Contemporary Deformation of the Basin and Range Lithosphere from GPS Observations, and What They Imply for Continental Dynamics

In the western United States three end-member tectonic elements, the San Andreas Fault system, the Cascadia subduction zone, and the arch-typical Basin and Range (BR) extensional province, interact to produce complex patterns of lithospheric deformation. These boundaries each represent a different tectonic process and interact with one another in ways that are not well understood, yet they control the tectonic evolution of a large part of intermountain North America where distributed deformation is presently creating new geologic structures. Roughly 25% of the relative motion between the Pacific and North American plates is accommodated in the BR, where the patterns and rates of deformation are sensitive to ongoing plate boundary processes occurring to the west.

These active tectonic processes can now be measured directly by using precise space geodesy. The Plate Boundary Observatory (PBO) component of EarthScope is an experiment ideally suited to making the GPS measurements with the necessary precision and scope, at roughly 1000 locations distributed over the entire plate boundary, to reveal the character of the interactions between the tectonic domains.

Synthesizing the new observations from PBO and other GPS networks into plate boundary-scale kinematic models provides a means to visualize and interpret the large (and growing) geodetic dataset. In this presentation I will provide an updated view of the patterns and rates of tectonic deformation of the western part of the BR, discuss the distribution of shear and extensional deformation, and what they might reveal about the dynamics of western U.S. continental lithosphere.