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Deformation of the subducted Indian lithospheric slab in the Burmese arc
Author(s) -
Rao N. Purnachandra
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl022034
Subject(s) - slab , geology , lithosphere , subduction , seismology , slab window , stress field , focal mechanism , geophysics , volcanic arc , eurasian plate , plate tectonics , arc (geometry) , tectonics , geometry , oceanic crust , physics , finite element method , mathematics , thermodynamics
Stress inversion of focal mechanism data in the Burmese arc region indicates distinct stress fields above and below 90 km along the subducted Indian lithospheric slab. In the upper part, the σ 1 and σ 3 axes trend NNE and ESE respectively, in conjunction with the ambient stress field of the Indian plate. However, in the lower part of the slab there is no preferred orientation of the σ 1 or σ 2 axes, but a very well defined σ 3 axis is observed, that trends steeply in the down‐dip direction. It is inferred that while the upper part is governed by the NNE oriented horizontal plate tectonic forces, the lower part is governed entirely by tensile forces due to gravitational loading on the subducted slab. A model of attempted slab detachment at the base of the lithospheric contact zone is suggested, which is supported by results of high‐resolution seismic tomographic studies in this region.