Lake Bonneville Uplift and a Fluid Lower Crust

最近对盆地和山脉伸展过程的数值模拟表明，为了使莫霍河保持平坦，下地壳必须具有低粘度，这是地震观测所要求的。假设这一模型是正确的，那么应该重新研究Bonneville湖隆起，寻找满足Bonneville湖残余岸线数据的低粘度下地壳的地球模型。对博纳维尔湖荷载的近似初步模拟表明，这种模型可以成功地预测博纳维尔湖的隆升。PI将使用一个真实的Bonneville湖模型并假设线性粘弹性流变学来检验一系列貌似合理的低粘度下地壳地球模型。他将进行有限元建模，以纳入幂律流动和弹性脆的上地壳等效应。该模型意义重大，因为它可以修正先前对盆地和山脉下地幔黏度的估计，并表明Bonneville湖隆起是否与其他模型所要求的下地壳流体相容。

Recent numerical modeling of the Basin and Range extension process indicates that the lower crust must have a low viscosity in order for the Moho to remain flat, as required by seismic observation. Assuming this modeling is correct, the Lake Bonneville uplift should be re-examined with the goal of searching for earth models with low-viscosity lower crusts which satisfy the Lake Bonneville relict shoreline data. Preliminary modeling using an approximation to the Lake Bonneville load indicates that such models may successfully predict the Lake Bonneville uplift. The PI will examine a range of plausible low-viscosity lower-crustal earth models using a realistic model of Lake Bonneville and assuming linear viscoelastic rheologies. He will undertake finite- element modeling to incorporate such effects as power-law flow and an elastic-brittle upper crust. The modeling is significant because it may revise previous estimates of the upper-mantle viscosity beneath the Basin and Range, as well as indicate whether the Lake Bonneville uplift is compatible with the fluid lower crust required by other modeling.