Parmi les différents minéraux argileux, la sépiolite, qui est un silicate fibreux naturel, est un potentiel nano-transporteur prometteur pour le transfert non-viral de biomolécules. Il a en effet été montré que la sépiolite interagissait avec des molécules biologiques telles que les lipides, les polysaccharides et les protéines. Dans ce travail, nous démontrons que la sépiolite interagit également efficacement avec différents types de molécules d'ADN (génomique, plasmidique, oligonucléotides simple et double brin), et nous présentons la première étude détaillée sur les mécanismes d'interaction entre la sépiolite et l'ADN, ainsi qu’une caractérisation physico-chimique de bionanocomposites ADN-sepiolite. Une analyse spectroscopique a montré tout d’abord que l’interaction de l'ADN avec la sépiolite était plus forte en présence de polycations, la valence de ces derniers accroissant le rendement d’absorption, et deuxièmement, que l'ADN ainsi adsorbé pouvait être récupéré avec un rendement modulé par la présence d’EDTA, la structure de l'ADN et son activité biologique étant conservées. Par spectroscopie infrarouge à transformée de Fourier (FTIR) nous avons identifié les groupes silanol externes comme les principaux sites d'interaction avec l'ADN. Nous avons ensuite prouvé qu'il est possible d'utiliser la sépiolite pour extraire l'ADN de bactéries, pour la purification de l'ADN et pour la purification de toute contamination bactérienne. En combinant la microscopie à fluorescence, la microscopie électronique à transmission (MET), la vidéo-microscopie et l’analyse par cytométrie en flux (FACS), nous avons montré que la sépiolite peut être spontanément internalisée dans des cellules de mammifère par le biais de deux voies, l’endocytose et la macropinocytose. En tant que preuve de concept, nous montrons que la sépiolite est capable de transférer de manière stable l'ADN de plasmide dans des bactéries et des cellules de mammifères. Il a également été prouvé qu’en incubant des bactéries avec des bionanocomposites ADN-sepiolite, initialement préparés en présence d'une faible concentration en cations divalents et avec de la sépiolite traitée aux ultrasons (sSep), il était possible d'augmenter l'efficacité de la transformation bactérienne 20 à 30 fois par rapport aux méthodes basées sur l'«effet Yoshida». En outre, nous montrons que l'efficacité du transfert de gènes par la sépiolite peut être optimisée : l'utilisation de sSep et l'exposition à la chloroquine augmentent d’un facteur 100 et 2, respectivement, l’efficacité de transfection. Ces résultats ouvrent la voie à l'utilisation de bionanocomposites à base de sépiolite comme de nouveaux potentiels nano-transporteurs hybrides potentiels, à la fois pour la thérapie génique et le développement de nouveaux modèles biologiques en sciences fondamentales et appliquées. / Among the various clay minerals, sepiolite, which is a natural fibrous silicate, isa potential promising nanocarrier for the non-viral transfer of bio-molecules. Indeed,sepiolite has been shown to interact with biological molecules such as lipids,polysaccharides and proteins. Here, we show that sepiolite efficiently binds differenttypes of DNA molecules (genomic, plasmid, single strand and double strandoligonucleotides), introducing the first detailed study on the interaction mechanismsbetween sepiolite and DNA, as well as the physicochemical characterization of theresulting DNA-sepiolite bionanocomposites. The interaction mechanisms aresuggested to be electrostatic interactions, van der Waals forces, cation bridges, andhydrogen bonding. Spectroscopy analysis showed that the binding of DNA to sepiolitewas increased by polycations with valence dependent efficiency, and the DNApreviously adsorbed could be recovered with an efficiency that could be modulatedusing a chelating agent (EDTA), preserving the DNA structure and biological activity.Fourier-transform infrared spectroscopy identified the external silanol groups as themain sites of interaction with the DNA. It was proved that it is possible to use sepiolitefor extracting DNA from bacteria, for DNA purification and for purification from bacterialcontamination. By combining fluorescence microscopy, transmission electronmicroscopy (TEM), time-lapse video microscopy and flow cytometry analysis (FACS),we show that sepiolite can be spontaneously internalized into mammalian cells throughboth endocytic and non-endocytic pathways. As a proof of concept, we show thatsepiolite is able to stably transfer plasmid DNA into bacteria and mammalian cells. Itwas also proved that with the incubation of bacteria with the Sep/DNAbionanocomposite initially prepared in the presence of a low concentration of divalentcation, and using sonicated sepiolite (sSep), it is possible to increase the bacterialtransformation efficiency from 20 to 30-fold compared to previously reported methodswhich are based in the “Yoshida effect”. Additionally, we show that the efficiency ofsepiolite-mediated gene transfer can be optimized: the use of sSep and the exposureto the endosome disrupter chloroquine 100-fold and 2-fold stimulated DNA transfectionefficiency, respectively. These results open the way to the use of sepiolite-basedbionanocomposites as a novel class of hybrid nanocarriers for both potential genetherapy and the development of novel biological models of interest for academic andapplied sciences.

Dans ce manuscrit, la synthèse et la caractérisation complète de différents matériaux hybrides dédiés à des applications dans le domaine optique ou thérapeutique sont décrites. Dans un premier temps, des systèmes macroscopiquement ordonnés sont obtenus par intercalation de colorants tels que le Styryl 722 ou la pyronine-Y dans plusieurs films à base d’argile de type smectite. Les films d’argile sont élaborés par spin-coating et les colorants intercalés par immersion des films dans les solutions de ces colorants. Les effets de l’argile sur les propriétés des colorants sont analysés en détail et leur orientation préférentielle dans l’espace inter-couches est étudié grâce à la réponse anisotropique des films en lumière linéairement polarisée. Dans la deuxième partie, la synthèse par chimie sol-gel de monolithes de silice de grande dimension contenant des colorants laser présentant une forte absorption et une émission de fluorescence dans le visible est abordée. Des colorants laser à l’état solide (SSDL) avec de bonnes stabilités photochimique, thermique et chimique sont ainsi proposés. Dans le troisième chapitre, la synthèse par voie sol-gel de nanoparticules de silice (NP) d’environ 50 nm de diamètre fonctionnalisées sur leur surface externe est ensuite décrite. Grâce à l’encapsulation de molécules de colorants fluorescents dans leur cœur et le greffage de photosensibilisateurs sur leur écorce, des nanoparticules biocompatibles adaptées à la bio-imagerie et la thérapie photodynamique (PDT) ont été préparées. Pour optimiser leurs performances, les propriétés photophysiques et plus particulièrement la production d’oxygène singulet d’une nouvelle série de photosensibilisateurs basés sur les chromophores de type PODIPY ont d’abord été étudiées en détail. A partir de ces résultats, des BODIPY particulièrement efficaces ont été greffés sur les nanoparticules de silice afin de les utiliser pour la PDT. Les propriétés photophysiques de ces matériaux ont été analysées par spectroscopie d’absorption et de fluorescence (stationnaire ou résolue en temps) et les rendements quantiques de production d’oxygène singulet déterminés par des méthodes directe (émission de luminescence de l’oxygène singulet à 1270 nm) ou indirecte (utilisation de sondes chimiques spécifiques à l’oxygène singulet). Par ailleurs les matériaux hybrides ont été complètement caractérisés par plusieurs techniques (SEM, TEM, XRD, XPS, IR, DLS, BET). / Along this manuscript different hybrid materials are synthesized and extensively characterized for several uses: from optical to therapeutic applications. First, by the intercalation of different dyes, styryl 722 and pyronine-Y into several smectite clay films, macroscopically ordered system are obtained. Clay films are elaborated by spin-coating technique and the dyes are intercalated by the immersion of clay thin films into dye solutions. The effect of clay on the dye properties is deeply analyzed and its preferential orientation in the interlayer space of the clay is studied by the anisotropic response of the films to the linear polarized light. Second, large silica monoliths with embedded laser dyes with strong absorption and fluorescence bands in different region of the Visible spectrum are attained by sol-gel chemistry to obtain solid-state dye laser (SSDL) with good photo, thermal and chemical stabilities. Third, silica nanoparticles (NP) with suitable size (50 nm) and functionalized external surface are also synthesised by sol-gel chemistry. Through the encapsulation of fluorescent dye molecules in their core and by the grafting of photosensitizers on their shell, biocompatible nanoparticles for bio-imaging and Photodynamic Therapy (PDT) applications are prepared. In order to optimize their properties, a careful investigation of the photophysical properties and mainly the singlet oxygen generation of a large range of new photosensitizers based on chromophores known as BODIPYs, is previously carried out. Based on these results, some efficient BODIPYs are selected for grafting on silica nanoparticles in order to use them for PDT. The photophysical properties of all these hybrid materials are analyzed by absorption and fluorescence (steady-state and time correlated) spectroscopies, and the singlet oxygen measurements are monitored by direct method (recording the singlet oxygen luminescence at 1270 nm) and by indirect method (using selective chemical probe). Moreover, the hybrid materials are fully characterized by several techniques such as, SEM, TEM, XRD, XPS, IR, DLS, BET.

The aim of the thesis has been to evaluate and understand the effect of caustic alkali solution of varying composition on the behaviour of expansive soil containing mixed layered minerals. Mixed layered minerals are formed of two or more kinds of inter grown layers, not physical mixtures. Illite - smectite is the most abundant and wide spread of the mixed layered clay minerals in sedimentary rocks and soils and also more common than either discrete illite or smectite. In geotechnical engineering much attention has not been paid to the behaviour of soils containing mixed layered minerals. Much less is known about the behaviour of these soils in polluted environment. Mixed layered minerals are more susceptible to environmental changes as the structural linkages between the layer minerals are weak compared to normal layered phyllosilicates. One important pollutant that can have considerable effect on the behaviour of soils is the caustic alkali contamination released from various industries. Recent studies have shown that the behaviour of even stable minerals is affected by alkali contamination. However, the effect of caustic alkali contamination on the behaviour of soils containing mixed layered minerals is not known and has been chosen for detailed study. Also to understand the mechanism of their interaction with alkali, it is necessary to study the effect of alkali solutions on the constituent clay minerals viz., montmorillonite and illite under similar conditions. To elucidate the mechanism of soil alkali interaction limited tests were conducted with simple electrolyte solution, as the alkali solution also acts as electrolyte apart from being alkaline. To confirm the mechanism of interaction, tests are also conducted on these soils with industrial spent liquor containing high caustic alkali and suspended alumina obtained from an alumina extraction plant treating bauxite with high alkali solutions at high temperatures. The results obtained in the laboratory are compared with the soil samples contaminated with leaking industrial Bayer's liquid in the field. Studies are also conducted to suggest remedial measures to control the adverse effects of alkali solutions on soil containing mixed layer minerals. The content of the thesis is broadly divide into 8 Chapters - viz., Introduction, Background and overview, Experimental program and procedures, Behaviour of soils containing mixed layer mineral illite - smectite (BCSI), Behaviour of montmorillonite and illite, Influence of Bayer's liquor and study on the field contaminated soils, Measures to control the influence of alkali contamination on BCSI and Summary and conclusions. The broad outline of these chapters is given in Chapter 1. A review of literature on the behaviour of soils containing different types of clay minerals with emphasis on mixed layer minerals has been presented in Chapter 2. The influence of different inorganic contaminants on the properties of soils in terms of their physical and chemical characteristics as well as their concentration has been summarized. The importance of changes in surface characteristics of soil particles and the changes in the thickness of diffuse double layer in altering the property of soils at low concentration of contaminants and changes in the mineralogy with high concentrated contaminants such as acids and alkalis has been highlighted. This forms the background information necessary to bring out the scope of the study. Four soils having different mineralogy have been used in this study. These soils are, black cotton soil containing predominantly mixed layer mineral illite - smectite mineral called rectorite, illite, montmorillonite (common smectite) and black cotton soil containing predominantly montmorillonite. The properties of the soils used are described in Chapter 3. Caustic alkali solutions of 1N, 4N concentration prepared in the laboratory and industrial alkali-spent liquor are used as contaminants. The spent Bayer's liquor had about 4N alkali concentration and 10% alumina in suspension. To simulate the effect of suspended alumina, two more caustic alkali solutions of 1N and 4N solutions containing 10% alumina by weight of solutions are also prepared. To isolate the effect of electrolyte solutions from that of alkali solution, two electrolyte solutions of 1N and 4N sodium chloride solutions are also used. Test procedures for conducting various tests such as pH, water adsorption characteristics, X-ray diffraction studies, SEM studies, thermal characteristics and geotechnical properties such as Atterberg limits, Oedometer tests and Shear Strength are given in this chapter. The test procedures are modified, wherever necessary, to bring out the effect of contaminants, particularly the effect of duration of interaction on the properties of soils. The source and properties of black cotton soil are presented in Chapter 4. Detailed x-diffraction studies have confirmed the presence of inter layered illite-smectite mineral viz., rectorite, which is uncommon in Indian expansive soils, and is classified as CH (Clay of high compressibility) as per ASTM soil classification. Effect of alkali and salt solutions of 1N and 4N concentration on all physico chemical and geotechnical properties are studied in this chapter. As it is known that presence of certain elements such as aluminium influence the soil alkali interaction, the effect of suspended alumina along with alkali solution has also been investigated. The effect of contaminating fluids such as 1N NaOH, 4N NaOH with and without alumina, 1N NaCl and 4N NaCl on the geotechnical properties of the soil has been studied. Mineralogical changes were observed by XRD and thermal studies in the soil treated with 4N NaOH solution and 4N NaOH + 10% alumina. The interlayer potassium of illite is released and potassium hydroxide is formed in soil treated with 4N NaOH. Swelling compounds such as sodium aluminium silicate hydroxide hydrate (SASH) has formed due to attack of 4N NaOH + 10% alumina on silica rather than on rectorite. Thus the studies clearly bring out that the rectorite present in the soil is dissociated only in the presence of strong alkali solutions of concentration of about 4N. The liquid limit of soil decreased with increase in the electrolyte concentration in the case of NaCl solutions. With 1N NaOH, the liquid limit of soil increased due to increase in the thickness of diffuse double layer due to increased pH. However, Proctor's maximum dry density increased and optimum moisture content decreased with 1N NaOH. With increase in the concentration of alkali solution to 4N, the rectorite dissociates into constituent minerals with the formation potassium hydroxide. The liquid limit of soil decreased probably due to the dominating influence of electrolyte nature of hydroxide solution over the effect of increased negative charge on clay particles due increase in the pH on the constituent minerals. Proctor's maximum dry density decreased and optimum moisture content increased with 4N NaOH. Sediment volume and oedometer free swell at seating/nominal surcharge load of 6.25 kPa of soil increased in 1N and 4N caustic alkali solutions, though by different mechanisms. The increase with 1N solution is essentially due to increased negative charges on clay mineral surface. However, the increase in swelling with 4N solution is associated with the dissociation of rectorite mineral and occurs in two distinct phases unlike in the case of 1N solution. While the first phase can be attributed to the effect of alkaline nature of the solution after reduction in its concentration due to reaction with rectorite and the consequent reduction in its electrolyte nature. The second phase is due to the swelling of the separated constituent minerals in the presence of excess of alkali and occurs after much delay. Consolidation behaviour of rectorite in 1N and 4N alkali solutions has been studied in two ways: 1). Loading without waiting for the second stage of swelling to occur, as in standard consolidation procedure and 2). Loading after completion of second stage of swelling which is occurring after considerable delay as explained earlier. Normally one would initiate loading after equilibrium is reached at the end of first stage of swelling and second stage of swelling is not suspected. As there is no second stage of swelling with 1N solutions, these two types of consolidation tests produced the same results. Abnormal rebound is observed during unloading with 4N solution in which loading cycle is initiated without waiting for second stage of swelling to complete. It is interesting to note that while the liquid limit of soil decreased with increase in the concentration of alkali solution, the swelling increased. The testing procedure and period of interaction as well as the concentration of alkali solution during the test in these two tests are different. The effects of alkali solution are more severe in case of liquid limit because of thorough mixing and consequent effective reaction during testing. Similarly, the volume changes in soil that has already reacted with 4N alkali solution when exposed to further to alkali contamination are considerably less compared to uncontaminated soil exposed to fresh contamination. The shear strength of soil treated with 4N-alkali solution has increased particularly after long period of interaction. This indicates that the soil after mineralogical changes posses good strength. Chapter 5 presents the effect of alkali and salt solutions on the physico chemical and geotechnical properties of component minerals of mixed layered illite/smectite. For this study, commercially obtained montmorillonite (bentonite), naturally occurring black soil containing montmorillonite and commercially pure illite are used. It was observed that montmorillonite alkali reactions would not produce significant mineralogical changes where as illite is dissociated into smectite with the formation of potassium silicate by the interaction of released potassium with soluble silica. This confirms that the ultimate products of rectorite with alkali solutions would be smectite and compounds of potassium. In the absence of mineralogical alterations the liquid limit of montmorillonite decreases due to suppression of diffuse double layer thickness due to dominating influence of alkali solutions on this highly active clay. However a small increase in liquid limit is observed in illite with alkali solutions. Thus the net effect of alkali on rectorite is to decrease the liquid limit with increase in alkali concentration. While the free swell and oedometer swelling of montmorillonite generally decreases with increase in the alkali concentration, they increase in illite. However, in both the minerals the swelling occurs only in one phase. Thus the second phase of swelling that has been observed in rectorite can be attributed to delayed swelling of montmorillonite that has been released by the attack of alkali on rectorite. The behaviour of black soil containing mixed layer mineral contaminated in the field and laboratory by leaking Bayer's spent liquor in an alumina extraction plant has been studied in Chapter 6. The Atterberg limits of the samples treated with liquor are reduced and sediment volume increased. Similarly the swelling at seating load in consolidation test is higher in sample compacted with water and inundated with liquor. X-ray diffraction studies showed that the mineralogical changes are similar to those occurred with 4N caustic alkali solution. The mineralogical and micro structural changes in the soil samples that are contaminated by leaked spent liquor in the field are relatively more marked. Also the behavior of highly montmorillonite clay, bentonite, has been studied contaminated with liquor in the laboratory. The study on the effect of high concentrated alkali solutions on montmorillonite can be useful to study the effect of interaction on the dissociated montmorillonite. These studies are helpful to suggest some possible remedial measures to control the adverse effect of alkali on soils. Possible Remedial schemes that can be adopted before and after contamination of the soil to control the adverse effect of alkali solutions on the black cotton soil containing mixed layered mineral are listed and their effectiveness examined in Chapter 7. The suggested remedial measures include flushing with water to dilute the effect of alkali, neutralisation with dilute hydrochloric acid, stabilisation of soil with lime and calcium chloride and use of impervious membrane to separate the foundation soil from alkali solution. The effectiveness of different measures as well as the method of their application has been described. Efforts are made to understand the mechanism of remedial action. Consolidation tests conducted on soil contaminated with 4N alkali solution and inundated with water showed increased swelling due to dilution of the alkali concentration. Though the swelling of contaminated soil can be controlled by passing dilute hydrochloric acid (1N), the method is not advocated as it can lead to ground water contamination. Mixing the soil with solutions containing up to 5% by weight of calcium compound in water could not prevent the alkali induced heave in the long run when inundated with 4N alkali solution. This was due to dissolution of silica by the strong alkali solutions and formation of swelling compounds such as sodium aluminium silicate hydroxide hydrate (SASH). The formation of sodium aluminates occurred only when the alkali solution contained alumina or soil contained calcium compounds. There are no significant variations in the effects of calcium chloride or calcium hydroxide on contaminated soil. Replacing the foundation soil with soil thoroughly contaminated with 4N alkali solutions and controlling the migration of contaminants into the foundation soil using high-density polyethylene (HDPE) geosynthetic membranes can be an effective measure to control the heaving in alkali contaminated foundation soil containing interstratified illite – smectite. Summary and the major conclusions of the thesis are presented in Chapter 8.

Η περιοχή μελέτης καλύπτει ένα μέρος των ανθρακικών αποθέσεων της Κεντρικής και Εξωτερικής Ιόνιας ζώνης οι οποίες αποτέθηκαν από το Τριαδικό έως το Ηώκαινο. Γεωγραφικά οριοθετείται, κατά τον άξονα Ανατολή – Δύση, από τον εθνικό δρόμο Άρτας – Ιωαννίνων και το Ιόνιο Πέλαγος, και κατά Βορά – Νότο από νοητούς, παράλληλους προς τον Ισημερινό άξονες που διέρχονται από την Άρτα και την Ηγουμενίτσα. Η περιοχή βρίσκεται ανάμεσα στις συντεταγμένες 20ο 12΄ και 21ο 00΄ Ανατολικά, και 39ο 00΄ με 39ο 30΄ Βόρεια και καλύπτεται από τα ακόλουθα γεωλογικά φύλλα του Ι.Γ.Μ.Ε, κλίμακας 1:50.000: Άρτα, Καναλάκι, Πάργα, Θεσπρωτικό και Παραμυθιά. Από την μικροφασική ανάλυση και την ανάλυση φασικών ζωνών που προηγήθηκε σε συνδυασμό με την βιοχρονολόγηση εξάγεται το συμπέρασμα ότι κατά το Α.Τριαδικό αποτέθηκαν μικριτικοί και κατά θέσεις λιθοκλαστικοί ασβεστόλιθοι σε περιβάλλον υφαλοκρηπίδας περιορισμένης κυκλοφορίας. Από το Α.Τριαδικό και μέχρι το τέλος του Λιασίου αποτίθενται σε όμοιες περιβαλλοντικές συνθήκες grapestones, rudstones, floatstones και grainstones. Από το Λιάσιο και μέχρι το Σαντώνιο αποτίθενται mudstone – wackestone και σπανιότερα packstone σε περιβάλλον πρόσθιας κατωφέρειας έως και υφαλοκρηπίδας ανοιχτής θάλασσας. Από το Καμπάνιο έως το Πριαμπόνιο, όπου τοποθετείται και το τέλος της ανθρακικής ιζηματογένεσης στην Ιόνιο ζώνη, αποτίθενται εναλλαγές από mudstone – wackestone και floatstone – packstone σε περιβάλλον πρόσθιας κατωφέρειας και βαθύτερο όριο υφαλοκρηπίδας. Στρωματογραφικά οι αποθέσεις της περιοχής μελέτης αποτελούνται από τέσσερις συνολικά ακολουθίες 3ης τάξης, δύο χαμηλής στάθμης (LST), μία υψηλής στάθμης (HST) και μια επικλυσιγενής (TST). Ο συνολικός όγκος των μελετηθέντων ιζημάτων ανέρχεται σε 3064,796 χλμ3, καταλαμβάνοντας χρονικό διάστημα από το Ανώτερο Τριαδικό έως το Παλαιογενές, από τα όποια 1398,050 χλμ3 αποτελούνται από τους ασβεστόλιθους του Ιουρασσικού οι οποίοι λόγω της απουσίας το Ammonitico Rosso δεν διαχωρίζονται. Επιπλέον 796,777 χλμ3 αποτελούνται από τους ασβεστόλιθους της Βίγλας οι οποίοι μαζί με τις πελαγικές αποθέσεις του Μέσου – Άνω – Ιουρασσικού απαρτίζουν την πελαγική ακολουθία 2ης τάξης. Τέλος 449,921 χλμ3 και 420,048 χλμ3 ανήκουν στους ασβεστόλιθους το Α.Κρητιδικού και του Παλαιογενούς οι οποίοι απαρτίζουν την δεύτερη ακολουθία 3ης τάξης. Οι αποθέσεις του Τριαδικού λόγω του άγνωστου υποβάθρου τους και τις ευδιάλυτης φύσης τους δεν συμπεριλήφθηκαν στους υπολογισμούς όγκου. Από την μελέτη με ηλεκτρονικό μικροσκόπιο σάρωσης προέκυψε ότι διεργασίες όπως μικριτίωση, ανακρυστάλωση, προσαύξηση και νεομορφισμός του υλικού τσιμεντοποίησης είναι καθολικές για όλα τα δείγματα. Σε κάποια δείγματα παρατηρήθηκαν πυριτικά συσσωματώματα τα οποία συνδέονται με την δράση θειοβακτηριδίων. Επίσης στο σύνολο των δειγμάτων παρατηρήθηκε ασήμαντο από άποψη υδραυλικών χαρακτηριστικών μεσοκρυσταλλικό και μεσοκοκκώδες πορώδες. Το πιο σημαντικό πορώδες παρατηρήθηκε σε δείγματα wackestone του Παλαιογενούς το οποίο συνίσταται από πορώδες διαλυσιγενών καναλιών, βιοδιάτρησης και ενδοκοκκώδες παρουσιάζοντας αυξημένο ενδιαφέρον από άποψη υδροχωριτικότητας και διαπερατότητας. Από την μελέτη των αργιλικών ορυκτών προκύπτει ότι τα ιζήματα το Μέσου Ιουρασσικού βρέθηκαν σε στάδιο Μέσης διαγένεσης και σε θερμοκρασίες που δεν υπερέβησαν τους 100 0C. Τα μεταγενέστερα ιζήματα βρεθήκαν όπως αναμένονταν σε ζώνες ασθενέστερης διαγένεσης με αποκορύφωμα τα ιζήματα του Παλαιογενούς που βρέθηκαν μόνο στο στάδιο της πρώιμης διαγένεσης ή ρηχής ταφής. Οι συνθήκες διαγένεσης κρίνονται ανεπαρκής για την ωρίμανση και γένεση υδρογονανθράκων. Από τη ανάλυση σταθερών ισοτόπων και οργανικού άνθρακα εξάγεται το συμπέρασμα ότι κανένα από τα δείγματα που μελετήθηκαν δεν συνδέεται με κανένα τρόπο με μητρικό πέτρωμα υδρογονανθράκων. Επίσης από ανάλυση μάζας πετρώματος δεν μπορούν να εξαχθούν ασφαλή συμπεράσματα ως προς την θερμοκρασία που επικρατούσε στο περιβάλλον απόθεσης, λόγω των διαγενετικών αλλαγών. Όλα τα δείγματα που εξετάστηκαν έχουν δ τιμές μέσα στο εύρος των κανονικών πελαγικών αποθέσεων. Η υπό αμφισβήτηση παραδοχή ότι από τα παλαιότερα σε νεότερα πετρώματα το περιεχόμενο σταθερών ισοτόπων γίνεται ελαφρύτερο, δεν επιβεβαιώθηκε και επιπρόσθετα από τα αποτελέσματα τεκμηριώνεται η μη ορθότητα της παραδοχής. Το ποσοστό οργανικού άνθρακα καθορίζεται από τις οξειδωτικές ή αναγωγικές συνθήκες που επικρατούσαν και από τη δράση θειοβακτηριδίων και παραμένει εξαιρετικά χαμηλο στο σύνολο των δειγμάτων (<0,05 %). Η Ιόνιος ζώνη αναπτύχθηκε πάνω από ένα παθητικό περιθώριο με υπόβαθρο παλαιοζωικά μεταμορφωμένα πετρώματα τα οποία δεν έχουν επιφανειακές εμφανίσεις. Αρχικά και μετά από ηπειρωτική διάρρηξη αποτέθηκαν εβαποριτικά και ανθρακικά ιζήματα σε περιβάλλον περιορισμένης υφαλοκρηπίδας με εκτεταμένες και διάσπαρτες υπεράλμυρες λίμνες (sabkhas). Μετά από μία σύντομη περίοδο επιφανειακής έκθεσης η στάθμη της θάλασσας αυξήθηκε και αποτέθηκαν κανονικής αλμυρότητας ασβεστόλιθοι υφαλοκρηπίδας σε όλη τη διάρκεια του Λιασίου (Κ.Ιουρασσικό, κυρίως οι λεγόμενοι ασβεστόλιθοι ‘‘Παντοκράτορα’’). Στη συνέχεια και μέχρι το Σαντώνιο (Α.Κρητιδικό) αποτίθενται πελαγικοί ασβεστόλιθοι σε περιβάλλον υφαλοκρηπίδας ανοιχτής κυκλοφορίας με γεωμετρία ράμπας ίσης κλίσης (homoclinal ramp). Το περιβάλλον παραμένει ίδιο, με κάποιες μικρές τροποποιήσεις, όπως μεταβολή της κλίσης σε συνάρτηση με τη απόσταση από την ακτή και μικρή μείωση της στάθμης της θάλασσας, μέχρι το τέλος του Ηωκαίνου (Παλαιογενές) οπότε γίνεται μετάβαση σε κλαστική ιζηματογένεση. Από όλα τα δείγματα που μελετήθηκαν αυτά που δείχνουν να έχουν εκτεθεί σε θερμοκρασίες πάνω από 90-100 0C είναι ηλικίας Ιουρασσικού ή παλαιότερα. Στη περιοχή μελέτης όλα τα δείγματα που μελετήθηκαν έχουν περιεκτικότητα σε οργανικό υλικό μέχρι 0,05 % το οποίο είναι πολύ χαμηλότερο από το ελάχιστο απαιτούμενο 0,7 % για να είναι πιθανή ή γένεση υδρογονανθράκων. Επιπλέον οι τιμές δ του σταθερού ισοτόπου 13C απέχουν πολύ από τις τιμές -18 ‰ έως -27 ‰ οι οποίες χαρακτηρίζουν τα μητρικά πετρώματα υδρογονανθράκων. Για τους παραπάνω λόγους πιθανά μητρικά πετρώματα φαίνεται να είναι οι Τοάρσιας ηλικίας, λεγόμενοι “Κατώτεροι σχιστόλιθοι με Poseidonia”, και οι πλούσιες σε οργανικό υλικό παρενστρώσεις που βρίσκονται μέσα στα Τριαδικής ηλικίας ιζήματα. Σημαντικό είναι ότι καμία από τις παραπάνω αποθέσεις δεν έχουν επιφανειακή εμφάνιση στην περιοχή μελέτης. Ταμιευτήρια πετρώματα μπορεί να είναι είτε οι ημιπελαγικές αποθέσεις του Α.Κρητιδικού και του Παλαιογενούς είτε οι μεταηωκαινικές κλαστικές αποθέσεις. Ολοκληρώνοντας το ρόλο καλυμμάτων μπορούν να παίξουν τόσο οι πελαγικές αποθέσεις από το Μ.Ιουρασσικό έως το Κ.Κρητιδικό όσο και οι μεταηωκαινικές κλαστικές αποθέσεις. / PhD Thesis title is “The sedimentological evolution of the Ionian basin during Triassic to Eocene and the possible existence of hydrocarbon plays in the central part of the basin”. The main target of the study is to reveal, in every detail, the sedimentation pattern during the above mentioned time interval. The study area is located in western Greece (Fig. 1). The sediments of the Ionian basin were studied in fifty outcrops and a number of 300 samples were collected (Fig 2). Thin sections were prepared for all the samples and they were studied under polar microscopy. The samples were classified using Dunham’s (1965) classification chart. Afterwards, SMF and FZ, after Flugel (1972) and Wilson (1975), were determined. In addition, stable isotope analysis; clay mineral analysis, organic carbon analysis and micropaleontological study were contacted. The Triassic rocks crop out sparsely and only in signs due to their stratigraphic position, the oldest rocks, and their soluble nature. The outcrops are consisted of chaotic masses with no preferred orientation and no primary structures, like bedding (Getsos et al., 2004). Often they have suffered extensive dissolution and collapsing giving rise to the formation “Solution Collapse Breccias” (Pomoni-Papaioannou, 1980; Pomoni-Papaioannou, 1985; Karakitsios & Pomoni-Papaioannou 1998). Extensive outcrops characterize lower Jurassic sediments with great thickness, completely absence of bedding or other similar primary structure and abundant fragments and fragmentation effects. Karstification, calichification and pedogenesis are common. The sediments were studied in the following six different outcrops: T45, T5, T6, T30, T33, and T38. Samples were studied under polar microscope and their sedimentological and diagenetical pattern were revealed. The studied Early to Late Cretaceous Vigla’s formation appear as extensive outcrops of thin to medium bedded limestones with an average thickness of 200-400 m. Samples were collected from fifteen outcrops around the study area and they were studied under polar microscope. The results of the sedimentological analysis were further combined with the results of low resolution stable isotope analysis, organic carbon and clay mineral analysis. The Paleogene limestones appear as extensive outcrops consisted of intercalations of thin bedded pelagic limestones and medium to thick bedded coarse bioclastic – lithoclastic limestones. Their thickness varies between 180 and 440 m. Triassic. The studied sediments are contributed to four 3rd order sequences, two low stand systems tracts (LST), one of high stand systems tract (HST) and one transressive systems tract (TST). The total volume of studied sediments amounts in 3000 km3, occupying the Late Triassic – Paleogene time interval. The first LST has a duration of 45 million years and average thickness more than 3000 metres. It is consisted of the Triassic rocks and the Early Jurassic shallow shelf limestones, the so called “Pantokrator Limestones”. The HST is constituted of the Late Jurassic to Late Cretaceous (Santonian) pelagic limestones with an average thickness of 600 metres. The duration of the sequence is almost 80 million years. Between the above mentioned sequences the TST were deposited. The deposition took part during the Middle Jurassic and duration was almost 20 million years with a maximum thickness of no more than 200 metres. Finally the last LST sequence is constituted by the Late Cretaceous (Campanian) to Paleogene (Eocene) limestones with an average thickness of 400 m. and 45 million years duration. The study of samples under SEM has revealed a common diagenetic pattern. It is consisted of early diagenetic micritization and early diagenetic neomorphism and recrystallization. In a small number of samples pyrite was studied. Usually pyrite is the product of sulphate reduction bacteria. The microporosity is mainly intecrystall and it has no importance for reservation and fluid circulation. The most important porosity was observed in samples consisted of wackestones and packstones Paleogene in age and it was consisted of solution channels, borings and intraparticle. Clay mineral analysis have revealed the Middle Jurassic sediments suffered the Middle diagenesis stage and their temperatures did not exceed 100 0C. The newer sediments reached up to the Middle stage as well with only exception the Paleogene sediments which suffered only Early diagenesis or “Shallow burial stage”. The diagenetical conditions are insufficient for the maturation and genesis of hydrocarbons. Oxygen and carbon stable isotopes analysis and organic carbon analysis has revealed that the studied sediments do not constitute oil source rocks or reservoirs. The obtained δ values of the studied sediments are within the -+ 4 ‰ which is the characteristic of the normal pelagic limestones. The organic carbon analysis was contacted with the wet oxidation method. The organic carbon content of the whole sediments is very low and do not exceeds the 0.05% value. The Ionian basin was developed on a Mesozoic passive margin. The basement is studied only in signs in nearby areas (Albania) and it is consisted of metamorphosed Palaeozoic rocks. The first sediments deposited were carbonates and sulfates. The depositional environment was restricted circulation shelf and tidal flats and evaporates on sabkhas – Salinas. During the transgressive phase the environment was deep shelf margin and it was part of a homoclinal ramp system (middle ramp). The homoclinal ramp was covered until the initialization of the deposition of the last LST phase when the environment was transformed into a distally steepened ramp or rimmed shelf. Afterwards the carbonate sedimentation came to an end and the clastic sedimentation was established in a foreland basin. The studied sediments with depositional age after the Middle Jurassic have been exposed in temperature much less than 100 0C and as a consequence they are immature. The older sediments have suffered diagenetical temperature almost 100 0C or more and as consequence they are mature. The organic carbon content, as have already been mentioned, is maximum 0.05 %. This value is much lower than minimum hydrocarbon source rock organic carbon content (0.7%). Furthermore the δ values of the carbon stable isotope are much heavier than the values -18 to -27 ‰ which are the typical values of the source rocks. Taking into account the above facts the possible source rocks of the studied area could be the Toarcian age “Lower Posidonia Shales” and the rich in organic matter clayey intercalation of Triassic age. These possible source rocks do not crop out anywhere in the study are. Potential reservoirs can be the hemipelagic LST sequence of Late Cretaceous – Paleogene age or the clastic post Eocene sediments. Potential seal rocks are the pelagic HST sequence of Middle Jurassic – Late Cretaceous limestone and the fine-grained post Eocene clastic sediments.

Στην παρούσα διατριβή ειδίκευσης παρασκευάσθηκαν νανοσύνθετα υλικά αργιλικών ορυκτών/διοξειδίου του τιτανίου (TiO2) για την περιγραφή και μελέτη των νέων βελτιωμένων χαρακτηριστικών τους και την εφαρμογή τους σαν φωτοκαταλύτες στη διάσπαση ανόργανων αέριων ρύπων οξειδίων του αζώτου (NOX). Τρία αργιλικά ορυκτά (σαπωνίτης, παλυγορσκίτης και αλλοϋσίτης) χρησιμοποιήθηκαν για την διεξαγωγή των πειραμάτων. Δείγματα σαπωνίτη και παλυγορσκίτη συλλέχθηκαν από τη λεκάνη του Βεντζίου στα Γρεβενά και αλλοϋσίτη από τη νήσο Λήμνο. Δύο διαφορετικές μορφές νανοσύνθετων αργιλικού ορυκτού/TiO2 παρήχθησαν με δύο διαφορετικές μεθόδους και χρησιμοποιήθηκαν για τη μελέτη της φωτοαποικοδόμησης ανόργανων αέριων ρύπων NOX : Υποστυλωμένα με TiO2 νανοσύνθετα σαπωνίτη (Ti-sap1, Ti-sap2) παρήχθησαν με τη μέθοδο της «solvothermal synthesis” χρησιμοποιώντας TiCl3 σαν πρόδρομο TiO2 και νανοσύνθετα TiO2/ παλυγορσκίτη (Ti-pal) και TiO2/ αλλοϋσίτη (Ti-hall) παρήχθησαν με τη μέθοδο κολλοειδούς διαλύματος σε πήκτωμα (sol-gel) χρησιμοποιώντας Titanium Tetraisopropoxide (Ti(OC3H7)4) σαν διάλυμα διασποράς-επικάθησης. Για τον χαρακτηρισμό των ιδιοτήτων των φυσικών και τροποποιημένων δειγμάτων εφαρμόστηκαν διαφορετικές τεχνικές (XRD, FTIR-ATR, SEM-EDS, TEM, DLS, BET, porosimetry). Τα νανοσύνθετα αποδείχθηκαν αρκετά αποτελεσματικά για τη φωτοδιάσπαση των αέριων ρύπων NOX συγκριτικά με τον standard τύπο διοξειδίου του τιτανίου, Degussa P25, που χρησιμοποιείται γιαυτό το σκοπό. Tα υποστυλωμένα νανοσύνθετα Ti-sap1 και Ti-sap2 (με αναλογίες μάζας TiO2:σαπωνίτη = 0.2:1 και 0.1:1 αντίστοιχα) έδειξαν αύξηση της ειδικής τους επιφάνειας συγκριτικά με το φυσικό δείγμα σαπωνίτη και μεσοπορώδη δομή με κατανομή πόρων 5.7-9.8nm για το Ti-sap1 και 3.8nm για το Ti-sap2. Και τα δύο νανοσύνθετα απέκτησαν αυξημένη φωτοκαταλυτική ικανότητα βάση του περιεχόμενου ποσοστού TiO2 συγκριτικά με τον standard P25 λόγω της ομοιογενούς διασποράς των σωματιδίων TiO2 στον σαπωνίτη αλλά συγκρίνοντας τα δύο δείγματα Tisap1 και Tisap2, το Tisap2 είχε καλύτερη φωτοκαταλυτική δράση από το Tisap1. Όσον αφορά τα νανοσύνθετα TiO2-pal και TiO2-hall τα αποτελέσματα έδειξαν τη δημιουργία μεσοπορώδους δομής με πόρους 6.5 και 5.6 nm αντίστοιχα για το κάθε υλικό ενώ η μακροπορώδης δομή (lumen) του αλλοϋσίτη δεν υπήρχε στο τροποποιημένο δείγμα λόγω του ότι καλύφθηκε από τα νανοσωματίδια του TiO2 με αποτέλεσμα να προκύψει ένα υλικό με μικρότερο μέγεθος πόρων. Τα δύο δείγματα έδειξαν υψηλή φωτοκαταλυτική ικανότητα στη διάσπαση των αέριων ρύπων NOX υπό την επίδραση ορατής (λ>510nm) και υπεριώδους (λ>290nm) ακτινοβολίας σε σύγκριση με τα αποτελέσματα που έδωσε ο standard τύπος TiO2 P25. / In this thesis TiO2/clay nanocomposites have been synthesized and characterized as photocatalysts in the decomposition of NOx gases. Three different clay minerals (saponite, palygorskite and halloysite) have been used. The saponite and palygorskite samples were collected from Western Macedonia (Grevena, Ventzia basin) and halloysite from Lemnos island. The two different forms of nanocomposites that synthesized by two different methods were: TiO2 -pillared saponite (Ti-sap1, Tisap2) were successfully prepared by solvothermal synthesis using titanium trichloride as the precursor and TiO2- Palygorskite (Ti-pal) and TiO2-Halloysite (Ti-hall) nanocomposites were prepared by deposition of anatase form of TiO2 on the clay surfaces using a sol–gel method with titanium isopropoxide as a precursor. The characterization of the natural and modified samples was done by using different techniques (XRD, FTIR-ATR, SEMEDS, TEM, DLS, BET, porosimetry) The photocatalytic properties of the TiO2-clay nanocomposites were found to be better than that of the standard titania, Degussa P25 in decomposing NOX gases. The pillared TiO2 nanocomposites Ti-sap1, Tisap2 (mass ratio of TiO2:saponite= 0.2:1 and 01:1 respectively) showed a mesoporous structure compared to the natural saponite, with the distribution of pore diameters centered at 5.7-9.8 and at 3.8 nm, with high specific surface areas. Both TiO2-saponite nanocomposites showed higher photocatlytic activity than the standard (Degussa P25) based on TiO2 content because the TiO2 was well dispersed on saponite. By comparing the two modified samples Ti-sap1, Ti-sap2, the second one showed better photocatalytic activity than Ti-sap1 The results of the other two nanocomposites, Ti-hall and Ti-pal, showed mesopores of about 5.6 and 6.5 nm, respectively, while the macropores of halloysite (lumen) disappeared. The latter is attributed to the covering of the lumen of halloysite tubes by TiO2 nanoparticles and for that reason the pore size of the TiO2–treated halloysite was significantly smaller. The clay minerals- TiO2 samples showed significantly higher activity in decomposing NOx gas under visible-light irradiation (λ> 510 nm) and UV light irradiation (λ> 290 nm) compared to that of the standard commercial TiO2, P 25.

Η ορυκτολογική σύσταση του αργιλικού υλικού που χρησιμοποιείται σε ένα χώρο υγειονομικής ταφής απορριμμάτων είναι καθοριστικής σημασίας όσον αφορά την πιθανή διαφυγή και μετανάστευση ρύπων στο περιβάλλον. Ο προσδιορισμός των αργιλικών ορυκτών που συμμετέχουν στο αργιλικό υλικό, θεωρείται βασική παράμετρος όσον αφορά την εκτίμηση της ικανότητας τους για συγκράτηση οργανικών και ανόργανων ρύπων. Για το σκοπό αυτό η αναγνώριση των ορυκτολογικών συστατικών του αργιλικού υλικού που χρησιμοποιήθηκε στο χώρο υγειονομικής ταφής της Ν. Ζακύνθου κρίθηκε απαραίτητη. Από τα αποτελέσματα της περιθλασιμετρίας ακτίνων Χ προέκυψε ότι στο αργιλικό υλικό που χρησιμοποιήθηκε μέσα στο χώρο υγειονομικής ταφής, διακρίθηκε μία ομάδα δειγμάτων πλούσια σε σμεκτίτη (μοντμοριλλονίτη) και μία δεύτερη πλούσια σε χλωρίτη και βερμικουλίτη. Παράλληλα, η χρήση της περιθλασιμετρίας ακτίνων Χ σε συνδυασμό με την ηλεκτρονική μικροσκοπία και τις γεωχημικές αναλύσεις έδωσαν πληροφορίες για την προέλευση των ιζημάτων, καθώς και για τη παρουσία ρύπων και τον τρόπο συγκράτησης τους στις ορυκτές φάσεις που τα απαρτίζουν. Η μελέτη των φασμάτων NMR στα εκχυλίσματα των δειγμάτων έδειξε την ύπαρξη κορυφών απορροφήσεως από πρωτόνια που σχετίζονται με ομάδες πολυσακχαριτών, πεπτιδίων/πρωτεϊνών, αλκοολών, αμινοξέων, ομάδων που περιέχουν –Cl, σουλφιδίων και μεθυλενίων –CH2– παρακείμενων σε ομάδες αιθέρων ή και εστέρων τα οποία παράγονται ως αποτέλεσμα υδρόλυσης και αναερόβιας ζύμωσης στα διαλύματα στραγγισμάτων. Επιπλέον, οι μικροαναλύσεις έδειξαν την παρουσία χλωρίου και θείου σε κρυστάλλους απατίτη, καθώς και χλωρίου, θείου και φωσφόρου σε αργιλικά ορυκτά στα δείγματα που βρίσκονταν σε επαφή με στραγγίσματα, ενισχύοντας την άποψη ότι οι παραπάνω ομάδες προέρχονται από την αλληλεπίδραση με τα στραγγίσματα. Η διαφορετική ορυκτολογική σύσταση του αργιλικού υλικού που χρησιμοποιήθηκε στο χώρο απόθεσης απορριμμάτων (χλωρίτης-μοντμοριλλονίτης) φαίνεται να ευνοεί την εκλεκτική προσρόφηση των διαφορετικών οργανικών ρύπων που συμμετέχουν στα στραγγίσματα και κατά συνέπεια θεωρείται επιθυμητή. Προς την κατεύθυνση αυτή εστιάστηκε το ενδιαφέρον της διατριβής οπότε και προέκυψε ότι ο χλωρίτης παρουσιάζει εκλεκτική προσρόφηση για τις αρωματικές ενώσεις σε αντίθεση με τον μοντμοριλλονίτη, ο οποίος επιδεικνύει εκλεκτική προσρόφηση εκείνων των αλειφατικών ομάδων που εκχυλίζονται από υδατικά διαλύματα. Επιπλέον, οι αρωματικές ενώσεις δεν εκχυλίζονται από υδατικά διαλύματα και κατά συνέπεια από ύδατα επιφανειακών απορροών με αποτέλεσμα να επιδεικνύουν περιορισμένη κινητικότητα. Αντίθετα, οι αλειφατικές ομάδες εκχυλίζονται από υδατικά διαλύματα ενώ η παρουσία τους ευνοεί το σχηματισμό ευδιάλυτων συμπλόκων με μέταλλα, γεγονός που οδηγεί τελικά σε κινητοποίηση τους μέσω των επιφανειακών απορροών. Τέλος, η προσρόφηση αμινομάδων από τα αργιλικά ορυκτά φαίνεται ότι οδηγεί μέσω μιας διαδικασίας φυσικής οργανοφιλίωσης στην μετατροπή των υδρόφιλων επιφανειών των αργιλικών ορυκτών σε υδρόφοβες και κατά συνέπεια την προσρόφηση των υδρόφοβων οργανικών συστατικών που περιέχονται στα διαλύματα στραγγισμάτων. Το γεγονός αυτό είναι ιδιαίτερα σημαντικό εφόσον δείχνει την δυνατότητα για in situ μετατροπή των αργίλων σε οργανόφιλες αργίλους δημιουργώντας νέες προοπτικές στην διαχείριση των μη πολικών οργανικών ρύπων. / The mineralogy of a clay liner used in a landfill may influence the mobility of contaminants. Therefore, the determination of the types of clay minerals that are present in the landfill is of great importance for the assessment of their efficiency in the retention of organic and inorganic pollutants. In the present work, clay materials from an operating waste disposal facility in Zakynthos Island, Western Greece were collected in order to determine the different clay minerals present and their pollutant retention potential. Mineralogical analyses by XRD of the clay material collected from the landfill revealed a smectite (montmorillonite) rich and a chlorite/vermiculite rich material. The information obtained from X-ray Diffraction and SEM-EDS combined with chemical analyses provided valuable information concerning the provenance of the sediments and their retention potential. 1H NMR revealed that some of the organic components which are present in the samples are aliphatics, polysaccharides, alcohols, esters, Cl halogens, sulphides, amines, peptide/protein groups, amide and aromatics which are produced in the landfill as a result of several complex phenomena involving solubilization, hydrolyzation and anaerobic biological processes. SEM-EDS analyses showed the presence of chlorine and sulphur in apatite crystals, and of chlorine, sulphur and phosphorus in clay minerals suggesting the interaction of these minerals with leachate. The different clay mineralogy of the material used in the landfill, smectite (montmorillonite) rich and chlorite/vermiculite rich material facilitated the adsorption of different organic compounds, which is significant for the retention of pollutants. NMR analyses showed that aromatic moieties are preferentially adsorbed on chlorite than on montmorillonite, while those aliphatic moieties that are water soluble are preferentially adsorbed on montmorillonite. Aromatics are not accessible to rainwater and therefore hardly migrate. The aliphatic chains that are water accessible can be released to the environment through natural leaching by rainwater and since they are known to form soluble metal-organic complexes, supervision of the landfill is considered essential. Moreover, the interaction of amine groups with clay minerals in an aqueous system is favoured by the formation of an "insoluble" hydrophobic product leading to the formation of naturally organically modified clays. Thus clays become organophilic and capable of removing non ionic organic contaminants. This is of great importance for environmental applications since it demonstrates the in situ formation of organophilc clays in landfills, hence enabling effective containment and immobilisation of toxic organic compounds.

Abstract In this Ph.D. thesis sediment cores from the central Arctic Ocean, southwestern Barents Sea and sediment exposures from the Kola Peninsula were investigated in order to reveal interactions between the late middle Pleistocene and late Pleistocene Arctic ice sheets, between Marine Isotope Stages 6 and 1 (MIS 6 and MIS 1). One of the main objectives of this work is to establish provenance areas for the sediments studied in the central Arctic, the southwestern (SW) Barents Sea and the Kola Peninsula, their transport mechanisms and through that their relationship to glaciations in the Arctic and to development in the Kola Peninsula during the late middle and late Pleistocene. Mineralogical and geochemical data from the core 96/12-1pc on the Lomonosov Ridge, central Arctic Ocean was studied to evaluate ice transport from circum-Arctic ice sheets and variability in sediment drainage systems associated with their decay. SW Barents Sea sediments contain important information on Late Glacial and Holocene sediment provenance characteristics in relation to ice flow patterns and ice rafting from different regional sectors. The studied SW Barents Sea sediment cores show that sediments were most likely derived from a combination of far-field Fennoscandian sources, local subcropping Mesozoic strata below the seafloor and sea ice transport. The investigation carried out on the Kola Peninsula indicates that the Eemian (MIS 5e) marine environment in the White Sea Basin and onshore coastal areas gradually changed into a glaciolacustrine environment during MIS 5d to MIS 5a. Subsequently, the Scandinavian Ice Sheet (SIS) covered the Kola Peninsula, most probably during MIS 4. The final deglaciation of the SIS on the Kola Peninsula took place, however, during the late Weichselian (MIS 2) between 16–12 ka. / Tiivistelmä Tässä väitöstutkimuksessa tutkittiin sedimenttikairanäytteitä keskeiseltä Jäämereltä ja Lounais-Barentsinmereltä sekä tarkasteltiin sedimenttiseurantoja Kuolan niemimaalla tarkoituksena selvittää myöhäisen keskipleistoseeni- ja myöhäispleistoseeniajan Arktisten jääkenttien keskinäiset vuorovaikutukset erityisesti merellisten isotooppivaiheiden 6 ja 1 (MIS 6 ja MIS 1) välillä. Tämän työn yhtenä päätavoitteena on määritellä sedimenttien lähdealueet keskeisellä Arktiksella, lounaisella Barentsinmerellä ja Kuolan niemimaalla, sedimenttien kuljetusmekanismit ja näiden perusteella riippuvuudet Arktisiin jäätiköihin ja Kuolan niemimaalla tapahtuneeseen myöhäiskeski- ja myöhäispleistoseenin kehitykseen. Mineraloginen ja geokemiallinen tieto Lomonosovin harjanteen kairauksesta 96/12-1pc, keskeisellä Jäämerellä on perusta arvioitaessa jääkuljetusmekanismeja ympäröiviltä sirkum-Arktisilta jäätiköiltä ja arvioitaessa valuma-alueiden osuutta suhteessa näiden jäätiköiden häviämiseen. Lounaisen Barentsinmeren sedimentit sisältävät tärkeätä tietoja viimeisen jäätiköitymisen loppuvaiheen ja holoseeni-ajan sedimenttien lähdealueista ja suhteista jäävirtauksiin ja jääkuljetukseen eri aluesektoreilta. Tutkitut Lounais-Barentsinmeren sedimentit osoittavat, että sedimentit olivat todennäköisimmin peräisin suhteellisen kaukaisilta Fennoscandian lähdealueilta, paikallisista mesotsoosista merenpohjan kerrostumista ja merijään kuljettamasta materiaalista. Kuolan niemimaalla tehty tutkimus osoittaa, että Eem-kauden (MIS 5e) meriympäristö Vienanmeren altaassa ja rannikkoalueilla vähitellen muuttui glaciolakustriseksi ympäristöksi MIS 5d:n ja MIS 5a:n välisenä aikana. Sen jälkeen Skandinavian jääkenttä (SIS) peitti Kuolan niemimaan, todennäköisimmin koko MIS:n 4 ajanjakson. SIS:n lopullinen deglasiaatio alkoi Kuolan niemimaalla kuitenkin myöhäisen Veiksel-jääkauden (MIS 2) aikana noin 16–12 ka sitten.

La récupération du pétrole par injection d’eau douce (LSW) a pour but de récupérer les huiles résiduelles piégées dans les réservoirs. Après des preuves d’une augmentation du taux de récupération lors de la LSW, des résultats controversés ont émergé et les mécanismes proposés dans la littérature font toujours l’objet de débat. Il est donc essentiel d'avoir une compréhension approfondie des interactions huile/saumure/roche (COBR) afin d’éclaircir les mécanismes engendrés par cette technique. Nous avons procédé en faisant une étude de la mouillabilité à l'eau des différentes argiles gonflantes en fonction des cations échangeables (Li+, Na+, K+ et Ca2+), de l'humidité relative, de la taille des particules et de la rugosité de la surface. Même si ces paramètres ont été étudiés séparément, la nature des cations, la rugosité de surface et la taille des particules sont étroitement liées. La nature du cation échangeable conduit indirectement l'état de rugosité des films d'argile cependant, c'est l'énergie d'hydratation qui entraine les angles de contact. D'autre part, pour une argile donnée avec un cation échangeable donné, la mouillabilité du film a été observée comme étant influencée par la taille des particules. Plus la taille des plaquettes d'argile est importante, plus le film est rugueux et plus l'angle de contact est élevé. En ce qui concerne l'influence de l'humidité relative, elle n'a eu qu’un effet marginal sur les angles de contact. Cependant, en travaillant à haute humidité le phénomène d'évaporation a été limité. En ce qui concerne la mouillabilité à l'huile des minéraux argileux, à une interface solide/huile/air, l'huile s’est rapidement étalée lors qu’elle a été déposée sur les différents minéraux. Dans la deuxième partie de la thèse, l'interaction biphasique huile/milieu aqueux a été étudiée par des mesures de tension interfaciale (IFT) en fonction de différents sels et de leurs concentrations. Les résultats obtenus avec deux huiles brutes et un système modèle (dodécane contenant de l'acide oléique) ont montré que l'IFT est minimum à une salinité optimale. En ce qui concerne les espèces de sel, un abaissement de l'IFT des huiles brutes a été observé en présence des cations petits, durs et fortement polarisants (tels que le Li+, Mg2+ et Ca2+) et en présence de cations gros, mous et fortement polarisables (tels que Rb+ et Cs+). Les résultats sur le système modèle ont montré que l'abaissement de l'IFT était dû aux interactions entre les petits cations qui sont durs et la tête polaire dure du tensioactif (oléate). La troisième partie de la thèse a été consacrée à l'étude des interactions triphasique huile/saumure/argile. Nos résultats montrent d'abord que, dans des conditions qui favorisent le « salting-in » des tensioactifs, l'adsorption des composants du pétrole brut sur les minéraux argileux a été favorisée (abaissement des angles de contact de l'huile sur les surfaces de mica en présence de saumure composée de cations divalents). L'interaction triphasique a également été étudiée par la stabilité des émulsions en présence des colloïdes d'argiles. Selon les différentes observations, nous avons émis l'hypothèse que certains composants de pétrole brut s'adsorbent directement sur des surfaces minérales tandis que d'autres ont besoin d'un pont cationique (Na+, Ca+ ou Mg2+) / The technique of low salinity waterflooding (LSW) during Enhanced Oil Recovery (EOR) processes, attempt to recover residual oils trapped in petroleum reservoirs. So far, after evidences of the benefits of LSW, some controversial results emerged and the mechanisms underlying the technology is still debated in the literature. It thus appears crucial to have a thorough understanding crude oil/brine/rock (COBR) interactions as the reservoir is a porous medium in which solid and fluid phases coexist. Firstly we studied the water wettability of different swelling clay minerals as a function of different interlayer cations (Li+, Na+, K+ and Ca2+), relative humidity, particle size and surface roughness. Even if these parameters have been investigated individually, the nature of the cations, surface roughness and particle size are closely linked. The nature of exchangeable cation indirectly drives the state of roughness of the clay films (in decreasing order: Ca2+ >>> K+ > (Li+, Na+)). However, it is the hydration energy which ultimately takes over during contact angle measurements. On the other hand, for a given clay mineral with a given exchangeable cation, wettability of the film has been observed to be influenced by the size of the particles. The larger the size of the clay platelets, the rougher the film and the higher the contact angle. As far as the influence of relative humidity is concerned, it only has a marginal effect on the contact angles. However, working at high humidity has shown to limit the phenomenon of evaporation. Regarding the oil wettability of clay minerals, at a solid/oil/air interface, the oil rapidly spread on the different clay minerals. In the second part, biphasic oil/aqueous medium interaction as a function of salt species and concentration has been studied via interfacial tension measurements (IFT). The results obtained with two crude oils and a model system (dodecane containing oleic acid) have shown that IFT is minimum at an optimum salinity. As far as salt species is concerned, IFT of the crude oils has been observed to be low in the presence of small, hard and highly polarising ions like Li+, Mg2+ and Ca2+ and in the presence of large, soft and highly polarisable ions like Rb+ and Cs+. The results on the model system has shown that lowering of IFT was due to ion paring between the small, hard cations and the hard polar headgroup of the surfactant (oleate). The third part of the thesis was dedicated to the study of triple phase oil/brine/clay interactions. Our results firstly show that in conditions favouring salting-in of surfactants, adsorption of crude oil components on clay minerals have been favoured (lowering of oil contact angles on mica surfaces in the presence of brines composed of divalent cations). Triple phase interaction has also been investigated by studying the stability of emulsions in the presence of clay colloids.According to the different observations we hypothesised that some crude oil components adsorb directly onto mineral surfaces while others need a cation bridge (Na+, Ca+ or Mg2+).

MENVSC / Department of Ecology and Resource Management / See the attached abstract below

PhD (Geology) / Department of Mining and Environmental Geology / Cretaceous-Tertiary Periods marked the break-up of Gondwana, a large landmass composed of most of the present-day southern continents. In understanding the events of the supercontinental break-up, paleoenvironmental studies need to be carried out. In such studies, kaolinites could be used as paleoenvironmental proxies due to their small particle sizes and large surface area. It is in this context that this research sought to reconstruct the paleoenvironments in which selected Cretaceous-Tertiary kaolin deposits in the Douala Sub-Basin in Cameroon formed. To achieve this objective, mineralogical and geochemical characterisations were carried out using x-ray diffractometry, scanning electron microscopy, Fourier transform infrared spectrometry, thermal analyses and x-ray fluorescence spectroscopy. Trace elements and stable isotopes were analysed using mass spectrometries. Ages of zircons in the kaolins were determined using laser ablation magnetic sector-field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS) U-Pb geochronology. Diagnostic evaluation for industrial applications of the kaolins were carried out using particle size distribution, texture, moisture content, pH, and electric conductivity. Six kaolin deposits from Cretaceous-tertiary Formations of the Douala Sub-Basin were studied; namely, Bomkoul (Tertiary), Dibamba (Tertiary), Ediki (Cretaceous), Logbaba (Cretaceous), Missole (Tertiary) and Yatchika (Cretaceous). The nature and occurrences of these kaolin deposits in Cameroon were determined through thorough mineralogical and geochemical characterisations of bulk (< 2 mm size fraction), silt (2-63 μm size fraction) and clay samples (< 2 μm size fraction). By quantifying the mineral phases present, the morphology and the functional groups in the kaolins are presented as the mineralogical characteristics of kaolins of each study site; whereas, the major oxides geochemistry and the micro-elemental composition constitute the geochemical characteristics of these kaolins. The minerals’ geneses were also determined and the prevailing paleoenvironmental and paleoclimatic conditions in which they were formed were reconstructed using trace elements and stable isotopes of oxygen and hydrogen in kaolinite. The maximum age of the kaolins were determined using U-Pb LA-SFICP-MS dating of zircons in the kaolin deposits. Diagnostic evaluation of the kaolins was carried out, and involved the determination of physical characteristics (particle size, texture, colour and moisture content) and physico-chemical characteristics (pH and electrical conductivity). Results showed that kaolinite and quartz (as major phases), smectite and/or illite (as minor phases), anatase and rutile (as minor or trace phases), goethite and hematite (as trace viii phases) were the mineral phases present in bulk and silt samples. Whereas, in the < 2 μm fractions, the mineral phases are made up of kaolinite and smectite (as major phases), smectite and/or illite (as minor phases), anatase and rutile (as minor or trace phases), goethite and hematite (as trace phases). The kaolins are mostly made up of thin platy or pseudo-hexagonal particles or flakes, books or stacks of kaolinite. The Dibamba, Logbaba and Missole II kaolins have well-ordered structures. Exothermic peak temperatures were generally between 943-988oC. The most abundant major oxides are silica and alumina, followed by iron oxide and titania; though Logbaba and Missole II had higher titania than iron oxide. 85% of the kaolins, portrayed extreme silicate weathering (chemical index of alteration > 80%) and are compositionally mature (index of compositional variability > 0.78). The geochemical composition of the kaolins showed that source rocks of these kaolins vary between rhyolite/granite and rhyolite/granite + basalt. The geochemistry also suggested that the kaolins formed in a marine environment (except Logbaba samples). Trace elements results revealed that Cretaceous-Tertiary kaolins in the Douala Sub-Basin are mainly enriched in rare earth elements compared to the upper continental crust, and have negative Eu anomaly. Large ion lithophiles (mainly Rb and U) were highly enriched in samples, high field strength elements (Y and Nb) were enriched in studied samples of all fractions; and transition trace elements generally had concentrations quite similar to upper continental crust values. Stable isotopes showed that the kaolins were formed in a supergene environment; and temperatures of kaolinitisation (assuming equilibrium with the global meteoric water line) were 26.58oC ± 9.65oC for Cretaceous kaolins and 29.40oC ± 7.22oC for Tertiary kaolins. Assuming equilibrium with the local (Douala) meteoric water line, the temperatures of kaolinitisation were 24.64oC ± 9.48oC for Cretaceous and 27.42oC ± 7.08oC for Tertiary kaolins. Four main zircon populations were identified from radiogenic dating: the 1st between 550 and 650 Ma, the 2nd between 950 and 1050 Ma, the 3rd around 1600 Ma and the 4th between 2800-3200 Ma. These four zircon populations belong to the Proterozoic (Neo-, Meso- and Paleoproterozoic) and the Archean. The maximum depositional ages of the kaolins, reflected by the youngest weighted averages of zircon populations varied between 588 ± 2 Ma and 612 ± 2 Ma, all belonging to the Ediacaran Period (Neoproterozoic). The diagnostic evaluation of the kaolins revealed that the kaolins are very sandy, with 50% of the samples having a sandy loamy clay or sandy loam texture. The colour of the samples varied considerably from white to darker colours (dark grey); with 15% of the kaolins being light reddish brown. The moisture content was generally very low (< 2 wt %) in all size fractions, except in Yatchika samples (moisture content > 2 wt %). The kaolins are generally acidic, with ix a pH(KCl) varying between 3.06 and 3.81, except in Missole I samples, which had a pH (KCl) < 2. The electrical conductivity (EC) generally varied between 20 to ~ 50 μS/cm, except Dibamba and MSL II 01 samples which had EC values in the interval 50 μS/cm < EC < 80 μS/cm; and Missole I samples having an EC > 7500 μS/cm. In conclusion, no great distinction was found between Cretaceous and Tertiary kaolins of the Douala Sub-Basin based on their mineralogy and geochemistry. The best kaolins in terms of these characteristics, and in comparison with the Georgia Kaolins (known for their high kaolinite quality), were the Dibamba (Tertiary), Logbaba (Cretaceous) and Missole II (Tertiary) kaolins. Based on their compositional maturity and mineralogical characteristics, these three kaolins are considered to be second cycle sediments; unlike Bomkoul, Yatchika and Ediki kaolins, which are believed to be first cycle sediments. Based on the trace elements and stable isotopes composition, Cretaceous and Tertiary kaolins of the Douala Sub-Basin were derived from felsic rocks. However, Cretaceous kaolins were formed in a cooler anoxic reducing environment; whereas the Tertiary kaolins were formed in a warmer oxidising environment, with higher precipitation. Ages of zircons in Cretaceous-Tertiary kaolins suggested that the zircon formed during two main tectonic events: the Eburnean orogeny, during which older zircons crystallised and the Pan-African orogeny, during which younger zircons crystallised. The maximum depositional ages of the kaolins varied between 588 ± 2 Ma and 612 ± 2 Ma. The main identified sources of these zircons are the Archean Ntem Complex, the Paleoproterozoic Nyong Group and the Neoproterozoic Yaounde Group. The diagnostic evaluation indicated that the particle size greatly influences the mineralogy and geochemistry of the kaolins because the finer particles (< 2 μm) have higher amounts of kaolinite and Al2O3. The moisture content of the kaolins makes them suitable as paint fillers and in soap production. Paper coating, paper filler, ceramics, pharmaceutics and cosmetics are potential applications for the kaolins, though particle size reduction and beneficiation will give them a higher quality. However, because these kaolin deposits are not big and extensive, they cannot be recommended for large scale industrial applications; but they can be used for bricks, pottery and stoneware manufacturing.