Abstract Title: THE NORTHERN WALKER LANE, NORTHWESTERN GREAT BASIN: A YOUTHFUL 
PART OF THE NORTH AMERICAN-PACIFIC TRANSFORM MARGIN 

Abstract Author(s): Faulds, James E. (Nevada Bureau of Mines and Geology, 
University of Nevada, Reno)-Henry, Christopher D. (Nevada Bureau of Mines and 
Geology, University of Nevada, Reno)-Blewitt, Geoff (Nevada Bureau of Mines and 
Geology, University of Nevada, Reno)-Coolbaugh, Mark (Great Basin Center for 
Geothermal Energy, University of Nevada, Reno)  

Abstract: The San Andreas fault system (SAF) has periodically stepped inland, 
transferring parts of North America to the Pacific plate. One manifestation 
east of the Sierra Nevada (SN) is the Walker Lane strike-slip fault system 
(WL), which currently accounts for 15-25% of the Pacific-North American plate 
motion. Cumulative slip across the WL decreases from 60-80 to 30-40 km between 
west-central and northwest Nevada concomitant with a decline in slip rates from 
~12 to 4-8 mm/yr. The WL terminates northwestward in northern California near 
the south end of the Cascade arc and latitude of Mendocino triple junction 
(MTJ). The northern Walker Lane (NWL) is therefore the youngest part of the 
transform boundary and permits analysis of incipient strike-slip fault systems. 
In northwest Nevada, the NWL consists of a discrete belt of curiously 
left-stepping, NW-striking dextral faults, which gives way in northeast 
California to a diffuse zone of discontinuous, widely-spaced, NW-striking 
faults. This geometry may reflect progressive, Riedel shear development above 
an incipient lithospheric transform that is propagating northwest in step with 
northward MTJ migration, SAF growth, and arc retreat. These relations further 
suggest that the SN and northwestern Great Basin (GB) are one micro-plate and 
that the SN has been progressively decoupling from the GB during WL evolution. 
Dextral shear in the NWL transfers into WNW-extension in the northwest GB, 
accounting for accelerated recent extension. Testing models in this complex 
setting awaits deployment of Earthscope instruments, which will permit 
integration of upper mantle tomography and flow dynamics with upper crustal 
strain patterns.