Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France
In order to constrain the finite deformation pattern of the Variscan basement of the Agly massif, a detailed structural analysis over the whole Agly massif was performed. Our investigation combined geological mapping, reappraisal of published and unpublished data completed with our own structural wo...
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| Format: | Article |
| Language: | English |
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EDP Sciences
2020-01-01
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| Series: | BSGF - Earth Sciences Bulletin |
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| Online Access: | https://www.bsgf.fr/articles/bsgf/full_html/2020/01/bsgf190032/bsgf190032.html |
| _version_ | 1824025367540662272 |
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| author | Vanardois Jonas Trap Pierre Goncalves Philippe Marquer Didier Gremmel Josselin Siron Guillaume Baudin Thierry |
| author_facet | Vanardois Jonas Trap Pierre Goncalves Philippe Marquer Didier Gremmel Josselin Siron Guillaume Baudin Thierry |
| author_sort | Vanardois Jonas |
| collection | DOAJ |
| description | In order to constrain the finite deformation pattern of the Variscan basement of the Agly massif, a detailed structural analysis over the whole Agly massif was performed. Our investigation combined geological mapping, reappraisal of published and unpublished data completed with our own structural work. Results are provided in the form of new tectonic maps and series of regional cross-sections through the Agly massif. At variance from previous studies, we identified three deformation fabrics named D1, D2 and D3. The D1 deformation is only relictual and characterized by a broadly northwest-southeast striking and eastward dipping foliation without any clear mineral and stretching lineation direction. D1 might be attributed to thickening of the Variscan crust in a possible orogenic plateau edge position. The D2 deformation is a heterogeneous non-coaxial deformation, affecting the whole massif, that produced a shallowly dipping S2 foliation, and an anastomosed network of C2 shear zones that accommodated vertical thinning and N20 directed extension. D2 is coeval with LP-HT metamorphism and plutonism at ca. 315–295 Ma. D2 corresponds to the extensional collapse of the partially molten orogenic crust in a global dextral strike-slip at the scale of the whole Variscan belt. The D2 fabrics are folded and steepened along a D3 east-west trending corridor, called Tournefort Deformation Zone (TDZ), where the Saint-Arnac and Tournefort intrusives and surrounding rocks share the same NE-SW to E-W subvertical S3 foliation. Along the D3 corridor, the asymmetrical schistosity pattern and kinematic criteria suggest a D3 dextral kinematics. The D3 deformation is a record of E-W striking dextral shearing that facilitated and localized the ascent and emplacement of the diorite and granitic sheet-shaped plutons. D3 outlasted D2 and turned compressional-dominated in response to the closure of the Ibero-Armorican arc in a transpressional regime. The progressive switch from D2 thinning to D3 transpression is attributed to the lessening of gravitational forces at an advanced stage of extensional collapse that became overcome by ongoing compressional tectonic forces at the southern edge of the Variscan orogenic plateau. |
| first_indexed | 2024-12-19T11:00:37Z |
| format | Article |
| id | doaj.art-3522076881244a7e861af7bc4de6884e |
| institution | Directory Open Access Journal |
| issn | 1777-5817 |
| language | English |
| last_indexed | 2024-12-19T11:00:37Z |
| publishDate | 2020-01-01 |
| publisher | EDP Sciences |
| record_format | Article |
| series | BSGF - Earth Sciences Bulletin |
| spelling | doaj.art-3522076881244a7e861af7bc4de6884e2022-12-21T20:24:40ZengEDP SciencesBSGF - Earth Sciences Bulletin1777-58172020-01-011911510.1051/bsgf/2020009bsgf190032Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, FranceVanardois Jonas0Trap Pierre1Goncalves Philippe2Marquer Didier3Gremmel Josselin4Siron Guillaume5Baudin Thierry6UMR 6249 Chrono-environnement, Université de Bourgogne-Franche-ComtéUMR 6249 Chrono-environnement, Université de Bourgogne-Franche-ComtéUMR 6249 Chrono-environnement, Université de Bourgogne-Franche-ComtéUMR 6249 Chrono-environnement, Université de Bourgogne-Franche-ComtéUMR 6249 Chrono-environnement, Université de Bourgogne-Franche-ComtéWiscSIMS Laboratory, University of Wisconsin-MadisonBRGM-French Geological SurveyIn order to constrain the finite deformation pattern of the Variscan basement of the Agly massif, a detailed structural analysis over the whole Agly massif was performed. Our investigation combined geological mapping, reappraisal of published and unpublished data completed with our own structural work. Results are provided in the form of new tectonic maps and series of regional cross-sections through the Agly massif. At variance from previous studies, we identified three deformation fabrics named D1, D2 and D3. The D1 deformation is only relictual and characterized by a broadly northwest-southeast striking and eastward dipping foliation without any clear mineral and stretching lineation direction. D1 might be attributed to thickening of the Variscan crust in a possible orogenic plateau edge position. The D2 deformation is a heterogeneous non-coaxial deformation, affecting the whole massif, that produced a shallowly dipping S2 foliation, and an anastomosed network of C2 shear zones that accommodated vertical thinning and N20 directed extension. D2 is coeval with LP-HT metamorphism and plutonism at ca. 315–295 Ma. D2 corresponds to the extensional collapse of the partially molten orogenic crust in a global dextral strike-slip at the scale of the whole Variscan belt. The D2 fabrics are folded and steepened along a D3 east-west trending corridor, called Tournefort Deformation Zone (TDZ), where the Saint-Arnac and Tournefort intrusives and surrounding rocks share the same NE-SW to E-W subvertical S3 foliation. Along the D3 corridor, the asymmetrical schistosity pattern and kinematic criteria suggest a D3 dextral kinematics. The D3 deformation is a record of E-W striking dextral shearing that facilitated and localized the ascent and emplacement of the diorite and granitic sheet-shaped plutons. D3 outlasted D2 and turned compressional-dominated in response to the closure of the Ibero-Armorican arc in a transpressional regime. The progressive switch from D2 thinning to D3 transpression is attributed to the lessening of gravitational forces at an advanced stage of extensional collapse that became overcome by ongoing compressional tectonic forces at the southern edge of the Variscan orogenic plateau.https://www.bsgf.fr/articles/bsgf/full_html/2020/01/bsgf190032/bsgf190032.htmlcrustal thinningvariscan orogengneiss domeagly massifeastern pyrenees |
| spellingShingle | Vanardois Jonas Trap Pierre Goncalves Philippe Marquer Didier Gremmel Josselin Siron Guillaume Baudin Thierry Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France BSGF - Earth Sciences Bulletin crustal thinning variscan orogen gneiss dome agly massif eastern pyrenees |
| title | Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France |
| title_full | Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France |
| title_fullStr | Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France |
| title_full_unstemmed | Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France |
| title_short | Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France |
| title_sort | kinematics deformation partitioning and late variscan magmatism in the agly massif eastern pyrenees france |
| topic | crustal thinning variscan orogen gneiss dome agly massif eastern pyrenees |
| url | https://www.bsgf.fr/articles/bsgf/full_html/2020/01/bsgf190032/bsgf190032.html |
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