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2015

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Articles 961 - 990 of 1152

Full-Text Articles in Earth Sciences

Geologic Mapping In The Black Mountain Area, Northern Eastern California Shear Zone: Testing A Kinematic And Geometric Fault Slip Transfer Model, Kevin M. Delano Jan 2015

Geologic Mapping In The Black Mountain Area, Northern Eastern California Shear Zone: Testing A Kinematic And Geometric Fault Slip Transfer Model, Kevin M. Delano

All Master's Theses

New geologic mapping, structural, kinematic, and 40Ar/39Ar geochronology studies in the Black Mountain area, northern eastern California shear zone, are used to test a kinematic fault slip transfer model for the Owens Valley fault-Mina deflection transition. In the Black Mountain area, range bounding ~NNW- to ~NS-striking and lesser NW- to NE-striking normal faults cut Mesozoic, Miocene (22.42 ± 0.05 Ma), Pliocene (3.53 ± 0.06 to 3.29 ± 0.02 Ma), and early-middle Pleistocene (1936 ± 12.7 to 766 ± 3.1 ka) rocks. Palinspastically restored cross-sections show that offset Pliocene markers record 1.5 +0.7/-0.6 km of ~ENE-WSW extension since …


Timing And Source Of Alkali Enrichment At Mt. Etna, Sicily: Constraints From Clinopyroxene Geobarometry And In Situ Sr Isotope Data, Kaitlyn Nelson Jan 2015

Timing And Source Of Alkali Enrichment At Mt. Etna, Sicily: Constraints From Clinopyroxene Geobarometry And In Situ Sr Isotope Data, Kaitlyn Nelson

All Master's Theses

Since 1971, Mt. Etna, Europe’s largest and most active volcano, has exhibited increased eruption frequency and explosivity. Associated with this increased activity, researchers have documented higher abundances of alkali elements (K, Rb, Cs) as well as elevated 87Sr/86Sr in Etnean lavas. The source of this alkali-enrichment has been hotly debated, with end-member hypotheses involving mantle vs. crustal contributions. To further characterize the evolution of the subvolcanic magma storage and transport system, as well as the timing and source of alkali-enrichment, clinopyroxene from ten samples erupted between 1329 and 2004 was targeted for in situ textural, major element …


Using Modflow To Predict Impacts Of Groundwater Pumpage To Instream Flow: Upper Kittitas County, Washington, Zoe O. Futornick Jan 2015

Using Modflow To Predict Impacts Of Groundwater Pumpage To Instream Flow: Upper Kittitas County, Washington, Zoe O. Futornick

All Master's Theses

Surface waters in the Yakima River Basin in central Washington are considered over allocated. Since 1960, new water demands have been met through groundwater withdrawals, with most groundwater users holding a later priority date than senior and junior surface water users. As a result of the discussions surrounding this issue, the Upper Kittitas Groundwater Rule has been in effect since 2010. Pumping from new domestic (i.e., permit-exempt or “exempt”) groundwater wells in Upper Kittitas County is not allowed unless mitigation is used to offset the groundwater use. The United States Geological Survey (USGS) has already created a basin-wide model for …


Mesoamerican Sacred Geography And Archeological Landscapes: A Case Study In The Volcanic Highlands Of Michoacan, Mexico, Jarod Scott Drozdowski Jan 2015

Mesoamerican Sacred Geography And Archeological Landscapes: A Case Study In The Volcanic Highlands Of Michoacan, Mexico, Jarod Scott Drozdowski

All Master's Theses

US and Mexican teams have investigated the La Alberca Structure Complex with the community of Parangaricutiro. Their forest reserve, located near San Juan Nuevo in Michoacan, Mexico, contains several volcanic cones, including the famous Paricutin cinder cone. Sixteen earthen-rock structures have been mapped using aerial photography, GPS, GIS, and total station surveys. The structures range from 300 to 2,400 cubic meters in volume. The larger mound-like structures are traditionally called yacatas. Early radiocarbon dates for two of the three central structures (ca. 5200-2000 BCE) bracket dates for the Late Archaic burial in the La Alberca caldera. Arrangements of the larger …


Pressure-Temperature-Time Constraints For Exhumation Of Ultrahigh-Pressure Metamorphic Rocks, North Qaidam Terrane, Western China, Brittany Kristine Fagin Jan 2015

Pressure-Temperature-Time Constraints For Exhumation Of Ultrahigh-Pressure Metamorphic Rocks, North Qaidam Terrane, Western China, Brittany Kristine Fagin

All Master's Theses

Ultrahigh-pressure rocks of a Paleozoic continental suture zone are exposed in the southeastern North Qaidam terrane (Dulan region). Garnetite sample D119 contains minor Czo+Qtz+Chl+Ttn; rutile inclusions in titanite suggest that titanite replaced rutile during decompression. Pressure-temperature estimates of sample D119 are 16.1-18.4 kbar and 485-520 °C. Sample D130B is a mafic band in calc-silicate gneiss, with garnet porphyroblasts in a fine-grained Hbl-Cpx-Pl-Qtz symplectite that is interpreted as former omphacite. D130B symplectite pressure-temperature estimates are 7.7-9.4 kbar and 623-708 °C. Titanite U-Pb ages of 419.7±3.1 Ma and 415.9±4.2 Ma are interpreted to date retrogression of D119 and D130B, respectively. Average exhumation …


Measuring The Cost And Performance Of Lithic Industries At The Sunrise Ridge Borrow Pit Site (45pi408), Patrick Christropher Lewis Jan 2015

Measuring The Cost And Performance Of Lithic Industries At The Sunrise Ridge Borrow Pit Site (45pi408), Patrick Christropher Lewis

All Master's Theses

This thesis applies a theoretically informed protocol that focuses on variation in stone tool manufacture and use as measured in the 45PI408 lithic assemblage. The model used is based on the variables of stone tool cost and performance. Guided by this model, technological and functional paradigmatic classifications are employed to measure intra­site variation in lithic frequencies. This method avoids difficulties encountered by previous archaeologists by using mutually exclusive analytical units that measure subtle variation in the archaeological record. Variability in technological and functional paradigmatic classificatory dimensions such as stone tool heat treatment, raw materials, use wear, and reduction class were …


Front Matter [Preface And List Of Contributors], National Organizing Committee, International Grassland Congress Jan 2015

Front Matter [Preface And List Of Contributors], National Organizing Committee, International Grassland Congress

IGC Proceedings (1977-2023)

No abstract provided.


Promising Forage Options To Enhance Livestock Production In Mediterranean Climate Agricultural Systems, Serkan Ates, Hayley C. Norman, Hichem Ben Salem, Bradley Nutt, Harun Cicek Jan 2015

Promising Forage Options To Enhance Livestock Production In Mediterranean Climate Agricultural Systems, Serkan Ates, Hayley C. Norman, Hichem Ben Salem, Bradley Nutt, Harun Cicek

IGC Proceedings (1977-2023)

The increasing demand for food, fibre and animal products inevitably requires intensifying agricultural production worldwide. This can present a number of environmental and farming systems challenges in Mediterranean climate areas of the world. Developments of novel strategies, employing ecologically sound intensification practices, are crucial to enhance production in the Mediterranean agropastoral production systems. In this paper, we have discussed forage based systems that improve productivity, profitability, environmental quality and resilience of the farming systems. Key opportunities include better use and integration of diverse genetic resources, new agronomic techniques and the utilization of perennial forage plants that are adapted to land …


New Methodologies For Grasslands Monitoring, Katarzyna Dabrowska-Zielinska, Piotr Goliński, Marit Jorgensen, Jørgen Mølmann, Gregory Taff, Monika Tomaszewska, Barbara Golińska, Maria Budzynska, Martyna Gatkowska Jan 2015

New Methodologies For Grasslands Monitoring, Katarzyna Dabrowska-Zielinska, Piotr Goliński, Marit Jorgensen, Jørgen Mølmann, Gregory Taff, Monika Tomaszewska, Barbara Golińska, Maria Budzynska, Martyna Gatkowska

IGC Proceedings (1977-2023)

Monitoring grassland areas to assess changes in their condition over time has been the subject of a lot of research at different scales. Initially the techniques focused on field-based measurements, and modelling. However, several obtained data were site specific. Based on the increase in availability of remote sensing data and products, there is an expectation that remote sensing can provide rapid and definite answers to the challenges of detecting and monitoring grassland conditions and associated changes in productivity. At the time of European Copernicus Programme, the new possibilities of satellite data from the group of Sentinel satellites give the new …


Grazing Management Options For Maintaining Optimum Pasture Composition And Utilization, Glen E. Aiken Jan 2015

Grazing Management Options For Maintaining Optimum Pasture Composition And Utilization, Glen E. Aiken

IGC Proceedings (1977-2023)

Global demand for meat and dairy products will continue to increase over the 21st century, however, the global forage-based livestock industry will be challenged in meeting production goals with minimal impact of the environment. Sustainable production of grazing livestock will depend on the use of carefully planned grazing management strategies. Development of a grazing management plan involves making two decisions: determining the livestock density at which pastures are stocked and settling on the method used to graze the pastures. Stocking rate indirectly affects output per animal and per hectare through its direct effect on forage mass and pasture composition. A …


Enhancing Grassland Productivity Through Disease Management Of Grass And Forage Species, Tingyu Duan, Chunjie Li, Yanzhong Li, Binhua Yu, Zhibiao Nan Jan 2015

Enhancing Grassland Productivity Through Disease Management Of Grass And Forage Species, Tingyu Duan, Chunjie Li, Yanzhong Li, Binhua Yu, Zhibiao Nan

IGC Proceedings (1977-2023)

The total area of grassland in China is about 400 million hectares, accounting for 41.7% of the country’s land area, which plays important role in ecological construction and food security assurance of the national. However, diseases of grass and forage limited the development of the pastoral agriculture. There are more than1500 new diseases were reported in the past 16 years with more and more new diseases were discovered. The damage to grassland is becoming more severe with the known diseases prevalent areas expanding.


Management Of Pasture Soils: Biochar Stability, Carbon Storage Potential And Its Effect On Production And Quality, Bhupinder Pal Singh, Yunying Fang, Mark Boersma, Damian Collins, Lukas Van Zwieten, Lynne M. Macdonald Jan 2015

Management Of Pasture Soils: Biochar Stability, Carbon Storage Potential And Its Effect On Production And Quality, Bhupinder Pal Singh, Yunying Fang, Mark Boersma, Damian Collins, Lukas Van Zwieten, Lynne M. Macdonald

IGC Proceedings (1977-2023)

The use of biochar has been proposed as a stable carbon (C) amendment with long-term carbon (C) storage potential in agricultural soils while improving primary productivity. However, this concept has not been widely tested in contrasting soils under temperate pasture systems. To address this knowledge gap, a 13C-labelled biochar, produced from Eucalyptus saligna biomass by slow pyrolysis (450° C; d13C -36.7‰) was surface (0"10 cm) applied in C3 dominated, annual temperate pasture systems across Arenosol, Cambisol and Ferralsol. The results show that only 2% of the applied biochar-C was mineralised in a relatively clay- and C-poor …


Grassland Renovation And Consequences For Nutrient Management, Johannes Isselstein, Manfred Kayser Jan 2015

Grassland Renovation And Consequences For Nutrient Management, Johannes Isselstein, Manfred Kayser

IGC Proceedings (1977-2023)

Sward degradation is a serious threat to the functioning of grassland and the provision of ecosystem services. Renovation measures are frequently applied in order to restore degraded swards. However, the success is highly variable and substantial tradeoffs are often found following renovation such as among agronomic and environmental services. Starting from a general classification of renovation measures the paper investigates the processes induced by renovation that lead to a change of the vegetation and that affect carbon and nitrogen fluxes. These processes are strongly interrelated and dependent on site, climate and management condition as well as on the time scale. …


Accelerated Glacier Melt On Snow Dome, Mount Olympus, Washington, Usa, Due To Deposition Of Black Carbon And Mineral Dust From Wildfire, Susan Kaspari, S. Mckenzie Skiles, Ian Delaney, Daniel Dixon Jan 2015

Accelerated Glacier Melt On Snow Dome, Mount Olympus, Washington, Usa, Due To Deposition Of Black Carbon And Mineral Dust From Wildfire, Susan Kaspari, S. Mckenzie Skiles, Ian Delaney, Daniel Dixon

Geological Sciences Faculty Scholarship

Assessing the potential for black carbon (BC) and dust deposition to reduce albedo and accelerate glacier melt is of interest in Washington because snow and glacier melt are an important source of water resources, and glaciers are retreating. In August 2012 on Snow Dome, Mount Olympus, Washington, we measured snow surface spectral albedo and collected surface snow samples and a 7 m ice core. The snow and ice samples were analyzed for iron (Fe, used as a dust proxy) via inductively coupled plasma sector field mass spectrometry, total impurity content gravimetrically, BC using a single-particle soot photometer (SP2), and charcoal …


Divergent Responses Of Atlantic Coastal And Oceanic Synechococcus To Iron Limitation, Katherine R. M. Mackey, Anton F. Post, Matthew R. Mcilvin, Gregory A. Cutter, Seth G. John, Mak A. Saito Jan 2015

Divergent Responses Of Atlantic Coastal And Oceanic Synechococcus To Iron Limitation, Katherine R. M. Mackey, Anton F. Post, Matthew R. Mcilvin, Gregory A. Cutter, Seth G. John, Mak A. Saito

OES Faculty Publications

Marine Synechococcus are some of the most diverse and ubiquitous phytoplankton, and iron (Fe) is an essential micronutrient that limits productivity in many parts of the ocean. To investigate how coastal and oceanic Atlantic Synechococcus strains acclimate to Fe availability, we compared the growth, photophysiology, and quantitative proteomics of two Synechococcus strains from different Fe regimes. Synechococcus strain WH8102, from a region in the southern Sargasso Sea that receives substantial dust deposition, showed impaired growth and photophysiology as Fe declined, yet used few acclimation responses. Coastal WH8020, from the dynamic, seasonally variable New England shelf, displayed a multitiered, hierarchical cascade …


Geotechnical Statistical Evaluation Of Lahore Site Data And Deep Excavation Design, Aiza Malik Jan 2015

Geotechnical Statistical Evaluation Of Lahore Site Data And Deep Excavation Design, Aiza Malik

Civil and Environmental Engineering Master's Project Reports

Geotechnical characterization for foundation design is critical during preliminary planning, designing and feasibility studies of various engineering projects. In this research, an effort has been made to develop a geotechnical database for the city of Lahore, Pakistan. This database would aid geologists and engineers involved in the geotechnical design and planning of engineering projects in Lahore. The project area has been divided into zones geographically. Soil profiles have been developed for all zones, which provide ranges of soil properties and SPT-N values at regular intervals. Furthermore, the research also focuses on deep excavations in urban areas of Lahore, Pakistan and …


Potential For Geothermal Energy In Northern Louisiana: Analysis Of The Subsurface Environment In Union And Morehouse Parishes, Tessa Shizuko Hermes Jan 2015

Potential For Geothermal Energy In Northern Louisiana: Analysis Of The Subsurface Environment In Union And Morehouse Parishes, Tessa Shizuko Hermes

LSU Master's Theses

Efforts to mitigate greenhouse gas emissions and reduce dependence on fossil fuels have led to renewed focus on the exploration and development of alternative energy production. One such option is hydrothermal binary geothermal energy production from geothermal reservoirs with temperatures of at least 100 °C at depths no greater than 5 km. In the U.S., such systems have the potential to provide 5,400 % of 2013 total U.S. energy consumption. This study evaluates the potential for geothermal energy systems implementation in Morehouse and Union Parishes, Louisiana, by using publicly available bottom hole temperature (BHT), mud weight (MW), logged formation top …


Neodymium Isotope Ratios And A Positive Δ13c Excursion: Connecting Oceanographic And Climate Changes Near The M4-M5 Sequence Boundary Of The Late Ordovician, Zachary Wright Jan 2015

Neodymium Isotope Ratios And A Positive Δ13c Excursion: Connecting Oceanographic And Climate Changes Near The M4-M5 Sequence Boundary Of The Late Ordovician, Zachary Wright

LSU Master's Theses

A significant positive carbon isotope excursion first described from the Guttenberg Member of the Decorah Formation in Iowa called the GICE is a defining feature of Late Ordovician chemostratigraphy. It occurs near the M4-M5 sequence boundary of the Late Ordovician and has been correlated across the globe using prominent K-bentonite ash beds and conodont biomarkers. The cause of the GICE has been debated, with some arguing that it represents the initiation of a glacial period in a greenhouse climate 10 Ma before the end Ordovician glaciation and extinction. A variety of cooling signals have been identified across the M4-M5 sequence …


The Stratal Architecture Of The False River Point Bar (Lower Mississippi River, La), Alexandra Lechnowskyj Jan 2015

The Stratal Architecture Of The False River Point Bar (Lower Mississippi River, La), Alexandra Lechnowskyj

LSU Master's Theses

The False River point bar system is located roughly thirty miles north of Baton Rouge, LA. It is an oxbow lake cut off from the Mississippi River, and represents a large-scale modern analogue to the ancient systems of northeastern Alberta, Canada, specifically those of the Athabasca Oils Sands. While previous work has been done regarding the general architecture of a point bar, there is still omplexity associated with larger scale systems, as studies have been mostly based on small and medium-scale examples. Examination of the point bar was done through a combination of coring and geophysical logging, followed by software …


Rare Earth Element Patterns In Conodont Apatite From The Upper Ordovician: Testing Enrichment Sources And Possible Oceanographic Changes, Cody Christian Schulte Jan 2015

Rare Earth Element Patterns In Conodont Apatite From The Upper Ordovician: Testing Enrichment Sources And Possible Oceanographic Changes, Cody Christian Schulte

LSU Master's Theses

The Mohawkian series of the Middle Late Ordovician was a time of great lithological and faunal changes that coincide with a positive ä13C excursion known as the Guttenberg Isotopic Carbon Excursion (GICE). Two prevailing hypotheses have been proposed to explain the cause of these changes. The “cold-water” hypothesis suggests that global cooling caused the tropical belt to shrink and cold water to invade the epicontinental sea while the “tectonic-forcing” hypothesis suggests that increased weathering rates led to basinal deepening, resulting in cooler oceanic waters invading the midcontinent sea. This study tests if regional tectonics caused by the Taconic Orogeny led …


The Extraordinary Voyage Of Kamome; A Tsunami Boat Comes Home, Lori Dengler, Amya Miller, Amy Uyeki Jan 2015

The Extraordinary Voyage Of Kamome; A Tsunami Boat Comes Home, Lori Dengler, Amya Miller, Amy Uyeki

Trade & Scholarly Monographs

This sweet story, intended for lower elementary grades, is intended to provide a window for discussing earthquakes, tsunamis, marine debris, preparedness and cultural awareness in the classroom and within families.

On April 7, 2013, a little over two years after the magnitude 9 Tohoku-oki Japan earthquake triggered a massive tsunami off the coast of northeastern Japan, a lone boat washed up on the shores of Crescent City, California. The confirmation of the boat as belonging to a high school in Rikuzentakata was first step in an amazing story that has linked two tsunami-vulnerable communities on opposite sides of the Pacific …


Schreibersite: Synthesis, Characterization And Corrosion And Possible Implications For Origin Of Life, Nikita Latesha La Cruz Jan 2015

Schreibersite: Synthesis, Characterization And Corrosion And Possible Implications For Origin Of Life, Nikita Latesha La Cruz

USF Tampa Graduate Theses and Dissertations

We present study of the synthesis and reactions of an analog of the meteoritic mineral schreibersite with formula (Fe,Ni)3P, believed to be a prebiotic source of reactive phosphorus that may have prompted the formation of phosphorylated biomolecules near the time of the origin of life (Pasek and Lauretta, 2005). The mineral was synthesized by mixing stoichiometric proportions of elemental iron, nickel and phosphorus and heating in a tube furnace at 820°C for approximately 235 hours under argon or under vacuum, a modification of the method of Skála and Drábek (2002). The mineral was characterized using X-ray diffractometry (XRD), X-ray photoelectron …


Nearest Neighbor Foreign Exchange Rate Forecasting With Mahalanobis Distance, Vindya Kumari Pathirana Jan 2015

Nearest Neighbor Foreign Exchange Rate Forecasting With Mahalanobis Distance, Vindya Kumari Pathirana

USF Tampa Graduate Theses and Dissertations

Foreign exchange (FX) rate forecasting has been a challenging area of study in the past. Various linear and nonlinear methods have been used to forecast FX rates. As the currency data are nonlinear and highly correlated, forecasting through nonlinear dynamical systems is becoming more relevant. The nearest neighbor (NN) algorithm is one of the most commonly used nonlinear pattern recognition and forecasting methods that outperforms the available linear forecasting methods for the high frequency foreign exchange data. The basic idea behind the NN is to capture the local behavior of the data by selecting the instances having similar dynamic behavior. …


Modeling Intrusive Geometries Of A Shallow Crustal Intrusion: New Evidence From Mount Ellsworth, Utah, Nathan Nushart Jan 2015

Modeling Intrusive Geometries Of A Shallow Crustal Intrusion: New Evidence From Mount Ellsworth, Utah, Nathan Nushart

USF Tampa Graduate Theses and Dissertations

Surface displacements resulting from upper-crustal intrusion of melt are a paramount concern for communities and facilities located in or near active volcanic areas (e.g. Campi Flegrei, Yucca Mtn.). Study of active intrusions such as Campi Flegrei, Italy west of Mt. Vesuvius, is limited to remote observations through geophysical/geodetic procedures. While the surface displacement due to melt emplacement at depth can easily be determined, the geometries and depth of intrusions are often based on simplified assumptions (e.g. spheres and prolate or oblate ellipsoids). These models benefit from data constraining both the geometries of the individual intrusions, and the kinematics and mechanics …


Ground-Coupled Air Waves: A Seismological Case Study Of The Explosion Quakes Of The 2007 Eruption Of Pavlof Volcano, Alaska, Cassandra Marie Smith Jan 2015

Ground-Coupled Air Waves: A Seismological Case Study Of The Explosion Quakes Of The 2007 Eruption Of Pavlof Volcano, Alaska, Cassandra Marie Smith

USF Tampa Graduate Theses and Dissertations

An abnormally high number of explosion quakes were noted during the monitoring effort for the 2007 eruption of Pavlof Volcano on the Alaskan Peninsula. In this study we manually counted the explosion quakes from their characteristic ground-coupled air waves. This study makes an effort at better quantifying the number of explosion quakes and how the characteristic ground-coupled air waves are affected by wind direction and wind speed. Additionally this study investigates how the ground coupled air waves might be used in a monitoring or analysis effort by calculating energy release and gas mass release. Over 3.2x104 quakes were recorded. …


A Composite Spatial Model Incorporating Groundwater Vulnerability And Environmental Disturbance To Guide Land Management, Johanna L. Kovarik Jan 2015

A Composite Spatial Model Incorporating Groundwater Vulnerability And Environmental Disturbance To Guide Land Management, Johanna L. Kovarik

USF Tampa Graduate Theses and Dissertations

Research has long recognized and studied the dynamics of groundwater processes. More recently, groundwater dependent ecosystems (GDEs) are being recognized for their diversity and vulnerability to anthropogenic impact. Groundwater in karst landscapes presents a distinctive situation where flow through the subsurface often moves rapidly on the scale of days and weeks as opposed to years or millennia in other systems. This distinctive situation of karst systems and their vulnerability to human impacts necessitate an integrated and multifaceted approach for the management of these important resources. However, development of such an approach is complicated by the difficulty of obtaining detailed data …


Glaciological Applications Of Terrestrial Radar Interferometry, Denis Voytenko Jan 2015

Glaciological Applications Of Terrestrial Radar Interferometry, Denis Voytenko

USF Tampa Graduate Theses and Dissertations

Terrestrial Radar Interferometry (TRI) is a relatively new ground-based technique that combines the precision and spatial resolution of satellite interferometry with the temporal resolution of GPS. Although TRI has been applied to a variety of fields including bridge and landslide monitoring, it is ideal for studies of the highly-dynamic terminal zones of marine-terminating glaciers, some of which are known to have variable velocities related to calving and/or ocean-forced melting. My TRI instrument is the Gamma Portable Radar Interferometer, which operates at 17.2 GHz (1.74 cm wavelength), has two receiving antennas for DEM (digital elevation model) generation, and images the scenes …


Using Fault Kinematics To Evaluate The Relationship Between Cenozoic Fault Activity, Sedimentation Rates And Salt Movement In The Gulf Of Mexico - A Comparison Between Southwest Louisiana And Southeast Louisiana, Abah Philip Omale Jan 2015

Using Fault Kinematics To Evaluate The Relationship Between Cenozoic Fault Activity, Sedimentation Rates And Salt Movement In The Gulf Of Mexico - A Comparison Between Southwest Louisiana And Southeast Louisiana, Abah Philip Omale

LSU Master's Theses

ABSTRACT Fault initiation and reactivation across south Louisiana during the Cenozoic was driven by either clastic sediment progradation mobilizing underlying salt or by sediment progradation inducing tensional bending stresses during lithospheric flexure. Climate and tectonics within the North American continent during the Cenozoic created differences in the source location, amount of sediments transported, as well as the spatial and temporal distribution of sediments transported into the Gulf of Mexico. This study analyzes 140 fault intercepts along 11 regional cross sections containing well log data in south Louisiana. Cumulative throw, incremental throw, and fault slip rates indicate fault activity punctuated by …


Sub-Marine Sediment Instability Near Southwest Pass Of The Mississippi River: Evidence Of Mass Movements From Raciochemistry And Other Proxies, Gregory Paul Keller Jan 2015

Sub-Marine Sediment Instability Near Southwest Pass Of The Mississippi River: Evidence Of Mass Movements From Raciochemistry And Other Proxies, Gregory Paul Keller

LSU Master's Theses

Mass wasting events are an important geomorphic control on the Mississippi River Delta Front. Short multicores (<50cm) and longer gravity cores (<3m) were collected seaward of the Southwest Pass of the Mississippi River Delta and were analyzed to assess the frequency, extent, and potential causes of submarine mass wasting events. Cores were analyzed for radionuclide activity, grain size, and density at 2cm resolution. Short-term sedimentation rates calculated from 7-Be are 2-16cm/y, while longer-term accumulation from 210-Pb are only 1.3-7.3 cm/y. In most cores, 210-Pb activity steadily decreases downcore without displaying a “stairstep” nature. However, seven cores have layers of low 210-Pb activity stratigraphically above layers with higher activity. In a gravity core from a mudflow gully, 210-Pb steadily decreases for the upper 70 cm before stabilizing for the remaining 150 cm. Clay content generally ranges between 25-40% and sand ranges between 5-15% with silt making up the rest of each sample. Sediment accumulation rates derived from 210-Pb in the short cores indicate that proximity to the river mouth has stronger influence than depositional environment (mudflow gully, depositional lobe, prodelta). This finding may be explained by rapid sedimentation rates coupled with a reduced tropical cyclone activity over the delta in the last seven years (2006-2013) which is a known cause of mass wasting events. The regions of decreased 210-Pb activity may be evidence of scavenging effects of plume sedimentation because they do not correspond with decreases in clay fraction. The layer of homogenized activity below 70cm in the gully core corresponds with a layer of decreased density. This layer occurs at a depth equivalent to 9-18 years, indicating mixing on a decadal scale from mudflows. These results may be explained by a lack of recent mass failures corresponding with lulls in tropical cyclone activity over the delta, preceded by a period of more active hurricane-driven mudflow activity.


Impact Of Spatial Aliasing On Sea-Ice Thickness Measurements, Cathleen Geiger, Hans-Reinhard Müller, Jesse P. Samluk, E Rachel Bernstein, Jacqueline Richter-Menge Jan 2015

Impact Of Spatial Aliasing On Sea-Ice Thickness Measurements, Cathleen Geiger, Hans-Reinhard Müller, Jesse P. Samluk, E Rachel Bernstein, Jacqueline Richter-Menge

Dartmouth Scholarship

We explore spatial aliasing of non-Gaussian distributions of sea-ice thickness. Using a heuristic model and >1000 measurements, we show how different instrument footprint sizes and shapes can cluster thickness distributions into artificial modes, thereby distorting frequency distribution, making it difficult to compare and communicate information across spatial scales. This problem has not been dealt with systematically in sea ice until now, largely because it appears to incur no significant change in integrated thickness which often serves as a volume proxy. Concomitantly, demands are increasing for thickness distribution as a resource for modeling, monitoring and forecasting air–sea fluxes and growing human …