Curved orogenic belts, back-arc basins, and obduction as consequences of collision at irregular continental margins

• Published in: Geology
• Main Authors: Schliffke, Nicholas, van Hunen, Jeroen, Gueydan, Frédéric, Magni, Valentina, Allen, Mark
• Other Authors: Department of Earth Sciences Durham, Durham University, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Centre for Earth Evolution and Dynamics Oslo (CEED), Department of Geosciences Oslo, Faculty of Mathematics and Natural Sciences Oslo, University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences Oslo, University of Oslo (UiO)-University of Oslo (UiO), School of Psychology Wollongong, Faculty of Social Sciences Wollongong, University of Wollongong Australia -University of Wollongong Australia
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDU]Sciences of the Universe [physics]; Newfoundland
• Online Access: https://hal.science/hal-03761831; https://hal.science/hal-03761831/document; https://hal.science/hal-03761831/file/g48919.1.pdf; https://doi.org/10.1130/G48919.1

International audience Abstract Continental collisions commonly involve highly curved passive plate margins, leading to diachronous continental subduction during trench rollback. Such systems may feature back-arc extension and ophiolite obduction postdating initial collision. Modern examples include the Alboran and Banda arcs. Ancient systems include the Newfoundland and Norwegian Caledonides. While external forces or preexisting weaknesses are often invoked, we suggest that ophiolite obduction can equally be caused by internal stress buildup during collision. Here, we modeled collision with an irregular subducting continental margin in three-dimensional (3-D) thermo-mechanical models and used the generated stress field evolution to understand resulting geologic processes. Results show how tensional stresses are localized in the overriding plate during the diachronous onset of collision. These stresses thin the overriding plate and may open a back-arc spreading center. Collision along the entire trench follows rapidly, with inversion of this spreading center, ophiolite obduction, and compression in the overriding plate. The models show how subduction of an irregular continental margin can form a highly curved orogenic belt. With this mechanism, obduction of back-arc oceanic lithosphere naturally evolves from a given initial margin geometry during continental collision.