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Thermal Consequences of Lithospheric Deformation |
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| Lithospheric Thickening |
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Thickening produces heat advection as a volume of rock, and the heat attached to it, is displaced vertically resulting in an instantaneous cooling of the geotherm. It also increases the thickness of the radiogenic layer therefore increasing the production of radiogenic heat in the lithosphere. Isostasy produces the uplift of the lithosphere leading to erosion which in turn affects the amount and distribution of the radiogenic heat elements in the crust which also impacts on the geotherm. The interplay between the geometry of the thickening, the thickening rate and the erosion rate leads to contrasted thermal history.
The graphs show transient geotherms (0, 5, 10...Ma) following heterogeneous thickening (thickening is achieved by doubling the thickness of the crust via a single thrust, which explains the temperature discontinuity at t=0), and homogeneous thickening (the thicknesses of the crust and the lithospheric mantle are doubled by pure shear deformation). Erosion is discarded here. The discontinuity in the case of heterogeneous thickening is smoothed in a few Ma. Transient geotherms in both cases are similar for time>10 Ma. |
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