Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes Bibliographical Information (leaves 22-24).

TEIXEIRA, Zulene Almada. Processos determinantes da qualidade das águas subterrâneas da Formação Jandaíra na Chapada do Apodi/CE. 2015. 144 f. Dissertação (Mestrado em geologia)- Universidade Federal do Ceará, Fortaleza-CE, 2015. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-13T20:40:37Z No. of bitstreams: 1 2015_tese_zateixeira.pdf: 5203981 bytes, checksum: a82cb8b3c9515c36265e407495350072 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-18T18:19:31Z (GMT) No. of bitstreams: 1 2015_tese_zateixeira.pdf: 5203981 bytes, checksum: a82cb8b3c9515c36265e407495350072 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-10-18T18:43:05Z (GMT) No. of bitstreams: 1 2015_tese_zateixeira.pdf: 5203981 bytes, checksum: a82cb8b3c9515c36265e407495350072 (MD5) / Made available in DSpace on 2016-10-18T18:43:05Z (GMT). No. of bitstreams: 1 2015_tese_zateixeira.pdf: 5203981 bytes, checksum: a82cb8b3c9515c36265e407495350072 (MD5) Previous issue date: 2015 / The Jandaíra Aquifer, located in the Apodi Plateau in Quixeré, Ceará, is used predominantly for irrigated agriculture and is an aquifer of nature karst and is unconfined. In the area was found contamination by human activities and due to high heterogeneity and anisotropy of permeability, rain infiltration differs from one point to another, resulting in different concentrations in the same aquifer. Was realized monitoring of the static level and the volume produced in 11 wells using datalogger. Six campaigns were realized for sampling 17 wells for analysis of major ions and measurements of electrical conductivity and pH; and 15 wells for measuring the presence of pesticides. Geochemical modelling was performed using PHREEQC to determine the molar ratios and saturation transfer to identify the processes which occur in the interaction of water and rock. The results indicate: i) static levels usually accompany seasonality and have different behaviors location to another with respect to recharge, due to the heterogeneous characteristics of the aquifer; ii) the hydrochemical analyzes show that predominate the relations HCO3- > Cl- and Ca2+ > Na+ > Mg2+ > K+, ions of natural origin; iii) NO3- is of anthropic origin, as well as part of K+; iv) 12 different types of pesticides were identified, mostly in the months of May, July, September and November/11, mostly in wells located in the discharge area; v) the Ca2+ ratio versus HCO3- indicates dissolution of carbonate minerals; vi) the geochemical modeling showed negative saturation indices of anhydrite minerals, gypsum and halite, indicating subsaturation solution in all waters of the sampled wells; aragonite and calcite had similar behavior, ranging from subsaturated to saturated; dolomite had a higher tendency to precipitation, especially in the second half, helped by the weather; vii) the increasing concentration of Na+ is due to the cation exchange process which reduces the saturation levels of carbonate minerals; viii) the molar transfers of calcite and dolomite in nine of the simulations indicate in five of them, dissolving condition; anhydrite and halite show evidence of dissolution in two simulations; ix) the simulated results show that the direction of flow is one of the dominant factors in the dissolution process and the cationic and gas exchange. / O Aquífero Jandaíra, localizado na Chapada do Apodi, em Quixeré, Ceará é utilizado, predominantemente, para a agricultura irrigada, sendo o mesmo de natureza cárstica e livre. Na área foi constatada contaminação por atividades antrópicas e por possuir elevada heterogeneidade e anisotropia da permeabilidade, a infiltração da chuva difere de um ponto a outro, resultando em concentrações distintas no mesmo aquífero. Foi realizado monitoramento do nível estático e volume explotado em 11 poços utilizando datalogger. Seis campanhas foram realizadas para coletas de amostras em 17 poços para análises dos íons maiores e medidas de condutividade elétrica e pH, e em 15 poços para medida da presença de agrotóxicos. Modelagem geoquímica foi realizada com o PHREEQC para determinação dos índices de saturação e transferência molar com o intuito de identificar os processos que ocorrem na interação água e rocha. Os resultados indicaram: i) os níveis estáticos, em geral acompanhando a sazonalidade, e tendo comportamentos distintos de um local a outro com relação à recarga, em função das características heterogêneas do aquífero; ii) que as análises hidroquímicas mostram a predominância das relações HCO3- > Cl- e Ca2+ > Na+ > Mg2+ > K+(íons de origem natural); iii) que o NO3- é de origem antrópica, assim como parte do K+; iv) que foram identificados 12 tipos diferentes de agrotóxicos, a maioria amostrados nos meses de maio, julho, setembro e novembro/11, em poços situados em área de descarga; v) que a relação Ca2+ versus HCO3- depende da dissolução de minerais carbonatados; vi) que a modelagem geoquímica mostrou índices de saturação negativos para os minerais anidrita, gipso e halita, sugerindo solução subsaturada em todas as águas dos poços amostrados. A aragonita e a calcita tiveram comportamento similares, variando de subsaturados a saturados. A dolomita apresentou maior tendência à precipitação, principalmente no segundo semestre, favorecida pela estiagem; vii) que o aumento da concentração de Na+ é decorrente do processo de troca catiônica diminuindo os índices de saturação dos minerais carbonatados; viii) que as transferências molares da calcita e da dolomita em nove simulações indicaram em cinco delas, condição de dissolução; anidrita e a halita mostraram evidência de dissolução em duas simulações; ix) que o sentido do fluxo é um dos fatores dominantes nos processos de dissolução e nas trocas catiônicas e gasosas.

The focus of this research is to characterize the risk of carbon sequestration under downhole conditions with regards to wellbore cement integrity. The primary research objective was to understand the geochemical interactions of simulated sequestration brines and wellbore cement. There are four key focuses of this study with regards to cement interaction: 1) Simulated brines saturated with Supercritical CO2 and CO2-O2; 2) Adjacent formation host rock under sequestration conditions; 3) Geochemical modeling using CHIM-XPT based on the experimental studies of points 1) and 2) above; 4) Geomechanical strength tests of CO2 exposed cements. First, the interaction of cement with supercritical CO2, CO2-saturated brines, and CO2-O2 mixtures at 50 °C, 85 °C, and 28.9 MPa was evaluated. Cement exposed to a lower salinity brine (1 M) had a larger alteration depth (1.25 mm) compared to cement exposed to a higher salinity brine (2.2 M) (0.836 mm). CO2-O2 exposed cements displayed alteration depths of 1.6 mm at 85 °C and 0.7 mm at 50 °C for 1 M. The cement exposed to the 2.17 M solution had an alteration extending 1.685 mm. The second focus studied the influence of adjacent formations and observed mineral trapping in the Grande Ronde Basalt-cement. Studies of Mt. Simon Sandstone-cement interaction provided evidence for high CO2 storage capacity. The third focus is geochemical modeling using CHIM-XPT. Pure CO2 saturated brines yielded a pH of 3.0 at 1 M and 3.85 at 2.17 M. The CO2-O2 gas run calculated a pH of 3.96 at 1 M and 3.85 at 2.17 M. The Pasco solution after exposure had a pH of 6.97 and an estimated dissolved 161 g of CO2 (g). The pH of the Illinois Basin brine and Mt. Simon sandstone [and cement paste] was 5.8 with an estimated 139 g of CO2 consumed. Lastly, geomechanical tests on CO2 exposed cements indicated that addition of oxygen or changes in temperature play a key role in compressive and tensile strength, decreasing strength by 20-35%. This research highlighted the importance of representing the in-situ wellbore environment when conducting laboratory experiments. This dissertation includes previously published and unpublished co-authored material.

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.

M.Sc. (Geology) / The purpose of this study was to assess the MLA’s ability to characterise (e.g. modal mineralogy, elemental assay, particle size distribution, particle density distribution and mineral associations) a coal product from New Vaal Colliery, with the aim to determine any liberation and beneficiation characteristics. In general the MLA assessment on coal is comparatively new and novel, especially at Spectrum (University of Johannesburg), hence research in this regard is required. For the first time New Vaal coal product was characterised with the MLA 600 FEG SEM. The coal product supplied to Lethabo Power Station for the study’s samples, consisted of Top Seam and Middle Seam coal from New Vaal Colliery which is located in the Cornelia subbasin of the Vereeniging-Sasolburg coalfield, South Africa. The proximate analysis characterised the coal as a high-ash (42.25% air-dried) and low calorific value (13.92 MJ/kg air-dried) product. Chemically SiO2 was the most abundant oxide followed by Al2O3 for the XRF analysis, which was mostly derived from the abundant kaolinite clay mineral (determined by petrography, XRD and MLA analysis). Mineralogically inertinite was the most abundant coal maceral encountered during the petrographic analysis. With geochemical characterisation, chalcophile, siderophile, lithophile and radioactive trace elements were found to be mostly comparable to the global average.

Magister Scientiae - MSc / The complex nature and composition of regolith cover in Southern Africa is a major challenge to geochemical mapping for concealed mineralization. Some of the setbacks to successful geochemical exploration may be ascribed to the use of various partial extraction techniques,without a profound understanding of the regolith components and their composition. This investigation therefore focuses on the use of hydroxylamine partial extraction geochemistry for geochemical mapping in regolith over two contrasting environments viz; aeolian sand-calcrete regolith over Au mineralization at Amalia Blue Dot Mine in South Africa and lateritic regolith covering the Ni-Cu deposit at Kabanga Main and Luhuma in Tanzania. Regolith samples from the above areas were sieved and extracted with hydroxylamine hydrochloride solution and analyzed for multi-element by AAS and ICP-MS techniques. A stepwise optimization of the hydroxylamine extraction technique of samples from both areas was carried out and incorporated into the analytical programme (in a pilot study). Results of hydroxylamine partial extraction generally gave better anomaly contrast and reflection of bedrock mineralization than the conventional aqua regia techniques that were previously used in the region. The results however show that lateritic regolith may be best extracted using 0.25M hydroxylamine while 0.1M concentration appears most suitable for extraction of aeolian-calcrete regolith. The above results are corroborated by principal component analysis of the analytical data that show various element associations, e.g. with Fe-Mn oxides while others possibly belong to the loosely adsorbed or exchangeable group. The gochemical maps in the pilot study areas at Amalia, Kabanga and Luhuma show elevated element contents or clusters of anomalies of diverse elements associated with Fe-Mn oxides. Geochemical mapping at Kabanga with deeply concealed mineralization however shows variability of subdued element patterns over mineralized areas. Geochemical signatures associated with hydroxylamine hydrochloride partial leach are therefore characterized by a lower geochemical background than that using conventional aqua regia leach. This study leads recommending for further investigations into partial extraction of the exchangeable group of elements, possibly using ammonium acetate. / South Africa

An awareness of mercury (Hg) contamination in various aquatic environments around the world has increased over the past decade, mostly due to its ability to concentrate in the biota. Because the presence and distribution of Hg in aquatic systems depend on many factors (e.g., pe, pH, salinity, temperature, organic and inorganic ligands, sorbents, etc.), it is crucial to understand its fate and transport in the presence of complexing constituents and natural sorbents, under those different factors. An improved understanding of the subject will support the selection of monitoring, remediation, and restoration technologies. The coupling of equilibrium chemical reactions with transport processes in the model PHREEQC offers an advantage in simulating and predicting the fate and transport of aqueous chemical species of interest. Thus, a great variety of reactive transport problems could be addressed in aquatic systems with boundary conditions of specific interest. Nevertheless, PHREEQC lacks a comprehensive thermodynamic database for Hg. Therefore, in order to use PHREEQC to address the fate and transport of Hg in aquatic environments, it is necessary to expand its thermodynamic database, confirm it and then evaluate it in applications where potential exists for its calibration and continued validation. The objectives of this study were twofold: 1) to develop, expand, and confirm the Hg database of the hydrogeochemical PHREEQC to enhance its capability to simulate the fate of Hg species in the presence of complexing constituents and natural sorbents under different conditions of pH, redox, salinity and temperature; and 2) to apply and evaluate the new database in flow and transport scenarios, at two field test beds: Oak Ridge Reservation, Oak Ridge, TN and Everglades National Park, FL, where Hg is present and is of much concern. Overall, this research enhanced the capability of the PHREEQC model to simulate the coupling of the Hg reactions in transport conditions. It also demonstrated its usefulness when applied to field situations.

SUMMARY: The diploma thesis is focused on application of natural science methods - geophysics and above all geochemistry - in archaeology. Geophysical and geochemical techniques have become an integral part of non-destructive archaeology over time. While geophysical methods have been practiced in a wide array of archaeological surveys for many decades, geochemical methods have been used to a greater extent up to in recent years. In addition, the application of geochemistry in archaeology is, in most cases, limited only to the analysis of phosphates in soil applied to small spatial units. The potential of geochemistry in dealing with archaeological issues remains still unused due to the limited understanding of the context. This is also reflected in the absence of publications that would allow a good-quality interpretation of geochemical data in connection with archaeology. Geophysical and geochemical procedures were applied during the survey of the selected area in the locality of Hillfort Vinoř, located on the northeastern outskirts of Prague. The aim of this survey was to contribute to the widening of the existing knowledge of the locality with an emphasis on the wider context. Two methods were chosen for the geophysical survey - dipole electromagnetic profiling (DEMP) and electrical resistivity...

Groundwater is documented to flow through solution-widened fractures and bedding planes in limestone and dolostone units in low-relief topography. This enhancement, or karstification, is much harder to study in alpine environments like the Bear River Range of northern Utah. This is problematic, due to the fact that the Bear River Range karst aquifer system supplies the City of Logan with a large quantity of water at Dewitt Spring. Furthermore, the karst aquifer sustains the Logan River for much of the year, and may allow groundwater to flow directly in the subsurface to the Cache Valley principal aquifer system. Flow measurements along the Logan River constrain a minimum volume of 2.32x106 m3 /y (1.88x103 af/y) that could recharge the Cache Valley principal aquifer. Hydraulic characteristics of alpine karst were estimated by analysis of major ions, stable isotopes, and dissolved gases in spring waters. These data reflect quick groundwater flow through caverns, with no evidence for “diffuse” flow anticipated by some to occupy interstitial space. In fact, the oldest reasonable estimated recharge age for groundwater is 70 years. Young recharge, fast flow, and low storage capability indicate that alpine karst aquifers are very sensitive to droughts and that related water resources are vulnerable to longer-term changes in climate.

Lithic source analysis, or “sourcing,” is a geochemical compositional analysis of lithic materials for both major and trace elements. Sourcing analysis assigns lithic sources to geochemical groups according to distinct geochemical compositions, where unique elemental signatures represent separate lithic sources. In archaeological research, sourcing informs upon mobility strategies, trade and exchange networks, and lithic conveyance studies. While obsidian sourcing is a relatively reliable and popular technique, chert sourcing is more difficult and historically less successful largely due to variability in chert formation processes. X-ray fluorescence spectrometry (XRF) offers a possible sourcing technique, and is non-destructive, as well as time and cost-effective. In this thesis, I test the reliability of XRF in determining the geochemical characterization of Tosawihi Quarries chert, a unique chert source located in the Humboldt River Basin of north-central Nevada. The Tosawihi Quarries archaeological district (26EK6624) is a significant lithic resource that has hosted human occupation and activity for millennia. The Tosawihi Quarries offers a high quality toolstone that was intensely used, as indicated by numerous quarry locales and biface tool caches. Additionally, the Tosawihi Quarries is a social identity marker for the Tosawihi band of Western Shoshone, also serving as a source of spirituality and medicine. Tosawihi chert is a distinct, white lithic material type that also has a characteristic fluorescence pattern when exposed to ultraviolet light. While these are defining attributes, they are not unique to Tosawihi chert, as they occur in other Great Basin white chert sources. Identifying Tosawihi chert has been problematic, and misidentifications may have led to erroneous interpretations of the archaeological and ethnographic records. If successful, a geochemical characterization by XRF would provide an elemental signature specific to Tosawihi chert, thus eliminating discrepancies in visual and ultraviolet fluorescence readings and permitting archaeologists to accurately asses the distribution and use of this sacred material. In this thesis research, I first conducted an XRF analysis of a source standard collection of Tosawihi Quarries chert, which yielded a preliminary methodology for identifying Tosawihi chert. This protocol was tested against two comparative collections of other Great Basin white cherts: Mono Lake Spillway located in western Nevada and Pahute Mesa (26NY1408) located in southern Nevada. The methodology, now refined, was then run against the archaeological collection, where five collections of white chert artifacts were tested for the presence of Tosawihi chert. Incorporating both the qualitative and quantitative data from XRF analysis, the results show that this proposed methodology can successfully discriminate between Tosawihi chert and other Great Basin white cherts based on its XRF signature.