Strain partitioning in basement rocks and tectonic evolution of intramountain basins within oblique deformation regimes (transpression and transtension)

Josselin Gremmel, Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, Clermont-Ferrand, France

Vendredi 7 mars 2025 à 13 heures en salle 303

Oblique tectonic systems, characterised by the combination of strike-slip and compressional or extensional components, are widespread on Earth and have become more commonly described as our understanding of geologic structures advances. These systems, including their end-members transpression and transtension reveals structural complexity that makes interpretation of fabrics challenging, especially in the context of hot orogens. A wide variety of structures and strain patterns are observed during their evolution, notably due to a strong strain partitioning. This structural complexity enhanced polyphase opening and deformation of typical narrow intramountain basins defined by intricate architecture. The investigation of crustal fabrics formed by oblique tectonic flow, and the associated syn-sedimentary basin deformation, in a transtensional regime example (Maures-Tanneron Variscan massif, France) and a transpressional regime example (Dumont d’Urville basin, Antarctica) has provided a detailed description of strain shape and partitioning evolution inside these specific tectonic frameworks. By combining structural analysis through detailed field mapping, microstructural observations and finite strain calculations, with thermobarometric and geochronological analyses, it has been possible to precise the nature, organisation and evolution of deformation. The synthesis of these results highlights the duality of deformation styles and structures orientations between transpressional and transtensional systems. The precise structural investigation of the Carboniferous Reyran basin also provides new insights on the feedback relationship between basement deformation and syn-tectonic (pull-apart) basin opening and deformation, while the tectonic evolution of the Dumont d’Urville basin give an interesting example of the fate of a intramountain basin involved in an orogenic event.

extrait:

lien_externe:

titre:

intervenant:

date:

kc_data:

a:8:{i:0;s:0:"";s:4:"mode";s:0:"";s:3:"css";s:0:"";s:9:"max_width";s:0:"";s:7:"classes";s:0:"";s:9:"thumbnail";s:0:"";s:9:"collapsed";s:0:"";s:9:"optimized";s:0:"";}

kc_raw_content:

Strain partitioning in basement rocks and tectonic evolution of intramountain basins within oblique deformation regimes (transpression and transtension)

Josselin Gremmel, Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, Clermont-Ferrand, France

Vendredi 7 mars 2025 à 13 heures en salle 303

 

Oblique tectonic systems, characterised by the combination of strike-slip and compressional or extensional components, are widespread on Earth and have become more commonly described as our understanding of geologic structures advances. These systems, including their end-members transpression and transtension reveals structural complexity that makes interpretation of fabrics challenging, especially in the context of hot orogens. A wide variety of structures and strain patterns are observed during their evolution, notably due to a strong strain partitioning. This structural complexity enhanced polyphase opening and deformation of typical narrow intramountain basins defined by intricate architecture. The investigation of crustal fabrics formed by oblique tectonic flow, and the associated syn-sedimentary basin deformation, in a transtensional regime example (Maures-Tanneron Variscan massif, France) and a transpressional regime example (Dumont d’Urville basin, Antarctica) has provided a detailed description of strain shape and partitioning evolution inside these specific tectonic frameworks. By combining structural analysis through detailed field mapping, microstructural observations and finite strain calculations, with thermobarometric and geochronological analyses, it has been possible to precise the nature, organisation and evolution of deformation. The synthesis of these results highlights the duality of deformation styles and structures orientations between transpressional and transtensional systems. The precise structural investigation of the Carboniferous Reyran basin also provides new insights on the feedback relationship between basement deformation and syn-tectonic (pull-apart) basin opening and deformation, while the tectonic evolution of the Dumont d’Urville basin give an interesting example of the fate of a intramountain basin involved in an orogenic event.