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Christian Teyssier, Principal Investigator

Thermal Mechanical Modeling of Uppermost Mantle Deformation at Micro- and Macro Sclaes

The dynamics of mid-ocean ridges are the subject of intensive multi-disciplinary research, approached through the study of active ridges and fossilized ridge segments emplaced onto continental margins (ophiolites). The aim of this project is to use numerical models of natural deformation at several scales (mm to tens of meters) to constrain the bulk rheology of the uppermost mantle at mid-ocean ridges, a quantity important for understanding the mechanical interaction of flowing mantle and crust forming at the ridge. Focus is put on chromite bodies in the Oman ophiolite, using finite element modeling to compare natural deformation and experimental laboratory deformation. This builds on previous modeling that has shown that the geometry of fracture simulated in the rigid chromite inclusion can provide estimates on the stress gradient in the surrounding olivine matrix. Using experimentally determined paleopiezometers to quantify natural stress gradients, these gradients are then simulated with numerical models, in hopes of constraining the elusive quantity of melt pressure. Series of models at different points along a deformation gradient in a chromite body are combined to estimate bulk rheology. This provides a point constraint on bulk rheology that can be placed into much larger scale numerical models of dynamics of uppermost mantle flow and crust interactions.

This group's numerical modeling code, adeli, uses a FLAC-like Lagrangian finite element/finite difference scheme designed specifically for geodynamic problems. Currently, two-dimensional models are being run, but three-dimensional models will be started in the future. Also, numerical models are being applied to other related problems of crust/mantle and lithosphere/asthenosphere interactions.

This information is available in alternative formats upon request by individuals with disabilities. Please send email to alt-format@msi.umn.edu or call 612-624-0528.

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