Glacial isostatic adjustment of the British Isles: new constraints from GPS measurements of crustal motion
Glacial isostatic adjustment of the British Isles: new constraints from GPS measurements of crustal motion
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DOI：
10.1111/j.1365-246x.2008.04033.x
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发表时间：
2009-07-01
影响因子：
2.8
通讯作者：
Orliac, E. J.
中科院分区：
文献类型：
--
作者：
Bradley, S. L.;Milne, G. A.;Orliac, E. J.
我们比较了地壳速度的估计在英国的基础上连续的全球定位系统（CGPS）的测量预测模型的冰川均衡调整（GIA）。垂直运动的观测值和预测值是高度相关的，表明GIA是主导的地球动力学过程，有助于这个领域。相反，欧亚板块的运动在水平运动分量中占主导地位。为了估计与GIA相关的板内水平运动，采用了一个板块运动模型来去除该信号。然而，水平运动的相干模式在所得到的速度场中并不明显。我们采用了最近发表的英国-爱尔兰冰盖模型来预测大量球对称地球粘性模型的地壳垂直运动。我们的研究结果显示，所采用的icc模式能够产生高品质的拟合观测。CGPS导出的垂直运动估计提供了一个有用的约束上地幔内的粘度的平均值。然而，模型岩石圈厚度和下地幔粘度的值不太好解决。一套替代冰模型的基础上的预测表明，垂直运动的数据是相对不敏感的不确定性，在冰加载的历史，因此上地幔粘度的约束是强大的。
We compared estimates of crustal velocities within Great Britain based on continuous global positioning system (CGPS) measurements to predictions from a model of glacial isostatic adjustment (GIA). The observed and predicted values for vertical motion are highly correlated indicating that GIA is the dominant geodynamic process contributing to this field. In contrast, motion of the Eurasian plate dominates the horizontal motion component. A model of plate motion was adopted to remove this signal in order to estimate intraplate horizontal motion associated with GIA. However, a coherent pattern of horizontal motion was not evident in the resulting velocity field. We adopted a recently published model of the British-Irish ice sheet to predict vertical crustal motion for a large number of spherically symmetric Earth viscosity models. Our results show that the adopted icc model is capable of producing a high-quality fit to the observations. The CGPS-derived estimates of vertical motion provide a useful constraint on the average value of viscosity within the upper mantle. Values of model lithospheric thickness and lower mantle viscosity are less well resolved, however. A suite of predictions based on an alternative ice model indicates that the vertical motion data are relatively insensitive to uncertainties in the ice loading history and so the constraints on upper mantle viscosity are robust.