2. Mineralogy – Petrology – Geochemistry - SWISS GEOSCIENCE ...

46
Symposium 1: Structural Geology, Tectonics and Geodynamics
1.B.3
Extension of chemically stratified mantle lithosphere: numerical modeling
Jie Liao, Taras Gerya
Department of Earth Sciences, Swiss Federal Institute of Technology, Sonneggstrasse 5, CH-8092 Zurich (jie.liao@erdw.ethz.ch)
Using a 2D coupled thermo-mechanical numerical mode, we investigate the extension and breakup of the continental lithosphere.
Different from the ‘standard’ lithospheric model setup where the mantle lithosphere is a homogeneous layer,
we introduce a hydrated mantle layer in the mantle lithosphere in our model.
By changing the depth and thickness of the hydrated layer, we find out, the extension and breakup of the compositional
layered mantle lithosphere significantly differ from the ‘standard’ case, and the deformation is mainly affected by the
depth rather than the thickness of this hydrated layer (Figure. 1). In a low depth, the hydrated layer is only a low viscosity
layer emplacing into the overlying mantle and curst. In a deep depth, due to the water, partial melting occurs in the
hydrated layer. The partial melting upwells and thins the overlying mantle, and this may apply to North China Craton
where the old, depleted continental lithospheric mantle has been replaced by young, fertile ‘oceanic’ mantle(Menzies et
al., 2007).
Figure 1. Modeling results with the hydrated layer at different depth and thickness.
REFERENCES
Menzies M, Xu Y G, Zhang H F, et al. 2007: Integration of geology, geophysics and geochemistry: A key to understanding
the North China Craton, Lithos, 96, 1-21
Swiss Geoscience Meeting 2011
Platform Geosciences, Swiss Academy of Science, SCNAT