A tomographic glimpse of the upper mantle source of magmas of the Jemez lineament, New Mexico
- Geological Survey, Denver, CO (USA)
- Univ. of Colorado, Boulder (USA)
The 800-km-long Jemez lineament is the most active volcanic feature in the southwestern United States. To infer spatial distributions of partial melt in the upper mantle source zones for the Rio Grande rift and the Jemez lineament, the authors investigated the lateral variations of P wave velocity in the upper mantle beneath these features. In their best resolved volume the inversion showed no significant concentration of relative low velocity for P waves beneath the Rio Grande rift. However, directly beneath the Jemez lineament there is a {approximately}100-km-wide, 1-2% low-velocity feature in the depth range of 50-160 km. Because of the association of the low P wave velocity with the Jemez volcanic lineament but not with the Rio Grande rift, because lowered P wave velocity can be associated with increased partial melt, and because the volume of recent volcanism at the lineament greatly exceeds that at the rift, the authors infer that a large magmatic source zone exists beneath the Jemez lineament but not beneath the Rio Grande rift. This implies that the volcanic potential of the Jemez lineament continues to greatly exceed that of the Rio Grande rift. The mantle source zones for volcanics of the Jemez lineament are not overridden by, but rather track, the motion of the North American plate; this implies that these sources are within the lithospheric plate, as is clarified in the discussion. The magmatic source zones of the Jemez lineament are modeled as due to clockwise rotation of the Colorado Plateau about a pole in northeastern Colorado. This rotation caused extension of the lithosphere beneath the Jemez lineament, permitting concentration there of partially melted rock in the upper mantle.
- OSTI ID:
- 5387259
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B7; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
DATA ANALYSIS
DETECTION
DEVELOPED COUNTRIES
EARTH MANTLE
FEDERAL REGION VI
GEOLOGIC FORMATIONS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GEOTHERMAL SYSTEMS
JEMEZ MOUNTAINS
LINEAMENTS
MAGMA SYSTEMS
MOUNTAINS
NEW MEXICO
NORTH AMERICA
ORIGIN
PLATE TECTONICS
RIFT ZONES
SEISMIC DETECTION
SEISMIC P WAVES
SEISMIC SURVEYS
SEISMIC WAVES
SURVEYS
TECTONICS
USA
VOLCANIC REGIONS
WAVE PROPAGATION