Conodont color and textural alteration: An index to regional metamorphism, contact metamorphism, and hydrothermal alteration
V.A. Rejebian, A. G. Harris, J.S. Huebner
1987, Geological Society of America Bulletin (99) 471-479
Experimental and field data are used to extend the utility of conodonts as semi-quantitative thermal indices into the regimes of regional and contact metamorphism, as well as hydrothermal alteration. An Arrhenius plot of data from induced conodont color alteration by pyrolysis in air at 1 atm was used to generate...
Isotopic composition of pyrite: Relationship to organic matter type and iron availability in some North American cretaceous shales
D. L. Gautier
1987, Chemical Geology: Isotope Geoscience Section (65) 293-303
The S isotope composition of pyrite in Cretaceous shales from the Western Interior of North America is related to organic C abundance, kerogen type and Fe availability. Both calcareous and noncalcareous rocks show a correlation between S and C, but noncalcareous...
Quaternary silicic pyroclastic deposits of Atitlán Caldera, Guatemala
William I. Rose Jr., Christopher G. Newhall, Theodore J. Bornhorst, Stephen Self
1987, Journal of Volcanology and Geothermal Research (33) 57-80
Atitlán caldera has been the site of several silicic eruptions within the last 150,000 years, following a period of basalt/andesite volcanism. The silicic volcanism began with 5–10 km3 of rhyodacites, erupted as plinian fall and pyroclastic flows, about 126,000 yr. B.P. At 85,000 yr. B.P. 270–280 km3 of compositionally distinct rhyolite was...
Stable isotope compositions of fossil mollusks from southern California: Evidence for a cool last interglacial ocean.
D.R. Muhs, T.K. Kyser
1987, Geology (15) 119-122
Stable isotope compositions have been determined for modern mullusks and fossil mollusks collected from uplifted marine terraces at three localities in southern California. By using a paleoclimatic model that decouples the temperature and ice-volume signals in ocean water, ocean-water temperatures off southern California...
Regional geochemical studies in parts of Maine, New Hampshire and Vermont, U.S.A.
G.A. Nowlan, F. C. Canney, F. H. Howd, J. A. Domenico
1987, Journal of Geochemical Exploration (29) 129-150
A geochemical survey of the Sherbrooke and Lewiston 1° × 2° quadrangles was conducted from 1979 to 1982 by the U.S. Geological Survey as part of the Conterminous United States Mineral Assessment Program. The area covers about 23,000 km2. The region is characterized by a temperate climate, abundant rainfall, and...
Convergent tectonics and coastal upwelling: a history of the Peru continental margin ( Pacific).
Roland E. von Huene, E. Suess, K.C. Emeis
1987, Episodes (10) 87-93
Late in 1986, scientists on the ODP drillship JOIDES Resolution confirmed that the upper slope of the Peruvian margin consists of continental crust whereas the lower slope comprises an accretionary complex. An intricate history of horizontal and vertical movements can be detected, and the locations of ancient centers of upwelling...
Pressure-composition relations for coexisting gases and liquids and the critical points in the system NaCl-H2O at 450, 475, and 500°C
Robert J. Rosenbauer, James L. Bischoff
1987, Geochimica et Cosmochimica Acta (51) 2349-2354
Pressure-temperature-composition (P, T, x) relations for the co-existing vapor and liquid phases in the system NaCl-H2O were determined experimentally at 450, 475, and 500°C. Data for each isotherm includeP-x relations near the critical point and extend to the three-phase assemblage vapor-liquid-halite on the vapor side. On the liquid side the P-x data range from the...
Geology and origin of the Death Valley uranium deposit, Seward Peninsula, Alaska
Kendell A. Dickinson, Kenneth D. Cunningham, Thomas A. Ager
1987, Economic Geology (82) 1558-1574
A uranium deposit discovered in 1977 in western Alaska, by means of airborne radiometric data, is the largest known in Alaska on the basis of industry reserve estimates. At about latitude 65 degrees N, it is the most northerly known sandstone-type uranium deposit in the world. The deposit lies in...
DIGITAL CARTOGRAPHY OF THE PLANETS: NEW METHODS, ITS STATUS, AND ITS FUTURE.
R. M. Batson
1987, Photogrammetric Engineering and Remote Sensing (53) 1211-1218
A system has been developed that establishes a standardized cartographic database for each of the 19 planets and major satellites that have been explored to date. Compilation of the databases involves both traditional and newly developed digital image processing and mosaicking techniques, including radiometric and geometric corrections of the images....
Diagenesis and fluid flow in the San Juan Basin, New Mexico - regional zonation in the mineralogy and stable isotope composition of clay minerals in sandstone.
C. Gene Whitney, H. R. Northrop
1987, American Journal of Science (287) 353-382
The Westwater Canyon Member of the Upper Jurassic Morrison Formation is a relatively homogeneous, hydrologically continuous 100-m-thick sequence of massive fluvial sandstone, bounded above and below by relatively heterogeneous, hydrologically discontinuous units and has served as a primary conduit for fluids within this stratigraphic interval. Patterns of mineral-fluid reactions suggest...
Computer simulations of large asteroid impacts into oceanic and continental sites--Preliminary results on atmospheric, cratering and ejecta dynamics
D. J. Roddy, S.H. Schuster, M. Rosenblatt, L.B. Grant, Paul J. Hassig, K.N. Kreyenhagen
1987, International Journal of Impact Engineering (5) 525-541
Computer simulations have been completed that describe passage of a 10-km-diameter asteroid through the Earth's atmosphere and the subsequent cratering and ejecta dynamics caused by impact of the asteroid into both oceanic and continental sites. The asteroid was modeled as...
A preliminary report on the bentonite beds of the lower Virgin Creek Member of the Pierre Shale, Stanley County, South Dakota ( USA).
D. S. Collins
1987, Mountain Geologist (24) 81-85
The Virgin Creek Member of the Pierre Shales has been divided by earlier workers into lower and upper zones based on weathering and shale differences. Of the 49 bentonite beds of the lower Virgin Creek, the Government Draw Bentonite Beds, and bentonite bed 20 are the best markers for correlation...
Slab pull and the seismotectonics of subducting lithosphere
William Spence
1987, Reviews of Geophysics (25) 55-69
This synthesis links many seismic and tectonic processes at subduction zones, including great subduction earthquakes, to the sinking of subducted plate. Earthquake data and tectonic modeling for subduction zones indicate that the slab pull force is much larger than the ridge push force. Interactions between the forces that drive and...
A model for tides and currents in the English Channel and southern North Sea
Roy A. Walters
1987, Conference Paper, Advances in Water Resources
The amplitude and phase of 11 tidal constituents for the English Channel and southern North Sea are calculated using a frequency domain, finite element model. The governing equations - the shallow water equations - are modifed such that sea level is calculated using an elliptic equation of the Helmholz type...
Ecological aspects of microorganisms inhabiting uranium mill tailings
C.L. Miller, E. R. Landa, D.M. Updegraff
1987, Microbial Ecology (14) 141-155
Numbers and types of microorganisms in uranium mill tailings were determined using culturing techniques. Arthrobacter were found to be the predominant microorganism inhabiting the sandy tailings, whereas Bacillus and fungi predominated in the slime tailings. Sulfate-reducing bacteria, capable of leaching radium, were isolated in low numbers from tailings samples but...
Suspended sediment and metals removal from urban runoff by a small lake
Robert G. Striegl
1987, Water Resources Bulletin (23) 985-996
A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an...
The inventory and distribution of water on Mars
M. H. Carr
1987, Advances in Space Research (7) 85-94
Terrain softening, fretted channels, debris flows, and closed depressions indicate that at least the upper 2 km of the cratered uplands at high latitudes (>30??) contain ice in amounts that exceed the porosity, estimated to be 10-20 percent. Theoretical studies, and lack of these features in the cratered uplands at...
Natural-field and very low-frequency tipper profile interpretation of contacts
Victor F. Labson, Alex Becker
1987, Geophysics (52) 1697-1707
Anomalous vertical magnetic field (tipper) profiles acquired using natural or very low-frequency (VLF) radio transmitter sources can be interpreted simply and rapidly for a number of geologic settings. The relations between computed numerical models, and outcropping dipping and buried vertical contacts are presented here in a series of interpretation charts....
Seismic stratigraphy and facies of continental slope and rise seaward of Baltimore Canyon Trough
John S. Schlee, K. Hinz
1987, American Association of Petroleum Geologists Bulletin (71) 1046-1067
As part of a survey of the United States continental rise seaward of the northern Baltimore Canyon Trough, four major depositional sequences were mapped on a grid of 2,350 km of multichannel seismic reflection profiles. The sequences, which range in age from Jurassic (?) to Quaternary, record a gradual sedimentary...
Crystal structure and crystal chemistry of melanovanadite, a natural vanadium bronze.
J.A. Konnert, H. T. Evans Jr.
1987, American Mineralogist (72) 637-644
The crystal structure of melanovanadite from Minas Ragra, Peru, has been determined in space group P1. The triclinic unit cell (non-standard) has a 6.360(2), b 18.090(9), c 6.276(2) A, alpha 110.18(4)o, beta 101.62(3)o, gamma 82.86(4)o. A subcell with b' = b/2 was found by crystal-structure analysis to contain CaV4O10.5H2O. The...
CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.
Andrew Simon, Cliff R. Hupp
1987, Transportation Research Record 16-24
This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of...
Rocks of the Thirtynine Mile volcanic field as possible sources of uranium for epigenetic deposits in central Colorado, USA.
K. A. Dickinson
1987, Uranium (4) 43-65
The most likely volcanic source rock for uranium in epigenetic deposits of the Tallahassee Creek uranium district and nearby areas is the Wall Mountain Tuff. The widespread occurrence of the Tuff, its high apparent original uranium content, approx 11 ppm, and its apparent loss of uranium from devitrification and other...
Submersible observations along the southern Juan de Fuca Ridge: 1984 Alvin program.
William R. Normark, Janet L. Morton, Stephanie L. Ross
1987, Journal of Geophysical Research B: Solid Earth (92) 11283-11290
In September 1984, the research submersible Alvin provided direct observations of three major hydrothermal vent areas along the southernmost segment of the Juan de Fuca Ridge (JFR). The submersible operations focused on specific volcanologie, structural, and hydrothermal problems that had been identified during the preceding 4 years of photographic, dredging,...
Cretaceous gastropods: contrasts between tethys and the temperate provinces
N. F. Sohl
1987, Journal of Paleontology (61) 1085-1111
During the Cretaceous Period, gastropod faunas show considerable differences in their evolution between the Tethyan Realm (tropical) and the Temperate Realms to the north and south. Like Holocene faunas, prosobranch gastropods constitute the dominant part of Cretaceous marine snail faunas. Entomotaeneata and opisthobranchs usually form all of...
On predicting changes in the geomagnetic field
L.R. Alldredge
1987, Journal of Geophysical Research Solid Earth (92) 6331-6338
The present method of using constant secular variation rates to forecast magnetic components at a given site or to forecast spherical harmonic coefficients is known to be inaccurate. A new predictive method using trend and trigonometric functions fitted to known past values is used to extrapolate for a few years...
