Implications of a magnetic model of the Long Valley Caldera, California

Journal Article · Sun Jul 10 04:00:00 EDT 1977 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB082i020p03030· OSTI ID:7101363

Williams, D L; Berkman, F; Mankinen, E A

A quantitative magnetic model of Long Valley, California, shows that the magnetic field above this caldera is dominated by intracaldera Bishop tuff, part of the ash flow tuff whose eruption precipitated the caldera collapse. We propose that about half of the 350 km/sup 3/ of intracaldera Bishop tuff, or that part beneath the resurgent dome, has been subjected to extensive hydrothermal alteration. The heat that produced this alteration is apparently associated with the residual magma chamber, and much of the formation may still be hot (>200degreeC). The magnetic minerals in the remaining intracaldera Bishop tuff have not been drastically altered, presumably because the tuff was not heated sufficiently. As a result, the tuff may not be very hot today. The model also reveals the existence of parts of two large precaldera mountains beneath the caldera fill. The resolving power attained in this investigation was possible because we were dealing with large, magnetically distinct lithologic units and a large amount of geological and geophysical data were available constraints to produce the solution.

• Research Organization: U. S. Geological Survey, Denver, Colorado 80225
• OSTI ID: 7101363
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 82:20; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150301* -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
CALDERAS
CALIFORNIA
EXPLORATION
GEOPHYSICAL SURVEYS
GEOTHERMAL EXPLORATION
IGNEOUS ROCKS
KGRA
LONG VALLEY
MAGMA
MAGNETIC FIELDS
MAGNETIC SURVEYS
NORTH AMERICA
ROCKS
TUFF
USA
WESTERN REGION