Geologic evidence for a magma chamber beneath Newberry Volcano, Oregon

Journal Article · Sat Sep 10 00:00:00 EDT 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB093iB09p10067· OSTI ID:6834226

Macleod, N S; Sherrod, D R

At Newberry Volcano, central Oregon, more than 0.5 m.y. of magmatic activity, including caldera collapse and renewed caldera-filling volcanism, has created a structural and thermal chimney that channels magma ascent. Holocene rhyolitic eruptions (1) have been confined mainly within the caldera in an area 5 km in diameter, (2) have been very similar in chemical composition, phenocryst mineralogy, and eruptive style, and (3) have occurred as recently as 1300 years ago, with repose periods of 2000--3000 years between eruptions. Holocene basaltic andesite eruptions are widespread on the flanks but are excluded from the area of rhyolitic volcanism. Basaltic andesite in fissures at the edge of the rhyolite area has silicic inclusions and shows mixed basalt-rhyolite magma relations. These geologic relations and the high geothermal gradient that characterizes the lower part of a drill hole in the caldera (U.S. Geological Survey Newberry 2) indicate that a rhyolitic magma chamber has existed beneath the caldera throughout the Holocene. Its longevity probably is a result of intermittent underplating by basaltic magma.

• Research Organization: U.S. Geological Survey, Vancouver, Washington
• OSTI ID: 6834226
• Journal Information: J. Geophys. Res.; (United States), Vol. 93:B9
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
15 GEOTHERMAL ENERGY
CASCADE MOUNTAINS
VOLCANISM
VOLCANOES
GEOTHERMAL ENERGY
MAGMATISM
CALDERAS
GEOLOGIC HISTORY
MAGMA
OREGON
RHYOLITES
ENERGY
ENERGY SOURCES
FEDERAL REGION X
IGNEOUS ROCKS
MOUNTAINS
NORTH AMERICA
RENEWABLE ENERGY SOURCES
ROCKS
USA
VOLCANIC ROCKS
580202* - Geophysics- Volcanology- (1980-1989)
150200 - Geology & Hydrology of Geothermal Systems