Nature of the lower crust and moho in eastern Nevada from “wide‐angle” reflection measurements

Paul A. Valasek, Robert B. Hawman, Roy A Johnson, Scott B. Smithson

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Wide angle recordings at offsets between 20 and 40 km in the Ruby Mountains consistently show 5 strong reflections between 4 and 11 s with enough moveout to estimate velocities to the base of the crust. The uppermost “layer” with a temperature corrected velocity of 6.2 km/s and thickness of 9 km corresponds to quartzofeldspathic rocks such as metasedimentary rocks, migmatites and deformed granites and is underlain by a 7‐km‐thick “layer” with velocities of 6.4 km/s which corresponds to quartzofeldspathic material interlayered with amphibolites. The lower crust consists of a heterogeneous, 9 km‐thick zone with velocities of 6.7 to 6.8 km/s corresponding to mafic rocks interlayered with smaller amounts of quartzofeldspathic rock. The lowermost crust is marked by the “X” reflection overlying a 3‐km‐thick “layer” with velocities between 7.4‐7.8 km/s corresponding to anomolous material, possibly layered cumulates. The subhorizontal, layered structure of the crust is caused primarily by ductile extension, which may well be superposed on material added to the crust by underplating. At most, approximately one third of the present crust could have been added by underplating in the Cenozoic.

Original languageEnglish (US)
Pages (from-to)1111-1114
Number of pages4
JournalGeophysical Research Letters
Issue number11
StatePublished - Nov 1987

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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