Crustal velocity structure beneath the eastern flank of the Ruby Mountains metamorphic core complex: Results from normal-incidence to wide-angle seismic data

Peangta Satarugsa, Roy A Johnson

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

P-wave velocity structure along the eastern side of the Ruby Mountains metamorphic core complex, determined using 2-D ray-inversion modeling, shows that: (1) the crust can be divided into three layers corresponding to the upper, middle, and lower crust; (2) from east of Ruby Dome to the northern end of the seismic profile, velocities of the upper crust range from 6.12 (±0.1) to 6.20 (±0.1) km/s and near-surface velocities range from 1.90 (±0.1) to 4.80 (±0.1) km/s. From this point to the southern end of the profile, upper crustal velocities range from 5.80 (±0.1) to 6.25 (±0.1) km/s and near-surface velocities range from 3.01 (±0.1) to 4.80 (±0.1) km/s; (3) middle crustal velocities range from 6.35 (±0.15) to 6.45 (±0.15) km/s; (4) lower crustal velocities range from 6.60 (±0.15) to 6.80 (±0.15) km/s; and (5) depths to the Moho vary irregularly between 30.5 and 33.5 km. From interpretation of these results, we conclude that: (1) the transition in metamorphic grade from deep upper crustal rocks south of Harrison Pass to middle crustal rocks north of Harrison Pass does not correlate with an increase in seismic velocity; near-surface basement seismic velocities increase in the central part of the range (near Ruby Dome) well north of the major metamorphic transition; (2) depths to the Moho do not reflect local surface relief; isostatic balance is achieved predominantly in the crust rather than by formation of a local crustal root; and (3) the crust has been modified during extension by intracrustal processes rather than by large-scale magmatic underplating.

Original languageEnglish (US)
Pages (from-to)369-395
Number of pages27
JournalTectonophysics
Volume295
Issue number3-4
DOIs
StatePublished - Oct 15 1998

Fingerprint

ruby
velocity structure
mountains
seismic data
incidence
mountain
crusts
crust
seismic velocity
Moho
dome
crustal root
domes
underplating
velocity profile
upper crust
rock
lower crust
P-wave
rocks

Keywords

  • Crustal velocity structure
  • Metamorphic core complex
  • Ruby mountains
  • Wide-angle seismic data

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geophysics

Cite this

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title = "Crustal velocity structure beneath the eastern flank of the Ruby Mountains metamorphic core complex: Results from normal-incidence to wide-angle seismic data",
abstract = "P-wave velocity structure along the eastern side of the Ruby Mountains metamorphic core complex, determined using 2-D ray-inversion modeling, shows that: (1) the crust can be divided into three layers corresponding to the upper, middle, and lower crust; (2) from east of Ruby Dome to the northern end of the seismic profile, velocities of the upper crust range from 6.12 (±0.1) to 6.20 (±0.1) km/s and near-surface velocities range from 1.90 (±0.1) to 4.80 (±0.1) km/s. From this point to the southern end of the profile, upper crustal velocities range from 5.80 (±0.1) to 6.25 (±0.1) km/s and near-surface velocities range from 3.01 (±0.1) to 4.80 (±0.1) km/s; (3) middle crustal velocities range from 6.35 (±0.15) to 6.45 (±0.15) km/s; (4) lower crustal velocities range from 6.60 (±0.15) to 6.80 (±0.15) km/s; and (5) depths to the Moho vary irregularly between 30.5 and 33.5 km. From interpretation of these results, we conclude that: (1) the transition in metamorphic grade from deep upper crustal rocks south of Harrison Pass to middle crustal rocks north of Harrison Pass does not correlate with an increase in seismic velocity; near-surface basement seismic velocities increase in the central part of the range (near Ruby Dome) well north of the major metamorphic transition; (2) depths to the Moho do not reflect local surface relief; isostatic balance is achieved predominantly in the crust rather than by formation of a local crustal root; and (3) the crust has been modified during extension by intracrustal processes rather than by large-scale magmatic underplating.",
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N2 - P-wave velocity structure along the eastern side of the Ruby Mountains metamorphic core complex, determined using 2-D ray-inversion modeling, shows that: (1) the crust can be divided into three layers corresponding to the upper, middle, and lower crust; (2) from east of Ruby Dome to the northern end of the seismic profile, velocities of the upper crust range from 6.12 (±0.1) to 6.20 (±0.1) km/s and near-surface velocities range from 1.90 (±0.1) to 4.80 (±0.1) km/s. From this point to the southern end of the profile, upper crustal velocities range from 5.80 (±0.1) to 6.25 (±0.1) km/s and near-surface velocities range from 3.01 (±0.1) to 4.80 (±0.1) km/s; (3) middle crustal velocities range from 6.35 (±0.15) to 6.45 (±0.15) km/s; (4) lower crustal velocities range from 6.60 (±0.15) to 6.80 (±0.15) km/s; and (5) depths to the Moho vary irregularly between 30.5 and 33.5 km. From interpretation of these results, we conclude that: (1) the transition in metamorphic grade from deep upper crustal rocks south of Harrison Pass to middle crustal rocks north of Harrison Pass does not correlate with an increase in seismic velocity; near-surface basement seismic velocities increase in the central part of the range (near Ruby Dome) well north of the major metamorphic transition; (2) depths to the Moho do not reflect local surface relief; isostatic balance is achieved predominantly in the crust rather than by formation of a local crustal root; and (3) the crust has been modified during extension by intracrustal processes rather than by large-scale magmatic underplating.

AB - P-wave velocity structure along the eastern side of the Ruby Mountains metamorphic core complex, determined using 2-D ray-inversion modeling, shows that: (1) the crust can be divided into three layers corresponding to the upper, middle, and lower crust; (2) from east of Ruby Dome to the northern end of the seismic profile, velocities of the upper crust range from 6.12 (±0.1) to 6.20 (±0.1) km/s and near-surface velocities range from 1.90 (±0.1) to 4.80 (±0.1) km/s. From this point to the southern end of the profile, upper crustal velocities range from 5.80 (±0.1) to 6.25 (±0.1) km/s and near-surface velocities range from 3.01 (±0.1) to 4.80 (±0.1) km/s; (3) middle crustal velocities range from 6.35 (±0.15) to 6.45 (±0.15) km/s; (4) lower crustal velocities range from 6.60 (±0.15) to 6.80 (±0.15) km/s; and (5) depths to the Moho vary irregularly between 30.5 and 33.5 km. From interpretation of these results, we conclude that: (1) the transition in metamorphic grade from deep upper crustal rocks south of Harrison Pass to middle crustal rocks north of Harrison Pass does not correlate with an increase in seismic velocity; near-surface basement seismic velocities increase in the central part of the range (near Ruby Dome) well north of the major metamorphic transition; (2) depths to the Moho do not reflect local surface relief; isostatic balance is achieved predominantly in the crust rather than by formation of a local crustal root; and (3) the crust has been modified during extension by intracrustal processes rather than by large-scale magmatic underplating.

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