Structure and stratigraphy beneath a young phreatic vent: South Inyo Crater, Long Valley caldera, California

Journal Article · Thu Nov 10 00:00:00 EST 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB093iB11p13208· OSTI ID:6392555

Eichelberger, J C; Vogel, T A; Younker, L W; Dan Miller, C; Heiken, G H; Wohletz, K H

An 861-m-long hole has been cored on a slanted trajectory that passed directly beneath South Inyo Crater in the west moat of Long valley Caldera, California. The purpose of the hole was to investigate the magmatic behavior that led to surface deformation and phreatic activity during the 600-year-old eruption of the Inyo vent chain. The hole was sited 216 m southwest of the crater, passed beneath its center at a depth of 566 m, and terminated 79 m northeast of the crater center at a depth of 810 m. Metamorphic basement was encountered at a depth of 779 m. The volcanic and sedimentary sequence consists solely of post-Bishop Tuff caldera fill, including 319 m of moat basalt and 342 m of early rhyolite, and is nearly 900 m thinner than in a Unocal Corporation well 900 m to the southeast. Apparently, a major fault lies between the two holes and forms part of the western structural boundary of the caldera, 3--4 km inboard of its topographic boundary. Breccia zones that intrude the caldera fill were intersected at 12.0--9.3 m and 1.2--0.8 m SW and 8.5--25.1 m NE of the crater center.

• Research Organization: Sandia National Laboratories, Albuquerque, New Mexico
• OSTI ID: 6392555
• Journal Information: J. Geophys. Res.; (United States), Vol. 93:B11
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
LONG VALLEY
CALDERAS
GEOLOGIC STRUCTURES
BASEMENT ROCK
MAGMATIC WATER
METAMORPHIC ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
TECTONICS
VOLCANIC ROCKS
VOLCANOES
CALIFORNIA
FEDERAL REGION IX
GEOLOGY
GROUND WATER
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
USA
WATER
580202* - Geophysics- Volcanology- (1980-1989)