Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2542
Equivalent radiolarian ages from ophiolitic terranes of Cyprus and Oman Equivalent radiolarian ages from ophiolitic terranes of Cyprus and Oman
Radiolarian biostratigraphy shows that umberiferous strata overlying the Troodos ophiolite in Cyprus are Turonian in age and are thus essentially contemporaneous with similar strata that overlie the Samail ophiolite in Oman. However, this radiolarian age is markedly older than Campanian isotopic ages measured on the underlying rocks of the Troodos ophiolite. The revised age for the...
Authors
Charles D. Blome, William P. Irwin
On the line: Losing by a landslide, invited comment On the line: Losing by a landslide, invited comment
No abstract available.
Authors
E. E. Brabb
Origin and tectonic evolution of the Maclaren and Wrangellia terranes, eastern Alaska Range, Alaska Origin and tectonic evolution of the Maclaren and Wrangellia terranes, eastern Alaska Range, Alaska
Major portions of the eastern Alaska Range, south of the Denali fault, in the McCarthy, Nabesna, Mount Hayes, and eastern Healy quadrangles, consist predominantly of the Maclaren and Wrangellia tectono-stratigraphic terranes. The Maclaren terrane consists of the Maclaren Glacier metamorphic belt and the regionally deformed and metamorphosed East Susitna batholith. The Maclaren Glacier...
Authors
Warren J. Nokleberg, D. L. Jones, Norman J. Silberling
Geologic setting, petrology, and geochemistry of stratiform sphalerite-galena-barite deposits, Red Dog Creek and Drenchwater Creek areas, northwestern Brooks Range, Alaska Geologic setting, petrology, and geochemistry of stratiform sphalerite-galena-barite deposits, Red Dog Creek and Drenchwater Creek areas, northwestern Brooks Range, Alaska
Similar stratiform sphalerite-galena-barite deposits occur in the Red Dog Creek area, De Long Mountains quadrangle, and in the Drenchwater Creek area, Howard Pass quadrangle, northwestern Brooks Range, Alaska. The deposits, located approximately 180 km apart, are hosted by Mississippian and Pennsylvanian strata of the Kagvik structural sequence of late Paleozoic and early Mesozoic age...
Authors
Ian M. Lange, Warren J. Nokleberg, J.T. Plahuta, H.R. Krouse, B. R. Doe
Massive sulfide deposits on the southern Juan de Fuca Ridge: Results of investigations in the USGS study area, 1980-83 Massive sulfide deposits on the southern Juan de Fuca Ridge: Results of investigations in the USGS study area, 1980-83
No abstract available.
Authors
Randolph A. Koski, William R. Normark, Janet L. Morton
Mineralogy and geochemistry of a sediment‐hosted hydrothermal sulfide deposit from the Southern Trough of Guaymas Basin, Gulf of California Mineralogy and geochemistry of a sediment‐hosted hydrothermal sulfide deposit from the Southern Trough of Guaymas Basin, Gulf of California
Samples dredged from a 15‐m‐high hydrothermal mound atop the flat turbidite pond in the Southern Trough of Guaymas Basin consist of pyrrhotite‐rich massive sulfide, barite, barite + calcite, talc, and opaline silica as well as substrate material composed of fossiliferous, clay‐rich ooze. An 11‐m‐long sediment core taken near the dredge site shows increasing hydrothermal alteration with...
Authors
Randolph A. Koski, P. F. Lonsdale, Wayne C Shanks, M.E. Berndt, S. S. Howe
A new isostatic residual gravity map of the conterminous United States A new isostatic residual gravity map of the conterminous United States
In order to display more clearly the gravity anomalies caused by bodies of geologic interest in the crust, a new colored isostatic residual gravity map of the conterminous United States has been prepared using the gravity data set compiled for the Gravity Anomaly Map of the United States (SEG, 1982). The isostatic residual map is based on an Airy-Heiskanen model of local compensation...
Authors
Robert W. Simpson, Robert C. Jachens, Richard W. Saltus, Richard J. Blakely
Book review: Methods of rock magnetism and palaeomagnetism Book review: Methods of rock magnetism and palaeomagnetism
Book information: Methods of rock magnetism and palaeomagnetism — Techniques and instrumentation: D.W. Collinson. Chapman and Hall, London, 1983, xiv + 503 pp.
Authors
Ray E. Wells
The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism
The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This...
Authors
Edward A. Mankinen, M. Prevot, C. Sherman Gromme, Robert S. Coe
The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models
We carried out an extensive paleointensity study of the 15.5±0.3 m.y. Miocene reversed‐to‐normal polarity transition recorded in lava flows from Steens Mountain (south central Oregon). One hundred eighty‐five samples from the collection whose paleodirectional study is reported by Mankinen et al. (this issue) were chosen for paleointensity investigations because of their low viscosity...
Authors
M. Prevot, Edward A. Mankinen, Robert S. Coe, C. Sherman Gromme
In situ stress, natural fracture distribution, and borehole elongation in the Auburn Geothermal Well, Auburn, New York In situ stress, natural fracture distribution, and borehole elongation in the Auburn Geothermal Well, Auburn, New York
Hydraulic fracturing stress measurements and a borehole televiewer survey were conducted in a 1.6‐km‐deep well at Auburn, New York. This well, which was drilled at the outer margin of the Appalachian Fold and Thrust Belt in the Appalachian Plateau, penetrates approximately 1540 m of lower Paleozoic sedimentary rocks and terminates 60 m into the Precambrian marble basement. Analysis of...
Authors
Stephen H. Hickman, John H. Healy, Mark D. Zoback