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2014

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Articles 871 - 900 of 1044

Full-Text Articles in Earth Sciences

Tidal Pacing, Skipped Slips And The Slowdown Of Whillans Ice Stream, Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Douglas A. Wiens, Martin J. Pratt Jan 2014

Tidal Pacing, Skipped Slips And The Slowdown Of Whillans Ice Stream, Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Douglas A. Wiens, Martin J. Pratt

All Faculty Scholarship for the College of the Sciences

We summarize new observations of the deceleration and stick–slip motion of Whillans Ice Stream (WIS), Antarctica. We refine the location of the large sticky spots that resist motion between slip events, the locations of which are controlled by the patterns of subglacial water flow. Our examination of the long-term velocity time series for the ice stream reveals that the decadal-scale deceleration is not occurring at a steady rate, but varies at the sub-decadal timescale. This unsteady deceleration modulates the temporal evolution of a broad (~50 km across) surface-elevation bulge forming at the junction between the relatively narrow upstream portion of …

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Effects Of Climate Change And Perturbation In Biogeochemical Cycles On Oxygen Distribution And Ocean Acidification, Teresa Marie Beaty-Sykes Jan 2014

Effects Of Climate Change And Perturbation In Biogeochemical Cycles On Oxygen Distribution And Ocean Acidification, Teresa Marie Beaty-Sykes

Earth & Environmental Sciences Dissertations - Archive

Dissolved oxygen (DO) concentration in the ocean is an important component of the marine biogeochemical cycles. In this study a global oceanic carbon cycle model (HAMOCC 2.0) was used to address how oxygen minimum zones (OMZ) respond to changes due to CO₂ radiative forcing. Atmospheric pCO₂ was increased at a rate of 1% annually and the model is stabilized at 2 X, 4 X, 6 X, and 8 X preindustrial pCO₂ levels. With an increase in CO₂ radiative forcing, the OMZ in the Pacific Ocean was controlled largely by changes in particulate organic carbon (POC) export. In contrast, the vertical …

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Oxygen Isotope Composition Of Phosphate Along Vertical Weathering Profiles That Developed On Igneous Rocks: Testing Modern Analogues For Identifying Terrestrial Life In Ancient Paleosols, Dustin Warn Boyd Jan 2014

Oxygen Isotope Composition Of Phosphate Along Vertical Weathering Profiles That Developed On Igneous Rocks: Testing Modern Analogues For Identifying Terrestrial Life In Ancient Paleosols, Dustin Warn Boyd

LSU Master's Theses

Life on Earth began in its early oceans before moving on to land. Determining the exact timing of an established biosphere on land, however, has been elusive, due largely to the lack of either fossil or chemical evidence on land deposits. Here I test a hypothesis that the activity of land biota can be recorded in the oxygen isotope composition of phosphate in weathering profiles developed on igneous parent rocks. Igneous rock contains phosphate (PO43-), which is readily utilized for biological activities during soil development. The oxygen in PO43- does not readily exchange its oxygen …

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Carbonate Sealing And Its Controlling Factors: Cap Rock And Inner Barrier Layers Of Yingshan Formation On Tazhong Northern Slope, Tarim Basin, Xiaodong Lan, Xiuxiang Lu Jan 2014

Carbonate Sealing And Its Controlling Factors: Cap Rock And Inner Barrier Layers Of Yingshan Formation On Tazhong Northern Slope, Tarim Basin, Xiaodong Lan, Xiuxiang Lu

Turkish Journal of Earth Sciences

The Yingshan Formation, located on the Tazhong Northern Slope, contains oil- and gas-rich layers with the reserves of about 700 × 10^6 TOE. The high-resistivity inner layers isolate the hydrocarbon bearing zones and form the sequential sets of reservoir bed-seal assemblages in a vertical direction within the Yingshan Formation, which is directly bound above by a micritic carbonate cap rock that is overlain by the 3rd to 5th members of the Lianglitag Formation. The sealing capability of the cap rock and inner barrier layers was evaluated macroscopically and microscopically in terms of the core breakthrough pressure and thin-section identification. The …

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Fault Kinematics Along The Coastal Plain Of South Louisiana: Implications For Tectono-Climatic-Induced Deformation Along A Passive Continental Margin, Ali A. Al Dhamen Jan 2014

Fault Kinematics Along The Coastal Plain Of South Louisiana: Implications For Tectono-Climatic-Induced Deformation Along A Passive Continental Margin, Ali A. Al Dhamen

LSU Master's Theses

Kinematic analysis of faults along the northern coastal plain of the Gulf of Mexico shows a correlation between pulses of faulting during the late Cenozoic and changes in the tectonic and climatic settings acting on the source areas which provide sediments to the Gulf. Pulses of faulting during the Oligocene-Early Miocene, Late Miocene, Pliocene, and Pleistocene correlate to major tectonic and climatic changes in the source region of sediments. Slip rates of faulting increase with younger events. The increase in slip rates is likely related to a combination of increase in sedimentation rates and pre-weakened Oligocene –Miocene rock that resulted …

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Variations In Salinity And Temperature On The Flank Of An Offshore Louisiana Salt Structure, Candice M. Mccollum Jan 2014

Variations In Salinity And Temperature On The Flank Of An Offshore Louisiana Salt Structure, Candice M. Mccollum

LSU Master's Theses

Sediments located in the vicinity of salt structures in the northern Gulf of Mexico have highly complex structures and fluid dynamics associated with the dissolution and diapirism of salt. Past studies (Lin and Nunn, 1997; Bruno and Hanor, 2003; Richards, 2013) have shown that faults associated with salt structures can act both as migration pathways and barriers to the flow of formation waters. Bruno and Hanor (2003), Steen et al. (2011), and Richards (2013) also demonstrated that lithology was a controlling factor in the flow of formation waters. In this study, two sets of wireline logs, one used in salinity …

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How Unusual Is Tropical Storm Irene? A Case Study Of Storm Deposition In Littleville Lake, Huntington, Ma, Catherine Dunn Jan 2014

How Unusual Is Tropical Storm Irene? A Case Study Of Storm Deposition In Littleville Lake, Huntington, Ma, Catherine Dunn

Honors Papers

Tropical Storm Irene hit the northeastern United States in August 2011 with impressive rates of precipitation and river discharge. However, it was the combination of this heavy rain with high antecedent soil moisture that made Irene so unusual. The Connecticut River had a particularly high sediment yield after the storm, with a sediment concentration over 1,000 mg/L at the mouth of the river. Littleville Lake on the Westfield River was selected as a study site because of its flood control feature, which allows for the calculation of trapping efficiency in dammed rivers. Coring in the lake showed that there was …

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Full Of Hot Air: Heat Flow At The Medicine Lake Volcano Hot Spot, Modoc County, California, Katrina D. Gelwick Jan 2014

Full Of Hot Air: Heat Flow At The Medicine Lake Volcano Hot Spot, Modoc County, California, Katrina D. Gelwick

Honors Papers

Changes in volcanic hydrothermal systems can shed light on the physical processes associated with volcanic unrest such as changes in an underlying magma body. The U.S. Geological Survey recently implemented an experimental hydrothermal monitoring network throughout the Cascade volcanic arc. Despite being ranked as the 12th highest threat among all Cascade volcanoes, Medicine Lake Volcano in northeastern California is considered under-monitored. The primary hydrothermal-monitoring site at Medicine Lake Volcano is a weak fumarole contained within a small area of heated ground, called the Hot Spot, located near the caldera rim. This study uses data from a survey conducted in August …

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The Effect Of Rainfall And Post-Revolutionary Land-Use Changes On Sediment Yield In Weixi Basin, Yunnan, China : New Insights From Multi-Temporal Land-Use Classification And Radionuclide Analyses, Yue Qiu Jan 2014

The Effect Of Rainfall And Post-Revolutionary Land-Use Changes On Sediment Yield In Weixi Basin, Yunnan, China : New Insights From Multi-Temporal Land-Use Classification And Radionuclide Analyses, Yue Qiu

Honors Papers

This paper looks at the dynamic interphase connecting post-revolutionary politics, modern land use practices, precipitation patterns, basin slope, and sediment yield records in Weixi basin, a small mountainous watershed in Southwestern China with a total upstream area of 198 m2. The goal is to identify what processes, climatic or not, account for the changes in local sediment yield and erosion budget. Weixi basin has an average annual sediment yield of 175 ton/km2 with two anomalously large peaks in 1979 and 1984. Precipitation is moderately correlated with sediment yield at interannual scale. It also affects seasonal fluctuations in sediment yield as …

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Eclogites And Eclogites: Oxygen Isotope Evidence Of A Shared Subduction Origin For Franciscan Eclogites And Moses Rock Eclogite Xenoliths, William F. Hoover Jan 2014

Eclogites And Eclogites: Oxygen Isotope Evidence Of A Shared Subduction Origin For Franciscan Eclogites And Moses Rock Eclogite Xenoliths, William F. Hoover

Honors Papers

Eclogites can be found in two distinct tectonic settings in the western USA: in the Franciscan Complex as tectonic blocks in a fossil accretionary wedge, and in the Navajo Volcanic Field as xenoliths in diatremes. Intra-crystal oxygen isotope analyses of garnets from these two settings provide important information on the source, composition and timing of fluid interactions in both eclogite settings. Because of the well-documented relationship between Franciscan subduction and the volcanism in the Navajo Volcanic Field, the samples in this study can be directly compared to determine if they share a common origin. The Navajo eclogites in this study …

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East-Derived Strata In The Methow Basin Record Rapid Mid-Cretaceous Uplift Of The Southern Coast Mountains Batholith, Kathleen D. Surpless, Zachary T. Sickmann, Trevor Koplitz Jan 2014

East-Derived Strata In The Methow Basin Record Rapid Mid-Cretaceous Uplift Of The Southern Coast Mountains Batholith, Kathleen D. Surpless, Zachary T. Sickmann, Trevor Koplitz

Earth and Environmental Geosciences Faculty Research

The Jurassic–Cretaceous Methow basin of northern Washington State and southern British Columbia forms an overlap sequence linking several small tectonostratigraphic terranes. Sandstone petrography, sandstone and mudrock geochemistry, and detrital zircon U–Pb age and Hf analysis of mid-Cretaceous, east-derived Methow strata together document a remarkably uniform provenance signature that suggests proximal, abundant, and unchanging sediment sources throughout deposition. The eastern belt of the Coast Mountains batholith, intruded into Stikine and related inboard terranes of the Intermontane superterrane, along with Jurassic and Cretaceous plutons of the westernmost Okanogan Range, provide the best match to the provenance signature of east-derived sediment in the …

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Deformation And Exhumation Across Gianbul Dome, Nw India: Insight From Deformation Kinematics And Temperatures, And 40ar/39ar Thermochronology, Meilani Bowman-Kamaha’O Jan 2014

Deformation And Exhumation Across Gianbul Dome, Nw India: Insight From Deformation Kinematics And Temperatures, And 40ar/39ar Thermochronology, Meilani Bowman-Kamaha’O

All Master's Theses

New kinematic, microtextural, and thermochronology studies test the hypothesis that high temperature-moderate pressure rocks exposed in Gianbul Dome, NW India, were exhumed south of the southern Tibetan detachment system by the southward extrusion of a mid-crustal ductile channel. Mesoscopic and microscopic kinematic indicators record normal-sense shear in the Khanjar and Zanskar shear zones, which define the southwest and northeast flanks of Gianbul Dome, respectively. Microtextural analyses indicate deformation at >400°C along dome flanks increasing to > 700°C in the core. Moderate temperature cooling is asymmetric across the dome, initiating at ~22 Ma on the southwest flank of the dome-and at ~20 …

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Constraints On Interplate Locking Within The Makran Subduction Zone Using Gps, Elyse Erin Frohling Jan 2014

Constraints On Interplate Locking Within The Makran Subduction Zone Using Gps, Elyse Erin Frohling

All Master's Theses

We use GPS measurements from 20 stations located in Iran, Pakistan, and Oman along with International Seismological Centre hypocentral locations to create a fault coupling model for the Makran subduction zone. The 3-D geometry of the megathrust fault is estimated from five profiles landward of the Makran trench. Continuous GPS on the Arabian plate show convergence of ~27 mm/year, and interseismic deformation is calculated using the back-slip method of Savage [ 1983]. We find the entire subduction zone appears to be accumulating stress uniformly from ~15-60 km depth and find no evidence of along-strike segmentation in strain accumulation, suggesting the …

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Structural Deformation Across The Southwest Mina Deflection, California-Nevada: Field Studies In The Huntoon Spring Quadrangle, Eliya R. Hogan Jan 2014

Structural Deformation Across The Southwest Mina Deflection, California-Nevada: Field Studies In The Huntoon Spring Quadrangle, Eliya R. Hogan

All Master's Theses

New geologic data provides insight into Pliocene strain rates across the southwest Mina deflection. 40 Ar/39 Ar geochronology of geologic units indicate cooling of Miocene ignimbrite at 11.86 ± 0.01 Ma, Pliocene basalt lavas at 3.7241 ± 0.0051 and 3.5262 ± 0.0172 Ma, and basaltic andesite and andesite lavas at 3.4715 ± 0.0107 Ma and 3.1078 ± 0.0088 Ma. Pliocene cinder cones and Quaternary sediments are also exposed in the Huntoon Spring quadrangle. Volcanic units are cut by a dominant set of NNE-, NE-, and ENE- striking sinistral faults and a lesser set of NNW- and NW- striking normal …

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Proxy-Based Reconstructions Of Earthquakes And Tsunamis At Quidico, South-Central Chile, Isabel J. Hong Jan 2014

Proxy-Based Reconstructions Of Earthquakes And Tsunamis At Quidico, South-Central Chile, Isabel J. Hong

All Master's Theses

We utilized geomorphic, microfossil, sedimentological, and stratigraphic methods to investigate the paleotsunami history at Quidico, Chile (38.1° S, 73.2° W). A combination of pits, cores, and riverbank exposures provide stratigraphic evidence of 8 sand layers at Quidico, including tsunami deposits from 2010 and 1960. The sands are laterally continuous but display landward thinning, disappearing completely from the stratigraphy 1.2 km inland from the coast. Intervening sediment layers consist of organicrich silts and peat. Grain size analysis shows the sand units are bimodal in distribution whereas the organic-rich silts and peat have a broader, bimodal distribution. Lithological analysis showed similarities among …

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Controls On Fault Geometry During Early Stages Of Extension In The Larkspur Hills, Northwest Basin And Range, Diana Jean Strickley Jan 2014

Controls On Fault Geometry During Early Stages Of Extension In The Larkspur Hills, Northwest Basin And Range, Diana Jean Strickley

All Master's Theses

Detailed analyses of normal faults in the Larkspur Hills, CA-NV, northwest Basin and Range, offer insight into factors controlling normal fault initiation, growth, and distribution. N-trending faults in the southern portion of the study area share trends of major range-bounding structures and Pliocene linear volcanic vents; in contrast, NNW- and NNE- trending faults dominate further north and into south-central Oregon. Stress analyses and comparison with experimental and field data suggest that preexisting structures control faults in the northern Larkspur Hills, while faults form perpendicular to σ3 in the southern hills. The change in fault orientations is abrupt, occurring across a …

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Spatial Relationship Between Gps Slip And Seismic Tremor During Cascadia Slow Slip Events, Hillary Lynn Goodner Jan 2014

Spatial Relationship Between Gps Slip And Seismic Tremor During Cascadia Slow Slip Events, Hillary Lynn Goodner

All Master's Theses

We model GPS deformation and timing of seismic tremor associated with transient deformation in Cascadia to test the hypothesis that tremor and slip occur synchronously but are spatially offset. For the period 2010–2013, we use seismic tremor data with a duration-moment relationship to predict GPS time series and compare them to observations. We find that observed GPS displacements are best predicted when tremor locations on the plate interface are shifted 15 km up-dip of their published epicenter. To test whether the spatial offset of tremor and slip is due to systematic mislocation of published epicenters, we attempt to identify individual …

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Thermobarometry And Geochronology In The Dulan Region, North Qaidam Ultrahigh-Pressure Terrane: Resolving Spatial Variation Of Ages, Temperatures, And Pressures, Megan Eileen Regel Jan 2014

Thermobarometry And Geochronology In The Dulan Region, North Qaidam Ultrahigh-Pressure Terrane: Resolving Spatial Variation Of Ages, Temperatures, And Pressures, Megan Eileen Regel

All Master's Theses

The Dulan ultrahigh-pressure (UHP) terrane exposes 449-422 Ma eclogites in the east and 449-418 Ma high-pressure granulites to the west, but the relationship between the units is poorly understood. Zirconium-in-rutile temperatures show an east-west 3- 5°C/km gradient in four UHP eclogites: 662-716±10°C; garnet-omphacite-phengite thermobarometry of peak conditions yields 659-730±82°C, 25.3-27.1±3.2 kbars. Zircon U-Pb ages of four eclogites are the same within uncertainty, averaging 434±2.9 Ma. Tiin- zircon thermometry and rare earth element patterns indicate these ages represent eclogite facies metamorphism. One high-pressure/high-temperature (HP/HT) granulite yields a minimum rutile temperature of 773±4°C. Previous thermobarometry of highpressure granulites yields ≥800°C and 14-17 …

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Bramatherium (Artiodactyla, Ruminantia, Giraffidae) From The Middle Siwaliks Of Hasnot, Pakistan: Biostratigraphy And Palaeoecology, Muhammad Akbar Khan, Muhammad Akhtar, Ammara Irum Jan 2014

Bramatherium (Artiodactyla, Ruminantia, Giraffidae) From The Middle Siwaliks Of Hasnot, Pakistan: Biostratigraphy And Palaeoecology, Muhammad Akbar Khan, Muhammad Akhtar, Ammara Irum

Turkish Journal of Earth Sciences

We describe here new remains of the giraffid Bramatherium, from the late Miocene-early Pliocene of Hasnot, northern Pakistan. The fossil giraffid material from Hasnot represents 2 taxa of Bramatherium, B. megacephalum and B. grande. The Hasnot locality is characterised by high proportions of ruminants, namely Boselaphini, Antilopini, Sivatheriinae, Cervini, Dorcatherium, and Dorcabune. The Hasnot fossil ruminant assemblage is fairly typical for the Siwalik province and comparisons with the Greco-Iranian-Afghan and African palaeobiological provinces indicate a late Miocene-early Pliocene age. It is suggested that local Hasnot palaeoenvironments comprised wetlands to woodland biomes, perhaps devoid of expansive dense forests.

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Appraisal Of Active Tectonics Using Dem-Based Hypsometric Integral And Trend Surface Analysis In Emilia-Romagna Apennines, Northern Italy, Saima Siddiqui, Mauro Soldati Jan 2014

Appraisal Of Active Tectonics Using Dem-Based Hypsometric Integral And Trend Surface Analysis In Emilia-Romagna Apennines, Northern Italy, Saima Siddiqui, Mauro Soldati

Turkish Journal of Earth Sciences

The hypsometric integral (HI) has generally been used to explain the stages of landscape evolution and erosional processes. It is an important tool to investigate tectonics and lithologic and climatic effects on topographic change. We analyzed the significance of the HI to investigate active tectonics in the Emilia-Romagna Apennines of northern Italy. We used a digital elevation model of 5-m spatial resolution to calculate grid-based HI values. The HI distribution does not show clear spatial patterns of high and low HI values. However, when statistical methods of local indices of spatial autocorrelation were applied, it was possible to identify clear …

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Palynology Of The Upper Cretaceous Ferron-Notom Sandstone, Utah, Isil Akyuz Jan 2014

Palynology Of The Upper Cretaceous Ferron-Notom Sandstone, Utah, Isil Akyuz

LSU Master's Theses

ABSTRACT The Late Cretaceous Ferron-Notom Sandstone Member of the Mancos Shale Formation plays a dominant role in oil production in Utah. Although numerous sedimentological and sequence stratigraphic studies have been conducted in recent years on this sequence, palynological analyses had not yet been undertaken. Here we present palynological data from one hundred twenty eight samples collected in the Ferron-Noton Sandstone Member outcroping in south-central Utah. The purpose of this study is to refine our understanding of climatic and depositional environments and to build a biostratigraphic palynological framework. The dominance of terrestrial palynomorphs, especially the high yield in moisture-loving cryptogam spores …

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Evaluation Of Stromatolites From The 3.4 Ga Kromberg Formation, Barberton Greenstone Belt, South Africa, Corey E. Shircliff Jan 2014

Evaluation Of Stromatolites From The 3.4 Ga Kromberg Formation, Barberton Greenstone Belt, South Africa, Corey E. Shircliff

LSU Master's Theses

Silicified sedimentary rocks from the 3.4 Ga Kromberg Formation of the Barberton Greenstone Belt in South Africa contain laminated structures that have been identified as possible stromatolites in the field. Morphological evaluation and a variety of chemical analyses are presented here, in an effort to describe the samples in a sedimentary context and consider biogenicity of these laminated forms. Two major types of laminated structures were identified in the field – domical laminates and flat-laminated samples with little to no synoptic relief. The domical sample presents the best morphological evidence for biogenicity. There are several characteristics that suggest the deposition …

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Paleoclimatology And Paleotempestology Study Of Blue Hole, Lighthouse Reef, Belize Through Geochemical Proxies, Laura Carolyn Sorey Jan 2014

Paleoclimatology And Paleotempestology Study Of Blue Hole, Lighthouse Reef, Belize Through Geochemical Proxies, Laura Carolyn Sorey

LSU Master's Theses

A large Pleistocene age sinkhole, the Blue Hole on Lighthouse Reef off the coast of Belize in the Caribbean Sea is the site of a well preserved sedimentary record that serves as paleoclimatology and paleotempestology archive. The nutrient-starved surface waters of the Blue Hole and the surrounding lagoons are “fertilized” by the seasonal introduction of cool, nutrient-rich waters upwelled from the Caribbean deep water. These waters, which stimulate production of organic materials within the surface waters, carry a heightened isotopic signature that is imparted to the organics resultant from upwelling-induced production. These organics are then incorporated into the predominantly carbonate …

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Preliminary Investigation Of The Geometry And Kinematics Of The Bangong-Nujiang Suture At The Basu Metamorphic Massif, Se Tibet, Chase Michael Billeaudeau Jan 2014

Preliminary Investigation Of The Geometry And Kinematics Of The Bangong-Nujiang Suture At The Basu Metamorphic Massif, Se Tibet, Chase Michael Billeaudeau

LSU Master's Theses

There are many uncertainties associated with the development and deformation of the Tibetan Plateau. The Basu Massif, located along the eastern Bangong-Nujiang Suture Zone, is an ideal locality to help provide constraints to resolve the geologic evolution of the Tibetan Plateau. The Basu Massif is characterized by high pressure-ultra high pressure (HP-UHP) metamorphic rocks, syn- and post-collisional granites, and a central Upper Paleozoic unit bounded by discontinuous belts of serpentinite. Field data suggests that the carbonates of the central Upper Paleozoic unit, serpentinites, granites and metasedimentary rocks are part of an isoclinally folded shear zone that may have been thrust …

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Classification Of Four Meteorite Samples, Karla Farley Jan 2014

Classification Of Four Meteorite Samples, Karla Farley

University Honors Theses

The petrography, mineralogy, and mineral chemistry of four unclassified Northwest Africa meteorites in the Cascadia Meteorite Laboratory collection (CML0005, 0023, 0024, 0032) were studied using optical microscopy and scanning electron microscopy. The data will be used to classify the meteorites and to obtain official names for the meteorites. CML0023 has the preliminary classification of L6 (S3) W1, CML0024 has L6 (S3) W1, and CML0032 has L6 (S2) W1. CML0005 has chemistry and mineralogy that indicate it is an anomalous acapulcoite.

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Benthic And Pelagic Pathways Of Methylmercury Bioaccumulation In Estuarine Food Webs Of The Northeast United States, Celia Y. Chen, Mark E. Borsuk, Deenie M. Bugge, Terill Hollweg Jan 2014

Benthic And Pelagic Pathways Of Methylmercury Bioaccumulation In Estuarine Food Webs Of The Northeast United States, Celia Y. Chen, Mark E. Borsuk, Deenie M. Bugge, Terill Hollweg

Dartmouth Scholarship

Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concentrations …

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Dependence Of Ice-Core Relative Trace-Element Concentration On Acidification, Bess G. Koffman, Michael J. Handley, Erich C. Osterberg, Mark L. Wells, Karl J. Kreutz Jan 2014

Dependence Of Ice-Core Relative Trace-Element Concentration On Acidification, Bess G. Koffman, Michael J. Handley, Erich C. Osterberg, Mark L. Wells, Karl J. Kreutz

Dartmouth Scholarship

To assess the role of methodological differences on measured trace-element concentrations in ice cores, we developed an experiment to test the effects of acidification strength and time on dust dissolution using snow samples collected in West Antarctica and Alaska. We leached Antarctic samples for 3 months at room temperature using nitric acid at concentrations of 0.1, 1.0 and 10.0% (v/v). At selected intervals (20 min, 24 hours, 5 days, 14 days, 28 days, 56 days, 91 days) we analyzed 23 trace elements using inductively coupled plasma mass spectrometry. Concentrations of lithogenic elements scaled with acid strength and increased by 100–1380% …

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Winter Climate Change Affects Growing-Season Soil Microbial Biomass And Activity In Northern Hardwood Forests, Jorge Durán, Jennifer L. Morse, Peter M. Groffman, John L. Campbell, Lynn M. Christenson, Charles T. Driscoll, Timothy J. Fahey, Melany C. Fisk, Mryon J. Mitchell, Pamela H. Templer Jan 2014

Winter Climate Change Affects Growing-Season Soil Microbial Biomass And Activity In Northern Hardwood Forests, Jorge Durán, Jennifer L. Morse, Peter M. Groffman, John L. Campbell, Lynn M. Christenson, Charles T. Driscoll, Timothy J. Fahey, Melany C. Fisk, Mryon J. Mitchell, Pamela H. Templer

Environmental Science and Management Faculty Publications and Presentations

Understanding the responses of terrestrial ecosystems to global change remains a major challenge of ecological research. We exploited a natural elevation gradient in a northern hardwood forest to determine how reductions in snow accumulation, expected with climate change, directly affect dynamics of soil winter frost, and indirectly soil microbial biomass and activity during the growing season. Soils from lower elevation plots, which accumulated less snow and experienced more soil temperature variability during the winter (and likely more freeze/thaw events), had less extractable inorganic nitrogen (N), lower rates of microbial N production via potential net N mineralization and nitrification, and higher …

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Channel-Levee Complexes And Sediment Flux Of The Upper Indus Fan, Taylor Landry Berlin Jan 2014

Channel-Levee Complexes And Sediment Flux Of The Upper Indus Fan, Taylor Landry Berlin

LSU Master's Theses

The Indus Fan with a volume of 4.5 million km³ is the second largest submarine fan on Earth, only behind its neighbor to the east The Bengal Fan. It formed off the passive margin of Pakistan-India in the northern Arabian Sea. One of the more important aspects of the Indus Fan is its mostly complete sediment record of what has been eroded from the western Himalayan and Karakoram Mountains which act as the main source for the Indus River system. Since the initiation of the Himalaya about 50 Ma, sedimentation rates have fluctuated. This study attempts to calculate a new …

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Modeling Near Surface, Gas-Induced Seafloor Deformation Using Thin Plate Mechanics In The Thunder Horse Oil Field, Gulf Of Mexico And Ninilchik Field, Cook Inlet Basin, Alaska, Michael I. Thoma Jan 2014

Modeling Near Surface, Gas-Induced Seafloor Deformation Using Thin Plate Mechanics In The Thunder Horse Oil Field, Gulf Of Mexico And Ninilchik Field, Cook Inlet Basin, Alaska, Michael I. Thoma

LSU Master's Theses

Seabed topographic expressions such as pockmarks and domes caused by the vertical migration and accumulation of methane are found in muddy, cohesive sea beds around the world. These surface features range from 10-1000 m in diameter and 1-20 m in relief (Judd and Hovland, 2007). The mechanics of soft, cohesive sediment deformation due to overpressure from rising gas is not well understood or quantitatively defined despite the hazards they present to offshore drilling. Shallow gas pockets and overpressured sediments formed by the migration of subsurface gas to the seafloor can cause drilling blowouts, resulting in the release of large amounts …

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