Convective Instability of a Thickened Convecting Boundary Layer (and Thickened Lithosphere)

小行星9725648 私家侦探。合作者将对机械增厚的边界层的对流不稳定性进行调查，目标是了解地壳（可能还有地幔岩石圈）在造山过程中增厚时，山区带下方可能发生的过程。 他们将进行数值实验与流体在2和3维，与深度和温度依赖的粘度和非线性粘度。 他们寻求简单的标度律，将实验结果与温度相关和应变率相关的粘度转移到地球上合理的条件范围内。 三维计算将集中于确定平面形状如何取决于扰动的大小和分布的流体的边界层与深度相关的粘度和温度相关的粘度，无论有和没有移动的顶部边界。 二维计算将集中于非线性粘性对不稳定性增长率和边界层变薄幅度的影响。 预计他们将开发的比例律，扰动和流变结构的增长率和岩石圈变薄的幅度，可以与观察到的地质结构和测得的山带下的过程的时间关系的大小。 ***

9725648 Molnar The P. I. and collaborators will carry out an investigation of convective instability of a mechanically thickened boundary layer, with the goal of understanding processes that might occur beneath mountain belts when crust, and presumably mantle lithosphere too, is thickened during mountain building. They will perform numerical experiments with fluids in 2 and 3 dimensions, with depth- and temperature-dependent viscosity and with non- linear viscosity. They seek simple scaling laws that will allow a transfer of experimental results with temperature-dependent and strain-rate-dependent viscosity to the range of plausible conditions in the earth. Three-dimensional calculations will concentrate on determining how planforms depend on magnitudes and distributions of perturbations to the boundary layers of fluids with depth-dependent viscosity and later temperature-dependent viscosity, both with and without moving top boundaries. Two- dimensional calculations will focus on the effect of non-linear viscosity on growth rates of instabilities and on magnitudes of thinning of the boundary layer. It is anticipated that they will develop scaling laws that relate magnitudes of perturbations and rheological structure to growth rates and magnitudes of lithospheric thinning that can relate observed geologic structures and measured timing of processes beneath mountain belts. ***