Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

2003

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 361 - 368 of 368

Full-Text Articles in Earth Sciences

Effect Of Geochemical Processes And Environment On The Spatial Pattern Of Selenium In Soil, Surface Water, And Groundwater At The Hovland Ranch, Central South Dakota, Salah U. Sharif Jan 2003

Effect Of Geochemical Processes And Environment On The Spatial Pattern Of Selenium In Soil, Surface Water, And Groundwater At The Hovland Ranch, Central South Dakota, Salah U. Sharif

Theses and Dissertations

The objective of this paper is to test and review some of the published hypotheses as that may relate to selenium geochemistry in soil and water system at the Hovland Ranch, Haakon County, South Dakota. Representative samples were collected from soil, water, and soil moisture in the field. Preparation of samples and chemical analysis were done in the Water Quality Laboratory, Dept. of Geology and Geological Engineering, University of North Dakota and Human Nutrition Research Center Lab, USDA/ARS, Grand Forks, North Dakota. The analysis results were statistically analyzed to find correlation between the occurrence of selenium and other associated chemical …

Go to article

The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert Jan 2003

The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert

Geology Faculty Publications and Presentations

Narrow lateral shear margins are the most distinctive visual feature of the West Antarctic ice streams. Large shear stresses within these layers support the majority of the gravitational driving stress within a fast-flowing ice stream.The present contribution looks upstream, to the tributaries that feed ice-stream onsets, and considers the effects of both horizontal and vertical shear on their flow. Numerical and direct simulations of vertical and horizontal shear are used.Vertical shear, simulated using an anisotropic flow law, is of particular interest.We conclude that by isolating overlying ice from large-amplitude variations in bed elevation -vertical shear margins - play an important …

Go to article

A Geological And Geophysical Investigation Of Ice Mountain Algific Talus, Hampshire County, West Virginia, Kevin M. Andrews Jan 2003

A Geological And Geophysical Investigation Of Ice Mountain Algific Talus, Hampshire County, West Virginia, Kevin M. Andrews

Graduate Theses, Dissertations, and Problem Reports (ETD)

Ice Mountain is an algific talus slope located in Hampshire County, West Virginia, protected for its status as a biological refugium. Both the origin of the slope and the mechanism by which cold air is produced from the base of the slope have remained mysteries to local residents and tourists for many years. This research effort takes a scientific approach to exploring the mysteries of Ice Mountain. Bedrock and surficial geologic mapping provides an understanding of the physical environment of the slope area, while geophysical survey data provide clues to the subsurface of the slope. The algific talus consists of …

Go to article

Geostatistical Optimisation Of Sampling And Estimation In A Nickel Laterite Deposit, Mark P. Murphy Jan 2003

Geostatistical Optimisation Of Sampling And Estimation In A Nickel Laterite Deposit, Mark P. Murphy

Theses: Doctorates and Masters

Nickel and cobalt are key additives to metal alloys in modem industry. The largest worldwide nickel-cobalt resources occur in nickel laterite deposits that have formed during the chemical weathering of ultramafic rocks at the Earth's surface. At the Murrin Murrin mine in Western Australia, the nickel laterite deposits occur as laterally extensive, undulating blankets of mineralisation with strong vertical anisotropy, near normal nickel distributions, and positively skewed cobalt distributions. The mineral resources in nickel laterite deposits in Murrin Murrin are usually estimated from drilling and sampling on relatively wide-spaced drill patterns that are supported by local clusters of close-spaced sampling. …

Go to article

Wavelet-Based Simulation Of Geological Variables, T. T. Tran Jan 2003

Wavelet-Based Simulation Of Geological Variables, T. T. Tran

Theses: Doctorates and Masters

This thesis introduces a number of conditional simulation algorithms using wavelet bases. These make use of two orthogonal wavelet bases, the Haar and the Db2 bases. Firstly, two single-level algorithms are introduced, HSIM: with the Haar basis and DB2SIM with the Db2 basis. HSIM reproduces the histogram and semivariogram model of isotropic samples but not the semivariogrnm model of anisotropic samples. DB2SIM reproduces the histogram and semivariogram model in both the isotropic and anisotropic cases but, because of the conditioning method employed, is not as computationally efficient as we would wish. Because of the limitations of HSIM and Db2SIM two …

Go to article

Controls On Middle To Late Ordovician Synorogenic Deposition In The Southeastern Corner Of Laurentia, German Bayona Jan 2003

Controls On Middle To Late Ordovician Synorogenic Deposition In The Southeastern Corner Of Laurentia, German Bayona

University of Kentucky Doctoral Dissertations

Middle and Upper Ordovician strata in the southernmost Appalachians document initial collision along the southeastern margin of Laurentia during the Blountian orogeny, an early phase of the Taconic orogeny. Coeval drowning and exposure of different parts of the former platform and variations in stratal architecture have been attributed to tectonic and depositional loading along the collisional margin. Stratigraphic correlations, using a bentonite-graptoliteconodont time framework, a palinspastic map, and a map of subsurface basement structures, suggest that basement-fault reactivation, flexural subsidence, and eustasy variously controlled uplift, subsidence, and deposition at different sites within the peripheral foreland basin. This dissertation documents how …

Go to article

Subglacial Thermal Balance Permits Ongoing Grounding Line Retreat Along The Siple Coast Of West Antarctica, Byron R. Parizek, Richard B. Alley, Christina L. Hulbe Jan 2003

Subglacial Thermal Balance Permits Ongoing Grounding Line Retreat Along The Siple Coast Of West Antarctica, Byron R. Parizek, Richard B. Alley, Christina L. Hulbe

Geology Faculty Publications and Presentations

Changes in the discharge of West Antarctic ice streams are of potential concern with respect to global sea level. The six relatively thin, fast-flowing Ross ice streams are of interest as low-slope end-members among Antarctic ice streams. Extensive research has demonstrated that these "rivers of ice" have a history of relatively high-frequency (óO(100) years), asynchronous discharge variations with evolving lateral boundaries. Amidst this variability, a ~1300 km grounding-line retreat has occurred since the Last GlacialMaximum. Numerical studies of Ice Stream D (Parizek and others, 2002) indicate that a proposed thermal-regulation mechanism(Clarke and Marshall, 1998; Hulbe and MacAyeal,1999; Tulaczyk and others, …

Go to article

Anisotropic Ice Flow Leading To The Onset Of Ice Stream D, West Antarctica: Numerical Modelling Based On The Observations From Byrd Station Borehole, Weili Wang, H. Jay Zwally, Christina L. Hulbe, Martin J. Siegert, Ian R. Joughin Jan 2003

Anisotropic Ice Flow Leading To The Onset Of Ice Stream D, West Antarctica: Numerical Modelling Based On The Observations From Byrd Station Borehole, Weili Wang, H. Jay Zwally, Christina L. Hulbe, Martin J. Siegert, Ian R. Joughin

Geology Faculty Publications and Presentations

An ice-sheet flowline model is used to simulate the flow of ice along two particle paths toward the onset to Ice Stream D,West Antarctica. One path is near the centre line of the main tributary to the ice stream, while the second passes by the Byrd Station borehole site. In this paper, we analyze the flow of the moderately fast-flowing tributaries in terms of ice-fabric anisotropy and estimate the steady-state ice-flow regions with the compatible developed crystal orientation fabrics along two particle paths. Comparison between modelled isochrones and internal layers detected from radio-echo sounding surveys in the area is used …

Go to article

First Prev