Deviation between velocity trajectories from global positioning system (GPS) networks and strain trajectories from earthquake focal mechanisms and fault-slip inversion within the central Walker Lane are reconciled as the consequence of non–plane strain (constriction) within a transtensional zone separating the Sierra Nevada and central Great Basin. Dextral transtension within the central Walker Lane is produced by differential displacement of the Sierra Nevada with respect to the central Great Basin, and it is partitioned into domains exhibiting simple shear–dominated and pure shear–dominated strain. From east to west across the central Walker Lane, GPS velocities change orientation from west-northwest to northwest and increase from 2–3 to 12–14 mm/yr as the incremental-strain elongation axis changes from west-northwest to west-southwest. The deviation between strain and velocity trajectories increases to 50° as the Sierra Nevada Range is approached from the east. This deviation in strain and velocity trajectories is consistent with analytical models linking kinematic vorticity, particle velocity paths, and incremental non–plane strain during transtensional deformation. We link field observations to the analytical models using a polar Mohr construction in a system that conserves kinematic boundary conditions to graphically demonstrate that the relationship between velocity and strain fields is a consequence of constrictional deformation.

Integrated mapping, fault-kinematic, paleomagnetic, and gravity analyses around the Rhodes Salt Marsh extensional basin, located within the east-west–trending Mina deflection of the central Walker Lane, reveal that from 8.0 to 9.0 km of late Cenozoic displacement was accommodated on a curved array of faults. The dominant slip on the faults systematically varies from left-oblique, to normal, and to right-oblique as fault strike changes from east, to north-northeast, and to north-northwest, respectively. Kinematic consistency of fault slickenline rakes, preservation of displacement budget, and paleomagnetic data from a pluton and volcanic rocks in the fault-system hanging wall indicate that the curved fault geometry is primary and not due to superposition of two fault systems nor to later vertical-axis rotation. Large-magnitude extension was localized at the apex of the curved faults and resulted in the formation of an ~3.0-km-deep prismatic basin beneath Rhodes Salt Marsh. The offset geologic structures and geophysical basin models indicate that hanging-wall displacement diverged around the curved fault array and resulted in finite flattening, with primary and secondary extensional axes oriented west-northwest and north-northeast, respectively. Fault-slip inversion yields two directions of extension consistent with the finite strain axes, and slickenlines with mutually crosscutting relations indicate formation during incremental flattening. Although broadly contemporaneous, extension parallel to the primary and secondary extension axes alternated at periods ranging from months to as much as several hundred thousand years. Large through-going structures sustained extension directions recorded geodetically and seismologically through multiple seismic cycles. In contrast, the alternation between primary and secondary extension directions recorded by a strainmeter suggests that, on small structures contained within fault-bounded blocks, the two extension directions alternated over time scales of as little as 2 yr.