Ce travail évalue le potentiel du zinc et plus particulièrement des terres rares à tracer les différents processus le long d’une catena issue d’une formation carbonatée constituée d’une succession de bancs marneux et calcaires, et ayant subi des processus de décarbonatation, des conditions redox en lien avec l’hydromorphie et de l’éluviation. L’approche choisie repose (i) sur la spéciation des terres rares, à l’aide de méthodes physiques et chimiques, dans les traits pédologiques formés par les différents processus et des matériaux aux dépens desquels ils se sont développés, (ii) sur la quantification par bilan de masse des flux de terres rares et éléments majeurs associés. Ce travail a nécessité deux mises aux points méthodologiques : une méthode de normalisation des terres rares, basée sur l’enfoncement des fronts de transformation afin de quantifier l’impact des processus successifs sur le fractionnement des terres rares ; une méthodologie de reconstruction des matériaux parentaux pour chacun des horizons, l’approche par bilan de masse nécessitant une connaissance des stocks initiaux. L’impact de deux processus sur les fractionnements de terres rares est ensuite plus particulièrement abordé : la décarbonatation des matériaux parentaux et les processus d’oxydo-réduction. On montre ainsi l’importance de comparer les quantités mises en solution aux flux calculés par les bilans de masse pour prédire le devenir des éléments libérés et l’intérêt des terres rares pour quantifier les cycles de dissolution/précipitation des oxydes de fer et de manganèse. / This project aims at considering the potential of zinc and rare earth element (REEs) at quantifying pedogenetic processes along a soil sequence developed from a limestone formation consisting in a succession of marl and limestone strata which underwent carbonate dissolution, redox cycles related to soil hydromorphy and eluviation. The chosen approach relies on (i) the speciation of rare earth elements - by a method combining sequential extractions and physical separations - in the pedological features resulting from the different processes and in the materials from which they developed; (ii) the quantification of the REE and major element fluxes by mass balance calculation. To do so, two methodologies were developed: a methodology of normalization of REEs based on the theory of transformation fronts to quantify the impact of the processes on REE fractionations; an innovative approach of the reconstruction of the former parent material for each soil horizon as mass balance calculation requires the quantification of initial stocks in elements. Two processes were then further studied: carbonate dissolution and redox processes. We thus point out the necessity to compare max fluxes as computed by mass balance to quantities released by carbonate dissolution in order to forecast the fate of elements released into the soil solution. We also evidenced the potential of REEs to quantify the dissolution/precipitation cycles of iron and manganese oxides.

This study geochemically characterized a proposed Carbon Capture and Storage project in northeast British Columbia, and presents new dissolution kinetics data for the proposed saline aquifer storage reservoir, the Keg River Formation. The Keg River Formation is a carbonate reservoir (89-93% Dolomite, 5-8% Calcite) at approximately 2200 m depth, at a pressure of 190 bar, and temperature of 105 °C. The Keg River brine is composed of Na, Cl, Ca, K, Mg, S, Si, and HCO3 and is of approximately 0.4 M ionic strength. Fluid analysis found the Keg River brine to be relatively fresh compared with waters of the Keg River formation in Alberta, and to also be distinct from waters in overlying units. These findings along with the physical conditions of the reservoir make the Keg River Formation a strong candidate for CO2 storage. Further work measured the dissolution rates of Keg River rock that will occur within the Keg River formation. This was performed in a new experimental apparatus at 105 °C, and 50 bar pCO2 with brine and rock sampled directly from the reservoir. Dissolution rate constants (mol!m-2s-1) for Keg River rock were found to be Log KMg 9.80 ±.02 and Log KCa -9.29 ±.04 for the Keg River formation. These values were found to be significantly lower compared to rate constants generated from experiments involving synthetic brines with values of Log KMg -9.43 ±.09, and Log KCa -9.23 ±.21. Differences in rates were posited as due to influences of other element interactions with the >MgOH hydration site, which was tested through experiments with brines spiked with SrCl2 and ZnCl2. Results for the SrCl2 spiked solution showed little impact on dissolution rates with rate constants of Log KMg -9.43 ±.09, and Log KCa -9.15 ±.21, however the ZnCl2 spiked solution did show some inhibition with rate constants of Log KMg -9.67 ±.04, and Log KCa -9.30 ±.04. Rate constants generated in this work are among the first presented which can actually be tested by full-scale injection of CO2. / Graduate

Underground injection of acid gas has been studied for several decades for oil field applications, such as enhanced oil recovery (EOR), but is now being studied as a solution to climate change. This research aims to simulate underground conditions at injection sites, such as the pilot scale injection site located near the site of a coal fired power facility in the Black Warrior Basin of Alabama. This proposed carbon capture and sequestration (CCS) location would involve injection of liquid CO2 into a carbonaceous saline aquifer. The objective of this study was to investigate carbonate surface treatments that alter the kinetics and mechanism of mineral dissolution resulting from the injection of an acid gas (CO2) into a geologic formation. A variety of mineral coatings were tested in an attempt to preserve mineral integrity under acidic conditions. Surface active chemicals were first tested, including scale inhibitors, followed by a novel acid induced surface treatment that precipitates an inorganic layer on the calcite to preserve the acid soluble mineral. These experiments are the first to investigate the use of scale inhibitors for mineral preservation, although were found ultimately to have little impact on dissolution kinetics. However, anions of moderate to strong acids induced surface coatings that were determined to effectively inhibit dissolution. Additionally, a novel, high pressure flow-through experimental apparatus was developed to simulate pressure and temperature conditions relevant to injection sites. Similar mineralogical studies in the literature have used pressurized, unstirred, batch systems to simulate mineral interactions. Solids with an acid induced surface coating were tested in the high pressure column and no calcium was found to leave the column.

Underground injection of acid gas has been studied for several decades for oil field applications, such as enhanced oil recovery (EOR), but is now being studied as a solution to climate change. This research aims to simulate underground conditions at injection sites, such as the pilot scale injection site located near the site of a coal fired power facility in the Black Warrior Basin of Alabama. This proposed carbon capture and sequestration (CCS) location would involve injection of liquid CO2 into a carbonaceous saline aquifer. The objective of this study was to investigate carbonate surface treatments that alter the kinetics and mechanism of mineral dissolution resulting from the injection of an acid gas (CO2) into a geologic formation. A variety of mineral coatings were tested in an attempt to preserve mineral integrity under acidic conditions. Surface active chemicals were first tested, including scale inhibitors, followed by a novel acid induced surface treatment that precipitates an inorganic layer on the calcite to preserve the acid soluble mineral. These experiments are the first to investigate the use of scale inhibitors for mineral preservation, although were found ultimately to have little impact on dissolution kinetics. However, anions of moderate to strong acids induced surface coatings that were determined to effectively inhibit dissolution. Additionally, a novel, high pressure flow-through experimental apparatus was developed to simulate pressure and temperature conditions relevant to injection sites. Similar mineralogical studies in the literature have used pressurized, unstirred, batch systems to simulate mineral interactions. Solids with an acid induced surface coating were tested in the high pressure column and no calcium was found to leave the column.

abstract: Chemical and physical interactions of flowing ice and rock have inexorably shaped planetary surfaces. Weathering in glacial environments is a significant link in biogeochemical cycles – carbon and strontium – on Earth, and may have once played an important role in altering Mars’ surface. Despite growing recognition of the importance of low-temperature chemical weathering, these processes are still not well understood. Debris-coated glaciers are also present on Mars, emphasizing the need to study ice-related processes in the evolution of planetary surfaces. During Earth’s history, subglacial environments are thought to have sheltered communities of microorganisms from extreme climate variations. On Amazonian Mars, glaciers such as lobate debris aprons (LDA) could have hosted chemolithotrophic communities, making Mars’ present glaciers candidates for life preservation. This study characterizes glacial processes on both Earth and Mars. Chemical weathering at Robertson Glacier, a small alpine glacier in the Canadian Rocky Mountains, is examined with a multidisciplinary approach. The relative proportions of differing dissolution reactions at various stages in the glacial system are empirically determined using aqueous geochemistry. Synthesis of laboratory and orbital thermal infrared spectroscopy allows identification of dissolution rinds on hand samples and characterization of carbonate dissolution signals at orbital scales, while chemical and morphological evidence for thin, discontinuous weathering rinds at microscales are evident from electron microscopy. Subglacial dissolution rates are found to outpace those of the proglacial till plain; biologically-mediated pyrite oxidation drives the bulk of this acidic weathering. Second, the area-elevation relationship, or hypsometry, of LDA in the midlatitudes of Mars is characterized. These glaciers are believed to have formed ~500 Ma during a climate excursion. Hypsometric measurements of these debris-covered glaciers enable insight into past flow regimes and drive predictions about past climate scenarios. The LDA in this study fall into three major groups, strongly dependent on basal elevation, implying regional and climatic controls on ice formation and flow. I show that biologically-mediated mineral reactions drive high subglacial dissolution rates, such that variations within the valley can be detected with remote sensing techniques. In future work, these insights can be applied to examining Mars’ glacial regions for signs of chemical alteration and biosignatures. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2015

<p> An assemblage of coral skeletons of the species Desmophyllum cristagalli were obtained from the top of Orphan Knoll, 550 km northeast of Newfoundland, from depths of approximately 1600 and 1800 m. The corals were observed for their macro- and micro-boring assemblages, and the boring morphologies documented, using binocular and scanning electron microscopy. Samples of coral were embedded with resin and etched for examination of the micro-boring assemblages.</p> <p> The largest volumetric amount of skeletal material removed was by sponges forming Entobia. This further corroborates the assumption that various species of boring sponges are distributed ubiquitously throughout a wide bathymetric range.</p> <p> Four distinct fungal forms were found, two tubular forms interpreted to be hyphal filaments and two bulbous forms interpreted to be sporangia. These forms were described on the basis of their shape, size, mode of branching, association with other structures and texture. They were then compared to other micro-boring assemblages found in previous studies from various bathymetric ranges. Some forms described in this study were found to be similar to forms described in other studies. Other forms in this study were not found to be documented. It is suggested, therefore, that certain forms, as well as low ichnodiversity, may indicate deeper water environments.</p> <p> Destructive micritization structures were also found in resin casts as well as in thin section. The extent of micritization may indicate the intensity of the parameters at the substrate that affect carbonate dissolution, such as CaCO3 and CO2 concentrations, pH, temperature, and salinity. It would therefore indicate the ambient water conditions at the substrate. If a sufficiently large database could be obtained, as well as distinct separation of the parameters responsible for carbonate dissolution, micritization may be used in a mapping of the carbonate compensation depth through time and depth ranges.</p> / Thesis / Bachelor of Science (BSc)

Groundwater chemistry on the Niagara Peninsula has been identified as highly mineralized in comparison to groundwaters collected from the same bedrock formations elsewhere in southern Ontario. Three geochemical zones were discerned using hierarchical cluster analysis and other geochemical and isotopic methods. The Escarpment Zone, located along the Niagara and Onondaga Escarpments, is characterized by unconfined aquifer conditions, parameters reflective of surficial contaminants, including road salt, and elevated HCO3, DOC, NO3-, coliform bacteria and tritium. In contrast, in the Salina Zone thick, low-permeability sediments and gypsiferous bedrock results in highly mineralized groundwaters with Ca-SO4 geochemical facies and elevated S2-, Ca2+, Mg2+, K+, Na+, SO42-, Cl-, Br-, Sr2+, NH4+ and CH4. The Guelph Zone contains the lowest electrical conductivity of the three zones and elevated F-. Outliers exist with groundwater geochemistry that differs from the local geochemical zone and the host aquifer. These sites have elevated SO42- (>1000 to 5200 mg/L) with depleted δ34SSO4 (-2.2 to 14.3‰ VCDT) signatures that differs starkly from Devonian and Silurian evaporites (~20 to 32 ‰) in the host formations. This exogenic SO4 was identified in a cross-formational northeast – southwest linear trend crossing three major groundwater flow systems. The lack of down-stream impact in these systems and tritium groundwater ages that are typically only decades old indicate a young, non-geological origin and implicate anthropogenic activities. Additionally, nine samples were identified with elevated methane concentrations and δ13CCH4 signatures within the thermogenic range. As thermogenic methane is not produced within shallow aquifers and would be short-lived in the presence of the ubiquitous sulfate, these samples imply recent upward migration of methane from depth through vertical conduits. Taken together, the evidence supports large-scale upward movement of fluids in the centre of the Niagara geochemical anomaly and more sporadic upward transport of gases over a wider area of the peninsula. The most likely vector is through corroded and leaking casings or boreholes of abandoned (century) gas wells that are common across the peninsula. / Thesis / Master of Science (MSc)