Geologic and geophysical investigations of the Zuni-Bandera volcanic field, New Mexico
A positive, northeast-trending gravity anomaly, 90 km long and 30 km wide, extends southwest from the Zuni uplift, New Mexico. The Zuni-Bandera volcanic field, an alignment of 74 basaltic vents, is parallel to the eastern edge of the anomaly. Lavas display a bimodal distribution of tholeiitic and alkalic compositions, and were erupted over a period from 4 Myr to present. A residual gravity profile taken perpendicular to the major axis of the anomaly was analyzed using linear programming and ideal body theory to obtain bounds on the density contrast, depth, and minimum thickness of the gravity body. Two-dimensionality was assumed. The limiting case where the anomalous body reaches the surface gives 0.1 g/cm/sup 3/ as the greatest lower bound on the maximum density contrast. If 0.4 g/cm/sup 3/ is taken as the geologically reasonable upper limit on the maximum density contrast, the least upper bound on the depth of burial is 3.5 km and minimum thickness is 2 km. A shallow mafic intrusion, emplaced sometime before Laramide deformation, is proposed to account for the positive gravity anomaly. Analysis of a magnetotelluric survey suggests that the intrusion is not due to recent basaltic magma associated with the Zuni-Bandera volcanic field. This large basement structure has controlled the development of the volcanic field; vent orientations have changed somewhat through time, but the trend of the volcanic chain followed the edge of the basement structure. It has also exhibited some control on deformation of the sedimentary section.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); New Mexico Univ., Albuquerque (USA). Dept. of Geology
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6516124
- Report Number(s):
- LA-8827-MS; ON: DE81023984
- Country of Publication:
- United States
- Language:
- English
Similar Records
New Mexico Geochronology Research Laboratory: Zuni-Bandera volcanic field road log
Tectonic controls on magmatism in The Geysers--Clear Lake region: Evidence from new geophysical models
Related Subjects
NEW MEXICO
GRAVITY SURVEYS
MAGNETOTELLURIC SURVEYS
RESISTIVITY SURVEYS
BASALT
BASEMENT ROCK
DATA ANALYSIS
EXPERIMENTAL DATA
GEOLOGIC FAULTS
GEOPHYSICAL SURVEYS
GEOTHERMAL EXPLORATION
LAVA
MAGMA
VOLCANIC REGIONS
DATA
ELECTRICAL SURVEYS
ELECTROMAGNETIC SURVEYS
EXPLORATION
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
INFORMATION
NORTH AMERICA
NUMERICAL DATA
ROCKS
SOUTHWEST REGION
SURVEYS
USA
VOLCANIC ROCKS
Geothermal Legacy
150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys
150201 - Geology & Hydrology of Geothermal Systems- USA- (-1989)