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Page 2183, results 54551 - 54575

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Publication Extents

Not all publications have extents, not all extents are completely accurate
Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C
Wayne C. Shanks III, James L. Bischoff, Robert J. Rosenbauer
1981, Geochimica et Cosmochimica Acta (45) 1977-1995
Sulfate reduction during seawater reaction with fayalite and with magnetite was rapid at 350°C, producing equilibrium assemblages of talc-pyrite-hematite-magnetite at low water/rock ratios and talc-pyrite-hematite-anhydrite at higher water/rock ratios. At 250°C, seawater reacting with fayalite produced detectable amounts of dissolved H2S, but extent of reaction of solid phases was...
Gas hydrates (clathrates) causing pore-water freshening and oxygen isotope fractionation in deep-water sedimentary sections of terrigenous continental margins
R. Hesse, W.E. Harrison
1981, Earth and Planetary Science Letters (55) 453-462
The occurrence of gas hydrates in deep-water sections of the continental margins predicted from anomalous acoustic reflectors on seismic profiles has been confirmed by recent deep-sea drilling results. On the Pacific continental slope off Guatemala gas hydrates were brought up for...
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...
Dating of Archean basement in northeastern Wyoming and southern Montana.
Z. E. Peterman
1981, Geological Society of America Bulletin (92) 139-146
Rb-Sr whole-rock and U-Pb zircon ages of granite and gneiss cores from three deep drill holes extend known occurrences of Archean rocks in the subsurface of NE Wyoming and S Montanta. Rb-Sr and K- Ar mineral ages are discordant and reflect early or middle Proterozoic disturbance. Highly altered rocks occur...
Sand waves on an epicontinental shelf: Northern Bering Sea
Michael E. Field, C. Hans Nelson, David A. Cacchione, David E. Drake
1981, Marine Geology (32) 233-258
Sand waves and current ripples occupy the crests and flanks of a series of large linear sand ridges (20 km × 5 km × 10 m high) lying in an open-marine setting in the northern Bering Sea. The sand wave area, which lies west of Seward Peninsula and southeast of...
Interaction between diapirism and sediment loading at the shelf-slope boundary, northwest Gulf of Mexico
A. R. Trippet
1981, Geo-Marine Letters (1) 111-114
During the last low stand of sea level, rivers and streams drained across the present northwestern Gulf of Mexico continental shelf depositing sediments in several shallow-water deltas near the present shelf-slope boundary. The weight of these wedges of prograded sediments triggered or augmented both subsidence of local depositional basins and...
Tertiary carbonate-dissolution cycles on the Sierra Leone Rise, eastern equatorial Atlantic Ocean
Walter E. Dean, James V. Gardner, P. Cepek
1981, Marine Geology (39) 81-101
Most of the Tertiary section on Sierra Leone Rise off northwest Africa consists of chalk, marl, and limestone that show cyclic alterations of clay-rich and clay-poor beds about 20–60 cm thick. On the basis of biostratigraphic accumulation rates, the cycles in Oligocene and Miocene chalk have periods which average about...
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...
Geology and geochemistry of gas-charged sediment on Kodiak Shelf, Alaska
M. A. Hampton, K.A. Kvenvolden
1981, Geo-Marine Letters (1) 141-147
Methane concentrations in some sediment cores from the Kodiak Shelf and adjacent continental slope increase with depth by three or four orders of magnitude and exceed the solubility in water at ambient conditions. Acoustic anomalies in seismic-reflection records imply that methane-rich sediment is widespread. Molecular composition of hydrocarbon gases and...
Geochemical evidence for modern sediment accumulation on the continental shelf off southern New England
Michael H. Bothner, E.C. Spiker, P. P. Johnson, R.R. Rendigs, P. J. Aruscavage
1981, Journal of Sedimentary Petrology (51) 281-292
An area of fine-grained sediment approximately 170 km x 74 km in size, located in water depths between 60 m and 150 m, south of Martha's Vineyard, Mass., is a site of modern sediment deposition. The 14C ages systematically increase with sediment depth from about 1,300 years B.P. at the...
Flow through fractures
C. E. Neuzil, James V. Tracy
1981, Water Resources Research (17) 191-199
Flow through fractures is often idealized as flow between two parallel plates (plane Poiseuille flow). The opening or aperture between parallel plates is unambiguous and its relation to flowrate is well known. However, fractures in rock have uneven walls and a variable aperture. A model for flow in a fracture...
Did ice streams carve martian outflow channels?
Baerbel K. Lucchitta, D.M. Anderson, H. Shoji
1981, Nature (290) 759-763
Outflow channels on Mars1 are long sinuous linear depressions that occur mostly in the equatorial area (±30° lat.). They differ from small valley networks2 by being larger and arising full born from chaotic terrains. Outflow channels resemble terrestrial stream beds, and their origin has generally been attributed to water3–5 in catastrophic floods6,7 or mudflows8....
Small landslide types and controls in glacial deposits: Lower Skagit river drainage, northern cascade range, Washington
P.L. Heller
1981, Environmental Geology (3) 221-228
Observations of 167 small, shallow landslides spanning a 22-year period on extensively logged slopes of Quaternary terraces in the lower Skagit and Baker Valleys, Washington, shows that there is a relationship between the common slope failures in this area and the slope angle, stratigraphy, and logging practices. Landslide frequency increases...
Key to trematodes reported in waterfowl
Malcolm Edwin McDonald
1981, Resource Publication 142
This key is the second in a series for identification of the helminths reported in waterfowl (Family Anatidae, Order Anseriformes). The first was a key to nematodes (McDonald 1974). The trematodes show the greatest variety of forms among the helminth parasites of waterfowl, including over half of all species reported; sometimes...