Lithospheric-Scale Stresses and Shear Localization Induced by Density-Driven Instabilities
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The initiation of subduction requires the formation of lithospheric plates which mostly deform at their edges. Shear heating is a possible candidate for producing such localized deformation. In this thesis we employ a 2D model of the mantle with a visco-elasto-plastic rheology and enabled shear heating. We are able to create a shear heating instability both in a constant strain rate and a constant stress boundary condition setup. For the rst case, localized deformation in our specic setup is found for strain rates of 10-15 1/s and mantle temperatures of 1300°C. For constant stress boundaries, the conditions for a setup to localize are more restrictive. Mantle motion is induced by large cold and hot temperature perturbations. Lithospheric stresses scale with the size of these perturbations; maximum stresses are on the order of the yield stress (1 GPa). Adding topography or large inhomogeneities does not result in lithospheric-scale fracture in our model. However, localized deformation does occur for a restricted parameter choice presented in this thesis. The perturbation size has little effect on the occurrence of localization, but large perturbations shorten its onset time.
Place, publisher, year, edition, pages
2010. , 75 p.
Examensarbete vid Institutionen för geovetenskaper, ISSN 1650-6553 ; 187
Lithosphere, localization, numerical modeling, shear heating, stress, subduction initiation
IdentifiersURN: urn:nbn:se:uu:diva-183725OAI: oai:DiVA.org:uu-183725DiVA: diva2:563931
Subject / course
Master Programme in Physics
UppsokLife Earth Science
Hieronymus, ChristophKaus, Boris