| The geometric curvature of the Himalayan front has long been described, and plays an important role in governing stress and deformation fields throughout the Indo-Asian collision. Here, the arc is modeled as the result of a minimum-energy interface between rigid Indian crust and more ductile Asian crust. We find that the surface trace of this interface is best described as a small circle of radius 1745 ± 55 km, centered at 91.2° E ± 1° and 42.9° N ± 1°. We also find that, according to analogy with surface thermodynamics at smaller scales, such an interface should generate along-arc tensile stresses on the order of 10–20 MPa, which may be responsible for observed along-arc extension of 14 ± 2 mm/yr along the 1000 kilometer central region of the arc, and that such an interface should maintain a stable curved form over long periods of time. These along-arc tensile forces are presumably responsible for strain in many collision zones. They initiate the curvature of subduction zones and island arcs early in their formation and maintain their curved form for very long periods of active deformation. |
