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On 15 August, 1984, a lethal gas burst issued from a submerged 96-m-deep crater in Lake Monoun in Cameroun, western Africa, killing 37 people. The event was associated with a landslide from the eastern crater rim, which slumped into deep water. Waters below 50 m are anoxic, dominated by high...

Modeling transport of reacting solutes in porous media often requires a choice between models based on the local equilibrium assumption (LEA) and models involving reaction kinetics. Direct comparison of the mathematical formulations for these two types of transport models can aid in this choice. For cases of transport affected by...

Many Lower Paleozoic limestones and dolostones in the Valley and Ridge province of the central and southern Appalachians contain 10 to 25 weight percent authigenic potassium feldspar. This was considered to be a product of early diagenesis, however, 40Ar39Ar">40Ar39Ar analyses of overgrowths on detrital K-feldspar in...

Two hundred twenty-nine species of benthic foraminifera have been identified from 96 stations representing 33 localities on the eastern Pacific inner continental shelf, ranging from southern Peru to northern Baja California. Their distributions mark nearshore provincial boundaries that are nearly identical with those previously documented from the distribution of ostracodes...

The rate of Cd2+ sorption by a calcareous aquifer sand was characterized by two reaction steps, with the first step reaching completion in 24 hours. The second step proceeded at a slow and nearly constant rate for at least seven days. The first step includes a fast adsorption reaction which...

Besides providing an exact solution for steady-state heat conduction processes (Laplace-Poisson equations), the CVBEM (complex variable boundary element method) can be used for the numerical error analysis of domain model solutions. For problems where soil-water phase change latent heat effects dominate the thermal regime, heat transport can be approximately modeled...

Existing techniques for the quantitative interpretation of waveform data have been based on one of two fundamental approaches: (1) simultaneous identification of compressional and shear velocities; and (2) least-squares minimization of the difference between experimental waveforms and synthetic seismograms. Techniques based on the first approach do not always work, and...

K-Ar ages of illite alteration associated with Middle Proterozoic Athabasca unconformity-type U deposits in Saskatchewan range from 414 to 1493 Ma. The K-Ar ages correlate with water contents and δD values such that illites with young K-Ar ages have δD values as low as −169 and water contents as high...

The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded...

Methodologies that account for specific types of chemical reactions in the simulation of solute transport can be developed so they are compatible with solution algorithms employed in existing transport codes. This enables the simulation of reactive transport in complex multidimensional flow regimes, and provides a means for existing codes to...

An application is described of the branch-network flow model, BRANCH, to the upper Alabama River system in central Alabama. The model is used to simulate one-dimensional unsteady flows and water surface elevations in approximately 60 river miles of the Alabama River system. Preliminary calibration was made using 72 hours of...

The process of volcano-ground ice interaction on Mars is investigated by thermodynamic calculations and observations of Viking Orbiter images. We develop a numerical model of volcano-ground ice interaction that includes heat transport by conduction, radiation from the surface, heat transfer to the...

The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate δ34S measurements yielded a calculated sulfate input of 0.6%.. Sulfate transported into the sediments via diffusion...

Dissolution of synthetic strontianite-aragonite solid solutions was followed analytically to stoichiometric saturation using large solid to solution ratios in CO2-H2O solution at 25 and 76°C. The compositional dependence of the equilibrium constant was calculated from the composition of saturated (stoichiometric) solutions and used to calculate the activities and activity...

Aquatic humic- and fulvic-acid standards of the International Humic Substances Society were characterized, with emphasis on carbonyl-group nature and content, by carbon-13 nuclear-magnetic-resonance spectroscopy, proton nuclear-magnetic-resonance spectroscopy, and infrared spectroscopy. After comparing spectral results of underivatized humic and fulvic acids with spectral results of chemically modified derivatives, that allow improved...

A thin black shale overlying the B-coal underclay (in the Middle Pennsylvanian post-Pottsville strata of the Bernice Basin) contains a compression flora composed of large, prostrate, unidirectionally oriented lycopod trunks and randomly oriented pteridosperm stems. Analyses of modern log accumulations indicate that unidirectional...

The pattern of lattice preferred orientation (texture) in deformed rocks is an expression of the strain path and the acting deformation mechanisms. A first indication about the strain path is given by the symmetry of pole figures: coaxial deformation produces orthorhombic pole figures, while non-coaxial deformation yields monoclinic or triclinic...

Examples of the use of transient electromagnetic soundings for three ground-water exploration problems in sedimentary aquifers are given. The examples include: (1) estimating depths to water table and bedrock in an alluvium-filled basin, (2) mapping a confined fresh-water aquifer in bedrock sediments, and (3) locating...

Hydrologic, geologic, geomorphic, and mass-balance data suggest that most of the ∼30,000 playa lake basins on the Southern High Plains have developed by a combination of dissolution of caliche and piping of surface material into the unsaturated zone rather than by eolian processes as has generally been stated. A conceptual...

Reviews the development of hydrogeological concepts in the USA from 1879 to 1987, from early qualitative reconnaissance investigations to modern qualitative and multi-disciplinary studies involving predictive analytical techniques and a consideration of management practices. The authors present a sampling of historical milestone papers in US hydrology in the form of...

The Parkfield, California, segment of the San Andreas fault is transitional in character between the creeping segment of the fault to the northwest and the locked Carrizo Plain segment to the southeast. The rate of shallow fault slip decreases from 25–30 mm/yr northwest of the epicenter of the 1966 Parkfield...

Salt-water upconing describes the phenomenon where salt water is transported vertically upward under a well in response to pumpage in a fresh-water aquifer underlain by salt water. Sharp interface methods have been used successfully to describe the physics of upconing. A finite-element model is developed...

In 1977, the first Special Issue on remote sensing published by Geophysics contained papers selected from two special sessions at the 45th Annual International SEG Meeting, October 12–16, 1975, in Denver, Colorado. That first Special Issue consisted of eight papers: four are primarily tutorial (image processing, spectral signatures in the...

Measurements of cross-shore flow were made across the surf zone during a storm as a nearshore bar became better developed and migrated offshore. Measured infragravity band spectra were compared to synthetic spectra calculated numerically over the natural barred profile assuming a white run-up spectrum of leaky mode or high-mode edge...

Evaluation of potential high-level nuclear waste repository sites is an area where geophysical capabilities and limitations may significantly impact a major governmental program. Since there is concern that extensive exploratory drilling might degrade most potential disposal sites, geophysical methods become crucial as the only nondestructive means to examine large volumes...