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Reflection Seismology Program

Ruby Mts.



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Ruby Mts.

Crustal Structure and Evolution in NE Nevada

   The Ruby Mountains, one of a series of metamorphic core complexes extending in a narrow belt from Canada to Mexico, provide an unusual window into processes of large-scale crustal extension.  The northern Ruby Mountains expose ductilely deformed mid-Tertiary metamorphic rocks that have been tectonically exhumed from depths of ~13-14 km (from the middle crust) by extension.  However, the southern Ruby Mountains expose unmetamorphosed shallow-level sedimentary rocks.

    Regional determinations of crustal thickness, including new data collected by the Universities of Arizona, Wyoming and Georgia, indicate surprisingly uniform Moho depths throughout the region, with no significant isostatic gravity anomaly associated with the high topography of the Ruby Mountains.  Analysis of Moho reflections from our data along the eastern flank of the Ruby Mountains shows that crustal thickness varies between 30.5 and 33.5 km, with no apparent correlation between amounts of extension, exhumation, or local topographic relief.  Our interpretations of the reflection and refraction data lead to the speculation that lower crustal flow was the dominant factor in maintaining relatively uniform crustal thickness in the region.