http://hdl.handle.net/1811/5840 2013-05-21T16:41:28Z http://hdl.handle.net/1811/52989 Dissolved Organic Matter Contains Previously Unidentified Protein-like Fluorophores in Old Woman Creek Perez, Victor Jr Dissolved organic matter (DOM) constitutes a significant carbon pool in the global carbon cycle and is influential in many other processes e.g., altering the fate of contaminants, acting as redox and pH buffers, etc. The ubiquitous dispersal of DOM in the aqueous environment originates from sources ranging from autochthonous (microbial) to allochthonous (terrestrial) precursors. The source of the DOM dictates its composition, which in turn impacts its reactivity in the environment. The isolation of DOM from natural waters is a common practice to preserve and concentrate DOM, yet the extraction method may significantly alter its composition. This study explores the characteristics of DOM collected from Old Woman Creek (OWC) National Estuarine Research Reserve, located in Huron, Ohio, isolated using PPL solid phase extraction (SPE). Previous DOM extraction methods such as C-18 or XAD-8 are limited to hydrophobic compounds, while the novel PPL SPE cartridges capture more polar and non-polar components. PPL and previously collected XAD-8 isolated OWC DOM was characterized using fluorescence spectroscopy. Fluorescence analysis revealed protein-like components not present in previously collected XAD-8 isolated OWC DOM, demonstrating the significance of extraction method on the composition and potential reactivity of isolated DOM. 2012-01-01T00:00:00Z Perez, Victor Jr http://hdl.handle.net/1811/52963 CO2 Sequestration Capabilities of Upper Cambrian-Lower Ordovician Formations in Southern Ohio Hull, Brad Carbon dioxide sequestration into porous rock intervals beneath the Earth’s surface is an emerging technique of reducing the amounts gaseous CO2 emitted by energy production through the burning of coal/peat. Target intervals of rock must have sufficient pore space, permeability, thickness, depth from the surface, and must be located beneath an impermeable geologic seal to serve as a reservoir for the sequestration of supercritical CO2. The Upper Cambrian-Early Ordovician Knox Supergroup including the Copper Ridge Dolomite, Rose Run Sandstone, and Beekmantown Dolomite formations found within the Aristech Well in Scioto County, Ohio may have all the necessary requirements to serve as a viable combination of CO2 reservoir and geologic seal. This research seeks to characterize samples drawn from these formations on the basis of petrography, porosity, pore size and distribution, permeability, bulk mineralogy, and brine chemistry to distinguish suitable sequestration horizons in conjunction with an overlying caprock. Light microscopy, scanning electron microscopy, mercury porosimetry, and x-ray diffraction analyses established a porous and permeable reservoir interval including the upper Copper Ridge and entire Rose Run overlain by the impermeable Beekmantown Dolomite. The Rose Run Sandstone was the most favorable for CO2 storage, while vertical heterogeneity within the Copper Ridge Dolomite limited the reservoir thickness. Porosity measurements for the reservoir were between 3 and 8%, permeability was 16-50 mDarcies, while the caprock porosity was 1% and permeability of 7 mDarcies. Porosity and pore size distribution between and within samples is controlled by mineralogy, mineral nucleation, diagenesis, and heterogeneity. Volumetric estimations show that the Copper Ridge/Rose Run reservoir could hold up to 5.6 million metric tonnes of supercritical CO2 under the most favorable conditions. 2012-01-01T00:00:00Z Hull, Brad http://hdl.handle.net/1811/52928 The effect of repeat bleaching on stable C and N isotopes in the Caribbean coral Porites astreoides Scheuermann, Jordan 2012-01-01T00:00:00Z Scheuermann, Jordan http://hdl.handle.net/1811/52921 Characterization of mineralization in sediments around potential methane hydrate fractures. Buchwalter, Edwin Methane hydrates are a frozen mixture of natural gas and water which remain stable in sea floor sediment. In the future these could become a valuable source of energy however with current technology extraction is impractical. I believe that the hydrates change the sediment surrounding them both physically and chemically, potentially altering mineral makeup. This experiment used X-ray Computed Tomography (XCT) to measure density differences within the core, allowing me to interpret the mineralization of the sediment from hole KC 151 in the Gulf of Mexico. The initial results do show promise as the segment of core which is believed to have contain a methane hydrate fracture shows a significantly greater amount of pyrite (5.5% for 17H-4 versus .7% for 8C-1) than the sediments higher up in the core where there is little evidence for hydrates. An unexpected find was a change in the pyrite formation, with 8C-1 showing round pyrite nodules while 17H-4 shows pyrite forming in the bioturbation. Though promising, more research will be conducted on total organic carbon (TOC) and the physical evidence left behind by evaporating hydrates. 2012-01-01T00:00:00Z Buchwalter, Edwin http://hdl.handle.net/1811/52919 Microevolutionary Response in Lower Mississippian Camerate Crinoids to Predatory Pressures Thompson, Jeffrey Crinoids were relatively unaffected by the end-Devonian Hangenberg event, but the major clades of Devonian durophagous fishes suffered significant extinctions. These dominant Devonian fishes were biting or nipping predators. In response to the Hangenberg event, Lower Mississippian crinoids underwent an adaptive radiation, while fish clades with a shell-crushing durophagous strategy emerged. Durophagous predators were more effective predators on camerate crinoids and it is hypothesized that through the Lower Mississippian, camerate crinoids evolved more effective anti-predatory strategies in order to compensate for the more effective predatory strategy of the durophagous fishes. More convex plates and longer spines are commonly regarded to provide more effective anti-predatory strategies. Did convexity and spinosity increase among camerate crinoids during the Lower Mississippian? A new method was formulated to test for an increase in convexity of the calyx plates among species of 2 different genera, Agaricocrinus and Aorocrinus. Spine length was analyzed in the genus Dorycrinus and was a simple linear measurement. Data are analyzed using a runs test to determine if morphological change is statistically significant of represents a random walk. Change in plate convexity and spine length in different species is representative of microevolutionary change as new species evolve to changing ecological conditions. 2012-01-01T00:00:00Z Thompson, Jeffrey http://hdl.handle.net/1811/52906 Insights on Induced Seismicity in Ohio from the Youngstown M4.0 Earthquake Mills, Jacqueline A. Hydraulic fracturing (fracking) is the process in which a solution, consisting of sediments and chemicals, is injected below the crustal surface at high pressures to break up rock and enhance natural gas and oil production. This process produces waste water, which is then injected deep into the earth’s crust for disposal. The deep injection well in Youngstown, Ohio became operational in January 2011 and just three months later, the first induced earthquakes occurred. After the 10th earthquake in a matter of months, the well was voluntarily shut down. The shutdown was followed days later with a magnitude 4.0 earthquake. Researching the correlation between deep well injections and the earthquakes can help us better understand not only how but where the ground is fracturing. By bringing attention to these faults, we can avoid placing deep injection wells around them to limit induced seismicity. This can also help us learn how to better utilize the Ohio’s subsurface for deep well injection and storage. Research was completed through studying Ohio’s geological history, the stratigraphy of eastern Ohio, and articles collected from newspapers and the scientific literature on the geology of Youngstown and its utility for deep well injection and storage. 2012-01-01T00:00:00Z Mills, Jacqueline A. http://hdl.handle.net/1811/52889 Gradient analysis for fault detection in the Rome Trough Phillips, Zachary Faulting in the formations that make up the Rome trough beneath Southeastern Ohio and Eastern Kentucky was caused by the mountain building processes uplifting the Appalachian Mountains. Though generally inactive at present, these faults reflect zones of weakness within the basement rocks activated by current crustal stresses. With the increase in subsurface engineering in Ohio and Kentucky, the detailed structure of rock units is becoming more important for aspects of oil and gas migration and recovery, CO2 sequestration, and waste injection. Knowing the position of faults allows engineers to better estimate pathways for subsurface fluid and gas migration. It is also important for scientists and engineers to understand the fault structures in order to pinpoint earthquake epicenters and plan for earthquake hazards. For example, injecting waste near a fault may cause the triggering of an earthquake due to the lubrication of a fault surface. The basement faults mapped within Ohio and the surrounding states are poorly understood (Hansen 2012). The purpose of this research is to develop a more detailed view of fault structures from available sedimentary isopach and structure data using the grid manipulation software known as Mirone. Mirone is an in-depth grid operation and analysis program with the capability of taking the gradients of gridded isopach and structural data. This isolates the areas of the largest offset in the dataset and after adjusting the color palette the faults show up as lines in the dataset. These data will be useful for anyone in need of a comprehensive view of the structures found in the Rome trough. Future work will include the 3-dimensional mapping of Rome trough faults to better demonstrate the detail and nature of the faulting and bedding planes involved. 2012-01-01T00:00:00Z Phillips, Zachary http://hdl.handle.net/1811/52882 Carbon in watershed bedrock and its importance in global carbon cycling Clendenin, Chad Over geologic timescales, weathering of silicate rocks plays a significant role in the regulation of atmospheric carbon dioxide and thereby global climate. The Sierra de las Minas of Guatemala, my study area, has high physical erosion, frequently occurring from landslides. This erosion increases water throughflow and water contact with fresh mineral surfaces, which in turn may increase chemical weathering in the region. Carbonation, the mode of chemical weathering of particular interest to this study, involves dissolution of atmospheric carbon dioxide by rain water, forming soluble carbonates. My study aims to describe components of an important process in the carbon cycle, and to contribute to a better understanding of the functions and interactions of Earth systems. Shale samples which had undergone various degrees of weathering, collected from streambeds and outcrops of watersheds in the region, have been analyzed for total inorganic and organic carbon (TOC) to quantify and distinguish carbon derived from decomposition of living organisms and the carbonation weathering process. Samples were also analyzed for major, minor and trace elements by X-Ray Fluorescence Spectrometry to determine the elemental composition of the rocks, indicating the lithology of the weatherable rocks in the region. TOC levels range 1.8-5% and 1-4% for TIC. 2012-01-01T00:00:00Z Clendenin, Chad http://hdl.handle.net/1811/52881 Evaluating Anthropogenic Impact on Water Quality of Ohio Rivers Over Time Dailey, Kelsey Many natural and anthropogenic factors affect the geochemistry of surface waters like rivers and streams in rural and urban areas. Much impact on fresh water in the United States comes from non-point sources, with population and land use playing an important role. Major components of input into surface waters are chloride and sodium, derived mostly from urban contributions such as road salt, and nitrate, largely from agricultural sources like fertilizers, as well as the burning of fossil fuels. Fresh water quality historical data exists for many Ohio rivers, however much of it has never been further utilized to observe ion concentration trends over past decades. I have tabulated past data from state and federal sources such as USGS and data from Dr. Lyon’s research group from the 2000’s to identify long-term trends in ion concentrations in rivers at multiple locations throughout the greater Columbus area. In June, I sampled the same sites examined in the past and analyzed the filtered samples for major ions and nutrients. By comparing the summer 2012 samples to those from same sites in the past, the magnitude of the effects of urban and rural contributions on surface runoff and fresh water quality will be determined. 2012-01-01T00:00:00Z Dailey, Kelsey http://hdl.handle.net/1811/52880 Ecosystem Dynamics in an Extreme Environment: Lake Fryxell, Taylor Valley, Antarctica. Rytel, Alex The McMurdo Dry Valleys of Antarctica constitute a large and significantly ice free area of Antarctica at 78 degrees south latitude. Over the past 19 years data have been gathered on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Valley Long-Term Ecological Research program (MCM-LTER). This study is part of a larger study that seeks to understand the impact of climate on the biological processes in all the ecosystems within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are permanently covered with ice. The work presented here focuses on one of the three main lakes in Taylor Valley, Lake Fryxell, which is fed by 13 streams. We use a statistical approach to link the physical, chemical, and biological processes within the lake and the streams that feed it. In our statistical approach we use light, phosphorus, nitrogen, and other lake parameters as explanatory variables for biological production and biomass profiles, and attempt to link the physiochemical properties of the lake to biological changes within the lake. 2012-01-01T00:00:00Z Rytel, Alex http://hdl.handle.net/1811/52879 Go East Young Man: Trends in the Ohio Utica Shale Harrington, Jake The recent shale gas boom has brought much attention to Ohio because of its location above the Utica Shale, an Ordovician age rock formation that acts as both a source rock and reservoir rock for large amounts of hydrocarbons. Gas exploration is recent so minimal information is currently available to the scientific community. The goal of this research project is to measure the mineralogy and total organic carbon (TOC) of Utica Shale samples and to determine the relationships among these data with depth and east-west location. The mineralogical analysis focuses on the amount of clay minerals with respect to non-clay minerals. During hydraulic fracturing, rock must break cleanly to release hydrocarbons. Clays do not fracture in such an orderly way, complicating extraction. X-ray diffraction of randomly-oriented powder samples is employed to determine the qualitative and quantitative mineralogies. TOC is measured using an elemental analyzer after treating each sample with acid to dissolve inorganic carbon. Results are expected to show a correlation between TOC and clay content and an east to west pattern. This information could help locate drilling sites and lead to newly discovered shale gas plays. 2012-01-01T00:00:00Z Harrington, Jake http://hdl.handle.net/1811/52878 An Inquiry Into the Evolution and Sediments of Caves Along the Scioto River Parker, Eric Cave passages and the sediments contained in them often preserve large scale climate changes. The major rivers and tributaries in the Columbus area served as outlets for glacial melt waters. The down cutting of these rivers led to the formation of a phreatic to vadose transition in numerous local caves. There were two components to the research: Collection of sediment samples and searches of the surrounding area for clues to explain the caves’ evolution. Samples were collected in two major ways. The first, involved extracting surface sediment from caves with a rock hammer. The second employed a manual corer to extract deeper layers of sediment whenever possible. After collection, images of the samples were recorded to scale using a light station and camera. Many aspects of the caves were discovered, including that the parallel sets of caves on the banks were likely bisected by the river / stream. The sediment from the caves is a fine, clay-based mixture with some larger grains intermixed. Unfortunately, this composition is incompatible with the planned sieve analyses. Further research will explore the changes in spring locations along the Scioto River over time and analyze pollen and carbon data from new sediment samples. 2012-01-01T00:00:00Z Parker, Eric http://hdl.handle.net/1811/52877 Proving it Works: Fluid Viscosity Verification in a Diamond Anvil Cell Eymold, William 2012-01-01T00:00:00Z Eymold, William http://hdl.handle.net/1811/38964 High Impact Earthquake Risk in the Greater Cleveland, Ohio Area Saddler, David 2009-01-01T00:00:00Z Saddler, David http://hdl.handle.net/1811/38963 Discharge of the Congo River Estimated from Satellite Measurements Schaller, Lisa Although Central Africa’s Congo River is the world’s second largest river based on drainage area and discharge; little in-situ hydrologic data has been collected from this area. This lack of data limits our understanding of the water cycle throughout the region. The region receives significant rainfall on both sides of the equator at different times of the year, due to the annual south-north migration of the Intertropical Convergence Zone (ITCZ, a low-pressure zone around the equator which leads to heavy precipitation). Many satellite missions have been launched that image the earth using visible band frequencies or radar technologies (e.g., LandSat and various SAR missions, respectively), but none are specifically designed to measure surface water variables such as river discharge and changes in lake storage. Our objective is to determine the discharge of the Congo River and several of its largest tributaries (Sangha, Ubangi, Aruwimi, Tshuapa, Kasai), using only remotely sensed data. We use remote sensing data from these various satellite missions for measurements of channel width, length and water surface elevation. Data sets showing open water in channels (the JERS-1 SAR data from the Global Rain Forest Mapping project, or GRFM) are combined with data sets showing water surface elevation (Shuttle Radar Topography Mission, or SRTM) to determine the slope of the water surface. By using measurements of width, estimates of depth can be approximated by noting that discharge in short reaches should remain constant and thus width variations can indicate depth variations. Manning’s n is estimated within reasonable bounds for rivers having cohesive sediments along their banks. These variables are combined utilizing Manning’s Equation to estimate the discharge of the river. We calculate slope for 100's of kilometer long reaches by fitting polynomials to SRTM derived water surface heights and their respective flow distances. Our results show discharge variations of various tributaries and the Congo main stem for February 2000, the time of the SRTM overpasses. 2009-01-01T00:00:00Z Schaller, Lisa http://hdl.handle.net/1811/38952 Environmental Assessment of Industrial (Mine) Tailing Migration and Reclamation Tactics, Cobalt, Ontario McCarthy, Ashley Starting in 1904 through the mid 1930’s, Cobalt’s mines and mills operated continuously. From then until 1989, operations were intermittent. Mining practices predating the 1930’s left significant pollution. Evident as; historic remnant mine workings, waste rock piles, and tailings ponds. Within the Cobalt mining camp, we must familiarize ourselves with the geomorphic setting to proper facilitate the rehabilitation of the tailings as well as the environment. Cobalt’s mining legacy has taught us how arsenic has poisoned the landscape, but what is there to learn from this, and how can we revitalize Ontario’s most historic City. 2009-01-01T00:00:00Z McCarthy, Ashley http://hdl.handle.net/1811/38951 Potential Risk of High Magnitude Earthquakes in the Western Ohio Seismic Zone Verdibello, Steven 2009-01-01T00:00:00Z Verdibello, Steven http://hdl.handle.net/1811/38948 Carbon Sequestration: Super Critical CO2’s effect on subsurface brines in the Illinois Basin Blake, Daniel The impact of CO2 on global warming has become a reality and major CO2 producers must take steps to address a 40% increase in concentration that has occurred globally since the early 1800’s. This study looked at the relationship between supercritical CO2 and sandstone reservoirs in the Illinois Basin. Specifically the Mt. Simon and St. Peter sandstone were studied and their characteristics were compared to data collected in the Tough-React model (Xu) response for a normalized sandstone. The data compared showed that with an increase in depth, the ion concentration increases allowing for more secondary mineralization to occur along with the formation of clays. Major minerals are present in both the Mt. Simon and St. Peter that raise concerns for sequestering CO2. 2009-01-01T00:00:00Z Blake, Daniel http://hdl.handle.net/1811/38944 Mantle Origin of Oceanic Carbonatites Hulett, Sam The goal of this research was to determine the mantle origin of oceanic carbonatites through the analysis of stable and radiogenic isotopes. This was also compared to rift carbonatites and kimberlites to see if there is a correlation in the isotope configurations pointing to a similar mantle origin. 2009-01-01T00:00:00Z Hulett, Sam http://hdl.handle.net/1811/38943 Urban Runoff in Dry Run, Scioto Watershed, Ohio Burns, Patrick 2009-01-01T00:00:00Z Burns, Patrick http://hdl.handle.net/1811/34930 Lithology, mineralogy and chemical weathering of volcanic rocks from Panama Dugan, Matthew R. H.; Carey, Anne E.; Goldsmith, Steven T. 2008-09-18T00:00:00Z Dugan, Matthew R. H. Carey, Anne E. Goldsmith, Steven T. http://hdl.handle.net/1811/34825 A Geostatistical Analysis of the Major Controlling Factors Affecting Stream Geochemistry in Taylor Valley, Antarctica Whisner, Carla; Lyons, W. Berry In Taylor Valley, Antarctica, there are three closed-basin lakes that each have different chemistries. One lake is fresh (Lake Hoare), one is brackish (Lake Fryxell), and the other is hyper-saline (Lake Bonney). The fact that these ice covered lakes are of various ages and have been subjected to different histories, supports their chemical diversity. This study focused on another contributing factor to differences in lake chemistry, which is the source of the solutes from the streams. The streams come from glacial meltwater. These freshwater streams accumulate and transport ions, nutrients, and biomass as they flow during the austral summer. This creates a certain “fingerprint” for each stream. The goal of this study was to discern between the stream chemistry variance and find trends associated with these differences. I expected to see an east-west trend because the eastern side of Taylor Valley has younger soils. To demonstrate my results, I used chloride, alkalinity, nitrate and soluble reactive phosphorus (SRP). Chloride is an excellent tracer because it is conservative. Alkalinity represents weathering of carbonates and silicates. N and P are essential nutrients for plant life and assist in explaining the algal mat distribution. Landscape position and age, the presence and absence of algal mats, and stream length had most significant impact on stream chemistry. 2008-09-18T00:00:00Z Whisner, Carla Lyons, W. Berry http://hdl.handle.net/1811/34816 The Stability of RbAlSi3O8 Under High Pressure Conditions Hyung, Eugenia; Whitaker, S. A. R. A.; Panero, Wendy R. Potassium and Rubidium are minor and trace elements of the Earth’s mantle, both of which have long-lived radioactive isotopes. 40K is a significant energy source that contributes to the convection of the mantle and outer core, while 87Rb is a geochemical tracer for long-lived mantle processes. In the Earth’s crust, K and Rb are stored in feldspar, KAlSi3O8, the most abundant mineral in the crust. The mineral host of K and Rb in the mantle is uncertain, with implications on reactivity of alkali metals with the Earth’s core. Sample preparation consisted of compressing RbAlSi3O8, Rubidium microcline (rubicline), under pressures of ~15 GPa (gigapascals) in a laser-heated diamond anvil cell (LHDAC). Synchrotron-based x-ray diffraction gives the structure and density at high pressures. The high-pressure structure of Rubidium microcline is similar to that of the high-pressure structure of feldspar, transforming to the hollandite structure at ~15 GPa, then to the hollandite II structure at ~25 GPa. Preliminary results yield the bulk modulus of Rubidium hollandite to be 210 (±10) GPa. 2008-09-18T00:00:00Z Hyung, Eugenia Whitaker, S. A. R. A. Panero, Wendy R. http://hdl.handle.net/1811/34815 Crustal Shortening Rates in Correlation to Structural Geology in the Sub-Andean Zone of Bolivia Judy, K.; Bevis, Michael The fold and thrust belt of the Bolivian Sub-Andes has been a topic of much discussion and debate for the past twenty years. Varying ideas regarding the Sub-Andean zone (SAZ) structural geology have been published, documenting conflicting ideas on the evolution of this complex region. Variations in balanced cross-sections result in a wide range of shortening estimates, thus highlighting the need for accuracy and precision when constructing balanced cross-sections. 2008-09-18T00:00:00Z Judy, K. Bevis, Michael http://hdl.handle.net/1811/34814 Chemical Weathering Soil Profiles of the Rio Chagres Watershed Hannah, Lindsey; Lyons, W. Berry; Goldsmith, Steve Chemical weathering is a major process in the development and resultant bulk chemistry of soils, yet little research has been done in moist tropical climates investigating the relationship between the chemistry of soil and extent of weathering as related to depth. For this research project, two sample soil pits were dug in the Rio Chagres watershed in central Panama, and 13 samples from each soil pit were collected at approximately 12 cm increments from surface to close to bedrock. The soil pits were located directly above a gabbro and a greenstone, two of the dominate lithologies of the basin. Analysis for this research project was done by grain size and carbon and nitrogen analysis, and by use of X-ray fluorescence spectrometry (XRF) to measure major and trace elements present. Calculation of the Chemical Index of Alteration (CIA) and Vogt’s index of weathering (V) were also completed to evaluate degree of weathering as related to depth to establish an accurate weathering profile for each pit. In Pit 1, located above the gabbro, grain size decreases and weathering index increases with depth, suggesting a greater influence of subsurface groundwater during weathering. In pit 9, located above the greenstone, grain size fluctuates with depth and is overall more course than in pit 1, and the weathering index is highest at the surface and decreases with depth. This represents a more traditional and expected weathering profile, with the greatest weathering occurring at the surface. Future research is needed to provide a more continuous data set as well as information on trace element behavior in these profiles. 2008-09-18T00:00:00Z Hannah, Lindsey Lyons, W. Berry Goldsmith, Steve http://hdl.handle.net/1811/34813 Enigmatic Sea Floor Mounds in Antarctica--analysis of bathymetry data from geophysical cruise NBP04-01 Magee, W. R.; Wilson, T. J. As part of the 2004 Nathaniel B. Palmer-0401 geophysical cruise, a structural geology enigma was identified on the Ross Sea floor off the Antarctica coast. Using multibeam bathymetry, a series of eight mysterious, “pepperoni-shaped” mounds were identified on the sea floor. My research entails the morphological study of these structures and the determination of their relationship to either nearby volcanism or subglacial features. Through the use of the IVS-Fledermaus© software program, bathymetric data obtained from the cruise was projected in a 3-dimensional model. Morphological data from the seafloor hills is compared to the attributes of glacial drumlins and volcanic tuya. Future work will include adding seismic and magnetic profiles of the area to the 3D model to constrain their composition and the internal subsurface structure associated with the hills. Once the origin of these features has been determined, a search for their existence in similar environments worldwide can be conducted in order to determine their uniqueness. 2008-09-18T00:00:00Z Magee, W. R. Wilson, T. J. http://hdl.handle.net/1811/34812 Development of a New Method for Calculating Viscosity at High Pressures Pigott, J. S.; Reaman, D. M.; Panero, Wendy R. Fluids released by a subducting plate 100 km below the Earth’s surface cause melting in the overlying mantle, leading to arc volcanism, such as that found in the Andes Mountains. The viscosity of the released fluid is a first-order constraint on the transport of material from the plate to the mantle. Accurate determination of fluid viscosity at appropriate pressures (>30 kbar or 3 GPa) and temperatures (~800C) is hampered by the geometry of high-pressure devices. The goal of this research is to construct a new method for quantifying the viscosity of water at pressures similar to those in subduction zones. By observing the Brownian motion of polystyrene spheres suspended in fluid contained in a diamond anvil cell (DAC), the viscosity of the fluid can be calculated. Preliminary results yield an accuracy within half an order of magnitude of published values. Future experimental plans involve measuring the viscosity of water up to 3GPa and 800C. To further mimic conditions of subduction zones, dissolved hydrated minerals such as chlorite will be added to the water. 2008-09-18T00:00:00Z Pigott, J. S. Reaman, D. M. Panero, Wendy R. http://hdl.handle.net/1811/34811 Basin Compartmentalization in the Foreland: El Cajon Basin, Southwestern Argentina Pratt, Jonathan R.; Schoenbohm, Lindsay; Mortimer, Estelle 2008-09-18T00:00:00Z Pratt, Jonathan R. Schoenbohm, Lindsay Mortimer, Estelle http://hdl.handle.net/1811/34810 Seismic wave phase velocity variations in the state of Ohio Smith, Saskia; Hansen, Michael C. 2008-09-18T00:00:00Z Smith, Saskia Hansen, Michael C. http://hdl.handle.net/1811/34809 Uplift and Erosion in Taiwan and its effects on CO2 and C consumption Von Bargen, Justin M.; Goldsmith, Steve T.; Welch, Sue; Carey, Anne E. High Standing Islands (HSIs) experience extremely rapid physical and chemical weathering, resulting in large inputs of both sediments and solutes into the ocean. This can impact the global carbon cycle by the rapid burial of organic C and precipitation of calcium carbonate in the oceans. This poster will provide a progress report on a study of the role of uplift and erosion rates of various regions in Taiwan and its effect on the CO2 and C consumption rates of the area. Taiwan sits on top of a highly active convergent plate boundary between the Eurasian and Philippine Sea Plate, which is the cause of the intense uplift that creates the orogenic mountains that make up the island. The plate margin has uplift rates >10mm/yr and contains erosional features dominated by mass-wasting. The island also contains three of the nine rivers in the world which have average sediment concentrations >10g/l (Milliman and Syvitski,1992). Soil samples from locations on the island subjected to a range of uplift rates will be analyzed for carbon (C), carbonate (CO3), and particle size in order to determine whether variations in soil residence times can impact chemical weathering and CO2sequestration. I expect there to be a higher amount of CO2and C consumption on the island than most anywhere on Earth due to the readily weathered surfaces that result from the rapid uplift and fast erosion rates of the island. 2008-09-18T00:00:00Z Von Bargen, Justin M. Goldsmith, Steve T. Welch, Sue Carey, Anne E. http://hdl.handle.net/1811/34766 Coarse Terrigenous Fraction at IODP Site 1308, North Atlantic: Evidence For Changing IRD Sources Through Last 300ky Calhoun, J. Patrick; Krissek, Lawrence Integrated Ocean Drilling Program (IODP) Expedition 303 obtained ocean floor sediment cores from the North Atlantic, including Site 1308 at 50N 24W. These cores contain coarse terrigenous material, known as Ice Rafted ( IRD), which deposited by melting icebergs that had carried continental rock fragments and traversed the North Atlantic before melting. The abundance and composition of this IRD have been used as a proxy to understand the locations and history of glaciation on landmasses that border the North Atlantic. In this study, 78 samples were analyzed to produce an IRD record to ~288,000 years before present (ka), with an average spacing between samples of ~4 ky. IRD abundances within these samples vary from 0.1 to 12.23%. The IRD composition is dominated by a relatively constant content of unstained quartz (~55%). The second-most abundant IRD grain is volcanic glass, whose average abundance increases upsection. Iron-stained quartz is the third-most abundant grain type; its abundance reaches a maximum at ~88ka, with abundance in younger sediments. Variations in the abundances of individual IRD grain types appear to define three stratigraphic intervals with distinctive IRD assemblages; these are: ~73-0 ka – 55% qtz, 30-40% volc. glass, 5% Fe-stained qtz. ~150-73 ka – 55% qtz, 30% volc. glass, ~10% Fe-stained qtz. ~288-150 ka – 55% qtz, 10% volc. glass, ~7% Fe-stained qtz, ~10% rock frags. These compositional variations suggest that older IRD was supplied from a wider range of source regions, possibly indicating more geographically widespread glaciation. 2008-09-18T00:00:00Z Calhoun, J. Patrick Krissek, Lawrence http://hdl.handle.net/1811/34096 Quantification of Chromatic Aberration In the Laser-Heated Diamond Anvil Cell England, Emily V.; Clarey, Wes; Reaman, Daniel Earth materials subjected to the high pressure and temperature conditions of planetary interiors display unique changes in crystal structure, melting temperature, and transport properties. The laser-heated diamond anvil cell (LHDAC) is a tool to make in situ measurements of material properties, specifically at pressures up to 1 Mbar (100 GPa) and temperatures from 1500 to 7000 K. Temperatures above 1500 K are measured by the spectroradiometry of the thermal emission that passes through the diamond anvil and is collected on a intensity-calibrated spectrometer and coupled-charged device (CCD). The accuracy of the measured temperatures is not always reliable, due to optical dispersion of the diamond and lenses in the system. The size of the laser-heated spot on the sample is only about 20 micrometers. This small hot spot leads to large spatial variations in intensity as a function of wavelength.. This variation requires focusing and magnification of light through the optical system with minimal chromatic aberrations. State of the art LHDAC spectroradiometry systems underestimate the temperature gradients by as much as 100%. To quantify the chromatic aberrations, we will use a high birefringence material to test each component (lenses, mirrors, beam splitters, etc.) of the laser system. The material we have chosen to measure the system’s chromatic aberration is yttrium vanidate (YVO4), which has a birefringence of 0.205. The thickness of the material varies vertically, providing a spatially varying “color standard” to test how well the system focuses each wavelength of visible light (400-900 nm). Specifically, light will pass through YVO4 between crossed-polarizers to produce rainbows separated by 20 micrometers vertically. This rainbow then passes through a diamond and the rest of the optical system. Our test of the quality of the spectroradiometry system will improve temperature and temperature gradient measurements in the laser heated diamond anvil cell and provide an inter-lab cross-calibration standard. 2007-05-01T00:00:00Z England, Emily V. Clarey, Wes Reaman, Daniel http://hdl.handle.net/1811/34095 Effects of Development on the Big Darby Creek Watershed: Stream Geochemistry Maxwell, Catherine A. Surrounding ecosystems are affected by anthropogenic land use. Growing development encroaches on pristine environments and can drastically affect the species in that area. The scenic Big Darby Creek is one of Ohio’s most biologically diverse rivers being home to 86 species of fish and 41 species of freshwater mollusks. Recently, there has been increasing development in close proximity to the river as farm land is being purchased and turned into housing developments. Changing uses of land may threaten many of the Darby’s species, some of which are already endangered. Controversy over this issued has communities arguing about the best use of land. Scientific observation has been called in to quantify the effects. Research is currently being conducted to investigate how the environment responds to the invading development. This study focuses on the chemical changes in the water of the Big Darby Creek and its tributary, the Little Darby Creek. Changes in the geochemistry of the stream water will express the healthiness of the ecosystem while the development continues. As development increases and human activities get closer to the Darby presumably it will affect which is being expelled into the river; contaminants such as salt from the deicing of roads, fertilizers, and other pollutants will affect the ecosystem. For this study water samples were collected biweekly from the Little Darby Creek in West Jefferson and from the Big Darby Creek in Darbydale. The samples were analyzed from major cations and anions (F, Cl, NO3, PO4, SO4, Ca, Mg, NA, K) using Ion Chromatography (IC) methods. Our preliminary results show a decreasing trend in nitrate concentrations in both locations from spring into the fall. We suggest that this is related to the seasonal application of fertilizer in both watersheds. Chloride concentrations show contrasting trends between the two locations. In the Little Darby Creek chloride remained relatively constant through out the year, but in the Big Darby Creek the concentration of chloride increased. The higher chloride concentration may be related to the continual leaching of water-applied road salt from major highways draining into the Creek. To date the study is still on going. When completed, results of this experiment will be discussed in terms of land use in the Big Darby watershed. 2008-05-14T00:00:00Z Maxwell, Catherine A. http://hdl.handle.net/1811/34094 Lithology, mineralogy, and chemical weathering of volcanic rocks from Panama Dugan, Matthew Chemical weathering of silica rocks is the only know mechanism on a long-term geologic time scale (100s of million of years and longer) for sequestration of carbon dioxide. Lithologic and mineralogical analysis of rocks provides understanding of which minerals may be weathering preferentially, and thus what ratio of ions are released into the environment and sequestering the carbon. Collision of the Caribbean plate and the Cocos plate and the associated subduction causes melting of crustal layers and andesitic/dacitic volcanism. Rock samples were collected in summer 2006 and spring 2007 from several andesitic-dacitic volcanic centers located in the western part of the country. Previous research has shown that basalts are generally absent from the volcanic centers with basaltic andesites and andesites predominating. Collection was performed as part of a larger project which included water and sediment collection and stream gauging. Previous studes on volcanic centers in the region revealed ags from 17.5 Ma to 300 yr B.P. with the majority of dates focused between 12-7MA and around 1.3+1 Ma. Volcanism appears to have been significantly reduced between 6 and 1 MA, with increased activity from 2 Ma to present. Petrologic thin sections were prepared by cutting samples with a diamond blade saw into small bocks which were then processed into this sections. I will then analyze them underneath a microscope to determine the minerals present and their relative proportions. I will also perform X-ray fluorescence analysis of crushed samples to determine bulk chemical analysis. Mineralogical assemblages of these rock samples show relationships between the volcanic centers along with individual magma chamber evolution. Mineralogical assemblages and chemical content will reveal which minerals are lickely to weather fastest and will be used in association with geochemical analyses of stream water sample and associated weathering studies to determine the extent and rates of chemical weathering taking place. Results are expected to show that the silicate minerals of these andesitic-dacitic volcanic rocks of Panama are rapidly weathering and sequestering significant amounts of atmospheric carbon dioxide. 2008-05-14T00:00:00Z Dugan, Matthew http://hdl.handle.net/1811/32117 Magma plumbing system under the fast spreading Galapagos Ridge England, Emily The Galapagos Ridge System is one of the fastest spreading and most unique ridges on the Earth. Typical ridges spread at a rate of about 25-35 mm/yr, while the Galapagos spreads at between 47-63 mm/yr. Fast spreading rates are associated with increased magma output and with relatively thin crust beneath the ridge axis, as observed along the Galapagos Spreading Center (GSC). Spreading rate may also influence the depth of partial crystallization and the structure of magma plumbing systems beneath ridges. To constrain the depth at which partial crystallization of magmas occurs beneath the GSC, we have used a method to calculate the pressure of crystallization that is more accurate and reliable than similar methods such as that described by Claude Hertzberg (2004, Journal of Petrology). The method involves calculating the pressure at which a liquid, represented by volcanic glass, is chemically in equilibrium with olivine, plagioclase, and augite. Our data set is comprised of analyses of volcanic glass collected on scientific cruises along the Galapagos ridge. These analyses were downloaded from the RIDGE data base maintained by Lamont Earth Observatory. Filtering of the analyses was necessary to exclude glasses that were not in equilibrium with olivine, plagioclase, and augite. The 1,110 remaining glasses were then divided into twelve groups based on longitude. Results thus far indicate that Galapagos magmas crystallize over a range of pressure from 0.001- 10 kBar, equivalent to 0 to 30 km depth, but that most crystallization occurred between 2 and 6 kBar, or 8-18 km depth. This range of depth suggests that the magma plumbing system is complex and is likely composed of multiple, stacked chambers that are interconnected by dikes. Some of these chambers are probably located beneath the crust in the uppermost mantle. Further work is underway to determine whether there is any relation between magma chamber depth and other geochemical indicators of crustal thickness, such as Na concentrations (normalized to 8.0 wt % MgO). Emily Klein and co-workers have shown that Na8 is a measure of crustal thickness with low values indicating higher mantle temperatures and greater degrees of melting. Implications for the interpretation of the Galapagos magma plumbing system include the possible influence of the Galapagos hotspot and transform faults near the western end of the ridge on magma plumbing systems. 2008-05-14T00:00:00Z England, Emily http://hdl.handle.net/1811/24007 A Study of Ice-rafted Debris as a Paleoclimatic Proxy for the North Atlantic for the Last One Million Years Haack, Margaret E. The North Atlantic is a climatically sensitive region on Earth, due to the interactions between the ocean, atmosphere, and cryosphere (i.e., glaciers) that have occurred there on timescales of tens of thousands to hundred of thousands of years. In addition, the North Atlantic appears to be prone to periods of abrupt climate change (on the order of thousands of years or less). Understanding the mechanisms and causes of such episodes of abrupt climate change is one of the major challenges in global climate change research today. However, records with sufficient detail to reveal episodes of abrupt climate change only extend back for several tens of thousands of years. As a result, research in abrupt climate change requires the development of longer and more detailed records of paleoclimatic proxies (i.e., sediment components that carry information about past oceanographic, atmospheric, and glacial conditions). This study is a step toward developing such a record for sediments transported from land into the North Atlantic by icebergs (ie, ice-rafted debris or IRD). Increases in the abundance of IRD are interpreted to record times of glacial expansion to sea level (when icebergs can be released), and the composition of the IRD can be used to identify the source area(s) and/or the dispersal trajectory of those icebergs. This study will examine samples from cores takes at Site 1305 during Expedition 303 of the Integrated Ocean Drilling Program. Site 1305 is located on the Eirik Drift off the southeastern coast of Greenland, and lies within the zone where previous studies have identified abundant IRD. The cores taken from Site 1305 have been used to construct a continuous composite section for at least the last one million years. Approximately 400 samples have been taken for this study with an estimated time spacing of 3000-4000 years between samples. Over the next month, these samples from IODP Site 1305 will be analyzed to determine the abundance of IRD. Various definitions for IRD have been proposed in past studies; for this study, IRD will be defined as the lithic grains in the >150 m fraction. The IRD abundance will be defined two ways: as the weight percent of the >150 m fraction relative to the total sediment and as the number of lithic grains per gram of sediment. To obtain data, each sample will be dried, weighed, wet-sieved at 150 m and 2mm, dried, and reweighed. The >150 m fraction will then be examined using a binocular microscope to determine the number of lithic grains and the abundances of various grain types. Sample ages will be determined using an age-depth model developed by the Expedition 303 Scientific Party. 2006-05-10T00:00:00Z Haack, Margaret E. http://hdl.handle.net/1811/21902 Seasonal Variations of Major Ions at two Locations along the Olentangy River, Columbus, Ohio Jacobs, April N.; Welch, Kathleen A.; Landis, Carol E.; Carey, Anne E. The Olentangy River is a major tributary of the Scioto River and flows through agricultural lands prior to entering the Columbus metropolitan area. Human activities such as agriculture and urbanization should influence the chemistry of the river water as the river flows through different regions. In addition, there are natural geochemical processes such as chemical weathering that will impart a chemical signature to the water. By observing and analyzing the variation in the stream chemistry through different seasons, we can gain an understanding of how precipitation events, along with natural and human influences, impact the water quality of the river. River water samples were collected at two locations along the Olentangy River from December 2004 to January 2006. Samples were collected at a location north of Columbus, High Banks metro park (HB), as well as a downstream location, the Boat Launch near Nationwide Arena (BL). The HB location is thought to reflect both natural and agricultural inputs, while the BL location should include urban influences. After collection, the samples were filtered and analyzed for major anions and cations via ion chromatography. Ion concentrations from the samples were compared to stream flow data obtained from the USGS. The Olentangy River water consists of Ca > Mg = Na > K, reflecting the impact of the local geology. In general, all of the major ion concentrations vary with flow, having lower values at high flows. At both sites, calcium and chloride vary by a factor of 3 and 5, respectively through the year. The variation in nitrate is greater, with the lowest values observed in June. Calcium concentrations at base flow conditions varied as much as 43% at BL. The BL site has higher chloride and sodium, generally lower nitrate, and no trend in calcium and magnesium concentration compared to the HB site. This suggests a source of NaCl from the urban landscape, a nitrate decrease either by dilution or by biological uptake, and little to no addition of source in calcium and magnesium between the two sites. 2006-05-10T00:00:00Z Jacobs, April N. Welch, Kathleen A. Landis, Carol E. Carey, Anne E. http://hdl.handle.net/1811/6468 Hydrothermal Zoning in the Copper-Molybdenum System Beneath Red Cone Peak, Colorado McCudden, Corey B. Red Cone Peak lies one mile south of the Continental Divide, about 50 miles southwest of Denver, Colorado, and five miles south of the town of Montezuma. The Red Cone igneous complex is within the Colorado Mineral Belt, a zone of igneous bodies and associated hydrothermal activity that crosses the mountainous part of the state from southwest to northeast. Mineralization within the Mineral Belt probably resulted from igneous activity that accompanied eastward-directed subduction of the Farallon Plate below North America as the Rocky Mountains formed. This research addresses a fundamental question: was there an early copper-rich event in the Mineral Belt that has gone unrecognized, and which may be related genetically to the well known molybdenum event that to date has characterized large-scale mineralization in the Belt? The Red Cone complex intruded from 42 to 38 million years ago, which was 5 to 10 million years before world-class molybdenum deposits at Climax (25 km to the southwest) and Henderson (20 km to the northeast). The timing of emplacement of the Red Cone complex, and the characteristics of the hydrothermal mineralization could put it in a category that is unique from the surrounding deposits. Samples from a 2000 foot drill core at Webster Pass, about 1.0km west of Red Cone Peak, will be used to characterize the lateral extent of the hydrothermal mineralization, and the presence of vertical zoning within the Red Cone complex. Rocks in the vicinity have been pervasively mineralized with pyrite, and polished thin sections have been made from samples collected at nine locations down the core. Copper and other trace elements (including molybdenum and gold) will be analyzed for using multi-element EDAX and electron microprobe techniques. The analysis will focus on individual pyrite grains, and these data will document variations in the trace element compositions of pyrite with depth into the igneous and hydrothermal system. Studies have shown that the Red Cone complex displays characteristics of a large porphyry-type metal system. The Climax and Henderson deposits have been well documented and are currently being mined. These bodies are two of the richest molybdenum deposits in the world, and they provide clues to understanding the emplacement and zoning of the rocks at Webster Pass. Results from the present study will provide a better understanding of the Red Cone system and a more complete picture of mineralization in this part of the Colorado Mineral Belt, which formed as the Rocky Mountains uplifted and western North America evolved over the past 70 million years. 2006-05-10T00:00:00Z McCudden, Corey B. http://hdl.handle.net/1811/6452 Major, Minor and Trace Element Chemistry of Taiwan Bedrock Gordon, Christopher; Goldsmith, Steven T.; Bhattiprolu, Sreenivas N. Recent sediment flux estimates have shown that rivers draining Taiwan and other high-standing oceanic islands in Austral-Asia contribute a significant fraction of the total sediment flux to the oceans. Previous studies on weathering rates on these islands of the Pacific Ocean have revealed that although the ratio of chemical to physical weathering is low, the absolute rates of chemical weathering are some of the highest observed in the world. Chemical weathering studies in watersheds from these locales have traditionally focused on the comparison of water, sediment, and rock geochemistry. However, preliminary studies in Taiwan have often been limited by a lack of sufficient bedrock geochemical data. Therefore, the determination of local bedrock geochemistry in Taiwanese watersheds is critical to achieve an understanding of these weathering processes. In April and July of 2005, a total of 22 rock samples consisting of meta-sandstones, various grades of metamorphosed shales, and mafic igneous rocks were collected in watersheds throughout Taiwan. The samples were analyzed by x-ray fluorescensce (XRF) spectrometry in order to determine their major, minor and trace element composition. Prior to analysis, the outer weathered surfaces of the samples were removed in order to achieve a true chemical composition. During sample preparation, clean room procedures were also utilized so that the samples could be analyzed for organic carbon at a future time. The rock geochemical analyses are subsequently used in conjunction with preliminary stream water data from watersheds throughout Taiwan in order to determine a relationship with a source lithology. The rock data provide an enlarged database for future comparison to stream water sediment data in order to determine relative chemical weathering intensities of the sediment. 2006-05-10T00:00:00Z Gordon, Christopher Goldsmith, Steven T. Bhattiprolu, Sreenivas N. http://hdl.handle.net/1811/6378 Verification of a New Method in Determining the Visocity of Fluids Under High Temperature and Pressure Veres, Michael C. At convergent plate boundaries, where plate subduction occurs, volcanism is witnessed above the subducting plate. Hydrous minerals carried to depths of 100 km break down and release their stored water into overlying rock. As this water migrates toward the surface, mantle rock melts and also rises to the surface. This magma is seen as volcanic arcs on the surface. Viscosity measurements are important in the investigation of fluid transport. Previous measurements of water viscosity have been constrained to surface or near surface conditions. The dehydration reactions occur under much higher temperatures and pressures than those found on the surface. Prior to determining viscosity at these high pressures and temperatures (approximately 1300 K and 5 GPa), the method must be validated on fluids having well known viscosities. This is done by calculating the viscosity of water under conditions in which it is already well known (1 atm and 25º C). The hydrothermal diamond cell will be used in the high pressure and temperature experiments. The geometry of the hydrothermal diamond cell must also be reproduced when the method is tested. This geometry can be simply reproduced. Two glass slides were clamped together with a rhenium gasket between the slides. The gasket will be the same type as the one used in the hydrothermal diamond cell. Water with suspended particles was contained within a central gap within. Particle motion was monitored for preferential motion, in order to confirm accurate results. Particles in water exhibit random motions, called Brownian motion. These motions are completely random and by recording their motion, the viscosity of the water can be determined. Care must be taken when choosing the particles to track. Particles in close proximity to each other or to the surface of the gasket do not move randomly due to interactions. Digital recordings are then made of the 3 mm suspended particles. Using mean square displacement, the viscosity can then be calculated from the data. 2006-05-10T00:00:00Z Veres, Michael C. http://hdl.handle.net/1811/6362 The Geochemistry of Stream Sediments, Chagres River, Panama: Weathering in a Tropical Watershed McElwee, Gregg Chemical weathering of the earth’s surface is a primary process controlling landscape and soil development as well as the geochemistry of natural waters. In addition, chemical weathering of silicate minerals, which consumes atmospheric CO2, is a major control of long term climate variation. Although much has been published related to the rates and intensities of chemical weathering, very little data exist on chemical weathering in mountainous tropical regions. The Chagres River is considered Panama’s most important river with a total runoff of 4.4x105 m3 per year during years of higher flow. The highest areas of the watershed rise to elevations of 275m. The high rainfall, warm temperatures (mean annual T° of ~19°C) and steep topography all increase rates of chemical weathering in the watershed relative to more temperate locations. In this study I will analyze a series of stream sediment samples from the Chagres River with the purpose of establishing the intensity of chemical weathering in this environment. These samples will be analyzed for both major and trace element composition and compared to the geochemistry of the surrounding bedrock lithologies as well as the upper continental crustal average where data are available. The data from these Panamanian sediments will be compared to other high rainfall mountainous regions in more temperate climates, such as Taiwan and New Zealand, to determine the relative intensity of weathering within the Chagres basin. In addition to the sediment samples analyzed by me, I have compiled and interpreted a set of river samples that have been analyzed for dissolved silica (Si) by Dr. Lyons’ group at The Byrd Polar Research Center. Si is a major dissolved component of the chemical weathering of silicate minerals. The dissolved Si data will be normalized to chloride (Cl) in order to account for rainwater input, evaporation and evapo-transpiration so that the spatial locations of enhanced weathering (i.e. Si increase in the stream water) can be detected. These data are used to better confine the lithologic sources of more concentrated silicate mineral weathering within the watershed. 2006-05-10T00:00:00Z McElwee, Gregg http://hdl.handle.net/1811/6356 SIGNAL SEPARATION TO REVEAL SUBTLE FEATURES IN GRAVITY AND MAGNETIC DATA FROM THE BELLEFONTAINE OUTLIER, OHIO Fidler, Michael L. Jr.; Noltimier, Hallan C. Fidler, Michael L. Jr and Noltimier, Hallan C., 2006, Signal separation to review subtle features in gravity and magnetic data from the Bellefontaine outlier, Ohio [poster]: Geological Society of America North-Central Section 40th Annual Meeting, 2006, Session 38, Paper 38-2. Abstract published: Geological Society of America, Abstracts with Programs, Vol. 38, No. 4, p. 76; http://gsa.confex.com/gsa/2006NC/finalprogram/abstract_103533.htm At previous GSA meetings the general basement topography and structure of the Bellefontaine Outlier region of Ohio has been presented in poster format based upon our own detailed gravity and magnetic survey data and the COCORP Ohio #1 seismic survey which crossed the region. Recent experimentation with signal separation has brought new structural details to light. By removing the major gravity and magnetic signals from their respective data sets and re-normalizing the resulting data to isolate small scale variations, many features become visible. Correlation of these new details hidden within the gravity and magnetic survey data sets is presented as well as correlation with surface topographic features. For example: A north-east trending basement fault correlates with surface topography. 2006-04-21T00:00:00Z Fidler, Michael L. Jr. Noltimier, Hallan C. http://hdl.handle.net/1811/6255 Thickness, Composition and Physical Properties of Crust in Iceland's Neovolcanic Zone Kelley, D. F.; Barton, M. Kelley, D. F., Barton, M., 2005, Thickness, composition, and physical properties of crust in Iceland’s neovolcanic zone, Eos Trans. AGU, 86(52), Fall Meet. Suppl., V13E-0591 We report the results of an ongoing effort to use petrologic data to estimate the thickness, composition and physical properties of crust in the neovolcanic zone of Iceland. The objectives are to constrain the depths of magma chambers, calculate geothermal gradients, and resolve discrepancies in the interpretation of geophysical data (primarily gravity and seismic). 1788 whole rock analyses and 170 glass analyses of erupted Icelandic lavas from the neovolcanic zone have been compiled from published papers. Variation diagrams indicate that Icelandic magmas evolved primarily by crystallization of Ol-Cpx-Plag, whereas the most primitive magmas evolved by crystallization of Ol alone. Phase equilibrium constraints were used to quantitatively estimate the pressure of crystallization along the Ol-Cpx-Plag cotectic and hence the depths of the magma chambers. The latter occur at 20±6.2 km, and the average temperature of magma in the chambers is 1207±26°C (also estimated from phase equilibrium constraints). The results suggest magma chambers located at the base of the crust indicating that the latter is ~20 km thick along the neovolcanic zone in agreement with estimates based on geophysical studies. It is argued that the average composition of erupted lavas provides an accurate estimate of crustal composition because magma evolution occurs in sub-crustal chambers. A representative geothermal gradient was calculated using the average crust composition and surface heat flow measurements. The calculated gradient is consistent with the periodic presence of shallow intracrustal magma chambers at ~5 km depth that have been detected seismically, with hydrothermal circulation in the uppermost 3 km of the crust, and with temperatures of ~1200°C at the base of the crust. The geotherm was used to calculate a density-depth profile for average crust. Densities decrease with depth if a low-pressure mineralogy is used for the crust. This density inversion can be avoided by assuming either that the crust varies in composition (becoming richer in MgO) with depth, or that the composition is uniform and the mineralogy changes to that of a low-P, high-T granulite at 20 km. The latter model involves fewer ad hoc assumptions and provides a close match to accepted densities and seismic velocities for the lower crust. The calculated density contrast between crust and mantle, Δρ, is 150 kgm-3 assuming a mantle density of 3300 kgm-3, whereas VP is calculated as 6.95 kms-1 at the base of the crust. 2005-01-01T00:00:00Z Kelley, D. F. Barton, M. http://hdl.handle.net/1811/6254 Petrologic Constraints on Iceland's Lower Crust Kelley, D. F.; Leftwich, T. E.; Barton, M. Kelley, D. F., Leftwich, T. E., Barton, M., 2005, Petrologic constraints on Iceland’s lower crust, EOS Transitions AGU, 86(18), Joint Assembly Supplement, V13A-02. ABSTRACT: Iceland is an area of relatively thick ocean crust that straddles the spreading MAR. Iceland was created by seafloor spreading originating about 55 Ma above abnormally hot mantle. The high temperatures resulted in greater melt volumes that enhanced crustal thickening. Geophysical investigations provide fundamental insight on crustal features, but results are contradictory. Early seismic, magneto-telluric, and resistivity studies predicted thin crust with partial melt regions at depths of 10-15 km beneath the neovolcanic zones. Reinterpretations based on recent seismic studies suggest thicker and cooler crust. These studies have shown magma lenses at shallow depths beneath volcanic centers, but cannot confirm their presence in the lower crust. Knowledge of the depth of magma chambers is critical to constrain the geothermal gradients in Icelandic crust and to resolve discrepancies in interpretation of geophysical data. Analyses of glasses in Icelandic lavas erupted from 11 volcanic centers throughout the rift zones have been compiled. The pressures of equilibration of these liquids with ol, high-Ca pyx, and plag were estimated qualitatively from projections into the pseudoternary system Ol-Di-Qtz. The results (ca. 0.6 GPa) indicate crystallization in magma chambers located at about 20 km depth. Equilibrium pressures also have been calculated quantitatively. These results (0.6±0.2 GPa) indicate magma chambers at 19.8±6.5 km depth beneath the volcanic centers. Magma chamber at these depths are located in the lower crust inferring that it must be relatively warm. Geothermal gradients have been calculated using the depths of the sourcing magma chambers and any shallow seismically detected magma chambers at each location. An average crustal composition has been calculated from the compiled geochemical data and was used to calculate density variations and seismic velocities along the geotherms. The distribution of sample locations in this study provides sufficient data to characterize the Iceland rift system in terms of magma chamber depths, rock type, geothermal gradient, density variation, and expected seismic velocity. Calculated density contrasts across the moho are consistent with those determined gravimetrically, and calculated seismic velocities are consistent with seismic studies beneath the rift system. 2005-01-01T00:00:00Z Kelley, D. F. Leftwich, T. E. Barton, M. http://hdl.handle.net/1811/6004 THE BATTLE AT GETTYSBURG: COMPETITION BETWEEN UTILIZATION AND REMEDIATION FOR A LIMITED GROUNDWATER RESOURCE Svitana, Kevin D.; Krissek, Lawrence Svitana, D. D., and Krissek, Lawrence, 2005, The Battle at Gettysburg: competition between utilization and remediation for a limited groundwater resource [poster]: Geological Society of America Annual Meeting, 2005, Session 68, Paper 68-4. Abstract published: Geological Society of America, Abstracts with Programs, Vol. 37, No. 7, p. 169; http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_92376.htm 2005-01-01T00:00:00Z Svitana, Kevin D. Krissek, Lawrence http://hdl.handle.net/1811/6003 BIOMARKERS IN PALEOZOIC CRINOIDS (BORDEN GROUP, MISSISSIPPIAN): IMPLICATIONS FOR PHYLOGENY O'Malley, Christina E.; Ausich, William I.; Chin, Yu Ping O'Malley, Christina E., Ausich, William I., and Chin, Yu Ping 2005, Biomarkers in Paleozoic crinoids (Borden Group, Mississippian): implications for Phylogeny [poster]: Geological Society of America Annual Meeting, 2005, Session 57, Paper 57-8. Abstract published: Geological Society of America, Abstracts with Programs, Vol. 37, No. 7, p. 133; http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_95335.htm 2005-01-01T00:00:00Z O'Malley, Christina E. Ausich, William I. Chin, Yu Ping