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The rocks of the Appalachian orogen are world-class examples of collisional and extensional tectonics, where multiple episodes of mountain building and rifting from the pre-Cambrian to the present are preserved in the geologic record. These orogenic events produced plutonic rocks, which can be used as probes of the thermal state of the source region. SIMS (secondary ion mass spectrometry) U/Pb ages of zircons were obtained for ten plutons (Leatherwood, Rich Acres, Melrose, Buckingham, Diana Mills, Columbia, Poore Creek, Green Springs, Lahore and Ellisville) within Virginia. These plutons are distinct chemically, isotopically, and show an age distribution where felsic rocks are approximately 440 Ma, and Mafic rocks are approximately 430 Ma. Initial strontium isotopic ratios and bulk geochemical analyses were also performed. These analyses show the bimodal nature of magmatism within this region. In order to facilitate management of geologic data, including radiometric ages, strontium isotope initial ratios and major element geochemistry, a GIS based approach has been developed. Geospatially references sample locations, and associated attribute data allow for analysis of the data, and an assessment of the accuracy of field locations of plutons at both regional and local scales. The GIS based assessment of plutons also allows for the incorporation of other multidisciplinary databases to enhance analysis of regional and local geologic processes. Extending such coverage to the central Appalachians (distribution of lithotectonic belts, plutons, and their ages and compositions) will enable a rapid assessment of tectonic models. / Master of Science

In order to evaluate the electron microprobe (EMP) method for chemical dating of monazite, we chemically analyzed selected suites of monazite grains that were previously dated by standard U/Pb isotopic methods at three laboratories each equipped with a sensitive high resolution ion microprobe (SHRIMP). Representing diverse igneous and metamorphic lithologies, these grains yielded conventional isotopic ages ranging in age from Neoarchean to Devonian. Chemical dating was performed at Virginia Tech using a Cameca SX-50 EMP in which the analytical routines and settings were specifically optimized for monazite geochronology, including correction of analytical peaks for all major spectral interferences and correction of peak intensities for local background emission. Placement of cross-grain analytical traverses was based on backscattered electron (BSE) images together with wavelength-dispersive (WD) generated X-ray maps for Y, Th, U, and Ca, which revealed the internal compositional complexity of each grain. Shorter EMP traverses were selected adjacent to each SHRIMP pit in order to provide the best possible comparison of ages obtained by the two dating methods. Synthesis protocol for key elemental measurements (Y, Th, U, and Pb) was developed utilizing the 1Ï elemental errors associated with individual analyses, providing an objective approach for data synthesis. Analytical dates were either accepted or excluded based on analytical and spatial justifications. Isotopic dating techniques utilize three independent age calculations, provided the sample is old enough to have accumulated sufficient 207Pb (i.e., ≥~1000 Ma). Similarly, the chemical dating method can utilize two independent age calculations (i.e., Th/Pb and U/Pb) and a U-Th-Pbtotal centroid age in Th/Pb vs. U/Pb space, verified independently against the calculated Th* or U* CHIME ages. Across the entire 2,200 m.y. age range represented by the sample set, the chemical ages calculated from the EMP data chemical ages are internally consistent (within 2Ï error) with the previously measured SHRIMP isotopic ages, except in one case where bulk mixing of discrete age domains within an ablation pit led to an isotopically discordant apparent age. Overall, this study illustrates that EMP chemical dating (1) represents both an accurate and precise primary method for dating monazite from igneous and polymetamorphic terrains; (2) provides superior spatial resolution for obtaining meaningful ages from small and/or irregular domains of discrete age that may be irresolvable or misinterpreted by other dating techniques that sample larger volumes; and (3) illuminates the geological meaning of isotopically discordant monazite ages obtained using conventional methods with lower spatial resolution (e.g., SHRIMP). / Ph. D.

<p>U-Pb zircon results are presented with a U-Pb zircon Datatables for Bedrock Samples excel data sheet that have information for location (GPS and Geographic) and sample information. In addition, raw data formats of each individual sample is included that have additional information about laser settings per analysis.</p> <p><br></p> <p>Note the raw dataset for sample 062618WA-01 is included with two other analyses that are NOT bedrock samples. Use caution.</p> <p><br></p> <p>All analyses were conduction at the University of Arizona LaserChron Center ( <strong>NSF-EAR 1649254 </strong> )</p>

<p>U-Pb zircon datasets for Plutonic Clasts collected from conglomerate are presented first as a summary that includes sample name, GPS location, and datatables for each sample.</p> <p><br></p> <p>Additionally, raw datasets for each sample are included that includes detailed information on laser settings for each analyses</p> <p><br></p> <p>Note: Sample 062618WA-01 is included in one raw dataset as three igneous samples were analyzed on the same sample mount. This particular sample is a bedrock sample. Use caution</p> <p><br></p> <p>All analyses were completed at the University of Arizona Laserchron Center (NSF-EAR 1649254)</p>

<p>This dataset includes a summary excel file that details all the datatables for each detrital zircon sample and their location relative to each site and depth collected.</p> <p><br></p> <p>In addition to this summary, raw datasets for each individual analyses is included that have detailed information regarding the laser settings used for analyses.</p> <p><br></p> <p>All datasets were analyzed at the University of Arizona LaserChron Center (NSF-EAR 1649254)</p>

L'exploitation, puis l'abandon, des sites miniers, dans l'oriental marocain, a entraîné une importante pollution des zones avoisinantes, générée par la dispersion de déchets riches en Pb. Pour résoudre ce problème, des programmes de phytomanagement sont à développer. Cependant, la réalisation de ces projets se heurte à deux contraintes : une faible diversité des plantes métallophytes et une méconnaissance des mécanismes de la tolérance au Pb.Dans ce contexte, l'objectif de mon travail de thèse a été de sélectionner une ou des plantes susceptibles d'entrer dans un programme de phytoremédiation et d'identifier des gènes impliqués dans la tolérance au Pb. Dans un premier temps, l'analyse des sols et des résidus miniers a révélé une importante contamination polymétallique du site d'étude. Des prospections floristiques ont ensuite permis d'identifier une plante de la famille des brassicacées, Hirschfeldia incana, prédominante sur les sites miniers pollués et qui accumule le Pb. L'accumulation du Pb chez H. incana a été confirmée en conditions contrôlées et une stratégie « gène candidat » a montré l'implication dans la tolérance au Pb de deux gènes, l'un codant pour une métallothionéine MT2a et l'autre pour un transporteur membranaire HMA4. Enfin, la comparaison des transcriptomes d'H. incana et d'A. thaliana a abouti à l'édification d'une liste de gènes candidats susceptibles d'être impliqués dans la tolérance au Pb. L'analyse fonctionnelle de quatre de ces gènes, codant pour une ferritine, une métallothionéine, une protéine fixatrice du cuivre et une défensine, a précisé leur rôle dans la tolérance au Pb. / Exploited, and then abandoned, mining sites, in the oriental Morocco, have polluted the neighboring regions, by dispersion of mining wastes containing Pb. Facing this problem, it is necessary to develop phytomanagement programs. Nevertheless, these project realisations encountered two major constraints: weak metallophyte plant diversity and misunderstanding of Pb tolerance mechanisms. In this context, the objectif of my work was to select plants compatible with a phytoremediation program and to identify genes implicated in lead tolerance. Firstly, soil and mining waste analysis has revealed an important polymetallic pollution of the studied region. Then, floristic explorations had permitted to identify a plant of the brassicaceae family, Hirschfeldia incana, which is predominant on the polluted mining regions and accumulated Pb. Pb accumulation in H. incana was confirmed in controlled conditions and a candidate gene approach has shown the lead tolerance implication of two genes, one coding for a metallothionein (MT2A) and the other a membrane transporter (HMA4). Finally, the transcriptome comparison from H. incana and A. thaliana has generated a list of candidate genes putatively implicated in Pb tolerance. Functional analysis of four genes, coding a ferretin, a metallothionein, a copper binding protein and a defensin, has permitted to clarify their role in Pb tolerance.

Os radionuclídeos naturais das séries radioativas do 238U, 235U e 232Th são frequentemente utilizados como traçadores em estudos ambientais para a compreensão da dinâmica que ocorre no ambiente marinho e terrestre, como por exemplo, em pesquisas de processos oceânicos e gerenciamento da região costeira. No ambiente marinho, estes radionuclídeos podem ser empregados para estimar fluxos biogeoquímicos de partículas e de nutrientes que ocorrem tanto na coluna dágua, quanto nos sedimentos. Várias pesquisas aplicam a distribuição e o respectivo desequilíbrio dos radionuclídeos naturais no meio ambiente, inclusive em modelos geocronológicos para se obter informações históricas em testemunhos sedimentares. Nesse estudo, realizou-se a caracterização radioquímica das distribuições de 226Ra, 228Ra e 210Pb de uma coluna sedimentar denominada 1B (248 cm de comprimento), coletada na Baía do Almirantado, Antártica. A metodologia utilizada incluiu a lixiviação ácida de amostras de sedimentos, seguida de separação radioquímica sequencial de 226Ra e de 228Ra pela co-precipitação com Ba(Ra)SO4 e de 210Pb pela co-precipitação com PbCrO4. Todas as medidas foram realizadas pela contagem alfa e beta total dos precipitados obtidos, em um detector proporcional de fluxo gasoso de baixa radiação de fundo. As concentrações de atividade de 226Ra e 210Pb foram empregadas para se estimar a atividade de 210Pbnão-suportado presentes no perfil sedimentar 1B. Considerando-se as concentrações de atividade de 210Pbnão-suportado obtidas e a aplicação do modelo CIC(Constant Initial Concentration), foi possível determinar a taxa de sedimentação de 0,59±0,05 cm/ ano. / The natural radionuclides from radioactive series of 238U, 235U and 232Th have been applied as tracers in environmental studies for understanding the dynamics that occur in both marine and terrestrial environment, as for example, in research of oceanic processes and management of the coastal region. In the marine environment, these radionuclides can be used to estimate biogeochemical fluxes of marine particles and nutrients that occur in the water column as well as in the sediment. Several research works applied the distribution and the respective disequilibrium degree of natural radionuclides in the environment, including geochronological models for obtaining historical information on samples of certain sediment profile. In this study we performed a radiochemical characterization of the distribution of 226Ra, 228Ra and 210Pb from a sedimentary column called 1B (248 cm long) collected in the Admiralty Bay, Antarctic Peninsula region. The methodology used included the acid leaching of sediment samples followed by the radiochemical sequential separation of 226Ra and 228Ra by co-precipitation with Ba(Ra)SO4 and 210Pb by co-precipitation with PbCrO4. All measurements were carried out by counting of gross alpha and gross beta measures in a low background gas flow proportional detector. The activity concentrations of 226Ra and 210Pb were used to estimate the unsupported 210Pb activities present in sediment profile 1 B. Based on unsupported 210Pb data and the application of the CIC model (Constant Initial Concentration), it was possible to determine the sedimentation rate of 0.59 ± 0.05 cm /year.

O presente trabalho teve por objetivo compreender o papel de íons metálicos na degradação de gordura vegetal e animal, assim como na geração de formiatos. Nesse contexto foram investigados: 1) o papel de formaldeído na corrosão de peças de chumbo e a possibilidade de CO2 ser reduzido a ácido fórmico (ou formiato) por íons metálicos presentes em vidro; 2) o papel de íons metálicos na degradação de gordura animal e vegetal, desde que um grande número de pigmentos são minerais e tais gorduras foram frequentemente utilizadas em pinturas. Espectroscopia Raman foi a principal técnica empregada nas investigações, nas quais também foram usadas FTIR, difratometria de raios X, microscopia eletrônica de varredura, refletância no visível e análise elementar (C e H). Os resultados obtidos indicaram que formaldeído é agressivo a Pb mesmo na ausência de oxidantes como H2O2 e formiatos foram detectados como produto de corrosão para concentrações de aldeído tão baixa quanto 100 ppb (100% de umidade relativa). As concentrações investigadas de H2CO foram 100 ppb, 500 ppb, 1,2 ppm, 44 ppm e 1,6x102 ppm e para todas essas foram observadas bandas de carbonato e de formiato, embora em muitos casos os espectros não foram simplesmente a soma das contribuições das bandas de Pb(HCO2)2 e PbCO3, revelando um complexo equilíbrio envolvendo as concentrações de H2CO, CO2 e H2O. O efeito de umidade relativa (54%, 75% e 100%) foi estudado e formiato foi detectado mesmo em umidade relativa de 54%. Os mesmos produtos de corrosão foram observados quando cupons de Pb e PbO foram expostos a formaldeído, evidenciando o papel da camada de óxido na oxidação de formaldeído a formiato. Quando o efeito de Fe(III) foi considerado, câmaras climáticas foram usadas e o efeito de íons metálicos foi investigado na presença e ausência de luz. Linoleato de metila, gordura vegetal e animal foram mantidos por 8 dias sob condições controladas e as mudanças na composição foram acompanhadas por espectroscopia Raman e FTIR. As amostras mostraram ser sensíveis tanto a luz quanto a Fe(III), no entanto, problemas com as duplicatas não permitiram que conclusões pudessem ser obtidas dos experimentos. Como uma etapa preliminar no intuito de estender os estudos de degradação de gorduras à química forense, um desenho de suposta autoria de Tarsila do Amaral que teria sido feito na década de 1920, foi analisado por microscopia Raman. Ftalocianina azul (ftalocianina de cobre) foi encontrada como componente dos traços verdes e desde que esse pigmento começou a ser comercializado em 1937, pelo menos a data assinalada ao desenho não é correta. / The present work aimed at the understanding of the role played by metal ions on the degradation of vegetal and animal fats and on formates formation. The following issues were addressed: 1) the effect of formaldehyde on the corrosion of Pb objects and the possibility of CO2 reduction to formic acid (or formate) by the metal ions present in glass framework; 2) the effect of metal ions on the degradation of vegetal and animal fats, since a large number of pigments are minerals and such fats were often used as paint binders in the past. Raman microscopy was the main technique employed in the investigations which also used FTIR, XRD, SEM, UV-VIS absorption and elemental analysis (C and H). The obtained results indicated that formaldehyde is harmful towards Pb even in the absence of oxidants such as H2O2 and formates were detected among the corrosion products for aldehyde concentrations as low as 100 ppb (100% relative humidity). The investigated H2CO concentrations were 100 ppb, 500 ppb, 1,2 ppm, 44 ppm and 1,6x102 ppm for all of them bands assigned to carbonates and formate were observed, although in most cases the spectra were not simply the sum of Pb(HCO2)2 and PbCO3 contributions revealing a quite complex equilibria involving H2CO, CO2 and H2O concentrations. The effect of relative humidity (54%, 75% and 100%) was studied and formate was detected even at 54% RH. The same corrosion products were observed when both Pb cupons and PbO were exposed to formaldehyde thus making clear the role played by the oxide layer in the formaldehyde to formate oxidation. When the effect of Fe(III) was considered, a home made environmental chamber was used and the effect of the metal ions was investigated in the presence and absence of light. Methyl linoleato, vegetal and animal fats were kept by 8 days under controlled conditions and the changes on composition were followed by Raman and FTIR spectroscopies. The samples proved to be sensitive to both light and Fe(III), however, problems with the replicates so far don\'t allow any conclusion to be driven from the experiments. As a preliminary step in the attempt to extend the fat degradation study to forensic, a draw supposedly authored by Tarsila do Amaral in the 1920 decade was investigated by Raman microscopy. Phthalocyanine Blue (copper phthalocyanine) was found as a component of the green traces and since phthalocynines trade started in 1937, at least the date assigned to the draw is not correct

L’agriculture urbaine et périurbaines, bien que très pratiquée partout dans le monde est parfois mis en difficulté à travers l’utilisation de fertilisants nocifs. L’objectif général de cette thèse est de mener une étude du risque de la contamination du système sol-plante par les composés organométalliques du Pb Hg et Sn, dans un contexte d’agriculture urbaine caractérisé par l’utilisation des débris de combustion (DC) d’ordures ménagères issus des décharges urbaines, pour fertiliser les sols maraîchers. Dans cet objectif, les espèces Lactuca sativa, Amaranthus hybridus et Corchorus olitorius ont été cultivées sur des sols amendés par les DC, comme le font les agriculteurs in situ. Les sols amendés et non amendés ont été échantillonnés et les légumes ont été récoltés à quatre stades de leur croissance. Les métaux tels que le plomb (Pb), le mercure (Hg) et l’étain (Sn) ont été analysés sous leurs formes inorganiques et organiques par ICP-MS et GC-ICP-MS respectivement. Les résultats obtenus révèlent la présence du mono méthylmercure (MMeHg) dans les sols et dans les plantes avec des concentrations variant respectivement d’une valeur non détectée (nd) à 172 ng/g et de 7,8 ng/g à 34,7 ng/g. Le tétra éthyl Plomb (TEtPb) se révèle être le composé organoplombique (COP) le plus représenté dans les sols avec des concentrations variant de 18,4 ng/g à 44612 ng/g. Alors que c’est plutôt le mono éthyl plomb (MEtPb) qui est le COP le plus représenté dans les plantes, avec des concentrations variant de 0,78 ng/g à 56,9 ng/g. Les composés organostannique (COT) ont également été identifiés dans les sols et dans les plantes avec une prédominance du dibutyl étain (DBT) dans le sol, et du mono phényl étain (MPhT) dans la plante. Le suivi de l’accumulation de ces organométalliques par les plantes à différents stades de leur croissance, révèle globalement une diminution des quantités de polluants accumulées dans la plante entre le 1er stade de croissance et le stade de maturité. Les résultats des facteurs d’absorptions (Fa) ont mis en évidence le caractère phytodisponible des formes organométalliques dans le sol à l’exception du DBT. Ils ont aussi révélé les aptitudes hyper accumulatrices de A. hybridus et L. sativa vis-à-vis du TBT. Les résultats combinés des Fa, des facteurs de translocation et des rapports de mobilité entre le sol et les feuilles ont permis de mettre en évidence une translocation aisée ou facilitée des formes éthylées (TEtPb), butylées (TBT) et phénylées (MPhT) des racines vers les feuilles. Des trois espèces de plantes, C. olitorius se révèle être l’espèce la plus accumulatrice de MMeHg, de COP et COT. Mais au vue des doses d’expositions journalières (DEJ) à ces polluants toxiques par ingestion de ces légumes, c’est la consommation de L. sativa qui présente le plus grand danger pour le consommateur. D’ailleurs la consommation de ce légume donne une DEJ de MPhT qui est supérieure à la dose journalière admissible (DJA) des composés phénylées de l’étain. / Urban and suburban agriculture though widely practiced all over the world, sometimes faces difficulties due to the use of poor fertilizers. The objective of this thesis is to study the contamination risks of the soil-plant system by organometallic compounds (Pb, Hg and Sn), in a particular context of urban and suburban agriculture. To meet this goal, the species Lactuca sativa, Amaranthus hybridus and Corchorus olitorius were cultivated on soils amended with combustion debris (CD), like the farmers do in situ. The amended and non-amended soils are sampled and vegetables harvested at maturity on one hand, and at different stages of their growth on the other. The samples are treated, then the inorganic and organics forms of Pb, Hg and Sn are analyzed by ICP-MS and GC-ICP-MS respectively. The results obtained reveal the presence of mono methylmercury (MMeHg) in the soils and in the plants with concentrations respectively varying between nd to 171.567 ng/g and 7.83 ng/g to 34.72 ng/g. Tetra ethyl lead (TEtPb) is the most represented organo lead compounds (OLC) in the soils with concentrations ranging from 18.45 ng/g to 44611.959 ng/g respectively. Whereas in the plants, mono ethyl lead (MEtPb) is the most represented OLC with concentrations ranging from 0.78 ng/g to 56.90 ng/g. OTC were equally identified in the soils as well as in the plants with a predominance of dibutyl tin (DBT) in soil, and mono phenyltin (MPhT) in plants. Amongst the three plant species, C. olitorius turns out to be the species which accumulates MMeHg, OLC and OTC most. But in view of the of daily exposure doses (DED) to these toxic pollutants by ingestion of these vegetables, it is the consumption of L. sativa which presents the greatest danger. Moreover, consumption of this vegetable gives a DED of MPhT which is higher than its acceptable daily intake. The follow up of the accumulation of these organometallics by plants at different stages of their growth, revealed that the quantities of pollutants accumulated, decrease in the plant between first stage of growth and the maturity stage. The results of the absorption factors (Fa) have allowed to underline of phyto availability character of organometallics forms in soil, except for DBT. They have also revealed hyper accumulator abilities of A. hybridus and L. sativa for TBT. The combined results of Fa, translocation factor (Ft) and reports of mobility between the soil and the leaves (Rm (f/s)) have allowed to underline the facilitated translocation of ethylated (TEtPb), butylated (TBT) and phenylated (MPhT) forms, from the roots to the leaves.