We analyze data from continuous GPS stations in the southwestern United States and present the first observations of a systematic motion of the Colorado Plateau region. Relative to a North America-fixed reference frame, westward velocities increase rapidly across the Wasatch fault system, which comprises the plateau's northwestern margin, but increase more gradually between the Great Plains and the Mojave Desert province. We detect no significant extension across most of the Rio Grande Rift, but extension could be as high as ∼0.5 mm yr-1 along its southernmost portion. We suggest that the motion between the plateau and stable continent may partly be accommodated instead across the Jemez Lineament. Only when we consider GPS velocities within the plateau's center, do the data support a rigid body rotation of 0.103° Ma-1 around a pole in the northern Rocky Mountains. We conclude that active extension has encroached into the plateau from both the east and west.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)