The northwestern margin of the Basin-and-Range Province, part 1: Reflection profiling of the moderate-angle (~ 30°) Surprise Valley Fault

• Published in: Tectonophysics Vol. 488; no. 1; pp. 143 - 149
• Main Authors: Lerch, Derek W., Klemperer, Simon L., Egger, Anne E., Colgan, Joseph P., Miller, Elizabeth L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-06-2010
• Subjects: Basin-and-Range Province; Dipping; Faults; Low-angle normal faults; Profiling; Reflection; Seismic engineering; Seismic phenomena; Seismic reflection profiling; Slip; Surprise Valley Fault; Valleys; INE, USA, California; Low-angle normal faults; Basin-and-Range Province; Seismic reflection profiling; Surprise Valley Fault
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2009.05.028

Seismic reflection profiling demonstrates that the active, significant-offset Surprise Valley Fault that marks the western boundary of the Basin-and-Range Province in northernmost California dips at a moderate angle, only ~
30° to ~
2 km depth. A nearby seismic refraction/wide-angle reflection profile, albeit of lower-resolution, shows the fault-plane remains approximately planar to at least 7 km depth. Variably-tilted volcanic strata of known ages within the Surprise Valley basin demonstrate that ≥
7 km of normal slip occurred along the Surprise Valley Fault within the past 8–4 Myr at a time-averaged slip rate of ~
1–2 mm/yr, and that the fault rotated from an initial dip of as much as 60° to its present dip of 30°. The rotation of this isolated fault was not accomplished by domino-style rotation as seen elsewhere in the Basin-and-Range province, but rather by flexural rift-shoulder uplift aided by mid-crustal flow.