In this dissertation, I discuss the role of organic residue analysis in identifying economic activities and subsistence practices associated with the first uses of pottery in the Middle East, and present the results of my analyses of 280 potsherds recovered from 22 Neolithic and early Chalcolithic settlements dating between 7300 and 4300 cal BC. The adoption of pottery vessels in the early agricultural villages and pastoral encampments of the Middle East was not a uniform phenomenon, with this new technology not immediately of benefit, apparently, to all human groups. Results of my analyses have demonstrated that ‘conventional’ solvent extraction and alkaline hydrolysis techniques have limited utility in the recovery of diagnostic organic compounds from pottery from early ceramic horizons in the Middle East (Gregg et al. 2007), and that increased yields can be achieved through the use of a microwave-assisted liquid chromatography protocol (Gregg et al. 2009; Gregg and Slater in press). My research has established that there is greater diversity in the fractionation of stable carbon isotopes associated with the synthesis of fatty acids in domesticated animals than has previously been reported. In many instances, the ranges of modern isotopic values that have been used to categorize animal fats in archaeological potsherds in northern Europe cannot distinguish between the ∂13C ratios of ancient dairy residues and carcass fats of ruminant and non-ruminant species in central Europe or the Middle East (Gregg et al. 2009; Gregg and Slater in press). In light of these results, I evaluate the diagnostic potential and limitations of different methodological approaches in the recovery and characterization of organic residues, and propose a series of measures that will allow more confident categorization of the substances in early pottery vessels from the Middle East. I also make a number of recommendations for archaeologists considering the use of organic residue analysis, and suggest some practical ideas on how to develop the degree of confidence necessary to assess the methods used in acquisition of molecular and isotopic data, and ultimately, to evaluate the adequacy of the analytical criteria used to address specific archaeological research questions.

Two new analytical methodologies were developed for chlorine and bromine stable isotope analyses of inorganic samples by Continuous-Flow Isotope Ratio Mass Spectrometry (CF-IRMS) coupled with gas chromatography (GC). Inorganic chloride and bromide were precipitated as silver halides (AgCl and AgBr) and then converted to methyl halide (CH3Cl and CH3Br) gases and analyzed. These new techniques require small samples sizes (1.4 µmol of Cl- and 1 µmol of Br-). The internal precision using pure CH3Cl gas is better than ∓0.04 ‰ (∓STDV) while the external precision using seawater standard is better than ∓0.07 ‰ (∓STDV). The internal precision using pure CH3Br gas is better than ∓0.03 ‰ (∓STDV) and the external precision using seawater standard is better than ∓0.06 ‰ (∓STDV). Moreover, the sample analysis time is much shorter than previous techniques. The analyses times for chlorine and bromine stable isotopes are 16 minutes which are 3-5 times shorter than all previous techniques. Formation waters from three sedimentary settings (the Paleozoic sequences in southern Ontario and Michigan, the Williston Basin and the Siberian Platform) were analyzed for 37Cl and 81Br isotopes. The δ37Cl and δ81Br values of the formation waters from these basins are characterized by large variations (between -1.31 ‰ and +1.82 ‰ relative to SMOC and between -1.50 ‰ and +3.35 ‰ relative to SMOB, respectively). A positive trend between δ81Br and δ37Cl values was found in all basins, where an enrichment of δ81Br is coupled by an enrichment of δ37Cl. In the Paleozoic sequences in southern Ontario and Michigan, the δ37Cl and δ81Br signatures of formation water collected from northwest of the Algonquin Arch are distinct from those collected from southeast of the Arch. All of the brines from the northwest of the Algonquin Arch are characterized by depleted isotopic values in comparison with the isotopic values from the brines from southeast of the Arch. The δ81Br signatures of the two brines show total separation with no overlaps. The δ37Cl values show some overlap between the two groups. One of the scenarios that can be put forward is that the Arch forms a water divide, where sediments southeast of the Arch are dominated by Appalachian Basin formation waters, and the sediments located northwest of the Arch are dominated by the Michigan Basin formation waters. The δ81Br and δ37Cl signatures of the Williston Basin brines suggest the existence of several different brines that are isotopically distinct and located in different stratigraphic units, even though they are chemically similar. The relatively wide range of δ37Cl and δ81Br of the formation waters suggests that the ocean isotopic signatures were variable over geologic time. A seawater temporal curve for δ81Br and δ37Cl was proposed with a larger variation of δ81Br in comparison with δ37Cl. The isotopic variations of these two elements agree very well with 87Sr/86Sr seawater variation during the same period. In general, the use of chlorine and bromine stable isotopes can be very useful in assessing the origin and the evolutionary processes involved in evolving formation waters and also in distinguishing different brines (end members). Furthermore, they can be employed to investigate the hydrogeological dynamics of sedimentary basins.

Two new analytical methodologies were developed for chlorine and bromine stable isotope analyses of inorganic samples by Continuous-Flow Isotope Ratio Mass Spectrometry (CF-IRMS) coupled with gas chromatography (GC). Inorganic chloride and bromide were precipitated as silver halides (AgCl and AgBr) and then converted to methyl halide (CH3Cl and CH3Br) gases and analyzed. These new techniques require small samples sizes (1.4 µmol of Cl- and 1 µmol of Br-). The internal precision using pure CH3Cl gas is better than ∓0.04 ‰ (∓STDV) while the external precision using seawater standard is better than ∓0.07 ‰ (∓STDV). The internal precision using pure CH3Br gas is better than ∓0.03 ‰ (∓STDV) and the external precision using seawater standard is better than ∓0.06 ‰ (∓STDV). Moreover, the sample analysis time is much shorter than previous techniques. The analyses times for chlorine and bromine stable isotopes are 16 minutes which are 3-5 times shorter than all previous techniques. Formation waters from three sedimentary settings (the Paleozoic sequences in southern Ontario and Michigan, the Williston Basin and the Siberian Platform) were analyzed for 37Cl and 81Br isotopes. The δ37Cl and δ81Br values of the formation waters from these basins are characterized by large variations (between -1.31 ‰ and +1.82 ‰ relative to SMOC and between -1.50 ‰ and +3.35 ‰ relative to SMOB, respectively). A positive trend between δ81Br and δ37Cl values was found in all basins, where an enrichment of δ81Br is coupled by an enrichment of δ37Cl. In the Paleozoic sequences in southern Ontario and Michigan, the δ37Cl and δ81Br signatures of formation water collected from northwest of the Algonquin Arch are distinct from those collected from southeast of the Arch. All of the brines from the northwest of the Algonquin Arch are characterized by depleted isotopic values in comparison with the isotopic values from the brines from southeast of the Arch. The δ81Br signatures of the two brines show total separation with no overlaps. The δ37Cl values show some overlap between the two groups. One of the scenarios that can be put forward is that the Arch forms a water divide, where sediments southeast of the Arch are dominated by Appalachian Basin formation waters, and the sediments located northwest of the Arch are dominated by the Michigan Basin formation waters. The δ81Br and δ37Cl signatures of the Williston Basin brines suggest the existence of several different brines that are isotopically distinct and located in different stratigraphic units, even though they are chemically similar. The relatively wide range of δ37Cl and δ81Br of the formation waters suggests that the ocean isotopic signatures were variable over geologic time. A seawater temporal curve for δ81Br and δ37Cl was proposed with a larger variation of δ81Br in comparison with δ37Cl. The isotopic variations of these two elements agree very well with 87Sr/86Sr seawater variation during the same period. In general, the use of chlorine and bromine stable isotopes can be very useful in assessing the origin and the evolutionary processes involved in evolving formation waters and also in distinguishing different brines (end members). Furthermore, they can be employed to investigate the hydrogeological dynamics of sedimentary basins.

Isotopic methods have been developed over the last 10 years as a method for determining chemical interactions of chlorinated solvents. These methods are especially promising for. This study attempts to employ and develop compound specific isotopic analyses of TCE and cDCE, along with chemical data, to characterize the degradation of TCE in a fractured bedrock aquifers. The Smithville site is a contaminated field site with extremely high levels of TCE contamination that is currently undergoing monitored remediation. From December 2008 until April 2010 extended samples were collected from the site to provide additional data analyses including isotopic data. The redox conditions at the site are anoxic to reducing, with sulfate reduction and methanogenesis as dominant terminal electron accepting processes. Redox data indicates that well electrochemical conditions are highly variable within the site, including areas near the source zone that not very reducing. Documented changes in groundwater conditions to much more reducing environments indicate that oxidation of organic matter is occurring at the Smithville site in select wells. Chemical analyses of TCE, DCE, VC, ethene and ethane are employed determine whether reductive dechlorination was occurring at the site. Results of field testing indicate that many wells on site, especially in the proximity of the source zone, dechlorination products were found. The isotopic data had a high range in both carbon and chlorine isotopes. Chlorine isotopic data ranges from a δ37Cl(TCE) of 1.39 to 4.69, a δ37Cl(cDCE) of 3.57 to 13.86, a δ13C(TCE) of -28.9 to -20.7, and a δ13C(cDCE) of -26.5 to -11.82. The range in values indicate varying degrees of degradation throughout the site, with the same wells grouping together. Combined chemical, redox and isotopic data shows that degradation seems to be a removal process for TCE at the Smithville site. Concentrations of chemicals created as a result of TCE degradation verify degradation, especially in wells 15S9, R7 and 17S9. Historically production of DCE in significant amounts, above 1.0 ppb, was observed to only occur after 2003. In addition to this, DCE data shows that the percentage of DCE made up of cDCE is above 96%. This indicates that microbes most likely mediate the processes that formed DCE from TCE. The linear regression of the delta-delta plot for isotopic TCE data shows line that is likely a direct function of the carbon and chlorine isotopic fractionation imparted upon the original TCE released. The slope found is consistent with data collected from other studies though cannot be applied to determining the process directly given the range of variability in isotopic field data.

Natural gas is an important transitional energy source to replace more carbon intensive coal combustion in the face of climate change and increasing global energy demands. A significant proportion of natural gas reserves (~20%) were recently generated by microorganisms that degrade organic-rich formations (i.e. coal, shale, oil) in-situ to produce methane. Recent studies have shown that these microbial communities may be potentially stimulated to generate more methane to extend the lifetime (~10 years) of existing biogenic gas wells. This dissertation investigates how microbial coalbed methane (CBM) systems are impacted by geochemical conditions, microbial community composition, and groundwater recharge. The first study is a review and synthesis of existing basic research and commercial activities on enhancement of microbial CBM generation, and identification of key knowledge gaps that need to be addressed to advance stimulation efforts. The second study couples water and gas geochemistry with characterization of microbial communities in coalbeds in the Powder River Basin (PRB), Wyoming to investigate the influence of microbiology on water and gas geochemistry. Geochemistry results indicated that nutrients are likely source in situ from coal, and that all sulfate must be removed from the system before methanogenesis will commence. Increased archaeal (i.e. methanogens) diversity was observed with decreasing sulfate concentration, while sulfate reducing bacterial communities were different in wells with high sulfate concentrations (sulfate reducing conditions) when compared to wells with low sulfate concentrations (methanogenic conditions). The third study uses noble gases to constrain the residence time of groundwater associated with CBM in the PRB. Measured diffusional release rates of 4He from PRB coals were ~800 times greater than typical rates observed in sandstone or carbonate aquifers, and measured 4He values far exceeded expected values from in-situ decay of U and Th. Groundwater 4He residence times ranged from <1 to ~800 years using the measured diffusion rates versus ~130 to 190,000 years using a standard model. Coal waters with the longest residence time had the highest alkalinity concentrations, suggesting greater extents of microbial methanogenesis, although there was no relationship between groundwater "age" and methane concentrations or isotopic indicators of methanogenesis. Constraining the relationship between microbial activity (e.g. mechanisms of coal biodegradation and methane generation), environmental geochemical conditions, and groundwater flow is important to better understand subsurface hydrobiogeochemical processes and to ensure the success of future projects related to stimulation of microbial CBM.

Following the 2010 Deepwater Horizon (DWH) spill, sediment cores were analyzed from marshes at various levels of oiling to determine how deeply oil penetrated sediment in these marsh environments, and if at these sites it had quantifiably affected benthic ecosystems. Minimum mixing depths were determined from penetration of the lithogenic radionuclide 234Th, which ranged from 0.25 to 4.5 cm. Sediment accumulation rates were determined using 210Pb, with verification from 137Cs in selected cores. Lead-210 profiles revealed long-term (decadal) mixing. Bay Jimmy, Louisiana was significantly affected by the DWH oil spill, as indicated by total polycyclic aromatic hydrocarbon concentrations of up to 21,913 ppb. This is far above the level at which adverse biological effects occur (4,022 ppb). Benthic foraminifera responded to the heavy oiling by decreases to standing stock and depth of habitation relative to unoiled sites, as well as exhibiting deformities. These data clearly show that oil can be quickly mixed into salt marsh sediments, with demonstrable impacts on indigenous benthos. Further, radioisotope inventories indicated that most of the sampled sites are in a net erosional state. Should marshes containing trapped DWH oil be submerged by rising sea level, there is a great potential for the remobilization of oil.

We investigated oceanic dissolved inorganic nitrogen (N) dynamics, focussing on processes removing bio-available N and ultimately affecting primary productivity, in sulfidic hydrothermal vent fluids discharging from the subsurface on the Juan de Fuca Ridge (northeast Pacific Ocean) and in anoxic bottom waters of Saanich Inlet, a British Columbia fjord, using a combination of geochemical and molecular microbial ecology techniques. During episodes of mixing with oxygenated sea-water, both systems can switch from anoxic to oxic conditions. Strong inter-site variations in the concentrations and δ15N of ammonium (NH4+) in high-T fluids suggested different N sources (deep-sea nitrate (NO3-) versus organic sediments) for hydrothermally discharged NH4+. Increase in the isotopic composition of NO3- (δ15N and δ18O), concomitant with decreased [NO3-], indicated NO3- assimilation or denitrification in the subsurface. NO3- isotope anomalies, i.e. deviations from the 15N:18O isotopic enrichment of 1:1 in marine environments, were observed and confirmed the occurrence of NO3- regeneration in vent fluids. Denitrification was the dominant N-loss pathway, suggesting that bacterial denitrification out-competes anaerobic NH4+ oxidation (anammox) in diffuse hydrothermal vent waters. The diversity of denitrifying bacteria encoding the nirS-form of nitrite reductase was low in vent fluids. Quantitative polymerase chain reaction (qPCR) analysis revealed that denitrifiers accounted for up to 38% (nirk-encoding γ-proteobacteria of the SUP05 cluster) and 8% (nirS-encoding bacteria) of the total bacterial abundance. Furthermore, nirS gene operational taxonomic units from two vent fields clustered into different groups in the phylogenetic tree, suggesting a link between denitrifying bacterial community membership and small-scale geographic isolation and/or fluid physico-chemical properties. Significant correlations existed between fixed N-loss rates and in-situ dissolved inorganic N deficits in the fluids. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated that up to ~10 Tg N yr−1 could be removed globally in the subsurface biosphere. In Saanich Inlet, a gradual increase in both the δ15N and δ18O of NO3- associated with a decrease in [NO3-] and an increase in biological excess N2, was observed after bottom water renewal events in fall 2008, following NO3- consumption by denitrifiers in an expanding suboxic zone. N-to-O negative NO3- isotope anomalies were observed in surface and bottom waters, confirming the occurrence of NO3- regeneration and/or external NO3- input. Closed and open-system-model derived NO3- isotope effects in anoxic bottom waters were lower (as low as ~11‰) than the ~25‰ for water column denitrification reported in other studies, suggesting that ~50% of the denitrification could occur, with a highly suppressed isotope effect, in the sediments of the Inlet. / Graduate

Isotopic methods have been developed over the last 10 years as a method for determining chemical interactions of chlorinated solvents. These methods are especially promising for. This study attempts to employ and develop compound specific isotopic analyses of TCE and cDCE, along with chemical data, to characterize the degradation of TCE in a fractured bedrock aquifers. The Smithville site is a contaminated field site with extremely high levels of TCE contamination that is currently undergoing monitored remediation. From December 2008 until April 2010 extended samples were collected from the site to provide additional data analyses including isotopic data. The redox conditions at the site are anoxic to reducing, with sulfate reduction and methanogenesis as dominant terminal electron accepting processes. Redox data indicates that well electrochemical conditions are highly variable within the site, including areas near the source zone that not very reducing. Documented changes in groundwater conditions to much more reducing environments indicate that oxidation of organic matter is occurring at the Smithville site in select wells. Chemical analyses of TCE, DCE, VC, ethene and ethane are employed determine whether reductive dechlorination was occurring at the site. Results of field testing indicate that many wells on site, especially in the proximity of the source zone, dechlorination products were found. The isotopic data had a high range in both carbon and chlorine isotopes. Chlorine isotopic data ranges from a δ37Cl(TCE) of 1.39 to 4.69, a δ37Cl(cDCE) of 3.57 to 13.86, a δ13C(TCE) of -28.9 to -20.7, and a δ13C(cDCE) of -26.5 to -11.82. The range in values indicate varying degrees of degradation throughout the site, with the same wells grouping together. Combined chemical, redox and isotopic data shows that degradation seems to be a removal process for TCE at the Smithville site. Concentrations of chemicals created as a result of TCE degradation verify degradation, especially in wells 15S9, R7 and 17S9. Historically production of DCE in significant amounts, above 1.0 ppb, was observed to only occur after 2003. In addition to this, DCE data shows that the percentage of DCE made up of cDCE is above 96%. This indicates that microbes most likely mediate the processes that formed DCE from TCE. The linear regression of the delta-delta plot for isotopic TCE data shows line that is likely a direct function of the carbon and chlorine isotopic fractionation imparted upon the original TCE released. The slope found is consistent with data collected from other studies though cannot be applied to determining the process directly given the range of variability in isotopic field data.

Os modelos para a formação de plútons alcalinos da Província Alcalina do Sudeste Brasileiro ou Alinhamento Poços de Caldas-Cabo Frio associam a gênese destas rochas a grandes reativações ou a passagem de uma pluma mantélica, registrada pelo traço de um hot spot. O objetivo desta tese é, apresentar novos dados e interpretações para contribuir com a melhor elucidação e discussão destes modelos. Os estudos incluem mapeamento, petrografia, litogeoquímica, geoquímica isotópica de Sr, Nd e Pb e datação 40Ar/39Ar. As intrusões selecionadas correspondem ao Morro Redondo, Mendanha e Morro de São João, no Rio de Janeiro, localizados em posições distintas no alinhamento Poços de Caldas-Cabo Frio. A intrusão alcalina do Morro Redondo é composta majoritariamente de nefelina sienitos e sienitos com nefelina, com rara ocorrência de rochas máficas e é caracterizada por uma suíte alcalina sódica insaturada em sílica, de caráter metaluminosa a peralcalina. Esta intrusão foi datada em aproximadamente 74 Ma (idade-platô 40Ar/39Ar). A intrusão alcalina do Mendanha é composta por diversos tipos de rochas sieníticas, além de brechas e estruturas subvulcânicas, como rochas piroclásticas e diques e caracteriza-se por ser uma suíte alcalina sódica saturada em sílica, de caráter metaluminosa, diferente do que ocorre no Marapicu, este subsaturado em sílica. Esta intrusão apresentou duas idades-platô 40Ar/39Ar distintas de magmatismo: 64 Ma para as rochas do Mendanha e 54 Ma em dique de lamprófiro, registrando magmatismo policíclico. O Morro do Marapicu foi datado em aproximadamente 80 Ma. Já a intrusão alcalina do Morro de São João possui uma ampla variedade de litotipos saturados a subsaturados em sílica, tais como sienitos, álcali-sienitos e monzossienitos (alguns portadores de pseudoleucita), com variedades melanocráticas, tais como malignitos e fergustios. Estas rochas definem suas distintas suítes alcalinas subsaturadas em sílica: Uma de composição sódica e outra potássica. Há também uma suíte alcalina saturada em sílica, definida por gabros alcalinos e shonkinitos. A petrogênese destas intrusões corresponde ao modelo de cristalização fracionada, com assimilação de rochas encaixantes (AFC) como indicado pela alta variabilidade de razões isotópicas de estrôncio. No Morro de São João é sugerido o modelo de mistura magmática. Estas intrusões foram geradas a partir de magmas mantélicos enriquecidos, possivelmente associados à antiga zona de subducção relacionada ao orógeno Ribeira. Em razão das novas idades obtidas, o modelo de hot spot proposto fica prejudicado, visto que o Marapicu é de idade mais antiga das intrusões analisadas, o que era esperado para o Morro Redondo. Alguns modelos projetam plumas mantélicas com aproximadamente 1000 km de diâmetro, o que poderia explicar o Mendanha ser contemporâneo ao Morro de São João. As assinaturas isotópicas obtidas para as intrusões não se associam à assinatura isotópica de Trindade e, caso o modelo de plumas mantélicas seja o correto, a pluma que teria maior semelhança de assinatura isotópica é a pluma de Tristão da Cunha. / The models for formation of alkaline plutons of the Southeastern Brazil Alkaline Province or Poços de Caldas-Cabo Frio Magmatic Lineament, which genetic modeling associates crust reactivations or mantle plumes, with definition of a hot spot track. The objective of this work is to report new data and interpretations to contribute to a better understanding and discussion about the model of alkaline rock generation. The studies involved geological mapping, petrography, litogeochemistry, Sr-Nd-Pb isotopes and 40Ar/39Ar geochronology. The selected alkaline complexes are the Morro Redondo, Mendanha and Morro de São João, located at Rio de Janeiro State. These intrusions are well-distributed along the Poços de Caldas-Cabo Frio Magmatic Lineament. The Morro Redondo alkaline intrusion is composed mainly by nepheline syenites and nepheline-bearing syenites and mafic rocks are rare. It was defined as a sodic silica-undersaturated alkaline suite, with metaluminous to peralkaline characteristics. The intrusion was dated at 74 Ma (40Ar/39Ar plateau age). The Mendanha alkaline intrusion is compose by various types of syenitic rocks, breccias and subvulcanic structures, as pyroclastic rocks and dikes. It was defined by a sodic silica-saturated alkaline suite with metaluminous characterisics. The intrusion presented two distinct 40Ar/39Ar ages for the magmatism: 64 Ma for Mendanha rocks and 54 Ma to lamprophyre dike, which illustrates a polycyclic magmatism. The Morro do Marapicu 40Ar/39Ar age yielded 80 Ma. The Morro de São João alkaline intrusion has a large variety of silica-undersaturated to silica-saturated rocks, as syenites, alkali-syenites and monzosyenites (some pseudoleucite-bearing), with melanocratic varieties, as malignites and ferguites. These rocks defined distinct alkaline silica-undersaturated suggenting sodic and potassic types. There was found an alkaline silica-saturated suite, defined by alkaline gabbros and shonkinites. The petrogenesis of these intrusions corresponds to the fractional crystallization, with assimilation of host rocks, and the crustal contamination is indicated by high variability of Sr isotope ratios. For Morro de São João origin is suggested a K-Na bimodal magma. These intrusions were generated from enriched mantle-derived magmas, possible associated to ancient subduction zone of Ribeira orogen. In terms of the new 40Ar/39Ar data, the hot spot model is not plausible, because the Morro do Marapicu is older than the other studied intrusions. Some models projected mantle plumes with 1000 Km size, what may explain the reason for Mendanha and Morro de São João have the nearly the same age. The obtained isotopic signatures for these intrusions were not associated to Trindade signature and, if the mantle plumes model is correct, the plume that has the most similar signature is Tristão da Cunha.

Understanding U-series isotopic disequilibria of partially melted crust is integral for determining the effect that crustal assimilation has on the U-series signature of magmas. In this work, U, Th and Ba (as a proxy for Ra) elemental abundances were gathered on the quenched glass in partially melted crustal xenoliths of granitic composition using microbeam techniques. The crustal xenoliths, which are found in basaltic lava, from Mirador Volcano in Chile, are old, and can be assumed to be at secular equilibrium, whereas melting occurred during eruption of Mirador in 1979. A comparison of the ratios Ba/Th and U/Th in the partial melts with those of the whole rock reveal how much fractionation has occurred during partial melting. Different ratios of U, Th and Ba compared to the whole rock substantiate fractionation via partial melting. Thus, assimilation of partial melts of crust can play a role in U-series isotopic disequilibria.