Controls of the lower crust on lithospheric deformation in an intraplate setting: Insights from scaled physical analogue models
Abstract
In light of recent research investigating the deep lithosphere and its effects on intra-plate tectonics, our study focuses on the lower crust of the lithosphere. It is important to study the behavior of this brittle ductile transition in order to understand the driving forces translated from the deep lithosphere that lead to different patterns of deformation in the brittle upper crustal tectonics. To understand the brittle and ductile interplay in the lithosphere we created 3D physical analogue models. The models consist of a brittle upper crust, viscous lower crust and mantle lithosphere that are deformed in a convergent setting and consist of a structural weakness in the lithospheric mantle. Recent models investigating intraplate deformation, have revealed that deep structures in the lithospheric mantle play a significant role in the surface tectonics. In our models, the structural weakness in the lithospheric mantle is employed to initiate deformation and to study how the lower crust responds and transfers stresses to the upper crust. In addition, we also test the impact of crustal strength by varying the rheology of the lower crust. The deformation of the models is recorded by high spatial and temporal resolution cameras and the resulting data are analyzed using a Particle Image Velocimetry (PIV) methodology. These data are compared to lateral cross-sections showing finite internal structures of the deformed layered model. Preliminary results show the thickening of the lower crust as deformation propagates to the upper crust. The rate of thickening of the lower crust determines how strain is distributed in the upper crust resulting in either localized or diffused deformation. This study has implications for understanding the initiation of both long-time scale phenomena like decoupling or delamination in the lithosphere and short time-scale events like seismic activity near the brittle ductile transition.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMDI44A..04S
- Keywords:
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- 1031 Subduction zone processes;
- GEOCHEMISTRYDE: 8031 Rheology: crust and lithosphere;
- STRUCTURAL GEOLOGYDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8124 Earth's interior: composition and state;
- TECTONOPHYSICS