title: The importance of structural softening for the evolution and architecture of passive margins.
abstract: Lithospheric extension can generate passive margins that bound oceans worldwide. Detailed geological and geophysical studies in present and fossil passive margins have highlighted the complexity of their architecture and their multi-stage deformation history. Previous modeling studies have shown the significant impact of coarse mechanical layering of the lithosphere (2 to 4 layer crust and mantle) on passive margin formation. We built upon these studies and design high-resolution (~100-300 m) thermo-mechanical numerical models that incorporate finer mechanical layering (kilometer scale) mimicking tectonically inherited heterogeneities. During lithospheric extension a variety of extensional structures arises naturally due to (1) structural softening caused by necking of mechanically strong layers and (2) the establishment of a network of weak layers across the deforming multi-layered lithosphere. We argue that structural softening in a multi-layered lithosphere is the main cause for the observed multi-stage evolution and architecture of magma-poor passive margins.
authors.affiliation: Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015 Lausanne, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Duretz
authors.affiliation: Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015 Lausanne, Switzerland.|École et Observatoire des Sciences de la Terre, Institut de Physique du Globe de Strasbourg - CNRS UMR7516, Université de Strasbourg, 1 rue Blessig, F-67084, Strasbourg Cedex, France.
authors.forename: B
authors.initials: B
authors.lastname: Petri
authors.affiliation: Département Géosciences et Environnement, Université de Cergy-Pontoise, 5, mail Gay Lussac, Neuville-sur-Oise, 95031 Cergy-Pontoise Cedex, France.
authors.forename: G
authors.initials: G
authors.lastname: Mohn
authors.affiliation: Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015 Lausanne, Switzerland.
authors.forename: S M
authors.initials: SM
authors.lastname: Schmalholz
authors.affiliation: Institute of Earth Sciences, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Via Trevano, CH-6952 Canobbio, Switzerland.
authors.forename: F L
authors.initials: FL
authors.lastname: Schenker
authors.affiliation: Institute of Earth Sciences, University of Lausanne, Géopolis, CH-1015 Lausanne, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Müntener