01 Dec 2022
01 Dec 2022
Status: this preprint is open for discussion.

Magnetic Fabric Analyses of Basin Inversion: A Sandbox Modelling Approach

Thorben Schöfisch1, Hemin Koyi1,a, and Bjarne Almqvist1 Thorben Schöfisch et al.
  • 1Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Uppsala, 75236, Sweden
  • acurrently at: Department of Earth Sciences, Khalifa University of Science and Technology, Abu Dhabi, 127788, United Arab5 Emirates

Abstract. Magnetic-fabric analysis is a useful tool to display deformation in nature and in models. In this study, three sandbox models represent basin inversion above a velocity discontinuity (base-plate). After complete deformation of each model, samples were taken in different parts of the models (along faults and areas away from faults) for magnetic fabric analysis. Model I, which simulates basin formation during extension, shows two kinds of magnetic fabric: an undeformed/initial fabric in areas away from faults, and a normal fault-induced fabric with a magnetic foliation that tends to align with the fault surface. Models II and III, which were initially extended before they were shortened, developed thrust faults during inversion. The thrusts show an alignment of magnetic foliation parallel to the fault surfaces that depends on the maturity of the thrust. Our results highlight that thrusting is more efficient in aligning the magnetic fabric along them compared to normal faults. Moreover, models II and III reveal a magnetic fabric overprint towards a penetrative strain-induced fabric (magnetic lineation perpendicular to shortening direction) in areas away from thrust faults. Such overprint shows a gradual transition of a magnetic fabric to a penetrative strain-induced fabric and further towards a thrust-induced fabric during shortening/inversion. In contrast, extension (Model I) developed distinct magnetic fabrics without gradual overprint. In addition, pre-existing normal faults are also overprinted to a penetrative strain-induced fabric during model inversion. They define weak zones within the main pop-up imbricate and steepen during model inversion. Steepening influences the magnetic fabric at the faults, and, in general, the strain propagation through the model during inversion.

The magnetic fabric extracted from the models presented here reflect the different stages of basin development and inversion. This study is a first attempt of applying magnetic-fabric analyses on models simulating inverted basins. However, the outcome of this study illustrates the possibility of applying a robust tool, i.e., magnetic-fabric analyses, to sandbox models, whose initial, intermediate, and final stages are well documented.

Thorben Schöfisch et al.

Status: open (extended)

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  • RC1: 'Comment on egusphere-2022-1258', Michele Cooke, 19 Jan 2023 reply

Thorben Schöfisch et al.

Thorben Schöfisch et al.


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Short summary
Magnetic-fabric analysis provides information about the reorientation of magnetic grains and is applied to three sandbox models that simulate different stages of basin inversion. The analysed magnetic fabrics reflect the different developed structures and provides insights in the different deformed stages of basin inversion. It is a first attempt of applying magnetic-fabric analyses to basin inversion sandbox models, but shows the possibility of applying it to such models.