456 resultados para Mancos Shale
Resumo:
Many three-dimensional (3-D) structures in rock, which formed during the deformation of the Earth's crust and lithosphere, are controlled by a difference in mechanical strength between rock units and are often the result of a geometrical instability. Such structures are, for example, folds, pinch-and-swell structures (due to necking) or cuspate-lobate structures (mullions). These struc-tures occur from the centimeter to the kilometer scale and the related deformation processes con-trol the formation of, for example, fold-and-thrust belts and extensional sedimentary basins or the deformation of the basement-cover interface. The 2-D deformation processes causing these structures are relatively well studied, however, several processes during large-strain 3-D defor-mation are still incompletely understood. One of these 3-D processes is the lateral propagation of these structures, such as fold and cusp propagation in a direction orthogonal to the shortening direction or neck propagation in direction orthogonal to the extension direction. Especially, we are interested in fold nappes which are recumbent folds with amplitudes usually exceeding 10 km and they have been presumably formed by ductile shearing. They often exhibit a constant sense of shearing and a non-linear increase of shear strain towards their overturned limb. The fold axes of the Morcles fold nappe in western Switzerland plunges to the ENE whereas the fold axes in the more eastern Doldenhorn nappe plunges to the WSW. These opposite plunge direc-tions characterize the Rawil depression (Wildstrubel depression). The Morcles nappe is mainly the result of layer parallel contraction and shearing. During the compression the massive lime-stones were more competent than the surrounding marls and shales, which led to the buckling characteristics of the Morcles nappe, especially in the north-dipping normal limb. The Dolden-horn nappe exhibits only a minor overturned fold limb. There are still no 3-D numerical studies which investigate the fundamental dynamics of the formation of the large-scale 3-D structure including the Morcles and Doldenhorn nappes and the related Rawil depression. We study the 3-D evolution of geometrical instabilities and fold nappe formation with numerical simulations based on the finite element method (FEM). Simulating geometrical instabilities caused by sharp variations of mechanical strength between rock units requires a numerical algorithm that can accurately resolve material interfaces for large differences in material properties (e.g. between limestone and shale) and for large deformations. Therefore, our FE algorithm combines a nu-merical contour-line technique and a deformable Lagrangian mesh with re-meshing. With this combined method it is possible to accurately follow the initial material contours with the FE mesh and to accurately resolve the geometrical instabilities. The algorithm can simulate 3-D de-formation for a visco-elastic rheology. The viscous rheology is described by a power-law flow law. The code is used to study the 3-D fold nappe formation, the lateral propagation of folding and also the lateral propagation of cusps due to initial half graben geometry. Thereby, the small initial geometrical perturbations for folding and necking are exactly followed by the FE mesh, whereas the initial large perturbation describing a half graben is defined by a contour line inter-secting the finite elements. Further, the 3-D algorithm is applied to 3-D viscous nacking during slab detachment. The results from various simulations are compared with 2-D resulats and a 1-D analytical solution. -- On retrouve beaucoup de structures en 3 dimensions (3-D) dans les roches qui ont pour origines une déformation de la lithosphère terrestre. Ces structures sont par exemple des plis, des boudins (pinch-and-swell) ou des mullions (cuspate-lobate) et sont présentés de l'échelle centimétrique à kilométrique. Mécaniquement, ces structures peuvent être expliquées par une différence de résistance entre les différentes unités de roches et sont généralement le fruit d'une instabilité géométrique. Ces différences mécaniques entre les unités contrôlent non seulement les types de structures rencontrées, mais également le type de déformation (thick skin, thin skin) et le style tectonique (bassin d'avant pays, chaîne d'avant pays). Les processus de la déformation en deux dimensions (2-D) formant ces structures sont relativement bien compris. Cependant, lorsque l'on ajoute la troisiéme dimension, plusieurs processus ne sont pas complètement compris lors de la déformation à large échelle. L'un de ces processus est la propagation latérale des structures, par exemple la propagation de plis ou de mullions dans la direction perpendiculaire à l'axe de com-pression, ou la propagation des zones d'amincissement des boudins perpendiculairement à la direction d'extension. Nous sommes particulièrement intéressés les nappes de plis qui sont des nappes de charriage en forme de plis couché d'une amplitude plurikilométrique et étant formées par cisaillement ductile. La plupart du temps, elles exposent un sens de cisaillement constant et une augmentation non linéaire de la déformation vers la base du flanc inverse. Un exemple connu de nappes de plis est le domaine Helvétique dans les Alpes de l'ouest. Une de ces nap-pes est la Nappe de Morcles dont l'axe de pli plonge E-NE tandis que de l'autre côté de la dépression du Rawil (ou dépression du Wildstrubel), la nappe du Doldenhorn (équivalent de la nappe de Morcles) possède un axe de pli plongeant O-SO. La forme particulière de ces nappes est due à l'alternance de couches calcaires mécaniquement résistantes et de couches mécanique-ment faibles constituées de schistes et de marnes. Ces différences mécaniques dans les couches permettent d'expliquer les plissements internes à la nappe, particulièrement dans le flanc inver-se de la nappe de Morcles. Il faut également noter que le développement du flanc inverse des nappes n'est pas le même des deux côtés de la dépression de Rawil. Ainsi la nappe de Morcles possède un important flanc inverse alors que la nappe du Doldenhorn en est presque dépour-vue. A l'heure actuelle, aucune étude numérique en 3-D n'a été menée afin de comprendre la dynamique fondamentale de la formation des nappes de Morcles et du Doldenhorn ainsi que la formation de la dépression de Rawil. Ce travail propose la première analyse de l'évolution 3-D des instabilités géométriques et de la formation des nappes de plis en utilisant des simulations numériques. Notre modèle est basé sur la méthode des éléments finis (FEM) qui permet de ré-soudre avec précision les interfaces entre deux matériaux ayant des propriétés mécaniques très différentes (par exemple entre les couches calcaires et les couches marneuses). De plus nous utilisons un maillage lagrangien déformable avec une fonction de re-meshing (production d'un nouveau maillage). Grâce à cette méthode combinée il nous est possible de suivre avec précisi-on les interfaces matérielles et de résoudre avec précision les instabilités géométriques lors de la déformation de matériaux visco-élastiques décrit par une rhéologie non linéaire (n>1). Nous uti-lisons cet algorithme afin de comprendre la formation des nappes de plis, la propagation latérale du plissement ainsi que la propagation latérale des structures de type mullions causé par une va-riation latérale de la géométrie (p.ex graben). De plus l'algorithme est utilisé pour comprendre la dynamique 3-D de l'amincissement visqueux et de la rupture de la plaque descendante en zone de subduction. Les résultats obtenus sont comparés à des modèles 2-D et à la solution analytique 1-D. -- Viele drei dimensionale (3-D) Strukturen, die in Gesteinen vorkommen und durch die Verfor-mung der Erdkruste und Litosphäre entstanden sind werden von den unterschiedlichen mechani-schen Eigenschaften der Gesteinseinheiten kontrolliert und sind häufig das Resulat von geome-trischen Istabilitäten. Zu diesen strukturen zählen zum Beispiel Falten, Pich-and-swell Struktu-ren oder sogenannte Cusbate-Lobate Strukturen (auch Mullions). Diese Strukturen kommen in verschiedenen Grössenordungen vor und können Masse von einigen Zentimeter bis zu einigen Kilometer aufweisen. Die mit der Entstehung dieser Strukturen verbundenen Prozesse kontrol-lieren die Entstehung von Gerbirgen und Sediment-Becken sowie die Verformung des Kontaktes zwischen Grundgebirge und Stedimenten. Die zwei dimensionalen (2-D) Verformungs-Prozesse die zu den genannten Strukturen führen sind bereits sehr gut untersucht. Einige Prozesse wäh-rend starker 3-D Verformung sind hingegen noch unvollständig verstanden. Einer dieser 3-D Prozesse ist die seitliche Fortpflanzung der beschriebenen Strukturen, so wie die seitliche Fort-pflanzung von Falten und Cusbate-Lobate Strukturen senkrecht zur Verkürzungsrichtung und die seitliche Fortpflanzung von Pinch-and-Swell Strukturen othogonal zur Streckungsrichtung. Insbesondere interessieren wir uns für Faltendecken, liegende Falten mit Amplituden von mehr als 10 km. Faltendecken entstehen vermutlich durch duktile Verscherung. Sie zeigen oft einen konstanten Scherungssinn und eine nicht-lineare zunahme der Scherverformung am überkipp-ten Schenkel. Die Faltenachsen der Morcles Decke in der Westschweiz fallen Richtung ONO während die Faltenachsen der östicher gelegenen Doldenhorn Decke gegen WSW einfallen. Diese entgegengesetzten Einfallrichtungen charakterisieren die Rawil Depression (Wildstrubel Depression). Die Morcles Decke ist überwiegend das Resultat von Verkürzung und Scherung parallel zu den Sedimentlagen. Während der Verkürzung verhielt sich der massive Kalkstein kompetenter als der Umliegende Mergel und Schiefer, was zur Verfaltetung Morcles Decke führ-te, vorallem in gegen Norden eifallenden überkippten Schenkel. Die Doldenhorn Decke weist dagegen einen viel kleineren überkippten Schenkel und eine stärkere Lokalisierung der Verfor-mung auf. Bis heute gibt es keine 3-D numerischen Studien, die die fundamentale Dynamik der Entstehung von grossen stark verformten 3-D Strukturen wie den Morcles und Doldenhorn Decken sowie der damit verbudenen Rawil Depression untersuchen. Wir betrachten die 3-D Ent-wicklung von geometrischen Instabilitäten sowie die Entstehung fon Faltendecken mit Hilfe von numerischen Simulationen basiert auf der Finite Elemente Methode (FEM). Die Simulation von geometrischen Instabilitäten, die aufgrund von Änderungen der Materialeigenschaften zwischen verschiedenen Gesteinseinheiten entstehen, erfortert einen numerischen Algorithmus, der in der Lage ist die Materialgrenzen mit starkem Kontrast der Materialeigenschaften (zum Beispiel zwi-schen Kalksteineinheiten und Mergel) für starke Verfomung genau aufzulösen. Um dem gerecht zu werden kombiniert unser FE Algorithmus eine numerische Contour-Linien-Technik und ein deformierbares Lagranges Netz mit Re-meshing. Mit dieser kombinierten Methode ist es mög-lich den anfänglichen Materialgrenzen mit dem FE Netz genau zu folgen und die geometrischen Instabilitäten genügend aufzulösen. Der Algorithmus ist in der Lage visko-elastische 3-D Ver-formung zu rechnen, wobei die viskose Rheologie mit Hilfe eines power-law Fliessgesetzes beschrieben wird. Mit dem numerischen Algorithmus untersuchen wir die Entstehung von 3-D Faltendecken, die seitliche Fortpflanzung der Faltung sowie der Cusbate-Lobate Strukturen die sich durch die Verkürzung eines mit Sediment gefüllten Halbgraben bilden. Dabei werden die anfänglichen geometrischen Instabilitäten der Faltung exakt mit dem FE Netz aufgelöst wäh-rend die Materialgranzen des Halbgrabens die Finiten Elemente durchschneidet. Desweiteren wird der 3-D Algorithmus auf die Einschnürung während der 3-D viskosen Plattenablösung und Subduktion angewandt. Die 3-D Resultate werden mit 2-D Ergebnissen und einer 1-D analyti-schen Lösung verglichen.
Resumo:
The solid by-product of the oil shale processing (PETROBRAS - Brazil) was used as raw material to synthesize zeolites A and faujasite. Alkaline fusion followed by hydrothermal treatment was the synthesis procedure used, and five different starting material compositions were obtained. The more crystalline zeolite-type materials synthesized, the pretreated oil shale ash and commercial zeolites were used as adsorbents in the purification of pollutant solutions with arsenic. The zeolite-type material composed of a mixture of zeolite A (42.6%) and faujasite (52.9%) presented an ion exchange capacity comparable to the pure zeolites A and faujasite, much better than the pretreated ash.
Resumo:
Coal, oil, natural gas, and shale gas are biomass that is formed millions of years ago. These are non-renewable and depleting, even considering the recent discovery of new sources of oil in the presalt and new technologies for the exploitation of shale deposits. Currently, these raw materials are used as a source of energy production and are also important for the production of fine chemicals. Since these materials are finite and their (oil) price is increasing, it is clear that there will be a progressive increase in the chemical industry to use renewable raw materials as a source of energy, an inevitable necessity for humanity. The major challenge for the society in the twenty first century is to unite governments, universities, research centers, and corporations to jointly act in all areas of science with one goal of finding a solution to global problems, such as conversion of biomass into compounds for the fine chemical industry.Non-renewable raw materials are used in the preparation of fuels, chemical intermediates, and derivatives for the fine chemical industry. However, their stock in nature has a finite duration, and their price is high and will likely increase with their depletion. In this scenario, the alternative is to use renewable biomass as a replacement for petrochemicals in the production of fine chemicals. As the production of biomass-based carbohydrates is the most abundant in nature, it is judicious to develop technologies for the generation of chain products (fuels, chemical intermediates, and derivatives for the fine chemicals industry) using this raw material. This paper presents some aspects and opportunities in the area of carbohydrate chemistry toward the generation of compounds for the fine chemical industry.
Resumo:
Coal, natural gas and petroleum-based liquid fuels are still the most widely used energy sources in modern society. The current scenario contrasts with the foreseen shortage of petroleum that was spread out in the beginning of the XXI century, when the concept of "energy security" emerged as an urgent agenda to ensure a good balance between energy supply and demand. Much beyond protecting refineries and oil ducts from terrorist attacks, these issues soon developed to a portfolio of measures related to process sustainability, involving at least three fundamental dimensions: (a) the need for technological breakthroughs to improve energy production worldwide; (b) the improvement of energy efficiency in all sectors of modern society; and (c) the increase of the social perception that education is a key-word towards a better use of our energy resources. Together with these technological, economic or social issues, "energy security" is also strongly influenced by environmental issues involving greenhouse gas emissions, loss of biodiversity in environmentally sensitive areas, pollution and poor solid waste management. For these and other reasons, the implementation of more sustainable practices in our currently available industrial facilities and the search for alternative energy sources that could partly replace the fossil fuels became a major priority throughout the world. Regarding fossil fuels, the main technological bottlenecks are related to the exploitation of less accessible petroleum resources such as those in the pre-salt layer, ranging from the proper characterization of these deep-water oil reservoirs, the development of lighter and more efficient equipment for both exploration and exploitation, the optimization of the drilling techniques, the achievement of further improvements in production yields and the establishment of specialized training programs for the technical staff. The production of natural gas from shale is also emerging in several countries but its production in large scale has several problems ranging from the unavoidable environmental impact of shale mining as well as to the bad consequences of its large scale exploitation in the past. The large scale use of coal has similar environmental problems, which are aggravated by difficulties in its proper characterization. Also, the mitigation of harmful gases and particulate matter that are released as a result of combustion is still depending on the development of new gas cleaning technologies including more efficient catalysts to improve its emission profile. On the other hand, biofuels are still struggling to fulfill their role in reducing our high dependence on fossil fuels. Fatty acid alkyl esters (biodiesel) from vegetable oils and ethanol from cane sucrose and corn starch are mature technologies whose market share is partially limited by the availability of their raw materials. For this reason, there has been a great effort to develop "second-generation" technologies to produce methanol, ethanol, butanol, biodiesel, biogas (methane), bio-oils, syngas and synthetic fuels from lower grade renewable feedstocks such as lignocellulosic materials whose consumption would not interfere with the rather sensitive issues of food security. Advanced fermentation processes are envisaged as "third generation" technologies and these are primarily linked to the use of algae feedstocks as well as other organisms that could produce biofuels or simply provide microbial biomass for the processes listed above. Due to the complexity and cost of their production chain, "third generation" technologies usually aim at high value added biofuels such as biojet fuel, biohydrogen and hydrocarbons with a fuel performance similar to diesel or gasoline, situations in which the use of genetically modified organisms is usually required. In general, the main challenges in this field could be summarized as follows: (a) the need for prospecting alternative sources of biomass that are not linked to the food chain; (b) the intensive use of green chemistry principles in our current industrial activities; (c) the development of mature technologies for the production of second and third generation biofuels; (d) the development of safe bioprocesses that are based on environmentally benign microorganisms; (e) the scale-up of potential technologies to a suitable demonstration scale; and (f) the full understanding of the technological and environmental implications of the food vs. fuel debate. On the basis of these, the main objective of this article is to stimulate the discussion and help the decision making regarding "energy security" issues and their challenges for modern society, in such a way to encourage the participation of the Brazilian Chemistry community in the design of a road map for a safer, sustainable and prosper future for our nation.
Resumo:
Waste combustion has gone from being a volume reducing discarding-method to an energy recovery process for unwanted material that cannot be reused or recycled. Different fractions of waste are used as fuel today, such as; municipal solid waste, refuse derived fuel, and solid recovered fuel. Furthermore, industrial waste, normally a mixture between commercial waste and building and demolition waste, is common, either as separate fuels or mixed with, for example, municipal solid waste. Compared to fossil or biomass fuels, waste mixtures are extremely heterogeneous, making it a complicated fuel. Differences in calorific values, ash content, moisture content, and changing levels of elements, such as Cl and alkali metals, are common in waste fuel. Moreover, waste contains much higher levels of troublesome trace elements, such as Zn, which is thought to accelerate a corrosion process. Varying fuel quality can be strenuous on the boiler system and may cause fouling and corrosion of heat exchanger surfaces. This thesis examines waste fuels and waste combustion from different angles, with the objective of giving a better understanding of waste as an important fuel in today’s fuel economy. Several chemical characterisation campaigns of waste fuels over longer time periods (10-12 months) was used to determine the fossil content of Swedish waste fuels, to investigate possible seasonal variations, and to study the presence of Zn in waste. Data from the characterisation campaigns were used for thermodynamic equilibrium calculations to follow trends and determine the effect of changing concentrations of various elements. The thesis also includes a study of the thermal behaviour of Zn and a full—scale study of how the bed temperature affects the volatilisation of alkali metals and Zn from the fuel. As mixed waste fuel contains considerable amounts of fresh biomass, such as wood, food waste, paper etc. it would be wrong to classify it as a fossil fuel. When Sweden introduced waste combustion as a part of the European Union emission trading system in the beginning of 2013 there was a need for combustion plants to find a usable and reliable method to determine the fossil content. Four different methods were studied in full-scale of seven combustion plants; 14Canalysis of solid waste, 14C-analysis of flue gas, sorting analysis followed by calculations, and a patented balance method that is using a software program to calculate the fossil content based on parameters from the plant. The study showed that approximately one third of the coal in Swedish waste mixtures has fossil origins and presented the plants with information about the four different methods and their advantages and disadvantages. Characterisation campaigns also showed that industrial waste contain higher levels of trace elements, such as Zn. The content of Zn in Swedish waste fuels was determined to be approximately 800 mg kg-1 on average, based on 42 samples of solid waste from seven different plants with varying mixtures between municipal solid waste and industrial waste. A review study of the occurrence of Zn in fuels confirmed that the highest amounts of Zn are present in waste fuels rather than in fossil or biomass fuels. In tires, Zn is used as a vulcanizing agent and can reach concentration values of 9600-16800 mg kg-1. Waste Electrical and Electronic Equipment is the second Zn-richest fuel and even though on average Zn content is around 4000 mg kg-1, the values of over 19000 mg kg-1 were also reported. The increased amounts of Zn, 3000-4000 mg kg-1, are also found in municipal solid waste, sludge with over 2000 mg kg-1 on average (some exceptions up to 49000 mg kg-1), and other waste derived fuels (over 1000 mg kg-1). Zn is also found in fossil fuels. In coal, the average level of Zn is 100 mg kg-1, the higher amount of Zn was only reported for oil shale with values between 20-2680 mg kg-1. The content of Zn in biomass is basically determined by its natural occurrence and it is typically 10-100 mg kg-1. The thermal behaviour of Zn is of importance to understand the possible reactions taking place in the boiler. By using thermal analysis three common Zn-compounds were studied (ZnCl2, ZnSO4, and ZnO) and compared to phase diagrams produced with thermodynamic equilibrium calculations. The results of the study suggest that ZnCl2(s/l) cannot exist readily in the boiler due to its volatility at high temperatures and its conversion to ZnO in oxidising conditions. Also, ZnSO4 decomposes around 680°C, while ZnO is relatively stable in the temperature range prevailing in the boiler. Furthermore, by exposing ZnO to HCl in a hot environment (240-330°C) it was shown that chlorination of ZnO with HCl gas is possible. Waste fuel containing high levels of elements known to be corrosive, for example, Na and K in combination with Cl, and also significant amounts of trace elements, such as Zn, are demanding on the whole boiler system. A full-scale study of how the volatilisation of Na, K, and Zn is affected by the bed temperature in a fluidised bed boiler was performed parallel with a lab-scale study with the same conditions. The study showed that the fouling rate on deposit probes were decreased by 20 % when the bed temperature was decreased from 870°C to below 720°C. In addition, the lab-scale experiments clearly indicated that the amount of alkali metals and Zn volatilised depends on the reactor temperature.
Resumo:
Tässä kandidaatintyössä tarkastellaan liuskekaasun haasteita ja mahdollisuuksia energianlähteenä nyt sekä lähitulevaisuudessa. Työn tarkoituksena on tarjota tietoa liuskekaasusta ja sen hyödyntämisestä yleisesti maailmalla sekä tarkemmin Euroopassa. Suurimmat edut paikallisesta liuskekaasuntuotannosta ovat riippuvuuden väheneminen tuontikaasusta sekä mahdollisuus hyödyntää maakaasua polttoaineena suurempipäästöisten polttoaineiden tilalla. Tuotannon kehittymistä hidastavat maailmalla epäilyt ympäristövaikutuksista sekä varsinkin Euroopassa puutteellinen lainsäädäntö ja poliittinen vastustus. Liuskekaasulla tulee olemaan tärkeä rooli maakaasun kulutuksen kasvun tyydyttämisessä tulevaisuudessa. Epäkonventionaalisen maakaasutuotannon osuuden ennakoidaan olevan 60 prosenttia kaikesta maakaasuntuotannon kasvusta vuoteen 2040 mennessä, josta taas liuskekaasun osuuden arvioidaan kattavan yli puolet.
Resumo:
This investigation of geochemistry and mineralogy of heavy metals in fine grained (<63^m) sediment of the Welland River was imdertaken to: 1) describe metal dispersion patterns relative to a source, identify minerals forming and existing at the outfall region and relate sediment particle size to chemistry; 2) to delineate sample handling, preparation and evaluate, modify and develop analytical methods for heavy metal analysis of complex environmental samples. Ajoint project between Brock University and Geoscience Laboratories was initiated to test a contaminated site of the Welland River at the base of Atlas Speciality Steels Co. Methods were developed and utilized for particle size separation and two acid extraction techniques: 1) Partial extraction; 2) Total extraction. The mineralogical assessment identified calcite, dolomite, quartz and clays. These minerals are typical of the carbonate-shale rock basement of the Niagara Peninsula. Minerals such as, mullite and ferrocolumbite were found at the outfall region. These are not typical of the local geology and are generally associated with industrial pollutants. Partial and total extraction techniques were used to characterize the sediments based on chemical distribution, elemental behaviour and analytical differences. The majority of elements were lower in concentration in the partial extraction technique; suggesting these elements are bound in an acid extractable phase (exchangeable, organic and carbonate phases). The total extraction technique yielded higher elemental concentrations taking difficult oxides and silicates into solution. Geochemical analyses of grain size separates revealed that heavy metal (Co, Ni, V, Mn, Fe, Ba) concentrations did not increase with decreasing grain size. This is a function of the anthropogenic mill scale input into the river. The background elements (Sc, Y, Sr, Mg, Al and Ti) showed an increase in concentration to the finest grain size suggesting that it is directly related to the local mineralogy and geology. Dispersion patterns ofmetals fall into two distinct categories: 1) the heavy metals (Co, Cu, Ni, Zn, V and Cr), and 2) the background elements (Be, Sc, Y, Sr, Al and Ti). The heavy metals show a marked increase in the outfall region, while the background elements show a significant decrease at the outfall. This pattern is attributed to a "dilution effect" ofthe natural sediments by the anthropogenic mill scale sediments. Multivariant statistical analysis and correlation coefficient matrix results clearly support these results and conclusions. These results indicate the outfall region ofthe Welland River is highly contaminated with to heavy metals from the industrialized area of Welland. A short distance downstream, the metal concentrations return to baseline geochemical levels. It appears, contaminants rapidly come out of suspension and are deposited in close proximity to the source. Therefore, it is likely that dredging the sediment from the river may cause resuspension of contaminated sediments, but may not distribute the sediment as far as initially anticipated.
Resumo:
A regional geochemical reconnaissance by bottom stream sediment sampling, has delineated an area of high metal content in the north central sector of the North Creek Watershed. Development of a geochemical model, relating to the relative chemical concentrations derived from the chemical analyses of bottom sediments, suspended sediments, stream waters and well waters collected from the north central sector, was designed to discover the source of the anomaly. Samples of each type of material were analysed by the A.R.L. Direct Reading Multi-element Emission Spectrograph Q.A. 137 for elements: Na, K, Ca, Sr, Si, As, Pb, Zn, Cd, Ni, Ti, Ag, Mo, Be, Fe, AI, Mn, Cu, Cr, P and Y. Anomalous results led to the discovery of a spring, the waters of which carried high concentrations of Zn, Cd, Pb, As, Ni, Ti, Ag, Sr and Si. In addition, the spring waters had high concentrations of Na, Ca, Mg, 504 , alkalinity, N03' and low concentrations of K, Cl and NH3. Increased specific conductivity (up to 2500 ~mho/cm.) was noted in the spring waters as well as increased calculated total dissolved solids (up to 2047 mg/l) and increased ionic strength (up to 0.06). On the other hand, decreases were noted in water temperature (8°C), pH (pH 7.2) and Eh (+.154 volts). Piezometer nests were installed in the anomalous north central sector of the watershed. In accordance with the slope of the piezometric surface from wells cased down to the till/bedrock interface, groundwater flow is directed from the recharge area (northwest of the anomaly) towards the artesian spring via the highly fractured dolostone aquifer of the Upper Eramosa Member. The bedrock aquifer is confined by the overlying Halton till and the underlying Lower Eramosa Member (Vinemount Shale). The oxidation of sphalerite and galena and the dissolution of gypsum, celestite, calcite, and dolomite within the Eramosa Member, contributed its highly, dissolved constituents to the circulating groundwaters, the age of which is greater than 20 years as determined by tritium dating. Groundwater is assumed to flow along the Vinemount Shale and discharge as an artesian spring where the shale unit becomes discontinuous. The anomaly is located on a topographic low where bedrock is close to the surface. Thermodynamic evaluation of the major ion speciation from the anomalous spring and surface waters, showed gypsum to be supersaturated in these spring waters. Downstream from the spring, the loss of carbon dioxide from the spring waters resulted in the supersaturation with respect to calcite, aragonite, magnesite and dolomite. This corresponded with increases in Eh (+.304 volts) and pH (pH 8.5) in the anomalous surface waters. In conclusion, the interaction of groundwaters within the highly, mineralized carbonate source (Eramosa Member) resulted in the characteristic Ca*Mg*HC03*S04 spring water at the anomalous site, which appeared to be the principle effect upon controlling the anomalous surface water chemistry.
Resumo:
A comprehensive elemental, isotopic and microstructural analyses was undertaken of brachiopod calcites from the Hamilton Group (Middle Devonian), Clinton Group (Middle Silurian) and Middle to Upper Ordovician strata of Ontario and New York State. The majority of specimens were microstructurally and chemically preserved in a pristine state, although a number of specimens show some degree of post-depositional alteration. Brachiopod calcites from the Hamilton and Clinton Groups were altered by marine derived waters whereas Trenton Group (Middle Ordovician) brachiopods altered in meteorically derived fluids. Analysis of the elemental and isotopic compositions of pristine Hamilton Group brachiopods indicates there are several chemical relationships inherent to brachiopod calcite. Taxonomic differentiation of Mg, Sr and Na contents was evident in three co-occuring species from the Hamilton Group. Mean Mg contents of pristine brachiopods were respectively Athyris spiriferoides (1309ppm), Mucrospirifer mucronatus (1035ppm) and Mediospirifer audacula (789ppm). Similarly, taxonomic differentiation of shell calcite compositions was observed in co-occuring brachiopods from the Clinton Group (Middle Silurian) and the Trenton Group (Middle Ordovician). The taxonomic control of elemental regulation into shell calcite is probably related to the slightly different physiological systems and secretory mechanisms. A relationship was observed in Hamilton Group species between the depth of respective brachiopod communities and their Mg, Sr and Na contents. These elements were depleted in the shell calcites of deeper brachiopods compared to their counterparts in shallower reaches. Apparently shell calcite elemental composition is related to environmental conditions of the depositional setting, which may have controlled the secretory regime, mineral morphology of shell calcite and precipitation rates of each species. Despite the change in Mg, Sr and Na contents between beds and formations in response to environmental conditions, the taxonomic differentiation of shell calcite composition is maintained. Thus, it may be possible to predict relative depth changes in paleoenvironmental reconstructions using brachiopod calcite. This relationship of brachiopod chemistry to depth was also tested within a transgressiveregressive (T-R) cycle in the Rochester Shale Formation (Middle Silurian). Decreasing Mg, Sr and Na contents were observed in the transition from the shallow carbonates of the Irondequoit Formation to the deeper shales of the lowest 2 m of Rochester Shale. However, no isotopic and elemental trends were observed within the entire T-R cycle which suggests that either the water conditions did not change significantly or that the cycle is illusory. A similar relationship was observed between the Fe and Mn chemistries of shell calcite and redox/paleo-oxygen conditions. Hamilton Group brachiopods analysed from deeper areas of the shelf are enriched in Mn and Fe relative to those from shallow zones. The presence of black shales and dysaerobic faunas, during deposition of the Hamilton Group, suggests that the waters of the northern Appalachian Basin were stratified. The deeper brachiopods were marginally positioned above an oxycline and their shell calcites reflect periodic incursions of oxygen depleted water. Furthermore, analysis of Dalmanella from the black shales of the Collingwood Shale (Upper Ordovician) in comparison to those from the carbonates of the Verulam Formation (Middle Ordovician) confirm the relationship of Fe and Mn contents to periodic but not permanent incursions of low oxygen waters. The isotopic compositions of brachiopod calcite found in Hamilton Group (813C; +2.5% 0 to +5.5% 0; 8180 -2.50/00 to -4.00/00) and Clinton Group (813C; +4.00/00 to +6.0; 8180; -1.8% 0 to -3.60/ 00) are heavier than previously reported. Uncorrected paleotemperatures (assuming normal salinity, 0% 0 SMOW and no fractionation effects) derived from these isotopic values suggest that the Clinton sea temperature (Middle Silurian) ranged from 18°C to 28°C and Hamilton seas (Middle Devonian) ranged between 24°C and 29°C. In addition, the isotopic variation of brachiopod shell calcite is significant and is related to environmental conditions. Within a single time-correlative shell bed (the Demissa Bed; Hamilton Group) a positive isotopic shift of 2-2.5% 0 in 013C compositions and a positive shift of 1.0-1.50/00 in 0180 composition of shell calcite is observed, corresponding with a deepening of brachiopod habitats toward the axis of the Appalachian Basin. Moroever, a faunal succession from deeper Ambocoelia dominated brachiopod association to a shallow Tropidoleptus dominated assocation is reflected by isotopic shifts of 1.0-1.50/00. Although, other studies have emphasized the significance of ±20/oo shifts in brachiopod isotopic compositions, the recognition of isotopic variability in brachiopod calcite within single beds and within depositional settings such as the Appalachian Basin has important implications for the interpretation of secular isotopic trends. A significant proportion of the variation observed isotopic distribution during the Paleozoic is related to environmental conditions within the depositional setting.
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Trilobites ¥tere collected from Ordovician and Devonian formations of Ontario} New York} Ohio} Oklahoma} and Indiana. Diversity was generally low} but 19..?telllS and Ph..~tY>ps ¥tere the most abundant species from the Ordovician and Devonian} respectively. Recent marine arthropods ¥tere collected from the Atlantic shore of the middle Florida Keys} and from the Pacific and lagoonal waters at Cape Beale} B. C. Fresh-water arthropods were collected along the shore of the Severn River in northcentral Ontario. Cuticles ¥tere analyzed for major} minor and trace elements, 180 and 13C isotopes, as ¥tell as examined by scanning electron micr?scope to identify original and diagenetic fabrics. Examination of trilobite cuticles by scanning electron microscope revealed several microstructures consistent with those observed in Recent arthropods. Microstructures} such as setae and tegumental gland duct openings} in like sized Lim/IllS and Isoteline trilobites may indicate common ancestral origins for these organisms, or simply parallel cuticle evolutions. The dendritic microstructure, originally' thought to be a diagenetic indicator, was found in Recent specimens and therefore its presence in trilobites may be suggestive of the delicate nature of diagenesis in trilobites. The absence of other primary microstructures in trilobites may indicate alteration, taxonomic control} or that there is some inherent feature of S EM examination which may' not allow detection of some features} while others are apparently visit·le onl~1 under SH.·1. The region of the cuticle sampled for examination is also a major influence in detecting pristine microstructures, as not all areas of trilobite and Recent arthropod cuticles will have microstructures identifiable in a SEM study. Subtleties in the process of alteration, however} ma~·· leave pristine microstructures in cuticles that are partial~/ silicified or do 10m itized, and degree and type of alteration may vary stratigraphically and longitudinally within a unit. The presence of fused matrices, angular calcite rhombs, and pyrite in the cuticle are thought to be indicative of altered cuticles, although pyritization may not affect the entire cuticle. t-~atural processes in Recent arthropods, such as molting, lead to variations in cuticle chemistries, and are thought to reflect the area of concentration of the elements during calcification. The level of sodium in Recent arthropods was found to be higher than that in trilobites, but highly mobile when sUbjected to the actions of VY'€'athering. Less saline water produced lovy'€'r magnesium and higher calcium values in Recent specimens .. and metal variations in pristine Ordovician trilobite cuticle appears to follow the constraints outlined for Recent arthropods, of regulation due to the chemislry of the surrounding medium. In diagenetic analysis, sodium, strontium and magnesium proved most beneficial in separating altered from least altered trilobites. Using this criterion, specimens from shale show the least amount of geochemical alteration, and have an original mineralogy of 1.7 - 2.4 mole % MgC03 (8000 t(> 9500 ppm magnesium) for both /s>..?/e/11S lJA'i.riff!11S and PseIAit'11J17ites I..itmirpin..itl/~ and 2.8 - 3.3 mole % MgC03 (5000 to 7000 ppm magnesium) for Ph.i{).?PS This is Slightly lower than the mineralogy of Recent marine arthropods (4.43 - 12.1 mole % MgC03), and slightly higher than that of fresh-water crayfish (0.96 - 1.82 mole % MgC03). Geochemically pristine trilobites were also found to possess primary microstructures. Stable isotope values and trends support the assertion that marine-meteoriclburial fluids were responsible for the alteration observed in a number of the trilobite specimens. The results of this stUdy suggest that fossil material has to be evaluated separately along taxonomic and lithological lines to arrive at sensible diagenetic and e nvironmenta I interpretations.
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During the Upper Cambrian there were three mass extinctions, each of which eliminated at least half of the trilobite families living in North American shelf seas. The Nolichucky Formation preserves the record of one of these extinction events at the base of the Steptoean Stage. Sixty-six trilobite collections were made from five sections In Tennessee and Virginia. The lower Steptoean faunas are assigned to one low diversity, Aphelaspis-dominated biofacies, which can be recognized in several other parts of North America. In Tennessee, the underlying upper Marjuman strata contain two higher diversity biofacies, the Coosella-Glaphyraspis Biofacies and the Tricrepicephalus-Norwoodiid Biofacies. At least four different biofacies are present in other parts of North America: the Crepicephalus -Lonchocephalus Biofacies, the Kingstonia Biofacies, the Cedaria Biofacies, and the Uncaspis Biofacies. A new, species-based zonation for the Nolichucky Formation imcludes five zones, three of which are new. These zones are the Crepicephalus Zone, the Coosella perplexa Zone, the Aphelaspis buttsi Zone, the A. walcotti Zone and the A. tarda Zone. The Nolichucky Formation was deposited within a shallow shelf basin and consists largely of subtidal shales with stormgenerated carbonate interbeds. A relative deepening is recorded In the Nolichucky Formation near the extinction, and is indicated In some sections by the appearance of shale-rich, distal storm deposits above a carbonate-rich, more proximal storm deposit sequence. A comparable deepening-upward sequence occurs near the extinction in the Great Basin of southwestern United States and in central Texas, and this suggests a possible eustatic control. In other parts of North America, the extinction IS recorded In a variety of environmental settings that range from near-shore to slope. In shelf environments, there is a marked decrease in diversity, and a sharp reduction in biofacies differentiation. Although extinctions do take place in slope environments, there IS no net reduction in diversity because of the immigration of several new taxa.
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The effect that plants {Typha latifolia) as well as root-bed medium physical and chemical characteristics have on the treatment of primary treated domestic wastewater within a vertical flow constructed wetland system was investigated. Five sets of cells, with two cells in each set, were used. Each cell was made of concrete and measured 1 .0 m X 1 .0 m and was 1.3 m deep. Four different root-bed media were tested : Queenston Shale, Fonthill Sand, Niagara Shale and a Michigan Sand. Four of the sets contained plants and a single type of root-bed medium. The influence of plants was tested by operating a Queenston Shale set without plants. Due to budget constraints no replicates were constructed. All of the sets were operated independently and identically for twenty-eight months. Twelve months of data are presented here, collected after 16 months of continuous operation. Root-bed medium type did not influence BOD5 removal. All of the sets consistently met Ontario Ministry of Environment (MOE) requirements (<25 mg/L) for BOD5 throughout the year. The 12 month average BOD5 concentration from all sets with plants was below 2.36 mg/L. All of the sets were within MOE discharge requirements (< 25 mg/L) for suspended solids with set effluent concentrations ranging from 1.53 to 14.80 mg/L. The Queenston Shale and Fonthill Sand media removed the most suspended solids while the Niagara Shale set produced suspended solids. The set containing Fonthill Sand was the only series to meet MOE discharge requirements (< Img/L) for total phosphorus year-round with a twelve month mean effluent concentration of 0.23 mg/L. Year-round all of the root-bed media were well below MOE discharge requirements (< 20mg/L in winter and < 10 mg/L in sumnner) for ammonium. The Queenston Shale and Fonthill Sand sets removed the most total nitrogen. Plants had no effect on total nitrogen removal, but did influence how nitrogen was cycled within the system. Plants increased the removal of suspended solids by 14%, BOD5 by 10% and total phosphorus by 22%. Plants also increased the amount of dissolved oxygen that entered the system. During the plant growing season removal of total phosphorus was better in all sets with plants regardless of media type. The sets containing Queenston Shale and Fonthill Sand media achieved the best results and plants in the Queenston Shale set increased treatment efficiency for every parameter except nitrogen. Vertical flow wetland sewage treatment systems can be designed and built to consistently meet MOE discharge requirements year-round for BOD5, suspended solids, total phosphorus and ammonium. This system Is generally superior to the free water systems and sub-surface horizontal flow systems in cold climate situations.
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Ce projet porte sur la reconstitution paléo-écologique d'un environnement forestier fossile retrouvé sur un plateau au sud-ouest de l'île Bylot. Il a comme objectifs 1) de préciser la chrono-stratigraphie du site; 2) d’établir une liste et une succession des différents taxons polliniques retrouvés dans les différentes unités stratigraphiques du site; 3) d’estimer leur âge et 4) d’en inférer des conditions climatiques (température et précipitations). Plusieurs coupes stratigraphiques ont été excavées puis échantillonnées afin de réaliser des analyses stratigraphiques, paléomagnétiques et polliniques. Un GPS différentiel fut également utilisé afin de caractériser à petite et grande échelle les unités stratigraphiques associées aux unités organiques fossiles. Les résultats des analyses granulométriques indiquent la séquence de dépôt suivante au sein d’une dépression dans la roche en place (schiste tertiaire) : 1) un diamicton glaciaire local ; 2) un sédiment limoneux d’origine glacio-lacustre ; 3) une unité organique tourbeuse; 4) une unité de type alluvial ; 5) un sédiment fluvio-glaciaire et 6) un diamicton glaciaire d’origine allochtone. Les analyses polliniques suggèrent une végétation similaire à celle présente près de la limite des arbres actuelle, environ 2000 km plus au sud. Les conditions climatiques plus humides et plus chaudes permettaient notamment la croissance du pin (Pinus type strobus et banksiana), de l’épinette (Picea cf. mariana), de l’aulne (type crispa et incana) et du mélèze (Larix, indifférencié). Enfin, les études paléomagnétiques et la présence d’espèces éteintes suggèrent un âge pour les dépôts organiques fossiles situé entre 2,14 et 2,15 Ma ou entre 2,581 et 3,040 Ma.
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Suite à une importante vague d’opposition contre l’exploration et l’exploitation du gaz de schiste au Québec, un quasi-moratoire sur les nouvelles technologies d’extraction a été promulgué par le gouvernement de la province. Cet article exposera comment l’application des concepts de responsabilité sociale des entreprises (RSE) aurait pu jouer en faveur de l’industrie dans le développement de cette activité peu règlementée au Québec. Dans un premier temps, un portrait de l’évolution du concept de RSE sera dressé. L’accent sera alors mis sur les concepts de consultation, de transparence et de collaboration avec les communautés affectées par une activité d’extraction. Par la suite, un portrait détaillé des événements ayant menés à l’adoption d’un quasi-moratoire dans la province sera dressé afin de comprendre comment l’industrie aurait pu agir autrement afin d’arriver à ses fins avec l’aval de la population et du gouvernement.
Resumo:
The distribution and accumulation of the rare earth elements (REE) in the sediments of the Cochin Estuary and adjacent continental shelf were investigated. The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments were more enriched with the lighter rare earth elements than the heavier ones. The positive correlation between the concentrations of REE, Fe and Mn could explain the precipitation of oxyhydroxides in the study area. The factor analysis and correlation analysis suggest common sources of origin for the REEs. From the Ce-anomalies calculated, it was found that an oxic environment predominates in all stations except the station No. 2. The Eu-anomaly gave an idea that the origin of REEs may be from the feldspar. The parameters like total organic carbon, U/Th ratio, authigenic U, Cu/Zn, V/Cr ratios revealed the oxic environment and thus the depositional behaviour of REEs in the region
