What Makes India such a Good Indenter?

Since about 50 Ma, the ongoing continental collision of India and Asia has led to widespread deformation within Central Asia. A similar pattern results when a rigid indenter pushes into a deformable medium. Therefore, for simplicity, many models have assumed that continental India is rigid. However, in reality, its northern margin has deformed, producing the Himalayan arc and syntaxes. To account for these, we have made physical models containing continental or oceanic plates. For realistic plate configurations and boundary conditions, our models have reproduced the Himalayan arc and syntaxes, as well as the asymmetric distribution of mountain ranges, high plateaus and basins in Central Asia. On this basis, we suggest that two features make India a good indenter. First, the Indian continental crust is buoyant and so resists subduction. Second, the surrounding oceanic crust is mechanically strong. The result is a V-shaped indenter, buoyant in the middle and strong at the sides.