Master of Science / Department of Geology / Saugata Datta / The incidence of high arsenic (As) and other oxyanions (e.g. Mn) has been examined in a ~410km[superscript]2 areas within the Bengal Delta between North and South Matlab, Bangladesh. The aim of this study was to examine the role of sediment geochemistry, coupled with microbial community studies and their relations with different colors and grain sizes of sediments, in determining evolved groundwater hydrochemistry within the aquifers in Matlab. Groundwaters are Ca–Mg–HCO[subscript]3- types in shallow aquifers, Mg-HCO[subscript]3- in the intermediate depths and Na-K-Cl rich in the deeper aquifers. Dissolved As concentration is high (~781μg/l) associated with shallow grey and dark grey sediments, whereas light grey sediments at intermediate depths contain lower As (<10 μg/l). Dissolved Fe[superscript]T on other hand in both sediment types (light grey and grey) shows good correlation with dissolved SO[subscript]4[superscript]2-. In plots of [delta]δ[superscript]18O vs [delta]δD, intermediate and deeper depth aquifer waters plot on the arrays for LMWL and GMWL, which indicates the principal recharge mechanism is likely to be from local precipitation within the shallow aquifers. Only the high As groundwaters deflect from the LMWL, indicating that recharge might be a mixture of precipitation and surficial discharges / infiltrations for these waters. Bulk extraction of sediments showed that grey and dark grey sediments from shallow depths have higher As concentrations (~31 mg/kg) and light grey sediments have comparatively less (~11mg/kg). Sequential extractions for sediment fractionations showed that most of the As was bound to amorphous and poorly crystalline hydrous oxides of Fe and Al phases. Synchrotron-aided bulk-XANES studies conducted on sediments revealed As and S speciation in the core samples at different depths indicating the occurrences of hotspots of As distributed randomly in light grey and grey sediments. As[superscript]3+ is the dominant species in Matlab sediments. More than 101 bacterial families were identified among the eight sediment samples from the South Matlab core and out of them fewer than six families comprised more than ~80% of total bacterial families. Our results indicate significant relationships between bacterial community structure, grain size fractionation, dissolved As concentration and sediment C, Mn, and Fe concentrations for these samples. Groundwater abstracted from these light grey sediments, in contrast to reduced greyish to dark greyish sediments, contain significantly lower amounts of dissolved As and can be a source of safe water for the future. Our work demonstrates that intermediate depth light grey sediments have geochemical and microbial features conducive with safe drinking water for the future.

Master of Science / Department of Geology / Matthew W. Totten / The Spivey-Grabs-Basil oil field is a highly developed field in south-central Kansas, having large variability in its production and in the Pineville Tripolite facies. The Pineville Tripolite is the primary producing formation of this field having major isopach variations, possibly influencing production. The hypothesis that the field is highly compartmentalized is from the varied production, isopach and structure of the field. This study investigated the Pineville Tripolite facies in the Spivey-Grabs-Basil Oil Field, with the Basil area the predominant focus, and its possible compartmentalization by looking at the gas chromatograms and their biomarker signatures. This field has had several studies investigating the geophysical attributes, depositional setting and large-scale compartmentalization. Post depositional sea-level changes and possibly syntectonics exposed the Reeds Spring to a sub-aerial environment where meteoric alteration created immense porosity and the Pineville Tripolite facies. Geochemical data shows evidence that this section of the field is sourced from both a marine shale and carbonate source at peak oil maturity, deposited in an anoxic environment. Biodegradation appears very slight, with most alterations transpiring in the alkane ranges only, leaving all other susceptible hydrocarbons unaltered. Compartments within the field are harder to identify when comparing geological data to oil data. Isopach data shows altered thickness of the Pineville Tripolite from well to well, as do Pineville structure values. The isopach and structural data point to possible areas for compartments, but it is from oil geochemical data that compartments become more visible. API gravities and GOR show motley values, but do indicate two significant areas of segregation. The deepest, most southern end of the study showed lighter gravity oils than the middle, suggesting possible fill and spill between the two. However, biomarker abundance indicates three possible compartments. The southern compartment has many more biomarker volumes than do the middle compartment, both divided by a reservoir pinch-out. The third most northeastern well has high biomarker abundance, but shows no geological separators from the other wells. Production from this field may be improved by investigating the biomarkers to allocate these compartments and possible barriers close to wells.

Clinopyroxene, olivine, plagioclase and hydrous fluid lithium partition coefficients have been measured between 800-1100oC at 1 GPa. Clinopyroxene-fluid partitioning is a function of temperature (ln DLicpx/fluid = -7.3 (+0.5) + 7.0 (+0.7) * 1000/T) and appears to increase with increasing pyroxene Al2O3 content. Olivine-fluid partitioning of lithium is a function of temperature (ln DLiol/fluid = -6.0 (+2.0) + 6.5 (+2.0) * 1000/T) and appears to be sensitive to olivine Mg/Fe content. Anorthite-fluid lithium partitioning is a function of feldspar composition, similar to the partitioning of other cations in the feldspar-fluid system. Isotopic fractionation between clinopyroxene and fluid, Licpx-fluid, has been measured between 900-1100oC and ranges from -0.3 to -3.4 ‰ (±1.4 ‰). Lithium diffusion has been measured in clinopyroxene at 800-1000oC and in olivine at 1000oC. The lithium diffusion coefficient is independent of the diffusion gradient as values are the same if the flux of lithium is into or out of the crystal and ranges from -15.19 ± 2.86 m2/s at 800oC to -11.97 ± 0.86 m2/s at 1000oC. Lithium diffusion in olivine was found to be two orders of magnitude slower than for clinopyroxene at similar conditions. Closure temperatures calculated for lithium diffusion in clinopyroxene range from ~400 to ~600oC. These results demonstrate that lithium equilibration between fluids and minerals is instantaneous, on a geological timescales. The confirmation of instantaneous equilibration, combined with min-fluid partition coefficients and values for Licpx-fluid, permits quantitative modeling of the evolution of lithium concentration and isotopic composition in slab-derived fluids during transport to the arc melt source. Our results indicate that fluids migrating by porous flow will rapidly exchange lithium with the mantle, effectively buffering the fluid composition close to ambient mantle values, and rapidly attenuating the slab lithium signature. Fluid transport mechanisms involving fracture flow are required to maintain a slab-like lithium signature (both elemental and isotopic) from the slab to the melt source of island arc basalts. This study demonstrates that mineral-fluid equilibration is rapid, and as a result the lithium content of minerals can only reliably represent chemical exchange in the very latest stages of the sample’s history.

Clinopyroxene, olivine, plagioclase and hydrous fluid lithium partition coefficients have been measured between 800-1100oC at 1 GPa. Clinopyroxene-fluid partitioning is a function of temperature (ln DLicpx/fluid = -7.3 (+0.5) + 7.0 (+0.7) * 1000/T) and appears to increase with increasing pyroxene Al2O3 content. Olivine-fluid partitioning of lithium is a function of temperature (ln DLiol/fluid = -6.0 (+2.0) + 6.5 (+2.0) * 1000/T) and appears to be sensitive to olivine Mg/Fe content. Anorthite-fluid lithium partitioning is a function of feldspar composition, similar to the partitioning of other cations in the feldspar-fluid system. Isotopic fractionation between clinopyroxene and fluid, Licpx-fluid, has been measured between 900-1100oC and ranges from -0.3 to -3.4 ‰ (±1.4 ‰). Lithium diffusion has been measured in clinopyroxene at 800-1000oC and in olivine at 1000oC. The lithium diffusion coefficient is independent of the diffusion gradient as values are the same if the flux of lithium is into or out of the crystal and ranges from -15.19 ± 2.86 m2/s at 800oC to -11.97 ± 0.86 m2/s at 1000oC. Lithium diffusion in olivine was found to be two orders of magnitude slower than for clinopyroxene at similar conditions. Closure temperatures calculated for lithium diffusion in clinopyroxene range from ~400 to ~600oC. These results demonstrate that lithium equilibration between fluids and minerals is instantaneous, on a geological timescales. The confirmation of instantaneous equilibration, combined with min-fluid partition coefficients and values for Licpx-fluid, permits quantitative modeling of the evolution of lithium concentration and isotopic composition in slab-derived fluids during transport to the arc melt source. Our results indicate that fluids migrating by porous flow will rapidly exchange lithium with the mantle, effectively buffering the fluid composition close to ambient mantle values, and rapidly attenuating the slab lithium signature. Fluid transport mechanisms involving fracture flow are required to maintain a slab-like lithium signature (both elemental and isotopic) from the slab to the melt source of island arc basalts. This study demonstrates that mineral-fluid equilibration is rapid, and as a result the lithium content of minerals can only reliably represent chemical exchange in the very latest stages of the sample’s history.

The purpose of this project was to determine the vanadium bearing ore minerals present at the Green Giant vanadium-graphite deposit in the S.W. of Madagascar owned by Toronto based Energizer Resources Inc. The rocks are mainly quartzofeldspathic gneiss, with alternating bands of hornblende biotite gneiss, marble, granitoid, and amphibolite. Using X-ray diffraction, electron microprobe analysis, and Raman spectroscopy, the vanadium bearing minerals were identified as vanadium bearing rutile, schreyerite, berdesinskiite, karelianite, a member of the karelianite-eskolaite solid solution, V-bearing phlogopite, V-bearing pyrrhotite, V-bearing pyrite, goldmanite, dravite, uvite, actinolite, and unidentified V-sulphide 1, V-sulphide 2, and V-silicate 1. The mineral assemblage present at Green Giant deposit is quite similar to that at Lake Baikal, Russia. Vanadium-bearing phlogopite is primary vanadium host in the deposit, although V-bearing oxides contribute substantially to the total V concentration, even where present in very trace amounts.

The purpose of this project was to determine the vanadium bearing ore minerals present at the Green Giant vanadium-graphite deposit in the S.W. of Madagascar owned by Toronto based Energizer Resources Inc. The rocks are mainly quartzofeldspathic gneiss, with alternating bands of hornblende biotite gneiss, marble, granitoid, and amphibolite. Using X-ray diffraction, electron microprobe analysis, and Raman spectroscopy, the vanadium bearing minerals were identified as vanadium bearing rutile, schreyerite, berdesinskiite, karelianite, a member of the karelianite-eskolaite solid solution, V-bearing phlogopite, V-bearing pyrrhotite, V-bearing pyrite, goldmanite, dravite, uvite, actinolite, and unidentified V-sulphide 1, V-sulphide 2, and V-silicate 1. The mineral assemblage present at Green Giant deposit is quite similar to that at Lake Baikal, Russia. Vanadium-bearing phlogopite is primary vanadium host in the deposit, although V-bearing oxides contribute substantially to the total V concentration, even where present in very trace amounts.

Master of Science / Department of Geology / Matthew W. Totten / Sands rich in volcanic ash have been encountered within the late Cenozoic sequence offshore Louisiana in the northern Gulf of Mexico. These beds are identified on well logs by their high radioactivity and low density. Paleontologic markers used to date these deposits give dates that are consistent with eruptions from the Snake River Plain (SRP) and Yellowstone calderas. Lead isotope ratios from the Gulf of Mexico samples are also consistent with the SRP-Yellowstone tuffs. The objective of this study was to compare the rare earth element (REE) and other trace element data from the GOM samples to determine whether they may be differentiated from one another, and also whether they compare to the SRP data. Well cuttings and sidewall core samples from sixteen wells known to contain volcanic ash were density separated using lithium metatungstate to isolate the low density volcanic glass from the remaining minerals. The concentrated ash was dissolved and analyzed using ICP-MS. Trace and REE variations were plotted by depositional age based upon paleontological markers. Variations in most trace elements are not useful criteria for discriminating ash by age. There is a wide spread in fairly mobile elements (i.e. Sr, Ba), suggesting that each ash bed has had a different diagenetic history. REE variations, in particular the magnitude of the Europium anomaly and the degree of fractionation between light and heavy REE, are good discriminates of each ash. A few anomalous samples plot within an older field, which might be explained by reworking of older ash into younger deposits. Direct correlation to SRP-Yellowstone eruptions is hindered by the lack of SRP samples analyzed using similar methods.

Master of Science / Department of Geology / Sambhudas Chaudhuri and Matthew Totten / The current model of hydrocarbon generation involves the thermogenic maturation of organic material as a consequence of burial. This process only considers energy generated from temperature increase due to burial. The majority of organic rich source beds contain high concentrations of radioactive elements, hence the energy produced from radioactive decay of these elements should be evaluated as well. Previous experiments show that α-particle bombardment can result in the generation of hydrocarbons from oleic acid. This study investigates the effects of γ-rays in a natural petroleum generating system. In order to determine the effects of γ-rays, experiments were conducted using cesium-137 as the γ-ray source at the KSU nuclear facilities to irradiate crude oil and organic material commonly found in petroleum systems. The samples were then analyzed using Fourier Transform Infrared Spectroscopy (FTIR) and Rock-Eval pyrolysis to determine changes in the samples. The FTIR results demonstrated that γ-radiation can cause the lengthening and/or shortening of hydrocarbon chains in crude oils, the dissociation of brine (H2O (aq)), the production of free radicals, and the production of various gases. These changes that come from γ-radiation hold the possibilities to distort the configuration of organic molecules, dissociate molecular bonds, and trigger oxidation-reduction reactions, all of which could provide an important step to the onset of dissociation necessary to create hydrocarbons in petroleum systems. Further understanding the effects of γ-radiation in hydrocarbons systems could lead to more information about the radiolytic processes that take place. This could eventually lead to further understanding of oil generation in organic-rich source beds.

Master of Science / Geology / Matthew Kirk / The Cherokee basin in southeastern Kansas is a declining coalbed methane (CBM) field where little is known about how the CBM formed, the extent to which it continues to form, and what factors influence its formation. An understanding of methanogenic processes and geochemistry could lead to potential enhancement of methane formation in the basin. The objectives of this project are to (1) determine the pathway of methane formation and (2) determine whether geochemistry has influenced gas formation. In order to reach the objectives, we analyzed formation water geochemistry, production history, and gas composition and isotopes. Post Rock Energy Corporation gave us access to 16 wells for sampling purposes. We collected gas samples in Isotubes® for compositional and isotopic analyses at a commercial laboratory. We analyzed major ion chemistry from formation water using standard methods. Co-produced water samples we collected are Na-Cl type with total dissolved solids content ranging from 35,367 to 91,565 mg/L. TDS tended to be highest in samples collected from wells with greater total depth. The pH and temperature of sampled water averaged 7.0 and 19°C with an alkalinity ranging from 3.33 to 8.59. Gas dryness and δ¹³C CH[subscript 4] range from 196 to 4531 and -69.95 to -56.5, respectively, which indicate that methane is being produced biologically. Comparing the δ¹³C CH[subscript 4] to the δD CH[subscript 4], which ranges from -228.2 to -217.2, suggest that the primary pathway of methanogenesis is H[subscript 2]/CO[subscript 2] reduction. We calculated Δ (the difference between δ values) in order to correlate isotope data to produced water chemistry. Samples ΔD and Δ¹³C values range from -189.1 to -168.7 and 61.52 to 69.99. Calculated ΔD[subscript CH4-H2O] and Δ¹³C[subscript CO2-CH4] values approach the range for the acetate/methyl pathways as Clˉ concentration increases, potentially indicating a slight shift in methanogenic pathway in deeper, more saline portions of the basin. The culturing results revealed that living methanogens are still able to utilize H[subscript 2], acetate, and methanol present in co-produced formation water from all tested wells.

Master of Science / Department of Geology / Sambhudas Chaudhuri / The exploration and development of unconventional shale plays provide an opportunity to study the hydrocarbon generation process. These unconventional plays allow one to investigate the interactions between the fluid, mineral, and organic material that occur in a hydrocarbon-generating source bed, before any changes in composition that may occur during secondary migration or post migration processes. Previous studies have determined the chemical constituents of formation waters collected from conventional reservoirs after secondary migration has occurred. This investigation targets formation waters collected from the Woodford shale that acts as both source and reservoir, therefore samples have yet to experience any changes in composition that occur during secondary migration. This investigation focuses on the major element and trace element chemistry of the formation water (Cl, Br, Na, K, Rb, Mg, Ca, Sr, and Rare Earth Elements), which has been compared to chemical constituents of the associated crude oil and kerogens. Analytical data for this investigation were determined by the following methods; Ion Chromatography, Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The information is used to assess the presence of different sources of water that constitute the formation water, and also to investigate interaction between different minerals and formation waters within the source beds. The formation water data also yields new insights into compartmentalization of oil-gas rich zones within the source beds.