Publications
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Monitoring the hydrologic system for potential effects of geothermal and ground-water development in the Long Valley caldera, Mono County, California, U.S.A. Monitoring the hydrologic system for potential effects of geothermal and ground-water development in the Long Valley caldera, Mono County, California, U.S.A.
In the early 1980's, renewed interest in the geothermal potential of the Long Valley caldera, California, highlighted the need to balance the benefits of energy development with the established recreational activities of the area. The Long Valley Hydrologic Advisory Committee, formed in 1987, instituted a monitoring program to collect data during the early stages of resource utilization...
Authors
C. D. Farrar, D. L. Lyster
Rhyolitic calderas of the Yukon-Tanana Terrane, east central Alaska: volcanic remnants of a mid-Cretaceous magmatic arc Rhyolitic calderas of the Yukon-Tanana Terrane, east central Alaska: volcanic remnants of a mid-Cretaceous magmatic arc
Four large but poorly exposed rhyolitic calderas are present in the Yukon-Tanana terrane (YTT) in east central Alaska. At least two are mid-Cretaceous in age (~93 Ma). Similar volcanic rocks, the South Fork Volcanics, occur northeast of the Tintina fault in Yukon Territory. Evidence for the calderas consists of thick deposits of devitrified crystal- and lithic-rich densely welded tuff...
Authors
C. R. Bacon, H.L. Foster, James G. Smith
A decade of dome growth at Mount St. Helens, 1980-90 A decade of dome growth at Mount St. Helens, 1980-90
The growth of the dacite dome at Mount St. Helens between 1980 and 1986 has been more intensively studied than that of any other dome-building eruption. The growth has been complex in detail, but remarkably regular overall. This paper summarizes some of what has been learned and provides many references to additional information. Whether dome building has ended is an open question...
Authors
D. A. Swanson
Mount Mazama and Crater Lake caldera, Oregon Mount Mazama and Crater Lake caldera, Oregon
No abstract available.
Authors
Charles R. Bacon
IGC field trip T312: South cascades arc volcanism, California and southern Oregon IGC field trip T312: South cascades arc volcanism, California and southern Oregon
No abstract available.
Authors
L.J. Patrick Muffler, Charles R. Bacon, Robert L. Christiansen, Michael A. Clynne, Julie M. Donnelly-Nolan, Cheryl Miller, David R. Sherrod, J.C. Smith
Measures of little gravity Measures of little gravity
No abstract available.
Authors
Robert I. Tilling
Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon
Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower δ18O values (−3.4 to +4.9‰) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0‰). Oxygen isotope fractionation between phases in granitoids is...
Authors
Charles R. Bacon, Lanford H. Adami, Marvin A. Lanphere
Dynamic pore-pressure fluctuations in rapidly shearing granular materials Dynamic pore-pressure fluctuations in rapidly shearing granular materials
Results from two types of experiments show that intergranular pore pressures fluctuated dynamically during rapid, steady shear deformation of water-saturated granular materials. During some fluctuations, the pore water locally supported all normal and shear stresses, while grain-contact stresses transiently fell to zero. Fluctuations also propagated outward from the shear zone; this...
Authors
Richard M. Iverson, Richard G. Lahusen
Crystallization of accessory phases in magmas by local saturation adjacent to phenocrysts Crystallization of accessory phases in magmas by local saturation adjacent to phenocrysts
Accessory minerals commonly occur attached to or included in the major crystalline phases of felsic and some intermediate igneous rocks. Apatite is particularly common as inclusions, but Fe-Ti oxides, pyrrhotite, zircon, monazite, chevkinite and xenotime are also known from silicic rocks. Accessories may nucleate near the host crystal/ liquid interface as a result of local saturation...
Authors
C. R. Bacon
South Arch volcanic field—Newly identified young lava flows on the sea floor south of the Hawaiian Ridge South Arch volcanic field—Newly identified young lava flows on the sea floor south of the Hawaiian Ridge
Several young lava fields were imaged by GLORIA sidescan sonar along the Hawaiian Arch south of Hawaii. The largest, 35 by 50 km across, includes a central area characterized by high sonar backscatter and composed of several flow lobes radiating from a vent area. Reflection profiling and sea-floor photography indicate that the central lobes are flat sheet flows bounded by pillowed...
Authors
Peter W. Lipman, David A. Clague, James G. Moore, Robin T. Holcomb