Coincident sediment slump/clathrate complexes on the U.S. Atlantic continental slope
G. Carpenter
1981, Geo-Marine Letters (1) 29-32
High-resolution seismic reflection data recorded on the continental slope off the east coast of the United States have revealed instances of sediment mass movement (slumps) which appear to occur above clathrate accumulations. The slumping is believed to be related to the liberation of free gas by clathrate decomposition and consequent...
Cretaceous Arctic silicoflagellates
D. Bukry
1981, Geo-Marine Letters (1) 57-63
Cretaceous silicoflagellate assemblages from Arctic Ocean USGS Core 437 show Vallacerta siderea the most abundant species; most species of Lyramula disappear halfway up the core; only L. burchardae, n. sp., persists into the upper sections. These occurrences are untypical of the few documented Cretaceous assemblages from other areas. A Campanian...
Oxygen isotope thermometry of basic lavas and mantle nodules
T.K. Kyser, J. R. O’Neil, I. S. E. Carmichael
1981, Contributions to Mineralogy and Petrology (77) 11-23
Measurements have been made of the oxygen isotope and chemical composition of glass and phenocrysts in lavas and coexisting minerals in mantle nodules. Temperatures of formation of these assemblages have been estimated from various chemical thermometers and range from 855?? to 1,300?? C. The permil fractionations between coexisting orthopyroxene and...
13C 12C exchange between calcite and graphite: A possible thermometer in Grenville marbles
J.W. Valley, J. R. O’Neil
1981, Geochimica et Cosmochimica Acta (45) 411-419
The fractionation of 13C between calcite and graphite, Δ(Cc-Gr). is consistently small (2.6–4.8 permil) in 34 assemblages from upper amphibolite- and granulite-facies marbles of the Grenville Province. In 25 samples from the Adirondack Mountains, New York, it decreases regularly with increasing metamorphic temperature. The fractionations are independent of absolute δ13C values...
Upper Oligocene evaporites in basin fill of Sevier Desert region, western Utah
D. A. Lindsey, Richard K. Glanzman, Charles W. Naeser, Douglas J. Nichols
1981, American Association of Petroleum Geologists Bulletin (65) 251-260
The basin fill beneath the Sevier Desert of western Utah contains evaporites that were deposited in a broad closed basin. All of the basin fill penetrated by the Gulf Oil 1 Gronning contains abundant volcanic detritus and its alteration products of Cenozoic age. Fission-track dating of tuffaceous sandstone yields ages...
Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio.
David A. Stith
1981, Geological Society of America Bulletin (92) 629-633
The chemical composition and stratigraphy of the Black River Group in southwestern Ohio were studied. Chemical analyses were done on two cores of the Black River from Adams and Brown Counties, Ohio. These studies show that substantial reserves of high-carbonate rock are present in the Black River at depths of...
Estimation of surface temperature variations due to changes in sky and solar flux with elevation
S. Hummer-Miller
1981, Geophysical Research Letters (8) 595-598
Sky and solar radiance are of major importance in determining the ground temperature. Knowledge of their behavior is a fundamental part of surface temperature models. These two fluxes vary with elevation and this variation produces temperature changes. Therefore, when using thermal-property differences to discriminate geologic materials,...
Stratigraphic and economic significance of Mississippian sequence at North Georgetown Canyon, Idaho
W.J. Sando, Charles Sandberg, R.C. Gutschick
1981, American Association of Petroleum Geologists Bulletin (65) 1433-1443
The Mississippian sequence exposed at North Georgetown Canyon, Idaho is newly recognised as a facies belt, which adds to knowledge of Mississippian stratigraphy and petroleum geology in the Overthrust belt of Idaho, Wyoming, and Utah. In the newly recognized facies belt in the Aspen Range, the Madison Group is represented...
Interpretation of changes in water level accompanying fault creep and implications for earthquake prediction
R. L. Wesson
1981, Journal of Geophysical Research Solid Earth (86) 9259-9267
Quantitative calculations for the effect of a fault creep event on observations of changes in water level in wells provide an approach to the tectonic interpretation of these phenomena. For the pore pressure field associated with an idealized creep event having an exponential displacement versus time curve, an analytic expression...
Reservoir properties of submarine- fan facies: Great Valley sequence, California
H. McLean
1981, Journal of Sedimentary Petrology (51) 865-872
Submarine-fan sandstones of the Great Valley sequence west of the Sacramento Valley, California, have low porosities and permeabilities (64 samples averaged 10.1% porosity and 0.87 millidarcies permeability). However, petrography and scanning electron microscope studies indicate that most sands in almost all submarine fan...
A lithologic-tectonic framework for the metallogenic provinces of California
J. P. Albers
1981, Economic Geology (76) 765-790
The lithologic-tectonic framework of California developed principally during Mesozoic time when various terranes of oceanic crust and island-arc crust were accreted to older sialic crust, resulting in westward growth of the continent. Emplacement of great batholithic masses of granitoid rocks cutting all these crustal types also took place during the...
Munsell color value as related to organic carbon in Devonian shale of Appalachian basin
John W. Hosterman, Sallie I. Whitlow
1981, American Association of Petroleum Geologists Bulletin (65) 333-335
Comparison of Munsell color value with organic carbon content of 880 samples from 50 drill holes in the Appalachian basin shows that a power curve is the best fit for the data. A color value below 3 to 3.5 indicates the presence of organic carbon but is meaningless in determining...
Systems for measuring thickness of temperate and polar ice from the ground or from the air.
R.D. Watts, D.L. Wright
1981, Journal of Glaciology (27) 459-469
Equipment has been designed and tested for ground-based and airborne sounding of temperate glaciers. The transmitter is a free-running pulse generator that uses avalanche-mode transistor breakdown to create high-voltage pulses. The transmit and receive antennas are resistively loaded dipoles; for the airborne system, a twin-lead transmit element...
Storm-built sand ridges on the Maryland inner shelf: a preliminary report
D.J.P. Swift, M.E. Field
1981, Geo-Marine Letters (1) 33-37
Several aspects of the Maryland ridge field are pertinent to the problem of ridge genesis in response to Holocene sea-level rise. There is a systematic morphologic change from shoreface ridges through nearshore ridges to offshore ridges, which reflects the changing hydraulic regime. Grain size is 90?? out of phase with...
Simplified method of deep-tow seismic profiling
James M. Robb, Richard E. Sylwester, Ronald Penton
1981, Geo-Marine Letters (1) 65-67
To improve resolution of seismic-reflection profiles in continental slope water depths of 900 to 1500 m, a single hydrophone was towed about 150 m off the bottom to receive reflected signals from a surface-towed sparker sound source. That deep-towed hydrophone data show that valleys which appear V-shaped in records from...
Thermal inertia mapping of Mars from 60°S to 60°N
Frank Don Palluconi, Hugh H. Kieffer
1981, Icarus (45) 415-426
Twenty-micrometer brightness temperatures are used to derive the thermal inertia for 81% of the Martian surface between latitudes ±60°. These data were acquired by the two Viking Infrared Thermal Mappers in 1977 and 1978 following the two global dust storms of 1977. The spatial resolution used is 2° in latitude...
Effects of the atmosphere on the detection of surface changes from Landsat multispectral scanner data
Joseph Otterman, Charles J. Robinove
1981, International Journal of Remote Sensing (2) 351-360
The atmospheric effects on radiometric data recorded in the Landsat multispectral scanner system (MSS) bands are compiled for cases of representative and ideal atmospheric conditions. The effects are expressed as a difference between the Earth's surface spectral reflectivity, a0, and the surface-atmosphere system spectral reflectivity, as, derived from the satellite...
Analysis of variance of thematic mapping experiment data.
G.H. Rosenfield
1981, Photogrammetric Engineering and Remote Sensing (47) 1685-1692
As an example of the methodology, data from an experiment using three scales of land-use and land-cover mapping have been analyzed. The binomial proportions of correct interpretations have been analyzed untransformed and transformed by both the arcsine and the logit transformations. A weighted analysis of variance adjustment has been used....
Determination of organic-matter content of Appalachian Devonian shales from gamma-ray logs
James W. Schmoker
1981, American Association of Petroleum Geologists Bulletin (65) 1285-1298
The organic-matter content of the Devonian shale of the Appalachian basin is important for assessing natural-gas resources. In most of the western part of the Appalachian basin the organic-matter content of the Devonian shale can be estimated from gamma-ray wire-line logs. Organic-matter contents estimated using these logs are compared with...
Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland
H.S. Pettingill, P. J. Patchett
1981, Earth and Planetary Science Letters (55) 150-156
Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9...
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....
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...
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...
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,...
