“Frame Wobbling” Causing Crustal Deformation Around the Ordos Block

Abstract

AbstractAn accurate and dense GPS velocity field across the Ordos block is presented based on extensive observations. We utilized velocities from evenly distributed GPS stations within the block to estimate the parameters of rigid block motion and internal strain. Our results indicate that the Ordos block behaves rigidly, with a negligible anticlockwise rotation. The velocity profiles, strain, and block motion suggest that: the interior of the block undergoes no differential motion and internal strain is insignificant; relative to the Ordos, the adjacent blocks move in different directions and at different rates, and exert varying forces on it; the adjacent blocks deform the Ordos block along its boundaries of grabens and fold‐thrust fault zones. The Ordos block accommodates the forces exerted by the adjacent blocks through strain and deformation across its boundaries, which should be high strain or strain gradient zones. This pattern of deformation is illustrated by frame wobbling.