Fission-track dating of apatite and zircon: An interlaboratory comparison
C. W. Naeser, R.A. Zimmermann, G. T. Cebula
1981, Nuclear Tracks (5) 65-72
Apatite and zircon separates from the Fish Canyon Tuff (K-Ar age, 27.9??0.7 Myr), San Juan Mtns., Colorado, have been given to over 50 laboratories for fission-track dating. Nineteen laboratories have reported fission-track ages that they have determined for apatites. Nine laboratories have reported their analysis of the zircons. The principal...
Rank of coal beds of the Narragansett basin, Massachusetts and Rhode Island
P.C. Lyons, H.B. Chase Jr.
1981, International Journal of Coal Geology (1) 155-168
Coal of the Narragansett basin generally has been considered to be anthracite and/or meta-anthracite. However, no single reliable method has been used to distinguish these two ranks in this basin. Three methods — chemical, X-ray, and petrographic — have been used...
Boulder deposits and the retreat of mountain slopes, or ' gully gravure' revisited
H. H. Mills
1981, Journal of Geology (89) 649-660
Observations on mountains composed chiefly of shale and capped with Tuscarora Sandstone in the Valley and Ridge province of southwest Virginia suggest that slopes retreat by a process similar to but different from Bryan's (1940) "gully gravure." The process appears to operate as follows: Bouldery alluvium protects the floors of...
Estimation of accumulation parameters for urban runoff quality modeling
William M. Alley, Peter E. Smith
1981, Water Resources Research (17) 1657-1664
Many recently developed watershed models utilize accumulation and washoff equations to simulate the quality of runofffrom urban impervious areas. These models often have been calibrated by trial and error and with little understanding of model sensitivity to the various parameters. Methodologies for estimating best fit values of the washoff parameters...
Two-mica granites of northeastern Nevada
D. E. Lee, R. W. Kistler, I. Friedman, R. E. Van Loenen
1981, Journal of Geophysical Research Solid Earth (86) 10607-10616
The field settings are described and analytical data are presented for six two-mica granites from north-eastern Nevada. High δ18O and 87Sr/86Sr values indicate that all are S-type granites, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X...
Tectonic setting for ophiolite obduction in Oman
R. G. Coleman
1981, Journal of Geophysical Research Solid Earth (86) 2497-2508
The Samail ophiolite is part of an elongate belt in the Middle East that forms an integral part of the Alpine mountain chains that make up the northern boundary of the Arabian-African plate. The Samail ophiolite represents a portion of the Tethyan ocean crust formed at a spreading center of...
Computer-assisted photogrammetric mapping systems for geologic studies-A progress report
C. L. Pillmore, K.S. Dueholm, H.S. Jepsen, C.H. Schuch
1981, Photogrammetria (36) 159-171
Photogrammetry has played an important role in geologic mapping for many years; however, only recently have attempts been made to automate mapping functions for geology. Computer-assisted photogrammetric mapping systems for geologic studies have been developed and are currently in use in offices of the Geological Survey of Greenland at Copenhagen,...
A routine high-precision method for Lu-Hf isotope geochemistry and chronology
P. J. Patchett, M. Tatsumoto
1981, Contributions to Mineralogy and Petrology (75) 263-267
A method for chemical separation of Lu and Hf from rock, meteorite and mineral samples is described, together with a much improved mass spectrometric running technique for Hf. This allows (i) geo- and cosmochronology using the176Lu???176Hf+??- decay scheme, and (ii) geochemical studies of planetary processes in the earth and moon....
The Lasky cumulative tonnage-grade relationship; a reexamination
J. H. DeYoung
1981, Economic Geology (76) 1067-1080
The need for interdisciplinary research on resource appraisal techniques was recognized by Samuel G. Lasky, a U.S. Geological Survey geologist, more than 30 years ago. His efforts to devise an appraisal technique that incorporated many attributes of mineral resources resulted in a cumulative tonnage-grade relationship that has been referred to...
Mars: Paleostratigraphic restoration of buried surfaces in Tharsis Montes
D. H. Scott, K. L. Tanaka
1981, Icarus (45) 304-319
Volcanism in the Tharsis province of Mars occurred in several different areas and was generally continuous without large time intervals between eruptive episodes. Major lava flow units are numerous and extensive, but relatively thin. In many places, impact craters on buried...
Paleoclimatic implications of Late Pleistocene marine ostracodes from the St. Lawrence lowlands.
T. M. Cronin
1981, Micropaleontology (27) 384-418
Using modern zoogeographic data and inferred temperature ranges for Champlain Sea ostracode species, bottom water paleotemperatures were estimated for three phases of deposition of this inland sea. The temporal distribution of these and other environmentally diagnostic species in Champlain Sea deposits reveals a significant local climatic change in the Champlain...
Geodetic analysis of reservoir depletion at the Geyser steam field in northern California
R.P. Denlinger, W.F. Isherwood, R. L. Kovach
1981, Journal of Geophysical Research Solid Earth (86) 6091-6096
Reservoir depletion at the Geysers from 1974 to 1977 is evident in measured changes in gravity, surface strain, and pore pressure drainage. The drainage area increased about 20%, the maximum gravity decrease was about −120 μGal, and the maximum elevation change was about 6 cm during this period. Since the...
Search for high-calcium limestone in Silurian reefs of northern Indiana
C.H. Ault, D.D. Carr
1981, Geological Society of America Bulletin (92) 641-647
During Silurian time, the Indiana part of the Wabash Platform was a shallow-water area between the proto-lllinois and pro-to-Michigan Basins and a site of growth of hundreds, or perhaps thousands, of reefs. Today, most reefs of northern Indiana are dolomite, but some are...
Pyrolysis gas chromatography-mass spectrometry to characterize organic matter and its relationship to uranium content of Appalachian Devonian black shales
J.S. Leventhal
1981, Geochimica et Cosmochimica Acta (45) 883-889
Gas Chromatographic analysis of volatile products formed by stepwise pyrolysis of black shales can be used to characterize the kerogen by relating it to separated, identified precursors such as land-derived vitrinite and marine-source Tasmanites. Analysis of a Tasmanites sample shows exclusively n-alkane">n-alkane and -alkene pyrolysis products, whereas a vitrinite...
The late-Neoglacial histories of the Agassiz and Jackson glaciers, Glacier National Park, Montana.
P. E. Carrara, R. G. McGimsey
1981, Arctic and Alpine Research (13) 183-196
Twenty-one tree-ring stations, totaling 116 trees, were sampled at various localities within the forest trimlines fronting the Agassiz and Jackson glaciers, Glacier National Park, Montana. Tree ages within these zones became progressively younger from the region of the maximum late-Neoglacial position to the bases of the bedrock slopes on which...
Ridges and scarps in the equatorial belt of Mars
Baerbel K. Lucchitta, J.L. Klockenbrink
1981, The Moon and the Planets (24) 415-429
The morphology and distribution of ridges and scarps on Mars in the ± 30° latitude belt were investigated. Two distinct types of ridges were recognized. The first is long and linear, resembling mare ridges on the Moon; it occurs mostly in plains areas. The other is composed of short, anastomosing...
Strain accumulation across the Denali fault in the Delta River canyon, Alaska
J.C. Savage, M. Lisowski, W.H. Prescott
1981, Journal of Geophysical Research Solid Earth (86) 1005-1014
Deformation along the Denali fault in the Delta River canyon was determined from geodetic surveys in 1941/1942, 1970, 1975, and 1979. The data were best for the 1975–1979 interval; in that period the average strain accumulation was essentially pure right lateral shear at a rate of 0.6 ± 0.1 μrad/a...
Magneto-stratigraphic studies in Neogene deposits of Taylor Valley and McMurdo Sound, Antarctica
D. P. Elston, S.L. Bressler
1981, Journal Royal Society New Zealand (11) 481-486
Magnetic polarity and susceptibility zonations obtained from drill cores have served to refine temporal correlations in glaciogenic sections cored in eastern Taylor Valley. The zonations have led to a better understanding of the glacial and structural history for an interval of time that extends from the late Miocene (about 7...
Rates and possible causes of neotectonic vertical crustal movements of the emerged southeastern United States Atlantic coastal plain
T. M. Cronin
1981, Geological Society of America Bulletin (92) 812-833
Emerged Pliocene and Pleistocene shorelines and associated marine deposits were used to determine the magnitude and rate of vertical crustal movement during the past 3 m.y. in the United States Atlantic Coastal Plain of South and North Carolina. On the basis of a...
210Pb method for estimating the rate of carbonate sand sedimentation
Charles W. Holmes
1981, Geo-Marine Letters (1) 237-241
The plot of 210Pb activity against depth in carbonate sands on the Virgin Island Bank is a negative asymmetric hyperbolic curve. As depth increases, an initial rapid decrease in 210Pb activity caused by the decay of unsupported 210Pb and 226Ra is followed by increasing activity as a result of 210Pb...
Audio-magnetotelluric investigation of the North End Wilderness Study Area, Cochise County, Arizona
Kevin H. Nervick, Frances M. Boler
1981, Open-File Report 81-774
No abstract available....
Seismic evidence for an extensive gas-bearing layer at shallow depth, offshore from Prudhoe Bay, Alaska
G. Boucher, E. Reimnitz, E. Kempema
1981, Cold Regions Science and Technology (4) 63-71
High-resolution seismic reflection data, recorded offshore from Prudhoe Bay, Alaska, were processed digitally to determine the reflectivity structure of the uppermost layers of the seafloor. A prominent reflector, found at 27 m below the mud line (water depths 7-9 m), has a negative reflection coefficient greater than 0.5. The large...
East Pacific rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis
Richard D. Ballard, Jean Francheteau, Tierre Juteau, Claude Rangan, William Normark
1981, Earth and Planetary Science Letters (55) 1-10
Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone 1) approximately 1 km wide. This...
News from the observatories; the Royal Observatory, Hong Kong
G. Bell
1981, Earthquake Information Bulletin (USGS) (13) 145-149
Identification of kaolins and associated minerals in altered volcanic rocks by infrared spectroscopy
Graham R. Hunt, Robert B. Halley
1981, Clays and Clay Minerals (29) 76-78
Mid-infrared spectroscopy (2.5-50 /µm) has been extensively used to identify and characterize clays and associated minerals in rocks and soils, with particular emphasis on the 3-, 10-, and 20-/µm regions (Farmer and Russell, 1967; Farmer, 1968; White, 1971; Van der Marel and Beutelspacher, 1976). However, application of mid-infrared spectroscopy in...
