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Geotherms, Lithosphere Thickness and Sedimentary Basins
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 11th SAGA Biennial Technical Meeting and Exhibition, Sep 2009, cp-241-00046
Abstract
A relation between the thickness of the lithosphere and geothermal gradients in the mantle can be extracted from two independent sets of observations. One set is the relation between lithosphere thickness determined from magnetotelluric measurements and surface heat flow. The other set of observations is the temperature-depth array that can be extracted from xenoliths in kimberlites. Both sets lead to the conclusion that an increase in the temperature at the Moho is accompanied by thinning of the lithosphere when the lithosphere is thinner than 180 km, but is accompanied by thickening of the lithosphere when the lithosphere is thicker than 200 km. The corollary of this conclusion is that the same high Moho temperature can be associated with very thin or very thick lithosphere. Switching from very thin to very thick lithosphere can initiate the formation of a sedimentary basin. Continued increase in Moho temperature results in further thickening of the lithosphere and growth of the sedimentary basin.