Earth Sciences Commons^™

Long-Term Droughtiness And Drought Tolerance Of Eastern Us Forests Over Five Decades, Matthew P. Peters, Louis R. Iverson, Stephen N. Matthews

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Droughts can influence forest composition directly by limiting water or indirectly by intensifying other stressors that affect establishment, growth, and mortality. Using community assemblages of eastern US tree species and drought tolerance characteristics assessed from literature, we examine recent drought conditions in relation to the spatial distribution of species and their tolerance to drought. First we calculate and compare a cumulative drought severity index (CDSI) for the conterminous US for the periods 1960–1986 and 1987–2013 using climate division Palmer Drought Severity Index (PDSI) values and a gridded self-calibrated PDSI dataset. This comparison indicates that drought conditions in the East tend …

Diatoms At >5000 Meters In The Quelccaya Summit Dome Glacier, Peru, Sherilyn C. Fritz, Bruce E. Brinson, W. E. Billups, Lonnie G. Thompson

Department of Earth and Atmospheric Sciences: Faculty Publications

Diatoms were found in late Holocene age ice-core samples recovered from the Quelccaya Summit Dome in the tropical Andes of Peru and were imaged by environmental scanning electron microscopy and identified. Freshwater diatoms in the genera Hantzschia, Pinnularia, and Aulacoseira were the most common taxa in the samples and indicate a freshwater source for the material, which also is suggested by the presence of the freshwater alga Volvox. The overall species composition of the diatoms suggests that the majority of taxa originated from a high-elevation lake or wetland in the cordillera surrounding the ice cap. The abundant …

First Report On Dinosaur Tracks From The Burro Can Yon Formation, San Juan County, Utah, Usa – Evidence Of A Diverse, Hitherto Un Known Lower Cretaceous Dinosaur Fauna, Jesper Milan, Luis M. Chiappe, David B. Loope, James I. Kirkland, Martin G. Lockley

Department of Earth and Atmospheric Sciences: Faculty Publications

The newly discovered White Mesa tracksite in the Burro Canyon Formation represents a snap shot of a diverse, Lower Cretaceous dinosaur fauna from south-eastern Utah. The tracks were found at a construction site where the sand stone had been bull dozed and broken up. All tracks were found as deep, well-preserved natural casts on the under side of the sand stone slabs. Individual theropod tracks are 19–57 cm in length; one peculiar track shows evidence of a possible pathological swelling in the middle of digit III and an apparently didactyl track is tentatively as signed to a dromaeosaurid. Individual sauropod …

The Footprints Of Ancient Co2-Driven Flow Systems: Ferrous Carbonate Concretions Below Bleached Sandstone, David B. Loope, Richard M. Kettler

Department of Earth and Atmospheric Sciences: Faculty Publications

Iron-rich carbonates and the oxidized remains of former carbonates (iron-oxide concretions) underlie bleached Navajo Sandstone over large portions of southern Utah. Iron in the carbonates came from hematite rims on sand grains in the upper Navajo that were dissolved when small quantities of methane accumulated beneath the sealing Carmel Formation. As a second buoyant gas (CO₂ derived from Oligocene–Miocene magmas) reached the seal and migrated up dip, it dissolved in the underlying water, enhancing the solution’s density. This water carried the released ferrous iron and the methane downward. Carbonates precipitated when the descending, reducing water degassed along fractures. The …

Diagenetic Incorporation Of Sr Into Aragonitic Bivalve Shells: Implications For Chronostratigraphic And Palaeoenvironmental Interpretations, Maria C. Marcano, Tracy D. Frank, Samuel B. Mukasa, Kyger C. Lohmann, Marco Taviani

Department of Earth and Atmospheric Sciences: Faculty Publications

Aragonite is easily altered during diagenesis, therefore presumed pristine when present. In effect, beyond polymorphic transformation to calcite, alteration paths of aragonite remain poorly understood despite heavy reliance on such material to produce palaeoenvironmental and chronostratigraphic interpretations. Previous work on core material from Southern McMurdo Sound, Antarctica, showed that unlike their calcitic counterparts, seemingly unaltered aragonite shell fragments invariably produced older than expected ⁸⁷Sr/⁸⁶Sr ages. In this study, we pursued additional analyses of these aragonite shells and of the porewater of the core to understand this discrepancy. Aragonite mineralogy was reconfirmed and elemental mapping of shell fragments …

Trans-Amazon Drilling Project (Tadp): Origins And Evolution Of The Forests, Climate, And Hydrology Of The South American Tropics, P. A. Baker, S. C. Fritz, C. G. Silva, C. A. Rigsby, M. L. Absy, R. P. Almeida, M. Caputo, C. M. Chiessi, F. W. Cruz, C. W. Dick, S. J. Feakins, J. Figueiredo, K. H. Freeman, C. Hoorn, C. Jaramillo, A. K. Kern, E. M. Latrubesse, M. P. Ledru, A. Marzoli, A. Myrbo, A. Noren, W. E. Piller, M. I. F. Ramos, C. C. Ribas, R. Trnadade, A. J. West, I. Wahnfried, D. A. Willard

Department of Earth and Atmospheric Sciences: Faculty Publications

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained …

Polarimetric Tornadic Debris Signature Variability And Debris Fallout Signatures, Matthew S. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Values of polarimetric radar variables may vary substantially between and through tornadic debris signature (TDS) events. Tornadoes with higher intensity ratings are associated with higher average and extreme values of reflectivity factor at horizontal polarization ZHH and lower values of copolar cross-correlation coefficient rhv. Although values of these variables often fluctuate through reported tornado life cycles, ZHH repeatably decreases and rhv repeatably increases across the volume scan immediately following reported tornado demise. Land cover has a relatively small effect on values of the polarimetric variables within TDSs, although near-radar urban TDSs may exhibit relatively high ZHH values. TDS areal extent …

The Effect Of Basement Fault Reactivation On The Triassic—Recent Geology Of Kurdistan, North Iraq, Caroline M. Burberry

Department of Earth and Atmospheric Sciences: Faculty Publications

The Zagros orogenic belt is underlain by a complex faulted Precambrian basement. Major fault trends originating in this basement have been invoked to explain large-scale structural changes along the strike of the orogen, e.g. the development of the Kirkuk Embayment (Kurdistan, Iraq) and the Lurestan Salient (Iran). However, within the Kirkuk Embayment, these structural trends have not previously been considered as an interacting group of faults which are periodically reactivated. This contribution first presents a revised basement fault map for the Kirkuk Embayment, created from interpreted gravity data, existing fault maps and remote sensing lineament analyses. This map is then …

Temporal And Spatial Variability In Dune Reactivation Across The Nebraska Sand Hills, Usa, Rebecca L. Schmeisser Mckean, Ronald J. Goble, Joseph B. Mason, James Swinehart, David B. Loope

Department of Earth and Atmospheric Sciences: Faculty Publications

The Nebraska Sand Hills is a stabilized dune field on the Great Plains of North America. Although it is well known that this dune field, like several others on the Great Plains, last experienced widespread activity during the Medieval Climatic Anomaly (MCA, ~AD 900–1300), spatial variation in the timing and nature of drought development is poorly constrained. To elucidate spatial trends in dune reactivation, samples potentially representing MCA activity across the Sand Hills were collected and dated using optically stimulated luminescence (OSL). Ages from the older part of the MCA were obtained from eolian sediments in the northwestern Sand Hills, …

Global Analysis Of Saturation Artifacts In The Viirs Infrared Channels And The Effects Of Sample Aggregation, Thomas N. Polivka, Edward Hyer, Jun Wang, David A. Peterson

Department of Earth and Atmospheric Sciences: Faculty Publications

Unlike previous spaceborne Earth observing sensors, the Visible Infrared Imaging Radiometer Suite (VIIRS) employs onboard sample aggregation to reduce downlink bandwidth requirements and preserve spatial resolution across the scan. To examine the potentially deleterious impacts of onboard sample aggregation when encountering detector saturation, nearly four months of the National Oceanic and Atmospheric Administration’s Nightfire product are analyzed, which contains a subset of the hottest observed nighttime pixels. An empirical method for identifying saturation is devised. The M12 band (3.69 μm) is the most frequently saturating band with 0.15% of the Nightfire pixels at or near the ~359-K detector saturation limit; …

Patterns Of Terrestrial And Limnologic Development In The Northern Greater Yellowstone Ecosystem (Usa) During The Late-Glacial/Early-Holocene Transition, Teresa R. Krause, Yanbin Lu, Cathy Whitlock, Sherilyn C. Fritz, Kenneth L. Pierce

Department of Earth and Atmospheric Sciences: Faculty Publications

A high-resolution record of pollen, charcoal, diatom, and lithologic data from Dailey Lake in south-western Montana describes postglacial terrestrial and limnologic development from ice retreat ca. 16,000 cal yr BP through the early Holocene. Following deglaciation, the landscape surrounding Dailey Lake was sparsely vegetated, and erosional input into the lake was high. As summer insolation increased and ice recessional processes subsided, Picea parkland developed and diatoms established in the lake at 13,300 cal yr BP. Closed subalpine forests of Picea, Abies, and Pinus established at 12,300 cal yr BP followed by the development of open Pinus and Pseudotsuga forests at …

Spatial And Temporal Variation In Penetrative Strain During Compression: Insights From Analog Models, Caroline M. Burberry

Department of Earth and Atmospheric Sciences: Faculty Publications

Penetrative strain constitutes the proportion of the total shortening across an orogen that is not accommodated by the development of macroscale structures such as folds and thrusts. The accommodation of shortening by penetrative strain is widely considered to be an important process during compression, but variation in the distribution of penetrative strain during a deformation sequence is not well understood. This study provides some first-order constraints on magnitude, timing, and distribution of penetrative strain during deformation. Eight simple models, each with a geometrically and mechanically similar starting configuration, within the limits of sandbox models, were shortened to different amounts. Model …

Atmospheric Circulation Processes Contributing To A Multidecadal Variation In Reconstructed And Modeled Indian Monsoon Precipitation, Qianru Wu, Qi Hu

Department of Earth and Atmospheric Sciences: Faculty Publications

An analysis of the recently reconstructed gridded May–September total precipitation in the Indian monsoon region for the past half millennium discloses significant variations at multidecadal timescales. Meanwhile, paleo-climate modeling outputs from the National Center for Atmospheric Research Community Climate System Model 4.0 show similar multidecadal variations in the monsoon precipitation. One of those variations at the frequency of 40–50 years per cycle is examined in this study. Major results show that this variation is a product of the processes in that the meridional gradient of the atmospheric enthalpy is strengthened by radiation loss in the high-latitude and polar region. Driven …

Temporal Dynamics Of Groundwater-Dissolved Inorganic Carbon Beneath A Drought-Affected Braided Stream: Platte River Case Study, Audrey R. Boerner, John B. Gates

Department of Earth and Atmospheric Sciences: Faculty Publications

Impacts of environmental changes on groundwater carbon cycling are poorly understood despite their potentially high relevance to terrestrial carbon budgets. This study focuses on streambed groundwater chemistry during a period of drought-induced river drying and consequent disconnection between surface water and groundwater. Shallow groundwater underlying vegetated and bare portions of a braided streambed in the Platte River (Nebraska, USA) was monitored during drought conditions in summer 2012. Water temperature and dissolved inorganic carbon (dominated by HCO₃^-) in streambed groundwater were correlated over a 3 month period coinciding with a decline in river discharge from 35 to 0 …

Hydrophobic Organic Contaminant Transport Property Heterogeneity In The Borden Aquifer, Richelle M. Allen-King, Indra Kalinovich, David F. Dominic, Guohui Wang, Reid Polmanteer, Dana Divine

Conservation and Survey Division: Faculty and Staff Publications

We determined that the spatial heterogeneity in aquifer properties governing the reactive transport of volatile organic contaminants is defined by the arrangement of lithofacies. We measured permeability (k) and perchloroethene sorption distribution coefficient (K_d) for lithofacies that we delineated for samples from the Canadian Forces Base Borden Aquifer. We compiled existing data and collected 57 new cores to characterize a 30 m section of the aquifer near the test location of Mackay et al. (1986). The k and K_d were measured for samples taken at six elevations from all cores to create a data …

Nebraska Statewide Groundwater-Level Monitoring Report 2015, A. R. Young, M. E. Burbach, L. M. Howard

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

North-Central Nebraska Geology: Niobrara River Valley In Brown, Cherry, And Keya Paha Counties, R. M. Joeckel, L. M. Howard, S T. Tucker

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Estimation Of Daily Air Temperature Based On Modis Land Surface Temperature Products Over The Corn Belt In The Us, Linglin Zeng, Brian D. Wardlow, Tsegaye Tadesse, Jie Shan, Michael Hayes, Deren Li, Daxiang Xiang

Center for Advanced Land Management Information Technologies: Publications

Air temperature (Ta) is a key input in a wide range of agroclimatic applications. Moderate Resolution Imaging Spectroradiometer (MODIS) Ts (Land Surface Temperature (LST)) products are widely used to estimate daily Ta. However, only daytime LST (Ts-day) or nighttime LST (Ts-night) data have been used to estimate Tmax/Tmin (daily maximum or minimum air temperature), respectively. The relationship between Tmax and Ts-night, and the one between Tmin and Ts-day has not been studied. In this study, both the ability of Ts-night data to estimate Tmax and the ability of Ts-day data to estimate Tmin were tested and studied in the Corn …

First Images Of Thunder: Acoustic Imaging Of Triggered Lightning, M. A. Dayeh, R. Lucia, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1kHz) and compare the acoustically inferred profile with optical …

Spectral Properties Of Titan’S Impact Craters Imply Chemical Weathering Of Its Surface, Catherine D. Neish

Aerospace, Physics, and Space Science Faculty Publications

We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water …

Effects Of Small Thundercloud Electrostatic Fields On The Ionospheric Density Profile, Mohammad A. Salem, Ningyu Liu, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

Small electrostatic fields of values not strong enough to activate electron impact ionization, attachment, and detachment processes can be established in the upper atmosphere by underlying thunderstorms. This paper investigates their effects on the ionospheric densities by using a simplified ion chemistry model. The modeling results indicate that under the steady state condition, the nighttime electron density profile can be reduced by up to ∼40% or enhanced by a factor of up to ∼6 because of the variation of the three-body electron attachment rate constant with the electric field.

Heavy Metal Uptake By Four Plant Species: Radish, Indian Mustard, Corn, And Soybean., Oluwasogo Bolaji Alonge

Graduate Theses, Dissertations, and Problem Reports (ETD)

Metal contaminated soils are a problem throughout the world. Because metals accumulate in the food chain they have been linked to adverse human and ecosystem health. One promising approach to remediating metal contaminated soils is phytoremediation but success has been limited by an incomplete understanding of the factors that control metal uptake by plants, including the effects when more than one contaminant metal is present in the system. Metal contaminated soil for this study was collected from near Spelter in Harrison County WV, the site of a former zinc smelting site that has contaminated residential soils and stream sediments with …

Magnetic Susceptibility Of North American Ordovician Epicontinental Seas: Spatial Variability And Sandbian-Katian Boundary Correlation, Thomas J. Schramm

LSU Doctoral Dissertations

Magnetic susceptibility (χ) has gained increased usage as a stratigraphic correlation tool. This project evaluates the utility of a χ correlation tool, including its shortcomings, and attempts its integration with other datasets. The Upper Ordovician of eastern North America represent the stratigraphic interval in which these experiments were conducted. 4566 samples were collected for the purposes of this study, and χ was measured on 3345 of the samples. This project includes three major facets, 1) the spatial variability of χ, 2) correlation of Sandbian-Katian boundary interval strata in eastern North America using χ, and 3) utility of χ for interpreting …

Interpretation Of Geochemical Signatures From Modern Carbonate Springs To The Rock Record, Benjamin Maas

LSU Doctoral Dissertations

Despite the importance of carbonate aquifers as reservoirs of oil, of water, and of carbon dioxide, questions remain about the diagenetic processes that enhance porosity and permeability. Some of the questions are: 1) what are the water-rock interactions that control the geochemistry of spring waters; 2) are the geochemical signatures of saline-fresh water mixing zones preserved in the carbonate rock record; and 3) how much carbon dioxide outgases along spring runs? To address these questions, two field sites, one in Oklahoma (the site of an active saline-fresh water mixing zone) and the other in Colorado, the location of a former …

Using Trace Fossils To Determine The Role Of Oceanic Anoxic Event Ii On The Cretaceous Western Interior Seaway Paleoenvironment, Jacob Frederick Grosskopf

LSU Doctoral Dissertations

Did well-oxygenated benthic conditions exist in all parts of the Cretaceous Western Interior Seaway (CWIS) during the deposition of Bed 63 at the onset Oceanic Anoxic Event II (OAE II), as suggested by findings from two cores from the central portion of the CWIS? This problem was approached by categorizing the bioturbation that is prevalent through Bed 63 into oxygen-related ichnofabrics (ORI) in order to describe benthic oxygen conditions. These data were collected from outcrop and core among seven different sites along West–East and North–South transects that traversed portions of the CWIS with differing depositional settings and proximities to the …

Patterns And Processes Of Salt Efflorescences In The Mcmurdo Region, Antarctica, Kelsey M. Bisson, Kathleen A. Welch, Susan A. Welch, Julia Meyer Sheets, W. Berry Lyons, Joseph S. Levy, Andrew G. Fountain

Geology Faculty Publications and Presentations

Evaporite salts are abundant around the McMurdo region, Antarctica (~78°S) due to very low precipitation, low relative humidity, and limited overland flow. Hygroscopic salts in the McMurdo Dry Valleys (MDVs) are preferentially formed in locations where liquid water is present in the austral summer, including along ephemeral streams, ice-covered lake boundaries, or shallow groundwater tracks. In this study, we collected salts from the Miers, Garwood, and Taylor Valleys on the Antarctic continent, as well as around McMurdo Station on Ross Island in close proximity to water sources with the goal of understanding salt geochemistry in relationship to the hydrology of …

Boundaries Of Governance: Social Responsibility In Mining In Western Australia, Gemma L. Broderick

Theses: Doctorates and Masters

This research investigated the boundaries of governance of social responsibility in three multinational mining organisations based in Perth, Western Australia. The mining industry has economic, environmental and social impacts, both positive and negative. While most of the attention of the media and supporters in government seems to focus on the positive impacts, a growing concern regarding the social implications of mining is clearly evident in public discourse and the academic literature. In response to public concern, the mining industry has adopted terms such as ‘sustainability’, ‘sustainable development’, ‘social licence to operate’ and ‘social responsibility’. Such phrases are widely used in …

Compositions, Logratios And Geostatistics: An Application To Iron Ore, Clint Ward

Theses: Doctorates and Masters

Common implementations of geostatistical methods, kriging and simulation, ignore the fact that geochemical data are usually reported in weight percent, sum to a constant, and are thus compositional in nature. The constant sum implies that rescaling has occurred and this can be shown to produce spurious correlations. Compositional geostatistics is an approach developed to ensure that the constant sum constraint is respected in estimation while removing dependencies on the spurious correlations. This study tests the applicability of this method against the commonly implemented ordinary cokriging method. The sample data are production blast cuttings analyses drawn from a producing iron ore …

Wedge Failure Analysis Of Anchored Rock Slopes Subjected To Surcharge And Seismic Loads, Yan Kou

Theses: Doctorates and Masters

Slope stability in mining and civil engineering projects is always a problem of great concern. Because the rock mass behavior is significantly governed by the presence of joints or other discontinuities, several types of slope failure, such as plane failure, wedge failure, toppling failure, buckling failure and circular failure, are often observed. The present work focuses on the study of the wedge failure, which occurs as sliding of a mass of rock on two intersecting planes, generally discontinuity planes.

Recently, the factor of safety of rock slopes against the wedge failure has been studied in a number of investigations under …

Integrated Assessment Of Interactions Between Surface Water And Groundwater Under Climate Variability And Change In The White Volta Basin, Ghana, Felix Mensah Oteng

Theses, Dissertations and Culminating Projects

The Nasia River, a tributary of the White Volta River system in Northern Ghana, is an important water resource for the area. In this research, a hydrological model that is able to simulate surface and subsurface flows in the Nasia catchment reasonably well was developed. The model was calibrated and verified using discharge and hydraulic head observations for the period 2000-2010. The complete simulation showed that the model was able to simulate the streamflow at the Nasia outlet quite well (Nash-Sutcliffe coefficient of 0.65, and correlation coefficient 0.805). The flow dynamics at three groundwater monitoring stations (HAP5, HAP 10, and …