Buffett B A, Garnero E J, Jeanloz R
Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Science. 2000 Nov 17;290(5495):1338-42. doi: 10.1126/science.290.5495.1338.
Unusual physical properties at the core-mantle boundary have been inferred from seismic and geodetic observations in recent years. We show how both types of observations can be explained by a layer of silicate sediments, which accumulate at the top of the core as Earth cools. Compaction of the sediments expels most of the liquid iron but leaves behind a small amount of core material, which is entrained in mantle convection and may account for the isotopic signatures of core material in some hot spot plumes. Extraction of light elements from the liquid core also enhances the vigor of convection in the core and may increase the power available to the geodynamo.
近年来，通过地震和大地测量观测推断出地核 - 地幔边界存在异常的物理性质。我们展示了这两种观测结果如何能用一层硅酸盐沉积物来解释，随着地球冷却，这些沉积物在核的顶部堆积。沉积物的压实排出了大部分液态铁，但留下了少量的核物质，这些核物质被卷入地幔对流，可能解释了一些热点地幔柱中核物质的同位素特征。从轻液态核中提取轻元素也增强了核内对流的活力，并可能增加地球发电机可利用的能量。
