Two-dimensional mantle flow beneath a rigid accreting lithosphere |
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| Authors: | EM Parmentier DL Turcotte |
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| Institution: | 1. Department of Geology and Mineralogy, University of Oxford, Oxford Great Britain;2. Department of Geological Sciences, Cornell University, Ithaca, N.Y. U.S.A. |
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| Abstract: | This study considers two-dimensional mantle flow beneath a rigid lithosphere. The lithosphere which forms the upper boundary of a convecting region moves with a prescribed uniform horizontal velocity, and thickens with distance from the accreting plate boundary as it cools. Beneath the lithosphere, the mantle deforms viscously by diffusion creep and is heated radiogenically from within. Solutions for thermal convection beneath the lithosphere are obtained by finite-difference methods. Two important conclusions have resulted from this study: (1) convective patterns of large aspect ratio are stable beneath a rigid moving lithosphere; (2) even for a lithosphere velocity as small as 3 cm/yr. and a Rayleigh number as large as 106, mantle circulation with large aspect ratio is driven dominantly by the motion of the lithosphere rather than by temperature gradients within the flow. Gravity, topography and heat flow are determined and implications for convection in the upper mantle are discussed. |
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