Publications
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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
Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon
The 6845 ± 50 BP climactic eruption of Mount Mazama discharged 47 ± 9 km3 of vertically zoned calc-alkaline magma, affording a virtually complete section through the chamber. Evidence for two andesitic parents with different trace-element (particularly Sr) and water contents is preserved in the ejecta. Prior to eruption, a dominant volume of rhyodacite was underlain successively by high...
Authors
T. H. Druitt, Charles R. Bacon
Voluminous submarine lava flows from Hawaiian volcanoes Voluminous submarine lava flows from Hawaiian volcanoes
The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from...
Authors
Robin T. Holcomb, James G. Moore, Peter W. Lipman, R.H. Belderson
Large-scale bedforms in boulder gravel produced by giant waves in Hawaii Large-scale bedforms in boulder gravel produced by giant waves in Hawaii
Approximately 105,000 yr ago (based on uranium-series dating), waves in a giant wave train swept up to an elevation of about 375 m on the island of Lanai. The waves deposited the Hulopoe Gravel, which near the present shoreline consists of basalt boulders, coral fragments, and calcareous beachrock slabs, and near the upper limit of the deposit consists of sand and shell fragments. The...
Authors
G. W. Moore, James G. Moore
The Mount Mazama climactic eruption (6900 BP) and resulting convulsive sedimentation on the continent, ocean basin, and Crater Lake caldera floor The Mount Mazama climactic eruption (6900 BP) and resulting convulsive sedimentation on the continent, ocean basin, and Crater Lake caldera floor
The climactic eruption of Mount Mazama and the resulting sedimentation may have been the most significant convulsive sedimentary event in North America during Holocene time. A collapse caldera 1,200 m deep and 10 km in diameter was formed in Mount Mazama, and its floor was covered by hundreds of meters of wall-collapse debris. Wind-blown pyroclastic ash extended 2,000 km northeast from...
Authors
C. Hans Nelson, Paul R. Carlson, Charles R. Bacon
Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides
Partitioning of Mg and Mn between titanomagnetite and ferrian ilmenite of volcanic rocks provides a test for equilibrium between coexisting phases. A plot of log(Mg/Mn)-, vs. log(Mg/Mn),, for 213 homogeneous oxide pairs from volcanic rocks yields a straight line over more than two orders of magnitude variation in Mg/Mn. Analyses that plot within reasonable limits of analytical precision...
Authors
Charles R. Bacon, M.M. Hirschmann
Diskette version of analytical results, and sample locality map for rock samples from the Iditarod quadrangle, Alaska Diskette version of analytical results, and sample locality map for rock samples from the Iditarod quadrangle, Alaska
No abstract available.
Authors
Robert G. McGimsey, Marti L. Miller, B. F. Arbogast
Historical unrest at large calderas of the world Historical unrest at large calderas of the world
No abstract available.
Authors
Christopher G. Newhall, Daniel Dzurisin
Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon
The climactic eruption of Mount Mazama has long been recognized as a classic example of rapid eruption of a substantial fraction of a zoned magma body. Increased knowledge of eruptive history and new chemical analyses of ∼350 wholerock and glass samples of the climactic ejecta, preclimactic rhyodacite flows and their inclusions, postcaldera lavas, and lavas of nearby monogenetic vents...
Authors
C. R. Bacon, T. H. Druitt