The role of melt induces lithospheric weakening on the dynamics of continental rifting
2010 (English)In: Geophysical Research Abstracts, ISSN 1029-7006, Vol. 12, 8974- p.Article in journal, Meeting abstract (Refereed) Published
Place, publisher, year, edition, pages
2010. Vol. 12, 8974- p.
IdentifiersURN: urn:nbn:se:uu:diva-186923OAI: oai:DiVA.org:uu-186923DiVA: diva2:573280
EGU General Assembly 2010, held 2-7 May, 2010 in Vienna, Austria
Active or passive continental rifting is accompanied by lithospheric weakening and thinning, ascent of asthenosphereand decompressional melting. Melt percolates through the partially molten source region, accumulatesbeneath its top and is extracted. After extraction it may either be extruded at the surface or intruded at any depthbetween the top of the melting zone and the surface. In case of intrusion the release of latent and internal heat heatsup the lithosphere and weakens it. In a feed back mechanism this weakening may assist rifting and melt production.Two-dimensional numerical extension models of the continental lithosphere-asthenosphere system are carriedout based on Eulerian visco-plastic formulation. The conservation equations of mass, momentum and energy aresolved for a multi-component (crust-mantle) two-phase (melt-matrix) system. Temperature-, pressure-, and stressdependentrheology is used based on laboratory data for granite, pyroxenite and olivine, representing the uppercrust, lower crust, and mantle, respectively. Rifting is modelled by externally applying a constant rate of extension.Model series are carried out in which the emplacement depth of extracted melts is varied between the top of themelting zone and the surface. It is found that in comparison with cases without melt intrusions these lithosphericregions may be heated by up to several 100 K, which leads to viscous weakening of one order of magnitude ormore. Consequently, in a feed back mechanism rifting is dynamically enforced, leading to a significant increase ofrift induced melt generation.2012-12-072012-11-302012-12-07Bibliographically approved