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2011

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Articles 91 - 120 of 691

Full-Text Articles in Earth Sciences

Biogeochemical Response Of Alpine Lakes To A Recent Increase In Dust Deposition In The Southwestern, Us, Ashley P. Ballantyne, Janice Brahney, C. L. Lawrence, J. Saros, Jason C. Neff Sep 2011

Biogeochemical Response Of Alpine Lakes To A Recent Increase In Dust Deposition In The Southwestern, Us, Ashley P. Ballantyne, Janice Brahney, C. L. Lawrence, J. Saros, Jason C. Neff

Watershed Sciences Faculty Publications

The deposition of dust has recently increased significantly over some regions of the western US. Here we explore how changes in dust deposition have affected the biogeochemistry of two alpine watersheds in Colorado, US. We first reconstruct recent changes in the mass accumulation rate of sediments and then we use isotopic measurements in conjunction with a Bayesian mixing model to infer that approximately 95% of the inorganic fraction of lake sediments is derived from dust. Elemental analyses of modern dust indicate that dust is enriched in Ca, Cr, Cu, Mg, Ni, and in one watershed, Fe and P relative to …


Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone Sep 2011

Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone

Dartmouth Scholarship

We used ground-penetrating radar (GPR), GPS and glaciochemistry to evaluate melt regimes and ice depths, important variables for mass-balance and ice-volume studies, of Upper Yentna Glacier, Upper Kahiltna Glacier and the Mount Hunter ice divide, Alaska. We show the wet, percolation and dry snow zones located below 2700ma.s.l., at 2700 to 3900ma.s.l. and above 3900ma.s.l., respectively. We successfully imaged glacier ice depths upwards of 480m using 40–100MHz GPR frequencies. This depth is nearly double previous depth measurements reached using mid-frequency GPR systems on temperate glaciers. Few Holocene-length climate records are available in Alaska, hence we also assess stratigraphy and flow …


Geomathematical Characterisation Of The Mineralization Indicators: A Case Study From Tincova Magmatic Intrusion (Romania), George Tudor Sep 2011

Geomathematical Characterisation Of The Mineralization Indicators: A Case Study From Tincova Magmatic Intrusion (Romania), George Tudor

Studia UBB Geologia

Indicators of the hydrothermal mineralization in the Tincova Laramian intrusion were tested at the contact zone between the intrusive body and the metamorphic host rocks. The mineralization consists of Cu, Pb and Zn sulfides, arsenopyrite, pyrrhotite and pyrite in gangue of quartz, carbonates, feldspar, sericite or clay minerals, and includes areas of hydrothermal alteration or oxidation. Seventy-nine samples were analyzed and processed as two distinct populations. Geomathematical methods highlight the importance of factors such as the shape, sizes of the mineralized zones and geological processes involved in the ore genesis. Trend maps for Cu, Pb + Zn, and Ag interpolated …


Mobile Technology As A Tool For Enhancing Student Learning In Geosciences, Sam Matson Sep 2011

Mobile Technology As A Tool For Enhancing Student Learning In Geosciences, Sam Matson

Mobile Learning Symposium

Incorporation of mobile technology into the post-secondary classroom is becoming increasingly common as universities seek to facilitate active, student-centered learning through rapid access to information, connect students with course content through social media, and evaluate digital alternatives to conventional instructor-student interaction. The m-Learning Scholars Program at Boise State University was initiated during the 2010 – 2011 academic year, and provides a venue for exploring the potential of mobile technology to enhance student learning in the geosciences. Through this program, 38 students in an introductory Earth History course for non-geoscience majors each purchased a subsidized handheld device (iPod touch) that they …


Dendrochronology Of Sloane House, Wooster, Ohio Sep 2011

Dendrochronology Of Sloane House, Wooster, Ohio

Historic Structures

Dating historical structures in Wayne County, Ohio using dendrochronology. The Historical Structures collection consists of reports that are the result of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Fado, Carolyn; Ford, Alexandra; Vargo, Lauren


Magnetic Properties Of Ilmenite‐Hematite Single Crystals From The Ecstall Pluton Near Prince Rupert, British Columbia, Sarah J. Brownlee, Joshua M. Feinberg, Takeshi Kasama, Richard J. Harrison, Gary R. Scott, Paul R. Renne Sep 2011

Magnetic Properties Of Ilmenite‐Hematite Single Crystals From The Ecstall Pluton Near Prince Rupert, British Columbia, Sarah J. Brownlee, Joshua M. Feinberg, Takeshi Kasama, Richard J. Harrison, Gary R. Scott, Paul R. Renne

Environmental Science and Geology Faculty Research Publications

Paleomagnetic studies of the 91 Ma Ecstall pluton and other Cretaceous plutons of British Columbia imply large northward tectonic movements (>2000 km) may have occurred during the tectonic evolution of western North America. However, more recent studies have shown that the eastern edge of the Ecstall pluton experienced considerable mineralogical changes as younger Eocene plutons, such as the ∼58 Ma Quottoon Pluton, were emplaced along its margins. We investigated changes in the rock magnetic properties associated with this reheating event by examining isolated grains of intergrown ilmenite and hematite, the primary paleomagnetic recorder in the Ecstall pluton. Measurements of …


Using Borehole Logging And Electron Backscatter Diffraction To Orient An Ice Core From Upper Fremont Glacier, Wyoming, Usa, R. W. Obbard, T. Cassano, K. Aho, G. Troderman, I. Baker Sep 2011

Using Borehole Logging And Electron Backscatter Diffraction To Orient An Ice Core From Upper Fremont Glacier, Wyoming, Usa, R. W. Obbard, T. Cassano, K. Aho, G. Troderman, I. Baker

Dartmouth Scholarship

While glacier fabric reflects the accumulated strain, detailed azimuthal information is required to link the microstructure to the flow, and this is not easily gathered at depth. Borehole logging provides a way to obtain a log of azimuthal orientation of tilted stratigraphic features that can be used to orient the core with respect to glacier flow. We demonstrate this using acoustic borehole logs and the ice core from a 162 m borehole in Upper Fremont Glacier, Wind River Range, Wyoming, USA. We measured the dip of tilted dust and bubble layers in the actual ice core, identified them on the …


Spatial Correlation Of Interseismic Coupling And Coseismic Rupture Extent Of The 2011 Mw=9.0 Tohoku-Oki Earthquake, John P. Loveless, Brendan J. Meade Sep 2011

Spatial Correlation Of Interseismic Coupling And Coseismic Rupture Extent Of The 2011 Mw=9.0 Tohoku-Oki Earthquake, John P. Loveless, Brendan J. Meade

Geosciences: Faculty Publications

Imaging the extent to which the rupture areas of great earthquakes coincide with regions of pre-seismic interplate coupling is central to understanding patterns of strain accumulation and release through the earthquake cycle. Both geodetic and seismic estimates of the coseismic rupture extent for the March 11, 2011 MW = 8.9–9.0 earthquake Tohoku-oki earthquake may be spatially correlated (0.26 ± 0.05 to 0.82 ± 0.05) with a region estimated to be partially to fully coupled in the interseismic period preceding the earthquake, though there is substantial variation in the estimated distribution and magnitude of coseismic slip. The ∼400 km-long region estimated …


Soil Assessment Of The Weaber Plain (Goomig) Farmlands, Henry Smolinski, Justin Laycock, Jim Dixon Sep 2011

Soil Assessment Of The Weaber Plain (Goomig) Farmlands, Henry Smolinski, Justin Laycock, Jim Dixon

Resource management technical reports

In 2008, the Ord Irrigation Expansion Project was approved by the Western Australian Government to develop irrigated agriculture on the Weaber Plain (Goomig)

As part of the environmental planning and approvals process, the WA Government was required to prepare a groundwater management plan and a hydrodynamic plan.

As a result, the Department of Agriculture and Food, Western Australia (DAFWA) was requested to lead an investigative program to support a second phase of modelling. The project was divided into five components: two addressing deficiencies related to groundwater, two relating to soils and subsoils, and one addressing surface and groundwater quality aspects. …


Effects Of Weathering On Aromatic Compounds In Beach Tars From The Deepwater Horizon Disaster, Gulf Of Mexico Coast, Usa, Michael A. Kruge Sep 2011

Effects Of Weathering On Aromatic Compounds In Beach Tars From The Deepwater Horizon Disaster, Gulf Of Mexico Coast, Usa, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Operators aboard the Deepwater Horizon drilling platform lost control of the Macondo No. 1 well about 90 km southwest of the Louisiana coast on April 20, 2010, leading to a catastrophic release of ca. 550 Gg of crude oil over the next 86 days [1]. Oil from the spill soon found its way to nearby coastal areas, leaving tarry deposits on beaches and marshes. Oil was reported on the beach at Gulf Shores, Alabama (180 km northeast of the well) on June 5 and the relatively fresh sample discussed herein (GSA) was collected that same day. Oil reached the beach …


Eerc Laboratory Capabilities, University Of North Dakota. Energy And Environmental Research Center Sep 2011

Eerc Laboratory Capabilities, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Brochure about the Energy & Environmental Research Center (EERC) laboratory facilities, equipment, and capabilities. Includes information on Analytical Research Laboratory, Natural Materials Analytical Research Laboratory, Applied Geology Laboratory, and Environmental Chemistry Laboratory. [This item is an outdated or superseded version and retained for historical purposes only. It may no longer reflect current information, policies, or practices.]


Homestead National Monument Of America, Geologic Resources Inventory Report, J. Graham Sep 2011

Homestead National Monument Of America, Geologic Resources Inventory Report, J. Graham

United States National Park Service: Publications

Executive Summary

This report accompanies the digital geologic map data for Homestead National Monument of America in Nebraska, produced by the Geologic Resources Division in collaboration with its partners. It contains information relevant to resource management and scientific research. This document incorporates preexisting geologic information and does not include new data or additional fieldwork.

Established as a memorial to pioneer life and the Homestead Act of 1862, Homestead National Monument of America preserves approximately 92 ha (228 acres) of terraced grassland and riparian, floodplain environments. Included in the monument are about 40 ha (100 acres) of restored tallgrass prairie and …


Tracking Solutes And Water From Subsurface Drip Irrigation Application Of Coalbed Methane–Produced Waters, Powder River Basin, Wyoming, Mark A. Engle, Carleton R. Bern, Richard W. Healy, James I. Sams, John W. Zupancic, Karl T. Schroeder Sep 2011

Tracking Solutes And Water From Subsurface Drip Irrigation Application Of Coalbed Methane–Produced Waters, Powder River Basin, Wyoming, Mark A. Engle, Carleton R. Bern, Richard W. Healy, James I. Sams, John W. Zupancic, Karl T. Schroeder

United States Geological Survey: Staff Publications

One method to beneficially use water produced from coalbed methane (CBM) extraction is subsurface drip irrigation (SDI) of croplands. In SDI systems, treated CBMwater (injectate) is supplied to the soil at depth, with the purpose of preventing the buildup of detrimental salts near the surface. The technology is expanding within the Powder River Basin, but little research has been published on its environmental impacts. This article reports on initial results from tracking water and solutes from the injected CBM-produced waters at an SDI system in Johnson County, Wyoming.

In the first year of SDI operation, soil moisture significantly increased in …


The Vinylguaiacol/Indole Or Vgi ("Veggie") Ratio: Assessing Relative Contributions Of Terrestrial And Aquatic Organic Matter To Sediments, Michael A. Kruge, Kevin K. Olsen, Jaroslaw W. Slusarczyk, Elaine Gomez Sep 2011

The Vinylguaiacol/Indole Or Vgi ("Veggie") Ratio: Assessing Relative Contributions Of Terrestrial And Aquatic Organic Matter To Sediments, Michael A. Kruge, Kevin K. Olsen, Jaroslaw W. Slusarczyk, Elaine Gomez

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

In studies of the organic matter (OM) fraction of marine, estuarine, fluvial, or lacustrine sediments, one of the most fundamental distinctions to be made is that between terrestrial and aquatic OM. To supplement the parameters commonly used for this purpose (e.g., C/N and stable isotope ratios), we proposed the Vinylguaiacol/Indole or VGI ("Veggie") ratio, defined as [vinylguaiacol / (indole + vinylguaiacol)] using data produced by analytical pyrolysis-gas chromatography/mass spectrometry of dried, homogenized sediment samples [1]. The ratio employs the peak areas of these two compounds on the mass chromatograms of their molecular ions (m/z 150 and 117, respectively). Major pyrolysis …


The Potential For Indicators In The Management Of Climate Change Impacts On Cultural Heritage, Caithleen Daly Sep 2011

The Potential For Indicators In The Management Of Climate Change Impacts On Cultural Heritage, Caithleen Daly

Conference papers

The global scale and unpredictable nature of climate change impacts on cultural heritage poses a challenge for conservation management. This article explores the potential of indicators as an aid for decision makers in the heritage sector. The author proposes a new indicator tool for addressing long-term stone recession impacts that may be related to climate change. The indicator is being installed at two World Heritage sites in Ireland but no results are available. The prototype was developed during doctoral research at the Technological University of Dublin.


Theory And Laboratory Experiments Of Elastic Wave Scattering By Dry Planar Fractures, Thomas E. Blum, Roel Snieder, Kasper Van Wijk, Mark E. Willis Aug 2011

Theory And Laboratory Experiments Of Elastic Wave Scattering By Dry Planar Fractures, Thomas E. Blum, Roel Snieder, Kasper Van Wijk, Mark E. Willis

CGISS Publications and Presentations

Remote sensing of fractures with elastic waves is important in fields ranging from seismology to nondestructive testing. In many geophysical applications, fractures control the flow of fluids such as water, hydrocarbons or magma. While previous analytic descriptions of scattering mostly deal with very large or very small fractures (compared to the dominant wavelength), we present an analytic solution for the scattering of elastic waves from a fracture of arbitrary size. Based on the linear slip model for a dry fracture, we derive the scattering amplitude in the frequency domain under the Born approximation for all combinations of incident and scattered …


Stromatolitic Knobs In Storrs Lake, San Salvador, Bahamas: Insights Into Organomineralization, Alexandre J. Fowler Aug 2011

Stromatolitic Knobs In Storrs Lake, San Salvador, Bahamas: Insights Into Organomineralization, Alexandre J. Fowler

Master's Theses

Storrs Lake, a hypersaline lake on the east coast of San Salvador Island, Bahamas, contains well-developed microbial mats, some of which have developed calcified structures called microbialites. Many of these microbialites are laminated, and therefore classified as stromatolites. This study focuses on small stromatolitic knobs located in the southern portion of Storrs lake, which are still actively forming, to gain insights into the early stages of stromatolite formation. These knobs appear to be forming as the result of in situ micritic precipitation mediated by both photosynthetic and heterotrophic microbial metabolisms. By comparing these small stromatolitic knobs to larger stromatolitic heads …


Does The Normal Stress Parallel To The Sliding Plane Affect The Friction Of Ice Upon Ice?, Andrew L. Fortt, Erland M. Schulson Aug 2011

Does The Normal Stress Parallel To The Sliding Plane Affect The Friction Of Ice Upon Ice?, Andrew L. Fortt, Erland M. Schulson

Dartmouth Scholarship

Sliding experiments were performed at –10 degrees C on smooth surfaces of freshwater columnar-grained S2 ice sliding against itself at a velocity of 8X10 –4 ms –1, with the purpose of examining whether normal stress parallel to the sliding plane affects frictional resistance. This component of the stress tensor was varied (0.20–1.83 MPa) using a loading system operated under biaxial compression, by orienting the sliding plane at two different angles, 26 degrees and 64 degrees, with respect to the principal loading direction. Under these conditions, no evidence was found to indicate that the normal stress in the direction of …


Extreme Variation In The Sagittal Crest Of Tapirus Polkensis (Mammalia Perissodactyla) At The Gray Fossil Site Northeastern Tn., Aaron Randall Abernethy Aug 2011

Extreme Variation In The Sagittal Crest Of Tapirus Polkensis (Mammalia Perissodactyla) At The Gray Fossil Site Northeastern Tn., Aaron Randall Abernethy

Electronic Theses and Dissertations

The preservation and quantity of fossil tapirs (Tapirus polkensis) from the Gray Fossil Site in northeastern Tennessee provides a unique opportunity for comparison and analysis of skeletal characters. Intraspecifically, modern tapirs show little to no variation in the morphology of the sagittal crest. However, several different morphologies exist within the sample at Gray. No osteological evidence of sexual dimorphism exists for tapirs, and no correlation between crest shape and sex was observed. Several juveniles display well defined crests, while some adults have only minor thickening of the temporal ridges; therefore, no distinct correlation between age and crest state …


Estimating The Rayleigh-Wave Impulse Response Between Seismic Stations With The Cross Terms Of The Green Tensor, Kasper Van Wijk, T. Dylan Mikesell, Vera Schulte-Pelkum, Josh Stachnik Aug 2011

Estimating The Rayleigh-Wave Impulse Response Between Seismic Stations With The Cross Terms Of The Green Tensor, Kasper Van Wijk, T. Dylan Mikesell, Vera Schulte-Pelkum, Josh Stachnik

CGISS Publications and Presentations

The development of ambient noise tomography has provided a powerful tool to investigate the Earth's subsurface with increased resolution. Most commonly, surface-wave tomography is performed on inter-station estimates of the vertical component of Rayleigh waves, stemming from crosscorrelations of ocean-generated noise. Here, we estimate the cross terms of the Rayleigh-wave Green tensor, and show this is less sensitive to signal not in-line with the seismic stations. We illustrate this result with the Batholiths temporary seismic deployment, showing estimates of the Rayleigh wave with a higher signal-to-noise ratio and a consequently better phase-velocity dispersion curve. This approach provides an opportunity for …


Development Of An Approach To Evaluate Fractured Crystalline Bedrock Water Resource Supply And Sustainability, Helen E. Spera Aug 2011

Development Of An Approach To Evaluate Fractured Crystalline Bedrock Water Resource Supply And Sustainability, Helen E. Spera

Master's Theses

Groundwater derived from fractured crystalline bedrock is an important resource in Connecticut. Despite its importance we know very little about this resource. This study was conducted at the Plant Science and Landscape Architecture Research and Education Facility, University of Connecticut, Storrs, CT. The objectives of this study were: to improve the characterization of the hydrogeology of the facility; to develop a method to determine the amount of recharge to the bedrock from the overburden during pumping and non-pumping periods; and to develop an approach that can be used in evaluating the sustainability and zone of contribution of bedrock pumping wells. …


Implications Of Dune Pattern Analysis For Titan's Surface History, Christopher Jon Savage Aug 2011

Implications Of Dune Pattern Analysis For Titan's Surface History, Christopher Jon Savage

Theses and Dissertations

Analyzing dune parameters such as dune width and spacing can be useful in determining the reaction of dunes to changes in atmospheric and sedimentary conditions currently and in the recent geologic past. Dune parameters, dune width and spacing, were measured for linear dunes in regions across Saturn's moon Titan from images T21, 23, 28, 44 and 48 collected by Synthetic Aperture RADAR aboard the Cassini spacecraft in order to reconstruct the surface history of Titan. Dunes in the five study swaths are all linear in form, but lack superimposed or flanking dunes. They have a mean width of 1.3 km …


Urban Development, Power Relations, And Water Redistribution As Drivers Of Wetland Change In The Tampa Bay Region Socioecosystem, David B. Lewis, Fenda Akiwumi, Shawn Landry, Rebecca K. Zarger, Mark C. Rains, Susan S. Bell, Thomas L. Crisman, Carl C. Trettin, Kenneth A. Nilsson, Cornelius O. Adjei, Sharon J. Feit, Gina M. Larsen, Ralph B. Perkerson, Paul E. Thurman Aug 2011

Urban Development, Power Relations, And Water Redistribution As Drivers Of Wetland Change In The Tampa Bay Region Socioecosystem, David B. Lewis, Fenda Akiwumi, Shawn Landry, Rebecca K. Zarger, Mark C. Rains, Susan S. Bell, Thomas L. Crisman, Carl C. Trettin, Kenneth A. Nilsson, Cornelius O. Adjei, Sharon J. Feit, Gina M. Larsen, Ralph B. Perkerson, Paul E. Thurman

School of Geosciences Faculty and Staff Publications

No abstract provided.


High Pressure Structural Studies On Baco3 Up To 20 Gpa, Justine Carryer, Ravhi S. Kumar Aug 2011

High Pressure Structural Studies On Baco3 Up To 20 Gpa, Justine Carryer, Ravhi S. Kumar

Undergraduate Research Opportunities Program (UROP)

Carbonate compounds are thought to make up a minor portion of the Earth's upper mantel. Shock heating of the surfaces of carbonate rocks, as in the instance of a meteor impact, has the potential to affect CO2 concentrations in the Earth's atmosphere. The bulkmodulus of carbonate materials is directly proportional to the rate of devolatilization under these conditions [1]. The interest in Barium Carbonate (BaCO3) specifically is motivated by its structural proximity to aragonite carbonates. Crystalline phase transitions occur in aragonite under extreme conditions that are difficult to maintain in a laboratory; BaC03 is isostructural with aragonite and therefore is …


Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath Aug 2011

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …


Correlation Between Grain Dislocation Density And Orientation For Naturally Deformed Mantle Xenolith From Jagersfontein Mine, Quinton Guerrero, Quinlan Smith Aug 2011

Correlation Between Grain Dislocation Density And Orientation For Naturally Deformed Mantle Xenolith From Jagersfontein Mine, Quinton Guerrero, Quinlan Smith

Undergraduate Research Opportunities Program (UROP)

Determining the reaction of poly-crystalline structures to induced stress is an extremely difficult problem in contemporary engineering and geology. The main challenge lies in the inhomogeneity of the grains inside of the poly-crystalline structures. To predict the response of a certain polycrystalline structure to a specific stress, you must resort to one of two views on grain interaction, an orientation or propagation based model. For every material there may be certain correlations between the prediction model used and the actual deformation that occurred. Our work centers around describing the correlation of these prediction models with a sample of naturally deformed …


Investigation Of Raman Active Modes Of Mgxzn1-Xcr2o4, Nichollas Macholl, Tyler Mosher Aug 2011

Investigation Of Raman Active Modes Of Mgxzn1-Xcr2o4, Nichollas Macholl, Tyler Mosher

Undergraduate Research Opportunities Program (UROP)

Using Raman spectroscopy, vibrational modes of the spinel structure MgxZn1-xCr2O4 were experimentally examined. The spinel compounds were synthesized by producing solid solutions via combustion method, of MgxZn1-xCr2O4 in the range x=0 to x=1 in 0.1 intervals. The purpose of which was to experimentally verify gradual shifts of Raman peaks as the samples transitioned between the two different compounds and gain information about the dependencies of the lattice vibrations on the tetrahedral and octahedral cations. X-ray diffraction was also used to verify spinel structure, and track the changes in lattice parameter of the samples.


Predicted Velocity And Density Structure Of The Exhuming Papua New Guinea Ultrahigh‐Pressure Terrane, Sarah J. Brownlee, Bradley R. Hacker, Matthew Salisbury, Gareth Seward, Timothy A. Little, Suzanne A. Baldwin, Geoffrey A. Abers Aug 2011

Predicted Velocity And Density Structure Of The Exhuming Papua New Guinea Ultrahigh‐Pressure Terrane, Sarah J. Brownlee, Bradley R. Hacker, Matthew Salisbury, Gareth Seward, Timothy A. Little, Suzanne A. Baldwin, Geoffrey A. Abers

Environmental Science and Geology Faculty Research Publications

New electron backscatter diffraction measurements show that the Papua New Guinea (PNG) ultrahigh‐pressure (UHP) terrane is dominated by rocks with weakly oriented quartz and feldspar and less abundant strongly oriented hornblende, clinopyroxene, and mica. Velocities measured at high pressures (600 MPa) show that VP is 5.8–6.3 km/s for gneiss samples, 6.5–7.7 km/s for amphibolite, and 7.7–8.2 km/s for eclogite and VS is 3.4–3.9 km/s for gneiss, 4.0–4.4 km/s for amphibolite, and 4.5–4.6 km/s for eclogite. Velocities and anisotropies calculated from mineral crystal preferred orientations (CPOs) are equivalent to within 5% of the measured values. The highest seismic anisotropy …


Subsurface Controls On Mainland Marsh Shoreline Response During Barrier Island Transgressive Submergence, Mary Ellison Aug 2011

Subsurface Controls On Mainland Marsh Shoreline Response During Barrier Island Transgressive Submergence, Mary Ellison

LSU New Orleans Theses and Dissertations

Many recent studies have sought to understand the response of barrier islands and their attendant marshes to sea level rise. The Mississippi River delta plain, specifically the Chandeleur Islands and associated interior wetlands in eastern Louisiana, serves as an excellent natural laboratory for studying these responses. This region is presently undergoing the highest rates of shoreline erosion (> 15 m yr -1) in North America as wetlands are converted to open water in a regime of subsidence-driven rapid relative sea-level rise (~1 cm yr-1). Three conceptual models were developed based on the geomorphic relationships observed in the marsh that describe …


Rock Porosity Analysis Using High Resolution X-Ray Tomography, Leo Groner, Dula Parkinson, Katya Bazilevskaya Aug 2011

Rock Porosity Analysis Using High Resolution X-Ray Tomography, Leo Groner, Dula Parkinson, Katya Bazilevskaya

STAR Program Research Presentations

Understanding rock porosity, the fraction of rock volume that is in pores, is a key to modeling weathering and flow of water, petroleum and CO2 through geological structures. Weathering of rocks affects the CO2 cycle, nutrient cycle and soil formation. Rock porosity affects water flow rates and, in turn, affects weathering. Avizo software was used to explore, visualize and measure the reconstructed high-resolution X-ray micro-tomography data collected from scanned rocks. Many Avizo approaches were tried before arriving at an acceptable process to determine their porosity characteristics. Porosity dynamics are affected by weathering and lithification. At micron resolution, the image is …