Images and videos of analogue centrifuge models exploring marginal flexure during rifting in Afar, East Africa

Abstract

This data set includes images and videos depicting the evolution of deformation and topography in 17 analogue experiments of passive margin development, to better understand the ongoing tec-tonics along the western margin of Afar, East Africa. The tectonic background that forms the basis for the experimental design is described in Zwaan et al. 2020a-d, and references therein. The ex-periments, in an enhanced gravity field in a large-capacity centrifuge, examined the influence of brittle layer thickness, strength contrast, syn-rift sedimentation and oblique extension on a brittle-viscous system with a strong and weak viscous domain.

All experiments were performed at the Tectonic Modelling Laboratory of the Istituto di Geoscience e Georisorse - Consiglio Nazionale delle Ricerche (CNR-IGG) and of the Earth Sciences Department of the University of Florence (CNR/UF). The brittle layer (sand) thickness ranged between 6 and 20 mm, the underlying viscous layer, split in a competent and weak domain (both viscous mixtures), was always 10 mm thick. Asymmetric extension was achieved by removing a 1.5 mm thick spacer at the side of the model at every time step, allowing the analogue materials to spread when en-hanced gravity was applied during a centrifuge run.

Differential stretching of the viscous material creates flexure and faulting in the overlying brittle layer. Total extension amounted to 10.5 mm over 7 intervals for Series 1 models that aimed at un-derstanding generic passive margin development in a generic orthogonal extension setting, where-as up to 16.5 mm of extension was applied for the additional Series 2 models aiming to reproduce the tectonic phases in Afar. In models involving sedimentation, sand was filled in at time steps 2, 4 and 6 (i.e. after 3, 6 and 9 mm of extension). Detailed descriptions of the experiments, monitoring techniques and tectonic interpretation of the model results are presented in Zwaan et al. (2020a).

Authors

• Zwaan, Frank;University of Florence, Florence, Italy;University of Bern, Bern, Switzerland
• Corti, Giacomo;CNR Italian National Research Council, Italy
• Keir, Derek;University of Southampton, Southampton, UK;University of Florence, Florence, Italy
• Sani, Federico;University of Florence, Florence, Italy

Contact

• Zwaan, Frank (Postdoc Researcher) ; University of Bern, Bern, Switzerland; ➦
• Corti, Giacomo; CNR Italian National Research Council, Italy;

Contributors

Tectonics Modelling Laboratory (IGG-CNR, Italy)

Keywords

EPOS, Analogue modelling results, multi-scale laboratories, Rifting, Passive margin, antiform, flexure/buckle, graben, normal fault, plateau, rift valley, deformation > ductile flow, deformation > folding, deformation > fracturing, geologic process, rifting, sedimentary process > deposition, tectonic process > continental_breakup > rifting, depression, tectonic and structural features, tectonic setting > extended terrane setting > continental rift setting, tectonic setting > plate margin setting > active continental margin setting, tectonic setting > plate spreading center setting, antiform, deformation > ductile flow, deformation > folding, deformation > fracturing, depression, flexure/buckle, geologic process, graben, graben, normal fault, plateau, rift valley, rifting, sedimentary process > deposition, tectonic and structural features, tectonic process > continental_breakup > rifting, tectonic setting > extended terrane setting > continental rift setting, tectonic setting > plate margin setting > active continental margin setting, tectonic setting > plate spreading center setting

GCMD Science Keywords

• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > CRUSTAL MOTION > CRUSTAL MOTION DIRECTION
• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > FAULT MOVEMENT > FAULT MOVEMENT DIRECTION
• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > PLATE BOUNDARIES
• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > STRAIN
• EARTH SCIENCE > SOLID EARTH > TECTONICS > PLATE TECTONICS > STRESS