Kinematic Constraints on the Average Rheological Structure of Continental Lithosphere Using Deformation of Parts of the Tibetan Plateau

两个系列的数值实验被用来研究一个薄的粘性板的变形，一个类似于大陆岩石圈的变形，由一个刚性模具的压痕，类似于印度渗透到欧亚大陆的其余部分。这些实验允许对控制大陆岩石圈变形的可能的本构定律施加限制。首先是研究带有薄粘性薄片的强夹杂物在多大程度上使其附近的变形局部化。沿着西藏北缘的阿尔金塔格断裂将变形的青藏高原与西藏北部本质上坚硬的塔里木盆地分开。实验解决了(a)幂律蠕变中应变率与应力的相关幂，以及(b)强度和重力（阿甘数）在抵抗变形方面的相对作用如何导致局部化。与阿尔金断裂带附近变形带的宽度进行比较，可以对这些量加以限制。第二个是在喜马拉雅东端附近检测应变和涡度（一种测量垂直轴旋转的方法）。中国的GPS测量显示，在顺时针方向的辐合周围有一股气流，由此可以确定涡度。我们正在进行实验，研究在不同的n和Ar值下，凹痕薄粘性片是如何变形的。通过比较涡度的空间分布来确定这些量的界限。该项目的最终目标是了解控制大陆岩石圈内部强度的过程。

Two series of numerical experiments are used to study the deformation of a thin viscous sheet, an analogue for continental lithosphere, deformed by indentation by a rigid die, analogous to India's penetration into the rest of Eurasia. The experiments allow constraints to be placed on possible constitutive laws that govern the deformation of continental lithosphere. The first is studying the extent to which a strong inclusion with a thin viscous sheet localizes deformation near it. The Altyn Tagh fault along the northern margin of Tibet separates the deforming Tibetan Plateau from an essentially rigid Tarim Basin north of Tibet. The experiments address how both (a) the power relating strain-rate to stress in power-law creep and (b) the relative roles of strength and gravity, the Argand number, in resisting deformation lead to localization. A comparison with width of the zone of deformation near the Altyn Tagh fault allows constraints to be placed on these quantities. The second is examining strain and vorticity (which is a measure of rotation about a vertical axis) near the eastern end of the Himalaya. Chinese GPS measurements show a flow around the syntaxis in a clockwise sense, and from these vorticity is being determined. Experiments are being carried out to study how the indented thin viscous sheet deforms for different values of n and Ar. Bounds on these quantities are being determined through comparisons of the spatial distributions of vorticity. The ultimate project goal is to understand the processes that control strength within continental lithosphere.