3-D Geodynamic Modeling of the India-Eurasia Collision Zone
The objective of this research is to use numerical simulations to forward model endmember models for vertical partitioning of continental lithospheric strength in the India-Eurasia collision zone and place allowable bounds on parameters describing lithospheric strength. Specifically, we investigate geometry and strength of the Indian and Burma slabs, the ratio between upper crustal and lithospheric mantle strength, strength of weak lower crust in Tibet, and the role of fault slip in driving observed surface motions about the Eastern Himalayan Syntaxis. We approximate the Indian-Eurasian collision zone geometry via a 3-D, spherical shell with Indian, Eurasian upper crust, Eurasian lower crust, and lithospheric mantle domains and apply Stokes flow to describe lithospheric deformation. We find a weak lower crust is important for numerically replicating observed horizontal and vertical surface motions, with a viscosity of 1020 Pa•s best producing deformation features matching observations. A strength of 1022 Pa•s for the Indian and Burma slabs best matches observed stress styles and surface deformation. We find a west-to-east decrease in crustal strength is required to match observations, which can be accomplished through a west-to-east increase in Indian slab dip and one-to-one ratio between upper crust and lithospheric mantle strength. Finally, we find localization of strain accommodation along large-scale strike-slip faults in tandem with a weak lower crust in Tibet is required to numerically replicate observed surface rotation about the Eastern Himalayan Syntaxis.
Flesch, Purdue University.
Geology|Geophysics|Continental Dynamics|South Asian Studies
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