En Méditerranée orientale, la paleo-marge sud de la Téthys a subit des épisodes polyphasés d'extension pendant le Paléozoïque et le Mésozoïque. Cette marge a été postérieurement inversée pendant des épisodes compressifs et discontinus depuis le Crétacé supérieur liés à la convergence entre l'Afrique et l'Eurasie.La marge Cyrénaïque (nord-est Libye) a enregistré ces épisodes extensifs et compressifs. Elle permet donc l'analyse des inversions et de leurs relations avec les évènements ayant eu lieu le long de la frontière de la plaque Africaine (i.e. subduction Hellenique).Le bassin de Sirte, adjacent à la Cyrénaïque montre une direction oblique, ne présente pas la même déformation et est caractérisé par une subsidence continue depuis le Mésozoïque.Des données de sismique (réflexion) combinées à des rapports et des corrélations de puits, nous ont permis d'examiner et de discuter les interactions entre la Cyrénaïque, le bassin de Sirte et les domaines profonds (i.e. bassin Ionien).Ce travail permet de mieux préciser les différents épisodes d'extension, de contraindre les évènements compressifs enregistrés par la région Cyrénaïque, d'observer les structures du bassin de Sirte et de clarifier en partie son évolution.Finalement cette partie de la marge est intégrée dans le cadre géodynamique régional de la Téthys sud et permet de discuter l'âge ainsi que le mécanisme d'ouverture pour la branche orientale de la Méditerranée. / In the Eastern Mediterranean, the South-Tethys paleo-margin experienced poly-phased rifting episodes during Paleozoic and Mesozoic times. This margin has been subsequently inverted by discontinuous events occurring since the Late Cretaceous as a consequence of the Africa-Eurasia convergence.The Cyrenaica margin (northeast Libya) has recorded these extensional and compressional events. It thus gives the opportunity to analyse these inversion and their possible causal links with events occurring along the plate boundary (i.e. within the Hellenic subduction).The adjacent Sirt Basin, follows an oblique direction, did not suffer the same deformation as Cyrenaica and has recorded a continuous subsidence since the Mesozoic.Offshore seismic data combined with well correlations have permitted us to investigate and discuss the interactions between Cyrenaica, Sirt Basin and the deeper domains (i.e. Ionian Basin).We were able to document the different rift episodes, better constrain the compressional events on Cyrenaica, observe characteristics of the architecture of the Sirt Basin and clarify part of its evolution.Finally we integrate this part of the margin, in the regional geodynamic frame of the East Mediterranean branch of the Neo-Tethys by discussing the timing and mechanism which led to its opening.

In this thesis, coda waves recorded by local seismographic networks will be analyzed to estimate the three-dimensional spatial distribution of scatterers (SDS). This will be done by using the single scattering approximation. This approach leads to a huge system of equations that can not be solved by traditional methods. For the first time, we will use the Simultaneous Iterative Reconstructive Technique (SIRT) to solve this kind of system in seismological applications. SIRT is slow but provides a means to carry out the inversion with greater accuracy. There is also a very fast non-iterative method that allows to carry out the inversion 102 times faster, with a higher resolution and reasonable accuracy: the Filtered Back-Projection (FBP). If one wishes to use this technique it is necessary to adapt it to the geometry of our problem. This will be done for the first time in this thesis. The theory necessary to carry out the adaptation will be developed and a simple expression will be derived to carry out the inversion.FBP and SIRT are then used to determine the SDS in southern India. Results are almost independent of the inversion method used and they are frequency dependent. They show a remarkably uniform distribution of the scattering strength in the crust around GBA. However, a shallow (0-24 km) strong scattering structure, which is only visible at low frequencies, seems to coincide with de Closepet granitic batholith which is the boundary between the eastern and western parts of the Dharwar craton.Also, the SDS is estimated for the Galeras volcano, Colombia. Results reveal a highly non-uniform SDS. Strong scatterers show frequency dependence, which is interpreted in terms if the scale of the heterogeneities producing scattering. Two zones of strong scattering are detected: the shallower one is located at a depth from 4 km to 8 km under the summit whereas the deeper one is imaged at a depth of ~37 km from the Earth's surface. Both zones may be correlated with the magmatic plumbing system beneath Galeras volcano. The second strong scattering zone may be probably related to the deeper magma reservoir that feeds the system.

Dur At Talah sedimentary sequence, located at the southern side of the Sirt Basin in central Libya, is composed of 150 m thick of mainly siliciclastic rocks. The importance of this sequence is linked to the importance of the Sirt Basin as one of large hydrocarbon reservoirs in Libya. The sequence is also an excellent site for vertebrate fossils of Late Eocene, the age of the sequence. Previous studies, though very limited compared to the importance of this area, are focused on its paleontological content. Sedimentology received only scant attention before this project. This thesis is an outcrop based study in which the focus is given to the sedimentary and biogenic (trace fossils) structures, aiming at defining and interpreting depositional facies which building up the sequence. The study is mainly based on field data which are analyzed on the light of related published literature and on the comparison with modern sedimentary environments. Results of facies analysis have led to splitting the entire sequence into three genetically related intervals. The oldest, we called the New Idam Unit (around 80m), is composed of very fine sandstones to mudstones. New Idam Unit is unconformably overlain by the Sarir Unit (around 50m), composed of medium grained cross bedded sandstones (the lower 25-30 m) changes up to very coarse and microconglomeratic sandstone (the upper 20-30 m). Thus, the Sarir Unit is split into the lower Sarir Subunit and upper Sarir subunit. The New Idam Unit presents both classical and unusual sedimentary and biogenic indicators that attribute this unit to estuarine depositional environment. It starts with outer estuarine (the lower 35 m) and ends up with inner estuarine (the upper 45 m). Maximum flooding surface is located in between. Above this surface the fluvial indicators increase and tidal indicators decrease, thus providing clue for basinward (North) migration of the shoreline. The lower Sarir subunit which was previously interpreted as fluvial deposits, preserves multi-scale sedimentary structures that undoubtedly belong to tidal processes. This is especially evidenced at the lower part of the lower Sarir Subunit (LLS). Fluvial indications over dominates the tidal ones in the upper part of the lower Sarir (ULS). Due to this configuration the whole lower Sarir subunit is interpreted as shallow marine, deltaic, depositional system, occurred during sea level ¨normal¨ regression. This time, maximum flooding surface is located between the LLS and ULS. The lower Sarir subunit is terminated by subaerial unconformity, with evidences of subaerial exposure preserved at the top of the ULS. These are intruded by the upper Sarir subunit which presents clear evidences of strictly fluvial environment of deposition. The deposits of the upper Sarir subunit record the low stand system tract part of the Dur At Talah sequence. In addition to the outlined results, the sequential pattern of the depositional events is suggested for the entire sequence of Dur At Talah. This study provides a valuable information regarding the depositional and sequential aspects of the Sirt Basin during the late Eocene, it also provide an unique case study for the better understanding of the shallow marine tidal deposits.

<b>Background:</b> Systemic chemotherapy and radiotherapy play an important role in the treatment of colorectal cancer. Tumour perfusion and oxygenation is known to influence radiosensitivity and chemosensitivity. In this thesis, I propose that the evaluation of changes in tumour perfusion using perfusion CT (pCT) and dynamic contrast-enhanced (Dce) MRI can guide the rational sequencing of drugs and radiation. <b>Methods:</b> Dce-MRI and pCT scans were incorporated into a clinical trial of hypofractionated pelvic radiotherapy and nelfinavir in 10 patients with rectal cancer. Toxicity and tissue biomarkers (tumour cell density, microvessel density, CAIX, HIF1-alpha, phospho-Akt and phospho-PRAS40) were evaluated. pCT liver scans were incorporated into an imaging study in patients with colorectal liver metastases randomised to receive either oxaliplatin/ 5FU chemotherapy or oxaliplatin/ 5FU chemotherapy plus selective internal radiotherapy. <b>Results:</b> After 7 days of nelfinavir concurrent with hypo-fractionated pelvic radiotherapy, there was a mean 42&percnt; increase in median K^trans (P=0.03, paired t test) on Dce-MRI and a median 30&percnt; increase in mean blood flow on pCT (P=0.028, Wilcoxon Rank Sum), although no statistically significant changes in perfusion parameters were demonstrated after 7 days of nelfinavir prior to radiotherapy. The feasibility of evaluating tumour cell density in rectal biopsies before and after radiotherapy and a radiosensitising drug as an early endpoint of response was demonstrated. In patients with colorectal liver metastases who received oxaliplatin and modified de Gramont chemotherapy alone, after 4 cycles of chemotherapy, a 28&percnt; decrease in the mean hepatic arterial fraction was observed (P=0.018, paired t test). Between pCT scans 2 days before SIRT and 39-47 days following SIRT and continued 2-weekly chemotherapy, there was a mean 62&percnt; (P=0.009) reduction in Blood Flow and 61&percnt; (P=0.006) reduction in Blood Volume (paired t test). <b>Conclusions</b> This research does not support the hypothesis that nelfinavir before radiotherapy improves blood flow to human rectal cancer. Increases in rectal tumour perfusion during radiotherapy and concurrent nelfinavir are likely to be primarily explained by the acute biological effects of radiation. Four or more cycles of oxaliplatin and modified de Gramont chemotherapy may result in changes in tumour perfusion of colorectal liver metastases which would be detrimental to subsequent radiotherapy. Selective internal radiotherapy resulted in substantial reductions in tumour perfusion 39-47 days after the treatment. Perfusion imaging can be used to detect changes in tumour perfusion in response to radiotherapy and systemic therapy which have implications for the sequencing of therapies.

La séquence sédimentaire du Dur At-Talah, située dans la partie sud du bassin de Syrte au centre de la Libye, est composée de 150 m d'épaisseur de roches principalement siliciclastiques (grès, siltites et argiles). L'importance de cette séquence est liée en partie à l'importance du bassin de Sirt qui est un des plus grands réservoirs d'hydrocarbures de Libye. La séquence est également un des plus important site de fossiles de vertébrés de l’Eocène supérieur, l'âge de la séquence. Les études antérieures, bien que très limitées par rapport à l'importance de cette zone, se sont concentrées principalement sur le contenu paléontologique de la séquence. L’étude sédimentologique n’avait été jusqu’à ce jour que très peu abordée. Cette thèse est un travail basé sur l’examen des affleurements et où l'accent est mis sur les structures sédimentaires et biogéniques (traces fossiles), visant à définir et à interpréter les faciès sédimentaires qui ont construit la séquence du Dur At Talah. L’ étude de la séquence a conduit à diviser la totalité de l’affleurement en trois intervalles génétiquement liés. Le plus ancien que nous avons appelé la « New Idam Unit » (environ 80 m d’épaisseur), est composé de grès très fins, de siltites et d’argiles. Cette unité (New Idam Unit) est recouverte en discordance par la « Sarir Unit » (environ 50 m d’épaisseur), composée de grès fins à moyens à faisceaux de litages entrecroisées dans sa partie inférieure (environ 25-30 m d’épaisseur) et de grès grossiers à microconglomératiques dans sa partie supérieure (environ 20-30 m d’épaisseur). La « Sarir Unit » est ainsi divisée en « Sarir inférieur » et « Sarir supérieur ». La « New Idam Unit » présente des dépôts qui sont attribués à un milieu main estuarien. La série débute par des dépôts d’environ 35 m d’épaisseur typiques d’un estuaire externe. Les 45 mètres qui lui font suite passent progressivement à des dépôts tidaux caractéristiques d’un estuaire interne. La Surface d'inondation maximale se situe entre les deux intervalles. Au-dessus de cette surface les indicateurs fluviaux augmentent et les indicateurs de marées diminuent progressivement, offrant ainsi un indice pour la migration de la rive de rivage vers le bassin (vers le Nord). La sous-unité du Sarir inférieur qui avait été interprétée avant ce travail comme dépôts fluviatiles, préserve pourtant des structures sédimentaires multi-échelles qui sont le résultat incontestable de processus de marée. Ceci est particulièrement évident dans la partie inférieure de l’unité « Sarir inférieur » (la Lower Lower Sarir Unit ; LLS). Dans la partie supérieure de l’unité Sarir inférieur (Upper Lower Sarir; ULS), les indicateurs de dynamique fluviale dominent largement sur ceux de la marée. Le Sarir inférieur est donc interprété comme un système deltaique mis en place lors d’une régression normale. Cette fois-ci, la surface maximale d'inondation se situe entre le LLS et ULS. Le « Upper Lower Sarir » (ULS) se terminée par une discordance subaérienne, avec de nombreuses traces d’émersion conservées au sommet de l'ULS. Celles-ci sont recoupées par le « Upper Sarir » qui montre des marqueurs fiables d'environnement de dépôt strictement fluvials. Les dépôts du « Upper Sarir » enregistre la séquence de bas niveau marin. Cette étude fournit des informations précieuses concernant le dépôt des séquences dans le bassin de Syrte au cours de la fin de l'Éocène. Elle fournit également une étude originale sur la dynamique tidale dans des milieux marins margino-littoraux. / Dur At Talah sedimentary sequence, located at the southern side of the Sirt Basin in central Libya, is composed of 150 m thick of mainly siliciclastic rocks. The importance of this sequence is linked to the importance of the Sirt Basin as one of large hydrocarbon reservoirs in Libya. The sequence is also an excellent site for vertebrate fossils of Late Eocene, the age of the sequence. Previous studies, though very limited compared to the importance of this area, are focused on its paleontological content. Sedimentology received only scant attention before this project. This thesis is an outcrop based study in which the focus is given to the sedimentary and biogenic (trace fossils) structures, aiming at defining and interpreting depositional facies which building up the sequence. The study is mainly based on field data which are analyzed on the light of related published literature and on the comparison with modern sedimentary environments. Results of facies analysis have led to splitting the entire sequence into three genetically related intervals. The oldest, we called the New Idam Unit (around 80m), is composed of very fine sandstones to mudstones. New Idam Unit is unconformably overlain by the Sarir Unit (around 50m), composed of medium grained cross bedded sandstones (the lower 25-30 m) changes up to very coarse and microconglomeratic sandstone (the upper 20-30 m). Thus, the Sarir Unit is split into the lower Sarir Subunit and upper Sarir subunit. The New Idam Unit presents both classical and unusual sedimentary and biogenic indicators that attribute this unit to estuarine depositional environment. It starts with outer estuarine (the lower 35 m) and ends up with inner estuarine (the upper 45 m). Maximum flooding surface is located in between. Above this surface the fluvial indicators increase and tidal indicators decrease, thus providing clue for basinward (North) migration of the shoreline. The lower Sarir subunit which was previously interpreted as fluvial deposits, preserves multi-scale sedimentary structures that undoubtedly belong to tidal processes. This is especially evidenced at the lower part of the lower Sarir Subunit (LLS). Fluvial indications over dominates the tidal ones in the upper part of the lower Sarir (ULS). Due to this configuration the whole lower Sarir subunit is interpreted as shallow marine, deltaic, depositional system, occurred during sea level ¨normal¨ regression. This time, maximum flooding surface is located between the LLS and ULS. The lower Sarir subunit is terminated by subaerial unconformity, with evidences of subaerial exposure preserved at the top of the ULS. These are intruded by the upper Sarir subunit which presents clear evidences of strictly fluvial environment of deposition. The deposits of the upper Sarir subunit record the low stand system tract part of the Dur At Talah sequence. In addition to the outlined results, the sequential pattern of the depositional events is suggested for the entire sequence of Dur At Talah. This study provides a valuable information regarding the depositional and sequential aspects of the Sirt Basin during the late Eocene, it also provide an unique case study for the better understanding of the shallow marine tidal deposits.

Ce manuscrit de thèse propose la première étude sédimentologique exhaustive de l’escarpement du Dur At Talah (150 km de long sur 120 m de hauteur). Ce dernier affleure dans la dépression d’Abu Tumayam, dans la partie méridionale du Bassin de Syrte (Libye). La Formation du Dur At Talah offre une séquence sédimentaire régressive (au 2nd ordre), allant de faciès marins peu profonds à des faciès fluviatiles, datée de l’Eocène supérieur. Les exceptionnelles conditions d'affleurement ont permis une analyse sédimentologique approfondie (lithofaciès, ichnofaciès, géométries et découpage séquentiel) conduisant à une caractérisation multiscalaire d'un système margino-littoral dominé par la dynamique tidale. Parmi les résultats saillants de cette étude figure l'identification de deux processus sédimentaires : la progradation signée par des structures clinoformes et l’accrétion latérale caractérisée par des stratifications hétérolithiques inclinées (IHS). Dès lors, plusieurs corps sédimentaires se distinguent sans ambiguïté tel que les barres d’embouchure hétérolithiques et les barres de méandres de chenaux tidaux. L'auscultation de ces grands corps sédimentaires permet alors d'en définir les critères de reconnaissance et le contexte séquentiel de mise en place, mais aussi d'en contraindre le potentiel réservoir. / This manuscript provides the first exhaustive sedimentological study of the Dur At Talah escarpment (≈120 m high and ≈150 km length). This latter is exposed in the Abu Tumayam Trough, in the southern Sirt Basin (Libya). The Dur At Talah Formation forms a 2nd order regressive sequence, from shallow marine to fluviatile deposits, dated as upper Eocene. This exceptional outcrop allows an extensive and detailed sedimentological analysis (lithofaciès, ichnofaciès, geometries and sequence stratigraphy) leading to a multi-scale characterization of nearshore to paralic environments dominated by tidal dynamic. Among outstanding results, two sedimentary processes have been recognized and characterized: the progradation is expressed by large-scale clinoform structures and the lateral accretion is characterized by inclined heterolithic stratifications (IHS). Several sedimentary bodies are, thus, unequivocally distinguishable such as heterolithic mouth-bars and tidal channel point-bars. Thorough analysis of these sedimentary bodies allows to define diagnostic criteria to recognize them. They can be replaced in a consistent stratigraphic framework explaining their architecture and their vertical evolution in order to be used as reservoir analog.