized by E-W to SE-NW north-verging folds, and D2, characterized by (i) upright or south-verging folds, and (ii) thrusts with E-W trend southward sense of tectonic transport and rooted at the Silurian base or at deeper levels.

Structure of the Paleozoic in the transition between the Garonna Dome and the Aran Valley Synclinorium and its relationship with metamorphism (Pyrenean Axial Zone)

2023-05-10T08:15:41+02:00

In the transition between the Garonne Dome and the Aran Valley Synclinorium of the Pyrenean Axial Zone, the Variscan structures dominate, whose chronological order and relationships with the metamorphism will be attempted to be established in this study. The first two episodes of Variscan deformation (D1 and D2) developed folds, tectonic foliations and thrusts in a compressive context. Between both events a first magmatic pulse occurred, with the intrusion of sills parallel to the regional foliation (S₁). The D3 deformation episode developed under extensional conditions at the end of the Variscan Orogeny, contemporaneously with the metamorphic climax and the intrusion of the Bossòst Granitoid.

La geología del área de Gréixer (La Cerdanya, Pirineos orientales): huellas sárdicas, variscas y alpinas

2023-05-10T08:22:00+02:00

Presentamos nuevos datos sobre la evolución pre-varisca, varisca y alpina de las rocas pre-Silúricas de los alrededores de Gréixer, en La Cerdanya, Pirineo oriental. El análisis estructural y cartografía de los meta-sedimentos de bajo grado metamórfico de edad cambro-ordovícica y ordovícica superior, sugieren la existencia de tres episodios de deformación así como el emplazamiento de cabalgamientos y de una vena de cuarzo de tamaño hectométrico. La comparación con otros sectores próximos sugiriere que todos ellos forman el flanco sur (invertido) de un antiforme “D₂” kilométrico E-O con vergencia hacia el sur, de edad varisca. Este pliegue fue deformado por pliegues “D₃” posteriores, de orientación NO-SE y vergencia sur, cuyos flancos buzan moderadamente hacia el norte y cuya edad es desconocida, varisca o alpina. Además, el análisis microestructural y la disposición de las meso-estructuras D₂ sugieren la existencia de un evento de deformación “D₁”, anterior al Ordovícico Superior, que afectaría tan solo a la sucesión Cambro-Ordovícica. Por comparación con zonas vecinas, se sugiere una posible edad alpina para el emplazamiento de la vena de cuarzo y para el desarrollo de los cabalgamientos.

Structure and metamorphism of the Paleozoic rocks of the southwestern sector Lys-Caillaouas Massif (Pyrenean Axial Zone, Huesca, Spain)

2023-05-10T08:31:07+02:00

Cambro-Ordovician to Devonian rocks crop out in the study area. This work aims to establish the deformation sequence to understand its tectonic meaning and its relationships with metamorphism. In the Lys-Caillaouas Massif, after the development of the main Variscan structures (D1), a medium-grade metamorphism occurs, with the growth of porphyroblasts that, later, undergo a shear deformation related to the intrusion of the Lys-Caillaouas Granitoid. Further south, the Eriste-Valarties Fault separates this Massif from an area dominated by D2 folds that deform the D1 structures. This fault seems to be responsible for the spatial distribution of Variscan structures and has also Alpine movement.