HR: 1330h
AN: V22D-0606    [PDF]
TI: Melt Redistribution During The Bending Of A Porous, Partially Melted Layer
AU: Simakin, A
EM: simakin@mail.und.nodak.edu
AF: Alexander Simakin, Geology & Geological Engineering, University of ND, Grand Forks, ND 58202-8358 United States
AU: * Petford, N
EM: n.petford@kingston.ac.uk
AF: Nick Petford, Kingston University, London, KT1 2EE United Kingdom
AB: A numerical, poro-viscoelastic finite element flow model has been developed to simulate the redistribution of partial melt during the folding of a horizontal layer. Important mechanical properties governing the overall rheology of the buckling layer including porosity, matrix viscosity, melt pressure and changes in deviatoric stress are tracked simultaneously with deformation. Melt migrates down gradients in melt pressure to the outer hinges of the folds, away from sites of compression to regions of local extension. For a matrix with dynamic power law rheology, deformation results in the formation of low viscosity, strain weakening zones that coincide with zones of enhanced deviatoric stress that are potential sites for plastic deformation. During fast deformation of layers with large width to height ratios, the more rapidly bending material splits into domains of higher viscosity separated by lower viscosity zones. Porosity (melt fraction) distribution patterns do not appear to be controlled by the matrix rheology. The numerical results and predictions of melt distribution and geometry during deformation corresponds well with data from some physical (analogue) laboratory experiments and field observations. The quantitative nature of our results should help refine more qualitative models for the rates and mechanisms of melt extraction and transport in folded crustal migmatite terranes.
DE: 1236 Rheology of the lithosphere and mantle (8160)
DE: 5114 Permeability and porosity
DE: 5139 Transport properties
DE: 8045 Role of fluids
DE: 8102 Continental contractional orogenic belts
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting