Publications
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Synthesis of silicoflagellate stratigraphy for maestrichtian to quaternary marine sediment Synthesis of silicoflagellate stratigraphy for maestrichtian to quaternary marine sediment
Cosmopolitan and low-latitude silicoflagellate distributions determined from Deep Sea Drilling Project cores are synthesized into a sequence of 23 biostratigraphic zones and subzones for tropical and subtropical ocean areas. The stratigraphic relation of major morphologic changes in silicoflagellates from all areas is summarized. Two new Neogene subzones, one new Paleogene subzone, one...
Authors
David Bukry
Late Cenzoic rhyolites from the Kern Plateau, southern Sierra Nevada, California. Late Cenzoic rhyolites from the Kern Plateau, southern Sierra Nevada, California.
Four late Cenozoic rhyolite domes lie atop the Kern Plateau, 30 to 40km S-SE of Mount Whitney. K-Ar and 40Ar/39Ar dating shows that Monache, Templeton, and Little Templeton Mountains are all about 2.4Ma old; a small dome nearby is approx 0.2Ma old. The three older rhyolites have SiO2 = 73-74% and have steep, fractionated rare earth element (REE) patterns; the youngest has SiO2 = 76% and...
Authors
C. R. Bacon, W. A. Duffield
Effects of volcanism on the glaciers of Mount St. Helens Effects of volcanism on the glaciers of Mount St. Helens
The cataclysmic eruption of Mount St. Helens May 18, 1980, removed 2.9 km2 (about 0.13 km3) of glacier snow and ice including a large part of Shoestring, Forsyth, Wishbone, Ape, Nelson, and all of Loowit and Leschi Glaciers. Minor eruptions and bulging of the volcano from March 27 to May 17 shattered glaciers which were on the deforming rock and deposited ash on other glaciers. Thick ash...
Authors
Melinda M. Brugman, Austin Post
Pleistocene high-silica rhyolites of the Coso volcanic field, Inyo County, California Pleistocene high-silica rhyolites of the Coso volcanic field, Inyo County, California
The high-silica rhyolite domes and lava flows of the bimodal Pleistocene part of the Coso volcanic field provide an example of the early stages of evolution of a silicic magmatic system of substantial size and longevity. Major and trace element compositions are consistent with derivation from somewhat less silicic parental material by liquid state differentiation processes in...
Authors
C. R. Bacon, R. Macdonald, R. L. Smith, P. A. Baedecker
Guides to some volcanic terranes in Washington, Idaho, Oregon, and Northern California Guides to some volcanic terranes in Washington, Idaho, Oregon, and Northern California
This guidebook arose out of a series of field trips held in conjunction with the Pacific Northwest American Geophysical Union meeting held in Bend, Oregon, September 1979. The PNAGU meeting included special volcanology sessions planned by William I. Rose, Jr., Bruce A. Nolf, amd David A. Johnston. Publication of the guidebook volume was originally planned for early 1980 by the Oregon...
Authors
David A. Johnston, Julie M. Donnelly-Nolan
Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Hughes, Kotzebue, Melozitna, Selawik, and Shungnak quadrangles, west-central Alaska, supplement to Open-file report 75-627: Part B — Lists of refe Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Hughes, Kotzebue, Melozitna, Selawik, and Shungnak quadrangles, west-central Alaska, supplement to Open-file report 75-627: Part B — Lists of refe
No abstract available.
Authors
Edward Huntington Cobb, Thomas P. Miller
Potassium-argon ages from the Mount Taylor Volcanic Field, New Mexico Potassium-argon ages from the Mount Taylor Volcanic Field, New Mexico
Fourteen new K-Ar dates for volcanic rocks of the Mount Taylor field, New Mexico, indicate that most activity occurred between 4.3 and 1.5 m.y. (million years) ago. Peak activity was at about 3.0-2.5 m.y., both on the central andesite-rhyolite shield volcano and on the surrounding alkali basalt-trachyte volcanic plateau, and occurred concurrently with an episode of NNE-trending basin...
Authors
Peter W. Lipman, Harald H. Mehnert
Late Cenozoic volcanism, geochronology, and structure of the Coso Range, Inyo County, California Late Cenozoic volcanism, geochronology, and structure of the Coso Range, Inyo County, California
The Coso Range lies at the west edge of the Great Basin, adjacent to the southern part of the Sierra Nevada. A basement complex of pre‐Cenozoic plutonic and metamorphic rocks is partly buried by ∼35 km3 of late Cenozoic volcanic rocks that were erupted during two periods, as defined by K‐Ar dating: (1) 4.0–2.5 m.y., ∼31 km3 of basalt, rhyodacite, dacite, andesite, and rhyolite, in...
Authors
Wendell A. Duffield, Charles R. Bacon, G. Brent Dalrymple
Comment and reply on ‘Comparison of Miocene provincial foraminiferal stages to coccolith zones in the California Continental Borderland’: Reply Comment and reply on ‘Comparison of Miocene provincial foraminiferal stages to coccolith zones in the California Continental Borderland’: Reply
No abstract avalable.
Authors
James K. Crouch, David Bukry