Geologic and geophysical investigations of the Zuni-Bandera volcanic field, New Mexico

Technical Report · Fri May 01 04:00:00 EDT 1981

DOI:https://doi.org/10.2172/6516124· OSTI ID:6516124

Ander, M E; Heiken, G; Eichelberger, J; Laughlin, A W; Huestis, S

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., NM (USA); Sandia National Labs., Albuquerque, NM (USA); 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

Related Subjects

15 GEOTHERMAL ENERGY
150201 -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
150301* -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
BASALT
BASEMENT ROCK
DATA
DATA ANALYSIS
ELECTRICAL SURVEYS
ELECTROMAGNETIC SURVEYS
EXPERIMENTAL DATA
EXPLORATION
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GEOTHERMAL EXPLORATION
GRAVITY SURVEYS
Geothermal Legacy
IGNEOUS ROCKS
INFORMATION
LAVA
MAGMA
MAGNETOTELLURIC SURVEYS
NEW MEXICO
NORTH AMERICA
NUMERICAL DATA
RESISTIVITY SURVEYS
ROCKS
SOUTHWEST REGION
SURVEYS
USA
VOLCANIC REGIONS
VOLCANIC ROCKS