Publications
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Iridium abundance measurements across the Cretaceous/Tertiary boundary in the San Juan and Raton Basins of northern New Mexico
During the past year we have been measuring trace element abundances and searching for anomalously high iridium (Ir) concentrations in continental sedimentary rocks that span the Cretaceous-Tertiary boundary in the Raton and San Juan Basins of northern New Mexico and southern Colorado. Using neutron activation and radiochemical separations, we have identified anomalous concentrations of Ir in samp
Authors
C. J. Orth, J. S. Gilmore, J.D. Knight, R.H. Tschudy, C. L. Pillmore, James E. Fassett
Water-soluble material on aerosols collected within volcanic eruption clouds
In February and March of 1978, filter samplers mounted on an aircraft were used to collect the aerosol fraction of the eruption clouds from three active Guatemalan volcanoes (Fuego, Pacaya, and Santiaguito). The samples were collected on Teflon (Fluoropore) filters with a nominal pore diameter of 0.5μm. The mass of air sampled by the filters ranged from 0.15 to 6.6 kg. The particulate material col
Authors
D. B. Smith, R. A. Zielinski, W.I. Rose, B.J. Huebert
Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska
U-Th-Pb analyses of zircons from an ortho-augen gneiss body in the Yukon-Tanana Upland of east-central Alaska yield strong evidence for the presence of early Proterozoic material in this area. U-Pb data define a chord that intersects concordia at about 2,300 and 345 m.y. We consider two interpretations: (1) the protolith was intruded during the Proterozoic and was subsequently metamorphosed in the
Authors
John N. Aleinikoff, Cynthia Dusel-Bacon, Helen L. Foster, Kiyoto Futa
Processed and interpreted U.S. Geological Survey seismic reflection profile and vertical seismic profiles, Niobrara County, Wyoming
No abstract available.
Authors
Myung W. Lee, J. J. Miller, R. T. Ryder, A. H. Balch
Processed and interpreted U.S. Geological Survey seismic reflection profile and vertical seismic profile, Powder River and Carter Counties, Montana
No abstract available.
Authors
John J. Miller, R. T. Ryder, A. H. Balch, M. W. Lee
Uranium contents of glassy and devitrified andesites and dacites, Mount Mazama, Oregon
By direct comparison of devitrified and granophyrically crystallized specimens with nonhydrated glassy materials from the same units, Rosholt and coworkers (Rosholt and Noble, 1969; Rosholt et al., 1971) showed that specimens of primarily crystallized but otherwise unaltered peralkaline and subalkaline rhyolite from the western United States had lost from 30 to 80 percent of the uranium that they
Authors
D. C. Noble, W.I. Rose, Robert A. Zielinski
Uranium in secondary silica: A possible exploration guide
Study of uraniferous silica precipitates in the Shirley Basin, Wyoming, identified areas where ancient uraniferous ground water once ponded. Chalcedony collected from and directly beneath thick accumulations of rhyolite ash contain as much as 250 ppm uranium in a pre-ash topographic low and lesser concentrations (10 to 160 ppm) elsewhere. Differences in the U concentration of chalcedony collected
Authors
Robert A. Zielinski
Organic composition of some Upper Cretaceous shale, Powder River Basin, Wyoming
The lower Upper Cretaceous strata in northeastern Wyoming, which have yielded major quantities of oil and gas, were sampled at boreholes in Converse, Johnson, and Weston Counties. Cores of noncalcareous shale of largely nearshore-marine origin were obtained from the Frontier Formation and the overlying Cody Shale at depths of 3,780.6 to 3,879.9 m in Converse County, near the axis of the Powder Riv
Authors
E. Allen Merewether, G. E. Claypool
Comments and replies on ‘Biostratigraphy and magnetostratigraphy of Paleocene terrestrial deposits, San Juan Basin, New Mexico’: Comment
No abstract available.
Authors
James E. Fassett
Frontier Formation and equivalent rocks in eastern Wyoming
No abstract available.
Authors
E. Allen Merewether, W. A. Cobban, E.T. Cavanaugh
Comment and reply on ‘Mapped offset on the right-lateral Kern Canyon fault, southern Sierra Nevada, California’: Reply
No abstract available.
Authors
James G. Moore, Edward A. du Bray
Uranium abundances and distribution in associated glassy and crystalline rhyolites of the western United States
The abundance and distribution of uranium have been determined in 11 units of rhyolitic lava and ash-flow tuff of calc-alkaline and transitional composition from the western United States in order to further evaluate the potential of rhyolitic glass as a source of uranium ores. Samples consist of coexisting obsidians, perlites, and felsites that range in age from Pleistocene to Oligocene. Uranium
Authors
Robert A. Zielinski