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Two-And-Three-Dimensional Crustal Thickness Of The Eastern Pontides (Ne Turkey), Nafiz Maden, Kenan Geli̇şli̇, Yener Eyüboğlu, Osman Bektaş Jan 2009

Two-And-Three-Dimensional Crustal Thickness Of The Eastern Pontides (Ne Turkey), Nafiz Maden, Kenan Geli̇şli̇, Yener Eyüboğlu, Osman Bektaş

Turkish Journal of Earth Sciences

The Eastern Pontide orogenic belt is divided into three subzones (northern, southern and axial zones) based on present lithologies and facies associations. NE-SW-, NW-SE- and E-W-trending fault systems, which play an important role in palaeotectonics and neotectonics of the Eastern Pontides, separate these zones. Three different methods were used to estimate the Moho depth from observed gravity value, namely (i) empirical relationship between Moho depth and Bouguer anomaly; (ii) spectral analysis of the radial wave number and; (iii) by the gravity inversion method. Power spectrum, a statistical approach, is a widely used technique to determine the depth of geological sources …

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Anomalous Strong Reflections On High Resolution Seismic Data From The Turkish Shelf Of The Eastern Black Sea: Possible Indicators Of Shallow Hydrogen Sulphide-Rich Gas Hydrate Layers, Derman Dondurur, Günay Çi̇fçi̇ Jan 2009

Anomalous Strong Reflections On High Resolution Seismic Data From The Turkish Shelf Of The Eastern Black Sea: Possible Indicators Of Shallow Hydrogen Sulphide-Rich Gas Hydrate Layers, Derman Dondurur, Günay Çi̇fçi̇

Turkish Journal of Earth Sciences

Some strong reflections about 3 to 5 m thick were observed at depths of 25-60 metres below the sea floor using deep-towed, 5 kHz subbottom profiler data in the Turkish shelf and upper slope of the Eastern Black Sea at water depths of 250 to 700 m. Strong reflections of this kind are generally attributed to shallow and localized gas accumulations. We, however, observed that the reflection polarity of these strong reflections was positive, suggesting that they do not correspond to reflections from the upper boundary of a possible gas front. In this study, we evaluate these reflections to determine …

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Benthonic Foraminiferal Biostratigraphy Of The Upper Cretaceous (Middle Cenomanian−Coniacian) Sequences Of The Bey Dağları Carbonate Platform, Western Taurides, Turkey, Bi̇lal Sari, Kemal Tasli, Saci̇t Özer Jan 2009

Benthonic Foraminiferal Biostratigraphy Of The Upper Cretaceous (Middle Cenomanian−Coniacian) Sequences Of The Bey Dağları Carbonate Platform, Western Taurides, Turkey, Bi̇lal Sari, Kemal Tasli, Saci̇t Özer

Turkish Journal of Earth Sciences

Identification of the benthonic foraminiferal assemblages from ten stratigraphic sections from the inner platform limestones of the Middle Cenomanian−Coniacian successions of the Bey Dağları carbonate platform (BDCP) allowed the recognition of one biozone and two subzones. The lower part of the platform limestones (Middle−Upper Cenomanian) is represented by relatively rich benthonic foraminiferal assemblages, while the upper part (Turonian−Coniacian) contains poor assemblages. The benthonic foraminiferal assemblages determined in the BDCP are dominated by long-ranging species. The shorter-ranging, stratigraphical index species have been selected to date the Upper Cretaceous platform limestones of the BDCP based on the distributions of the species in …

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Ophiolite-Hosted Copper And Gold Deposits Of Southeastern Turkey: Formation And Relationship With Seafloor Hydrothermal Processes, Ömer Tezcan Akinci Jan 2009

Ophiolite-Hosted Copper And Gold Deposits Of Southeastern Turkey: Formation And Relationship With Seafloor Hydrothermal Processes, Ömer Tezcan Akinci

Turkish Journal of Earth Sciences

The paper documents evidence about the physical and chemical controls on the behaviour of Au and Cu sulphide deposits in fossil seafloor hydrothermal systems of SE Turkey. Observations from actively forming sulphides at mid-ocean ridges (MOR) and in back-arc environments are compared briefly with ancient analogues of gold and pyritic copper deposits such as Kisecik, Ergani and Siirt-Madenköy, formed at mid-oceanic ridges, or possibly at seamounts and back-arc settings. Many ophiolite-hosted Au- and Cu-deposits, of various sizes, are known to exist along the Bitlis-Zagros Suture Zone (BZS), the boundary between Anatolian and Arabian plates in SE Turkey. These deposits are …

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Contemporaneous Late Cretaceous Calc-Alkaline And Alkaline Magmatism In Central Anatolia, Turkey: O Isotope Constraints On Petrogenesis, Nurdane İlbeyli̇, Julian A. Pearce, Ian G. Meighan, Anthony E. Fallick Jan 2009

Contemporaneous Late Cretaceous Calc-Alkaline And Alkaline Magmatism In Central Anatolia, Turkey: O Isotope Constraints On Petrogenesis, Nurdane İlbeyli̇, Julian A. Pearce, Ian G. Meighan, Anthony E. Fallick

Turkish Journal of Earth Sciences

A wide variety of rock types were produced by the latest Cretaceous magmatism in the Central Anatolian Crystalline Complex. These rocks can be divided into three distinct units: (i) calc-alkaline, (ii) subalkaline/transitional, and (iii) alkaline. The calc-alkaline rocks are mainly metaluminous (I-type) ranging from monzodiorite to granite. The subalkaline/transitional rocks are also metaluminous (I-type) ranging from monzonite to granite. The alkaline rocks are mainly peralkaline (A-type), ranging from feldspathoid-bearing monzosyenite to granite. Whole-rock oxygen isotope data from the complex have a considerable range of \delta18O values between 6.5 per thousand and 14.8 per thousand. Initial 87Sr/86Sr versus 143Nd/144Nd ratios, and …

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U-Pb Zircon Shrimp Ages, Geochemical And Sr-Nd Isotopic Compositions Of The Early Cretaceous I-Type Sarıosman Pluton, Eastern Pontides, Ne Turkey, Abdullah Kaygusuz, Bin Chen, Zafer Aslan, Wolfgang Siebel, Cüneyt Şen Jan 2009

U-Pb Zircon Shrimp Ages, Geochemical And Sr-Nd Isotopic Compositions Of The Early Cretaceous I-Type Sarıosman Pluton, Eastern Pontides, Ne Turkey, Abdullah Kaygusuz, Bin Chen, Zafer Aslan, Wolfgang Siebel, Cüneyt Şen

Turkish Journal of Earth Sciences

The petrogenesis and U-Pb SHRIMP zircon ages of the Late Cretaceous Sarıosman pluton in the Eastern Pontides is investigated by means of whole-rock Sr-Nd isotope data with field, petrographic and whole-rock geochemical studies. The bulk of the I-type Sarıosman pluton consists of biotite-hornblende monzogranite, with minor quantities of porphyritic hornblende-biotite monzogranite. The biotite-hornblende monzogranite contains a number of mafic microgranular enclaves (MMEs) of quartz monzodiorite composition. U-Pb zircon sensitive high-resolution ion microprobe dating (SHRIMP) dates the magma emplacement age of the biotite-hornblende monzogranite at 82.7±1.5 Ma. The rocks of the pluton show high-K calc-alkaline, metaluminous to slightly peraluminous characteristics, and …

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Subduction-Related Eocene Shoshonites From The Cenozoic Urumieh-Dokhrat Magmatic Arc (Qaleh-Khargooshi Area, West Of The Yazd Province, Iran), Ghodrat Torabi Jan 2009

Subduction-Related Eocene Shoshonites From The Cenozoic Urumieh-Dokhrat Magmatic Arc (Qaleh-Khargooshi Area, West Of The Yazd Province, Iran), Ghodrat Torabi

Turkish Journal of Earth Sciences

The fifth phase of Eocene volcanism in the central part of the Urumieh-Dokhtar magmatic arc (UDMA), comprises lavas with shoshonitic characteristics, ranging from trachybasalt to trachydacite. In shoshonites of the Qaleh-Khargooshi area, leucite changes to analcime, analcime to albite, sanidine to albite and anorthoclase, and clinopyroxene to albite. These reactions, together with other field, petrographic and geochemical features, are evidence of an original absarokitic magma which was changing to generate the different rock units. The parental magma of these shoshonites was produced by a low degree of partial melting from a metasomatized enriched mantle source. During the ascent of shoshonitic …

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Provenance Studies Of Volcanic Clasts From The Santa Fe Group, San Luis Basin, Colorado: A Guide To Tectonic Evolution, Corine Kay Armstrong Jan 2009

Provenance Studies Of Volcanic Clasts From The Santa Fe Group, San Luis Basin, Colorado: A Guide To Tectonic Evolution, Corine Kay Armstrong

LSU Master's Theses

Volcanic clasts at the base of the Tertiary Santa Fe Group of the San Luis Basin (SLB), a major extensional feature of the northern Rio Grande Rift, provide evidence for the direction of sediment transport and timing of regional tectonic events. A combination of clast whole rock geochemistry (major and trace element), mineral chemistry (amphibole, biotite, pyroxene and feldspar) and geochronology (40Ar/39Ar of amphibole and biotite and U-Pb of zircons) is used to constrain the possible source scenarios. Several potential sources with requisite geochemical and geochronological information exist for the Santa Fe Group volcanic clasts including rocks from Spanish Peaks …

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Phytoplankton Productivity Across Prairie Saline Lakes Of The Great Plains (Usa): A Step Toward Deciphering Patterns Through Lake Classification Models, Courtney R. Sahm, Jasmine E. Saros, Sherilyn C. Fritz, Christopher L. Osburn, David M. Reineke Jan 2009

Phytoplankton Productivity Across Prairie Saline Lakes Of The Great Plains (Usa): A Step Toward Deciphering Patterns Through Lake Classification Models, Courtney R. Sahm, Jasmine E. Saros, Sherilyn C. Fritz, Christopher L. Osburn, David M. Reineke

Department of Earth and Atmospheric Sciences: Faculty Publications

Abstract: We investigated patterns of primary production across prairie saline lakes in the central and northern Great Plains of the United States. Based on comparative lake sampling in 2004, seasonal predictors of algal primary productivity were identified within subsets of similar lakes using a combination of Akaike's information criterion (AIC) and classification and regression trees (CART). These models indicated complex patterns of nutrient limitation by nitrogen (N), phosphorus (P), and iron (Fe) within different lake groups. Nutrient enrichment assays (control, + Fe, + N, + P, + N + P) were performed in spring and summer of 2006 to determine …

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Benthic Faunal Assemblages Of The Holocene Sediments From The Southwest Black Sea Shelf, Demet Ongan, Oya Algan, Sevi̇nç Kapan Yeşi̇lyurt, Ati̇ke Nazi̇k, Mustafa Ergi̇n, Christ Eastoe Jan 2009

Benthic Faunal Assemblages Of The Holocene Sediments From The Southwest Black Sea Shelf, Demet Ongan, Oya Algan, Sevi̇nç Kapan Yeşi̇lyurt, Ati̇ke Nazi̇k, Mustafa Ergi̇n, Christ Eastoe

Turkish Journal of Earth Sciences

Benthic faunal content (benthic foraminifera, mollusca and ostracoda) of sediment cores from the SW Black Sea shelf were examined. Based on the vertical distribution of abundance and diversity of the benthic fauna, three benthic assemblages were distinguished. These assemblages are BF1, BF2 and BF3, and reflect the changes in bottom water from the termination of the Neoeuxinian period to present. BF1 displays high abundance and diversity in the surroundings of the Bosporus channel, diminishing in the shelf sediments further away from the channel. In the Mid-Shelf and Outer Shelf, it displays low abundance and low diversity. BF1 which started to …

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Empirical Attenuation Relationships For Western Anatolia, Turkey, Ni̇hal Akyol, Özlem Karagöz Jan 2009

Empirical Attenuation Relationships For Western Anatolia, Turkey, Ni̇hal Akyol, Özlem Karagöz

Turkish Journal of Earth Sciences

Seismic hazard studies have become progressively more important for earthquake engineering applications in western Anatolia, which contains one of the world’s best examples of a rapidly extending intra-continental tectonic regime. A two-stage regression analysis was applied to peak ground acceleration and 5%-damped spectral acceleration values of 168 recordings from 49 earthquakes in order to develop empirical attenuation relationships which can be used to predict ground motion for western Anatolia. Moment magnitudes for earthquakes range between 4.0 and 6.4 while the hypocentral distances range between 15 and 200 km in our dataset. Site classifications, as one of the predictor variables for …

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Atmospheric Soluble Dust Records From A Tibetan Ice Core: Possible Climate Proxies And Teleconnection With The Pacific Decadal Oscillation, B. Grigholm, P. A. Mayewski, S. Kang, Y. Zhang, Susan Kaspari, S. B. Sneed, Q. Zhang Jan 2009

Atmospheric Soluble Dust Records From A Tibetan Ice Core: Possible Climate Proxies And Teleconnection With The Pacific Decadal Oscillation, B. Grigholm, P. A. Mayewski, S. Kang, Y. Zhang, Susan Kaspari, S. B. Sneed, Q. Zhang

Geological Sciences Faculty Scholarship

In autumn 2005, a joint expedition between the University of Maine and the Institute of Tibetan Plateau Research recovered three ice cores from Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m above sea level) on the northern side of Mt. Geladaindong, central Tibetan Plateau. Isotopes (δ18O), major soluble ions (Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−), and radionuclide (β‐activity) measurements from one of the cores revealed a 70‐year record (1935–2005). Statistical analysis of major ion time series suggests that atmospheric soluble …

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A Geochemical Paleoecological Analysis Of Miocene Mammalian Mega Fauna Of Fort Polk, Louisiana, Travis Lamar Atwood Jan 2009

A Geochemical Paleoecological Analysis Of Miocene Mammalian Mega Fauna Of Fort Polk, Louisiana, Travis Lamar Atwood

LSU Master's Theses

Through a combination of vertebrate paleontology and geochemistry much can be discovered about the environments about the past. Fort Polk’s vertebrate fossil sites are important because they reflect a time when the Antarctic ice cap was just beginning to form during the middle Miocene cooling period just after the middle Miocene Climatic Optimum (~15Ma). This study tested the hypothesis that Miocene seasonality will be preserved in the isotopic geochemistry of terrestrial vertebrate remains at central North American Gulf Coastal sites. Geochemistry was used to understand fossil diagenesis, faunal communities and paleoenvironments. Fort Polk, LA sites range in age from 13.5 …

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Remote Measurements Of Thundercloud Electrostatic Fields, Joseph R. Dwyer, Martin A. Uman, Hamid K. Rassoul Jan 2009

Remote Measurements Of Thundercloud Electrostatic Fields, Joseph R. Dwyer, Martin A. Uman, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

Analytical and numerical models of the radio frequency emissions produced by relativistic runaway electron avalanches initiated by cosmic ray extensive air showers are presented. It is found that single-point measurements of the distant electromagnetic fields allow the remote determination of the electrostatic field in the runaway electron avalanche region. For instance, it is possible to use ground-based and/or remote airborne measurements of the radio frequency pulses from the runaway electron avalanches to map the magnitudes and directions of the electrostatic field within a thundercloud for regions with electric fields above the runaway avalanche threshold. Such measurements, which are difficult to …

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Biogenic Tracers Through The Holocene On The Alaskan Shelf, Carie A. Curry Jan 2009

Biogenic Tracers Through The Holocene On The Alaskan Shelf, Carie A. Curry

OES Theses and Dissertations

Dramatic environmental changes in the Arctic Ocean have been observed for the last two decades including changing the amount of sea ice thickness and extent, and increased river discharge. In order to put these and other current day observations into historical context and perhaps reveal mechanisms controlling them, a suite of paleo-proxies were used to analyze two high resolution cores collected on the 2005 HOTRAX expedition. The goals of this research were: (1) develop an analytical method for determining biogenic calcite, (2) identify the major sources of biogenic matter into the system over the Holocene, and (3) assemble the history …

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Do Laminated Sediment-Gravity-Flow Deposits On The Antarctic Peninsula Continental Shelf Record Ice Sheet Grounding Events?, Vincent Clyde Adams Jan 2009

Do Laminated Sediment-Gravity-Flow Deposits On The Antarctic Peninsula Continental Shelf Record Ice Sheet Grounding Events?, Vincent Clyde Adams

LSU Master's Theses

Barker and Camerlenghi (2002) proposed that drifts on the continental rise of the Antarctic Peninsula may record a high-resolution record of ice-sheet expansions on the adjacent continental shelf. In their view, laminated sediments were deposited during glacial periods, whereas during interglacial periods, sediment supply to drifts was negligible. As a consequence of low sediment supply, the tops of laminated sequences were bioturbated. Therefore, a bioturbated-laiminated couplet should represent a complete glacial cycle. Bioturbated and laminated (B-L) sediment couplets were compiled from cores at two drift sites obtained from Ocean Drilling Program (ODP) Leg 178 Sites 1095, 1096, and 1101. If …

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Role Of Shelf Morphology In Grounding-Line Stability: A Numerical Approach, Rhonika Robinson Jan 2009

Role Of Shelf Morphology In Grounding-Line Stability: A Numerical Approach, Rhonika Robinson

LSU Master's Theses

The main concern of this study is to discover how the transition from a shallow to an overdeepened, foredeepened shelf might affect grounding-line translation of the West Antarctic Ice Sheet (WAIS). Deep shelves permit a larger influx of relatively warm Circumpolar Deep Water (CDW), which melts the ice at grounding lines, and thereby, create a potentially unstable situation in which ice retreat may accelerate. Numerical analysis of the responses of marine ice sheets on various shelf profiles confirmed that a change in shelf morphology changes ice sheet dynamics. Ice sheet retreat on an overdeepened, foredeepened shelf is, at least, 3 …

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Glacial Deposits, Vol. 37, 2008-2009, Department Of Geography-Geology Jan 2009

Glacial Deposits, Vol. 37, 2008-2009, Department Of Geography-Geology

Glacial Deposits

Newsletter of the Department of Geography-Geology

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Holocene Evolution And Avulsion History Of The Lower Mississippi River, Yazoo Basin, Ms, Eric Prokocki Jan 2009

Holocene Evolution And Avulsion History Of The Lower Mississippi River, Yazoo Basin, Ms, Eric Prokocki

LSU Master's Theses

Optically stimulated luminescence dates coupled with paleohydrological estimations from lower Mississippi River (LMR) meander belts within the Yazoo Basin, MS provide new insight into the geochronological and hydrologic history of the LMR throughout the Holocene period. According to OSL dates, there are only three temporally equivalent LMR meandering river regime sediment packages, and not five as previously assumed from past geochronological research initiatives within the lower Mississippi Valley (LMV). The three geochronological sediment packages from oldest to youngest are thus represented by the following LMR meander belts: Early Holocene Chronostratigraphic Package – ca. 9.19 to 8.07 ka represented by the …

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Environmental Influences On The Mobility And Speciation Of Arsenic In The Geothermal Waters Of El Tatio Geyser Field, Chile, Lindsey R. Johnson Jan 2009

Environmental Influences On The Mobility And Speciation Of Arsenic In The Geothermal Waters Of El Tatio Geyser Field, Chile, Lindsey R. Johnson

LSU Master's Theses

El Tatio geyser field, northern Chile, impacts regional water quality, policy, and agricultural commerce due to the geothermal waters containing high concentrations of naturally-occurring arsenic (As). In the circumneutral pH, non-sulfidic thermal waters at El Tatio, dissolved arsenite [As(III)] dominates geyser discharge water upstream, but dissolved arsenate [As(V)] dominates downstream. Microbial mats and sediments were analyzed for changes in As speciation using X-ray spectroscopy methods, such as XANES and EXAFS at both the As and Fe K-edges, combined with ATR-FTIR spectroscopy and molecular genetics, to understand As cycling. The sediments and microbial mats were dominated by As(V) speciated as both …

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Source(S) Of Salinity In The Mississippi River Alluvial Aquifer, Iberville Parish, Louisiana, Stephanie Erin Welch Jan 2009

Source(S) Of Salinity In The Mississippi River Alluvial Aquifer, Iberville Parish, Louisiana, Stephanie Erin Welch

LSU Master's Theses

The Mississippi River Alluvial Aquifer extends from Southern Illinois to the mouth of the Mississippi and is comprised of fluvial sands and gravels of Late Pleistocene age. Several areas of the aquifer in Arkansas, Mississippi, and Louisiana are affected by elevated levels of salinity. One such area occurs in Iberville Parish, LA, where the aquifer is 150-240 m in thickness and is capped by 23-38 m of clay. Recharge of the aquifer from the Mississippi River on the east is fresh, but salinity is high in the western portions of the aquifer and chloride levels are as high as 1,000 …

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Calculating The Volume Of The May 18, 1980 Eruption Of Mount St. Helens, Dâvid Nuñez Wickham Jan 2009

Calculating The Volume Of The May 18, 1980 Eruption Of Mount St. Helens, Dâvid Nuñez Wickham

Environmental Science and Management Professional Master's Project Reports

The May 18, 1980 eruption of Mount St. Helens created a massive amount of sediment and debris, thought to be as much as 5.5 billion cubic yards. This sediment causes infill of river stretches and collects along levees protecting southwest Washington State. The sediment must be removed to ensure these areas do not flood. The US Army Corps of Engineers (USACOE) is tasked with flood protection for southwest Washington State and the levees protecting the cities of Castle Rock, Lexington, Kelso, and Longview. The Sediment Retention Dam, opened in 1989 is able to filter out larger particulate but fine grain …

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Setting Targets For Resource Condition In Yilliminning Catchment, Leon Van Wyk, Gregory Paul Raper Jan 2009

Setting Targets For Resource Condition In Yilliminning Catchment, Leon Van Wyk, Gregory Paul Raper

Resource management technical reports

No abstract provided.

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Does The Mg/Ca In Foraminifera Tests Provide A Reliable Temperature Proxy?, Sarah Clark, Figen Mekik Jan 2009

Does The Mg/Ca In Foraminifera Tests Provide A Reliable Temperature Proxy?, Sarah Clark, Figen Mekik

Student Summer Scholars Manuscripts

The Mg/Ca in foraminifera shells is commonly used as a proxy to estimate ocean temperatures in Earth’s past. However, studies have shown that both dissolution and salinity influence the Mg/Ca in shells of tropical foraminifera, which can cause paleotemperature estimates to be inaccurate. We measured Mg/Ca in shells of Globigernoides ruber and Globigerinoides sacculifer from core tops in the eastern equatorial Pacific. We compared our results with global core top data, which paleotemperature equations have been calibrated and published. We find that Mg/Ca values range greatly at the same surface ocean temperature. We also find that salinity and dissolution do …

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The ‘Benchmark Glacier’ Concept – Does It Work? Lessons From The North Cascade Range, Usa, Andrew G. Fountain, Matthew J. Hoffman, Frank Granshaw, Jon L. Riedel Jan 2009

The ‘Benchmark Glacier’ Concept – Does It Work? Lessons From The North Cascade Range, Usa, Andrew G. Fountain, Matthew J. Hoffman, Frank Granshaw, Jon L. Riedel

Geology Faculty Publications and Presentations

Benchmark glaciers were established in many alpine areas during the 1960s as part of the International Hydrological Decade to represent ‘typical’ mass and energy processes on glaciers in different climatic regions around the world. These glaciers have received new interest in the past decade because they are used to infer the contribution of alpine glacier wastage to global sea-level rise. We compare South Cascade Glacier, the benchmark glacier for the northwest contiguous USA, and four other secondary glaciers, against the topographic, area and mass changes of 321 glaciers in the surrounding region. Results show that South Cascade Glacier is unusually …

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Crustal Modification By Tectonic Events And Upper Mantle Anisotropy Beneath The Midcontinent Rift And New Madrid Seismic Zone: Insights From Receiver Function Studies And Teleseismic Shear Wave Splitting, Moikwathai Moidaki Jan 2009

Crustal Modification By Tectonic Events And Upper Mantle Anisotropy Beneath The Midcontinent Rift And New Madrid Seismic Zone: Insights From Receiver Function Studies And Teleseismic Shear Wave Splitting, Moikwathai Moidaki

Doctoral Dissertations

"The earth's crust and upper mantle have been continually modified by tectonic processes such as rifting, earthquake activity. In this dissertation, shear wave splitting and receiver function techniques were employed to study the extent of crustal and upper mantle modifications beneath the New Madrid Seismic Zone (NMSZ) and the Midcontinent Rift (MCR). Shear wave splitting analysis in the MCR reveals the presence of fossilised anisotropy along the rift axis...In the NMSZ, anticipated rift-parallel fast directions associated with vertical magmatic dikes or along-rift flow, rift-orthogonal fast directions from small-scale convection, or reduction in splitting times as a result of vertical asthenospheric …

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Desert Varnish As An Indicator Of Modern-Day Air Pollution In Southern Nevada, Piotr Nowinski Jan 2009

Desert Varnish As An Indicator Of Modern-Day Air Pollution In Southern Nevada, Piotr Nowinski

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rock varnish, often called desert varnish, is a slow-growing, manganese-rich coating that accumulates on exposed rock surfaces. The mechanism of varnish formation is not fully understood, however, most authors agree that varnishes derive their components from the atmosphere. The main goal of this study was to demonstrate the potential use of desert varnish as a passive environmental monitor of present and past atmospheric pollution. Analysis of varnishes is a new field that can potentially provide records of pre-anthropogenic levels of atmospheric metals and other environmental pollutants. To evaluate the potential of desert varnish as an environmental monitoring tool, the following …

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Measuring The Permeability Of Open-Framework Gravel, James Thomas Ferreira Jr. Jan 2009

Measuring The Permeability Of Open-Framework Gravel, James Thomas Ferreira Jr.

Browse all Theses and Dissertations

Open-framework gravel has permeability, k, above the measurement range of most conventional constant-head permeameters used in laboratories. Here I addressed the challenge of measuring such high k by using a permeameter long enough that the differences in head across it were on the order of 10-3 m and therefore measurable. I collected data over the range from linear-laminar flow to non-linear, non-Darcian flow. In doing so, I verified that k was measured under Darcian flow. I measured k between 4,000 and 100,000 Darcies among experiments using different sediments.

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Bench-Scale Conversion Of Carbon Dioxide To A Hydrocarbon Fuel, Melissa L. Kennedy Jan 2009

Bench-Scale Conversion Of Carbon Dioxide To A Hydrocarbon Fuel, Melissa L. Kennedy

Browse all Theses and Dissertations

There is a growing concern about the effects of global warming that many believe is anthropogenically caused. As such, scientists are trying to uncover a viable alternative fuel source and establish a way to reduce atmospheric carbon dioxide levels. A potential solution that addresses both of these aspects would be to capture atmospheric carbon dioxide and convert it into a natural gas, in particular methane, which could be used as an energy source. A laboratory-scale experiment using 6 160 mL microcosms (3 with anaerobic wetland soil and 3 relatively soil free) and 2 7.2 L bioreactors was conducted to learn …

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A Morphometric Analysis Of The Highly Variable Clypeasteroid, Periarchus Lyelli, Lauren Elizabeth Williamson Jan 2009

A Morphometric Analysis Of The Highly Variable Clypeasteroid, Periarchus Lyelli, Lauren Elizabeth Williamson

Browse all Theses and Dissertations

The Late Eocene echinoid, Periarchus lyelli (Conrad, 1834), known for its wide geographic range, high abundance, and specific stratigraphic range, is an ideal example of a guide fossil. However, due to its highly variable test morphology, many have questioned if, in fact, this sand dollar is actually two or three distinct species that have been misclassified. A preliminary study on this subject has been performed on specimens from Mississippi, North Carolina and South Carolina (Williamson, 2006), showing significant separation in test shapes. Continuing previous research, this study analyzes the test shapes of P. lyelli over its entire North American geographic …

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