Experimental research on rheology and seismic wave velocity properties of partially molten lower crustal rocks

为了评价熔体和水对下地壳流变性的影响，在Griggs型固体介质装置上进行了高压和高温变形实验。在水存在的情况下，熔体含量的增加会降低流动强度。流动应力随样品中水分含量的增加和应变速率的降低而减小。这表明钙长石集料的流动强度取决于引入集料中的水分含量。造成减弱所需的含水率与地球物理观测估计的下地壳含水率下限是一致的。变形实验后测得的弱化样品中残留的含水率与自然变形的长石一致。这表明下地壳水含量控制着下地壳岩石的流变性。

In order to estimate the effect of melt and water on the rheological behavior of the lower crust, high pressure and temperature deformation experiments were conducted using Griggs type solid medium apparatus. Increases in the melt content decreases flow strengths under the presence of water. The flow stress decreases with increasing the water content added to the sample and decreasing strain rate. This indicates that the flow strength of anorthite aggregates is determined by the amount of water contents introduced into the aggregate. The water content required to cause weakening was consistent with the lower bound of water contents in the lower crust estimated by geophysical observations. The water contents left in the weakened samples measured after deformation experiments are consistent with naturally deformed feldspars. This indicates that the amount of water in the lower crust controls the rheological behavior of lower crustal rocks.