Seismic Reflection Characterization of a Core-Complex and Low-angle Normal Fault, and Associated Basin Development, Ruby Mountains, Nevada

Reports: AC8 48467-AC8: Seismic Reflection Characterization of a Core-Complex and Low-angle Normal Fault, and Associated Basin Development, Ruby Mountains, Nevada

Simon Klemperer, Stanford University

Following a year of preparatory effort to permit access to federal lands, in June 2010 we deployed a 50-seismograph array using equioment supplied by the National Science Foundation' Earthscope Facility, to study the Ruby Mountain metamorphic core complex, northeastern Nevada. Competing theories of metamorphic core complexes stress the importance of either (1) low-angle detachment faulting and lateral crustal flow, likely leading to horizontal shearing and anisotropy, or (2) vertical diapirism creating dominantly vertical shearing and anisotropy. Our experiment aims to distinguish between these two hypotheses using densely spaced (5 to 10 km) broadband seismometers along two WNW-ESE transects across the Ruby Range and one NNE-SSW transect along the axis of the range. When data acquisition is complete we will image crustal structures and measure velocity and anisotropy with a range of receiver function, shear-wave splitting and surface-wave tomographic methods.

Analysis of preliminary data from the first week of deployment confirms data quality at our array and suggests that fast axis orientation is more North-South oriented over the Ruby range than in the surrounding region. Additional high-quality data that will start coming available in September 2010 from our Ruby Mountains experiment should allow better constraints on multi-layer anisotropic models.