Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-04-26T13:02:00Z No. of bitstreams: 1 anamariavieiramonteiro.pdf: 6372072 bytes, checksum: 8287fa23d6dcb9cef1223ad14330e57a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-05-02T00:50:33Z (GMT) No. of bitstreams: 1 anamariavieiramonteiro.pdf: 6372072 bytes, checksum: 8287fa23d6dcb9cef1223ad14330e57a (MD5) / Made available in DSpace on 2016-05-02T00:50:33Z (GMT). No. of bitstreams: 1 anamariavieiramonteiro.pdf: 6372072 bytes, checksum: 8287fa23d6dcb9cef1223ad14330e57a (MD5) Previous issue date: 2016-02-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A partir de 2012, verificou-se o ressurgimento de headsets de realidade virtual no contexto de sua apropriação por experimentos cinematográficos diversos. Dentre esses aparelhos, nenhum outro despertou tanto interesse midiático quanto o DK2 (Development Kit 2), protótipo final do Oculus Rift. Buscando compreender melhor tal fenômeno, partiu-se de leituras de Giorgio Agamben sobre o significado de “dispositivo” (dispositif) na obra de Michel Foucault e sobretudo da apropriação que Agamben faz desse termo para analisar os dispositivos sociotécnicos. Há, ainda, um entendimento segundo o qual máquinas de imagens não só atendem a demandas de visualidades preexistentes como também inauguram mecanismos de percepção, como Jean-Louis Baudry exemplifica com a estética do aparato cinematográfico. Segundo essa perspectiva, estética e política são indissociáveis do modo como o agenciamento do olhar coloca em jogo a percepção do mundo. Quanto ao papel do artista contemporâneo que queira pensar essas questões, caber-lhe-ia somente uma interferência significativa: alterar as funções em default do meio. Para Vilém Flusser, isso só é possível no nível dos códigos. No entanto, como apontam outros autores trazidos para o debate, mais importante do que interferir no programa é o que Agamben chama de “profanar” o aparelho. Acreditando que tal ideia seja pertinente para este trabalho, uma das suposições feitas em seu decorrer é a de que, até o presente, a maioria dos experimentos com a nova tecnologia em realidade virtual estaria no âmbito oposto da profanação, no que poderia ser a “atração”, da maneira como é entendida por teóricos do Primeiro Cinema e sua relação com o espectador. Como último esforço, por ora, criou-se uma narrativa tendo em vista atrair o observador para algo além do mero espetáculo tecnológico, de modo a explorar outras potencialidades do Oculus Rift. / Starting from 2012, there has been a significant interest in virtual reality headsets as cinematographic media. One of the most prominent devices, which has gained worldwide interest, is the DK2 (Development Kit 2), known as the final prototype of the Oculus Rift. Taking a closer look at this phenomenon, this very research has its origins in Giorgio Agamben's studies of Michel Foucalt's "dispositif", specially taking into account its impact on the former’s views on socio-technical devices. There is academic acknowledgement that such imaging technologies not only satisfy pre-existing visual demands but are also seen as a means of creating new methods of manipulating perception. An example of this is Jean-Louis Baudry's aesthetics of cinematic apparatus. According to such acknowledgement, aesthetics and politics are inherent in the way the world is captured to one’s gaze. As for the contemporary artist who wishes to work within this matter, there would be only one relevant move; to alter the medium's default functionality as established by the market. For Vilém Flusser, this interference lies with the device's actual code itself. However, other authors involved with this debate have pointed out that more importantly than interfering in the program is what Agamben calls the “profanation” of the device. Based on the forgoing assumption, the major appropriation of virtual technology can be categorized as an opposite to profanation: "attraction", as interpreted by theorists of early cinema and its spectatorship. In order to take this research to a new level, a virtual reality narrative has been intentionally created to alert the observer to something far beyond a mere technological spectacle, as well as to assist in exploring Oculus Rift's other potentials.

Please read the abstract in the 00front part of this document / Dissertation (MSc Agric (Microbiology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

La fièvre de la Vallée du Rift (FVR) est une zoonose émergente provoquée par un virus. La FVR affecte principalement le bétail. Chez l'Homme, la maladie peut évoluer sous deux formes mortelles: une fièvre hémorragique et une encéphalite. Malgré l'importance du fonds génétique dans l'issue de la FVR, l'identité des gènes responsables reste inconnue. Nous avons étudié les facteurs génétiques qui déterminent la sensibilité de la lignée de souris MBT/Pas et la résistance de la lignée BALB/c à la FVR. Nous avons identifié trois QTLs sur les chromosomes 2, 5 et 11, nommés, respectivement, Rvfs1, Rvfs3 et Rvfs2. Une infection des lignées congéniques correspondantes, C.MBT Rvfs1, -2 et -3, a confirmé le rôle de la région Rvfs2 dans la sensibilité à la FVR. Une analyse pathophysiologique a montré que les souris C.MBT Rvfs2 et BALB/c développent précocement une hépatite. Les souris C.MBT Rvfs2 meurent de cette hépatite aiguë. En revanche, les souris BALB/c régénèrent leur foie, ce qui leur permet de mieux tolérer l'atteinte du foie. La majorité des souris BALB/c sont décédées plus tard d'une encéphalite. Ces observations montrent que les modèles étudiés reproduisent chacune des deux formes de la maladie observées chez l'Homme. Nous avons produit des lignées sous-congéniques pour la région Rvfs2 et avons testé leur sensibilité à la FVR. Les résultats ont été croisés avec une analyse des variants de structure et de régulation présents dans l'intervalle. Cette stratégie a permis d'identifier 3 gènes candidats : Rnf213, Cd7 et Fasn. La fonction du gène Fasn suggère qu'il puisse jouer un rôle lors de la régénération du foie et ainsi être le facteur génétique que nous recherchons. / Rift Valley fever (RVF) is an emerging zoonosis caused by an arbovirus. The disease affects mainly livestock, but it can have a severe impact on human health. In humans, RVF may progress into fatal outcomes due to acute hepatitis or encephalitis. Despite the influence of the host genetic background on the outcome of the disease, the identity of causative genes remains unknown. We studied the genetic factors determining the susceptibility of MBT/Pas and the resistance of BALB/c mouse strains to RVF. We identified 3 QTLs linked to survival on chromosomes 2, 5 and 11 and named them, respectively, Rvfs1, Rvfs3 and Rvfs2. The infection of the corresponding congenic strains, C.MBT Rvfs1, 2 and 3, confirmed the role of Rvfs2 on the susceptibility to RVF. A pathophysiological investigation showed that both C.MBT Rvfs2 and BALB/c mice exhibit early onset severe hepatitis. However, while C.MBT Rvfs2 died rapidly from liver failure, BALB/c mice tolerated the liver disease and regenerated the hepatic tissue. These mice eventually died at a later stage from encephalitis. These observations indicate that each of the studied mouse models recapitulates one form of the human disease. We generated subcongenic strains harboring the Rvfs2 region and tested their susceptibility to RVF. The results were combined with high-throughput analyses of the structural and regulatory variants found in the region. Our combined approach allowed the identification of three candidate genes: Rnf213, Cd7 and Fasn. The function of the Fasn gene suggests that it could play a role in the mechanism of liver regeneration and, thus, Fasn is our best candidate gene to account for the susceptibility phenotype.

Rift Valley fever (RVF) belongs to the group of viral haemorrhagic fevers (VHFs), most of which are zoonotic diseases causing outbreaks in animals and humans all over Africa. In the absence of haemorrhagic or specific organ manifestations, these diseases are clinically difficult to diagnose. Rapid laboratory confirmation of cases is therefore essential for timely execution of supportive treatment, appropriate case management, infection control, and tracing of contacts. Rift Valley fever virus (RVFV), a mosquito-borne pathogen, is responsible for high mortality rates and abortion in domestic ruminants, resulting in significant socio-economic losses. Furthermore, the virus is potentially infectious by aerosol, can replicate in a wide range of mosquito species and poses a bioweapon threat. The recent spread of the virus outside of the African continent, demonstrates its ability to move northwards to RVF free regions, e.g. to Europe and Northern America. Such fears fuel the international demand for reliable and validated diagnostic tools for rapid diagnosis of RVF. The aim of this study was to develop a rapid and accurate molecular tool for the detection of RVFV. A real-time loop-mediated isothermal amplification assay (LAMP) targeting the L segment of RVFV, was developed and evaluated. The assay proved to be highly specific and able to detect RVFV strains representing the genetic spectrum of the virus. Furthermore, the assay did not amplify the RNA of other genetically and antigenically related phleboviruses. The sensitivity of the assay was compared to that of a previously published TaqMan RTD-PCR protocol and found to be equal. Similarly, the assay demonstrated very high diagnostic sensitivity and specificity in various clinical human and animal specimens, collected during natural outbreaks of the disease in Africa. The detection of specific viral genome targets in positive clinical specimens was achieved in less than 30 minutes. As a highly accurate, rapid and very simple nucleic acid detection format, the RT-LAMP assay has the potential to be used in less well equipped laboratories in Africa. The assay format can be adapted to a portable device that can be utilized during RVF outbreaks in remote areas, and can be a valuable tool for differential diagnosis of VHFs. / Dissertation (MSc)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

Master of Science / Department of Diagnostic Medicine/Pathobiology / Juergen A. Richt / Rift Valley fever virus (RVFV) is a vector-borne zoonotic pathogen endemic to sub-Saharan Africa and the Arabian Peninsula that causes severe disease in ruminants and humans. RVFV is a significant threat to US livestock and public health due to a lack of licensed, efficacious vaccines and its ability to become established in non-endemic areas. Subunit vaccine candidates based on RVFV N- and C-terminal glycoproteins (Gn and Gc) are a viable option for use in ruminants due to their ease of production, safety, and ability to induce immune responses that offer differentiation between infected and vaccinated animals (DIVA). Importantly, subunit Gn+Gc vaccine candidates have demonstrated efficacy in sheep. However, despite the efficacy of a dual glycoprotein vaccine, no studies have directly compared protective efficacies of the individual glycoproteins. Furthermore, although RVFV demonstrates 2.1% maximum pairwise amino acid strain divergence within Gn/Gc ectodomains, it remains unclear how this may affect cross-protective vaccine efficacy. In this study, we used a BALB/c mouse model to determine the median lethal dose (LD₅₀) of 3 wildtype RVFV strains and used this information to standardize challenge doses in subsequent vaccine efficacy studies using baculovirus-expressed Gn/Gc antigens derived from RVFV strain Zagazig Hostpital 1977 (ZH548). Strains Kenya 2006 (Ken06) and Saudi Arabia 2001 (SA01) demonstrated equally high virulence (LD₅₀= 7.9pfu), while recombinant strain South Africa 1951 (rSA51) was less virulent (LD₅₀=150pfu). Following prime-boost vaccination, 100% (10/10) of the Gn+Gc vaccinated mice survived challenge with x1000 LD₅₀ Ken06 and SA01, while only 50% (5/10) of Gn+Gc vaccinated mice survived challenge with rSA51. Additionally, 90% (9/10) of Gn-only vaccinated and 40% (4/10) of Gc-only vaccinated mice survived challenge with Ken06. These data suggest that a Gn-only subunit vaccine is an efficacious alternative to dual glycoprotein vaccine candidates and that our ZH548-derived Gn+Gc vaccine has the potential to cross-protect against divergent RVFV strains. Results from this study can be used to optimize current vaccine formulations and inform future vaccine efficacy and licensure studies in ruminants.

Tout modèle cinématique appliqué à la propagation du rift sud kenyan (RSK) et à sa divergence vers l’ouest au nord de la Tanzanie (DNT) doit nécessairement intégrer la vallée axiale Magadi-Natron (études antérieures), mais aussi le bloc soulevé Oldoinyo Ogol (OOB) à l’ouest (ce travail). Notre étude, basée pour l'essentiel sur l'interprétation d'imagerie satellitale SRTM 30 m, nous permet (1) de préciser l'organisation morphostructurale de l'ensemble du RSK, (2) d'identifier 2 systèmes successifs de failles bordières, (3) d'affirmer le rôle majeur de celle d'Oldoinyo Ogol, (4) d'élaborer un modèle de rifting en 2 étapes (7-3 Ma et <3 Ma) et (5) d'attribuer le « shift » latéral du domaine rifté (OOB), puis sa divergence le long de la branche d'Eyasi (DNT) à la présence d'une discontinuité transverse protérozoïque, à laquelle on rapporte aussi le développement précoce et 'hors axe' du segment magmatique des « Crater Highlands », démontrant ainsi l'importance de l'héritage structural sur la cinématique du rifting. L’analyse quantitative des populations de failles démontre le caractère « restricted » des failles intrarift et aboutit aussi à préciser l'évolution, dans l'espace et le temps, du taux d'extension, depuis un stade précoce à déformation localisée jusqu'à un stade récent à déformation diffuse (<3 Ma). L’analyse des réseaux de drainage identifiés sur le compartiment de socle bordant à l'ouest le dispositif RSK-NTD démontre (1) leur contrôle étroit par le dispositif lithologique et tectonique du socle, (2) la nature polyphasée du soulèvement lié aux failles bordières, et (3) le caractère déséquilibré du réseau actuel en cours de soulèvement. / Any kinematic model applied to the southerly-propagating and diverging South Kenya rift (SKR) should necessarily integrate the structure of the Magadi-Natron axial trough (previous studies), but also those of the Oldoinyo Ogol (OOB) offset block to the west. Our work is chiefly based on SRTM 30 m satellite imagery analysis, and allows us (1) to precise the morphostructural arrangement of the entire SKR,(2) to identify 2 successive border faults systems, (3) to emphasize the role of the Ol Doinyo Ogol master fault, (4) to elaborate a 2-stage rift model (7-3 Ma et <3 Ma), and (5) to attribute a key-role to a transverse Proterozoic discontinuity on the lateral shift of the OOB, as well as on the split of the rift into the Eyasi rift arm and on the off-axis location of the early Crater Highlands magmatic segment, hence demonstrating the importance of basement structural inheritance on rift kinematics.The quantitative analysis of fault populations shows the restricted nature of most intra-rift faults, and leads us to precise the spatiotemporal evolution of extension from a stage of localized strain (border faults) to a stage of diffuse extension (<3 Ma).From the analysis of the river drainage extracted from the basement uplifted block bounding the rift system to the west, it is assumed that (1) lithological and tectonic basement features exerted a strong control on the river network, (2) fault-related basement uplift is polyphased, and (3) the unsteady nature of the present-day river drainage is due to still active rift-flank uplift in the southern portion of the rift system.

Rift Valley fever (RVF) is a disease endemic to Africa, which has recently spread outside of Africa to the Arabian Peninsula. Rift Valley fever virus (RVFV) is the causative agent of RVF and manifests as severe hepatitis, encephalitis and haemorrhagic fever, resulting in mortality in approximately 1% of human cases. RVFV also affects agriculture as it causes high mortality rates in young ruminants (>90% in new-born lambs) and is associated with high levels of abortions, which results in devastating economic losses. RVFV is a single-stranded RNA virus with a genome comprising of three separate genetic elements referred to as the Large (L), Medium (M) and Small (S) segments. The negative sense L segment encodes an RNA-dependent RNA polymerase (RdRp) while the M segment encodes two glycoproteins, Gn and Gc, and two non-structural proteins, NSm1 and NSm2. The glycoproteins are important for viral entry, genome packaging and mature virion formation as well as being the main antigen for the elicitation of neutralising antibodies by humoral immunity. The NSm proteins are required for mosquito vector transmission and preventing viral-induced apoptosis in host cells. The ambisense S segment encodes in the positive orientation a non-structural (NSs) gene, and in the negative orientation the nucleocapsid (N) gene. NSs is an important virulence factor involved in subverting host defences and the loss of NSs results in a highly attenuated RVFV infection. N is required for RNA synthesis and encapsidation of viral genomes. There are currently very few treatments in the early stages of development and vaccines for RVFV are not readily available. The overall lack of therapeutic strategies for RVFV urges novel therapeutic development such as RNA interference (RNAi). Endogenous RNAi is triggered by dsRNA and is involved in gene regulation through sequence specific suppression of target mRNA. Therapeutic RNAi exploits the RNAi pathway to facilitate targeted degradation of viral genes and has been applied effectively to the inhibition of a number of viruses that cause chronic and acute infections. There are fewer studies that have used RNAi to inhibit highly pathogenic viruses. Efficacy has been demonstrated against Ebola virus, Lassa virus and Dengue fever virus, which suggests applicability to the inhibition of RVFV. In this thesis, short hairpin RNAs (shRNAs) were generated to target the NSs, N and M genes of RVFV, which are important proteins in the viral life cycle. To determine the knockdown efficacy of the shRNAs, HEK293 cells were transiently transfected with the shRNAs and a vector expressing the respective shRNA gene target fused to a luciferase reporter. The reporter levels were assessed using a dual-luciferase assay and several shRNAs were selected for further characterisation as a result of effective target knockdown. Consequently, the shRNAs reduced the levels of expressed FLAG-tagged NSs, N and M encoded proteins, which were detected using western blot analysis. ShRNAs directed against NSs were shown to disrupt this protein’s function to result in alleviation of pathogenic properties. Specifically, NSs was shown to suppress the transcription levels of a luciferase reporter as well as prevent the activation of an IFN-β promoter. When the shRNAs were transiently transfected into HEK293 cells, they were able to reverse NSs-induced suppression in the reporter assays. Furthermore, NSs is cytotoxic as determined by observing cell morphology under transmitted light microscopy, which was quantified using a MTT viability assay and cells that subsequently received anti-NSs shRNAs had improved viability. This class of anti-pathogenic shRNAs should be able to down-regulate NSs in vivo and attenuate RVFV virulence. However, NSs is not essential for viral replication and as a result of the aggressive pathology of haemorrhagic RVF, essential structural genes were targeted to investigate shRNAs with anti-replicative properties. ShRNAs directed against N were transfected 24 hrs prior to infection with RVFV. The inhibition of viral replication was determined by collecting supernatant over 3 days and measuring the levels of N antigen using an ELISA. The shRNAs demonstrated effective suppression of RVFV but N antigen was detected at 72 hrs post-infection, which suggested that the shRNAs were overwhelmed by the virus. A series of shRNAs against M were subsequently tested and the anti-M shRNAs effectively suppressed viral replication in cultured cells over an extended 96 hr experiment, demonstrating that M is a good target for RNAi-mediated inhibition of RVFV. In this thesis, the potential of RNAi-based therapeutics against RVFV was demonstrated and these data contribute to the growing knowledge that RNAi should be developed further as a potential treatment for haemorrhagic fever viruses. Finally, some DNA viruses such as HBV form cellular reservoirs from which new virus can be produced and the DNA is resistant to RNAi-mediated inhibition. RVFV is an RNA virus with an acute infection, which makes it more susceptible to RNAi and an excellent target for this particular therapeutic modality.

Bacias sedimentares distensionais estão entre as estruturas geológicas mais importantes e melhor estudadas, mas os modelos geológicos que associam tectônica, áreas de captação de drenagem, e distribuição e evolução de ambientes deposicionais ainda são qualitativos, apontando a falta de uma base estatística. Isso posto, é apresentado um estudo das características morfotectônicas de 25 bacias sedimentares distensionais e suas áreas de captação, representativas de cinco grandes províncias distencionais ativas: Rift do Leste Africano, Província Basin and Range, Rift Baikal, Graben do Reno e Sistema de Rift do Platô Tibetano. Os resultados mostram que as áreas de deformação total de cada bacia variam de 2.700 a 137.300 Km2, com 50% de bacias com áreas entre 8.500 e 33.600 Km2. A área com sedimentação ativa varia de 1.400 a 43.000 km2, e 50% destas estão entre 3.600 e 12.000 km2. Áreas de captação de drenagem apresentam um a variação muito maior, de 2.700 até 740.000 km2, 50% delas entre 15.000 e 112.000 km2. A relação entre área deformada e área de captação mostra uma clara divisão em duas classes, uma com bacias com área de captação com mais do dobro de tamanho da área deformada e outra composta por bacias com área de captação com tamanho até 10% maior que sua área deformada. Taxas de sedimentação aproximadas, calculadas a partir de dados coletados na literatura, variam de 0,05 até 0,49 m/Ka e a comparação deste dado com a área de captação não revela uma clara relação. 65% das zonas de transferência analisadas nas províncias distensionais estudadas apresentam drenagens, porém apenas 38% dos pontos de entrada de rios maiores, com parte de sua área de captação fora da área deformada, são associados a zonas de transferência. Esses dados contradizem modelos correntes no tocante à entrada de grandes rios na bacia sedimentar, que são responsáveis por grande parte do aporte sedimentar e não estão necessariamente ligados a estruturas deformacionais, como esperado. Sob outro ponto de vista, análises morfotectônicas das cinco áreas selecionadas revelaram o inesperado fato de que todas as bacias com grande área estão relacionadas a lagos profundos, independentemente da sua taxa de sedimentação ou tamanho da área de captação. Esta constatação sugere que talvez estes fatores não sejam o principal controle na formação de lagos profundos, mas que por outro lado a presença do próprio lago possa favorecer o desenvolvimento de um grande depocentro. De acordo com o modelo teórico proposto, a maior densidade do preenchimento sedimentar, quando comparada com a da água, pode por si só levar à divisão de depocentros e criar pequenas sub-bacias, através da ativação de planos de alto ângulo das falhas menores, cabendo às falhas lístricas mestras acomodar a distensão regional. Neste modelo, em bacias preenchidas com sedimento aluvial, o grande deslocamento das falhas antitéticas e sintéticas pode levar ao desenvolvimento de altos topográficos (associados à lapa das falhas) responsáveis por individualizar sub-bacias. A correlação entre lagos profundos e grandes depocentros também pode ser observada no Sistema de Rift Eocretáceo do leste da América do Sul, sugerindo que esta relação possa ser usada como ferramenta preditiva de fases famintas prolongadas em bacias sedimentares continentais, com implicações na previsão de rochas geradoras de hidrocarbonetos em bacias fósseis com base em dados geofísicos de sub-superfície. / Extensional sedimentary basins are among the most important and best studied geological structures, but geological models linking tectonics, drainage catchment and the distribution and evolution of depositional environments are still qualitative, lacking support from a statistical database. In order to addresses this problem we present and comprehensive study on the morphotectonic characteristics of 25 active extensional basins and their catchment areas, representative of five major active extensional provinces: the East African Rift System, the Basin and Range Province, the Baikal Rift, the Rhine Graben and the Tibetan Plateau Rift System. Our results show that the total areas of deformation of individual basins range from 2,700 km2 to 137,300 km2, with 50% of the basins having areas between 8,500 and 33,600 km2. The area with active sedimentation varies from 1,400 to 43,000 km2, and in 50% of the basins it is between 3,600 and 12,000 km2. Catchment areas of individual basins vary much more, from 2,700 to 740,000 km2, 50% of them measuring between 15,000 and 112,000 km2. The ratio of deformed area to catchment area for each basin shows a clear division into two natural classes, one composed of basins with a catchment more than twice the size of the deformed area, and another composed of basins with catchments less than 10% larger than the deformed area. Approximated long term sedimentation rates calculated from published data for several basins vary from 0,05 to 0,49 m/Ka, and the comparison of these rates with the catchment area of individual basins shows no clear relationship. 65% of the transfer zones in the studied extensional provinces show river channels but only 38% of the inlets of rivers with part of their catchment outside the deformed area are related to transfer zones. This contradicts current models, as most of the points of entrance of larger rivers, which are responsible for the greater part of the sediment input, are not clearly related to deformational structures. On the other hand, morphotectonic analysis of selected active extensional basins and their catchment areas from studied areas, lead to the recognition of the unexpected fact that the largest basins are those with deep lakes, regardless of sedimentation rate or relative size of catchment area, suggesting that maybe it is not the contribution of the area to the tridimensional accommodation that leads to the formation of a starved lake, but the other way round: an starved lake may favor the development of a large depocenter. According to our new theoretical model, the higher density of the sedimentary infill, when compared to that of water, can itself cause the division of a main depocenter into smaller sub-basins, through the activation of the steeper planes of minor faults, with the main listric faults accouting mostly for the regional extension. In basins filled with alluvial sediment through most of their evolution, the greater displacement of minor faults could lead to the development of foot-wall highs separating individual sub-basins. The correlation of deep lakes with larger depocenters is also observed in the Early Cretaceous Rift System of Eastern South America, suggesting that this relation can be used as a predictive model for the presence of long phases of sediment starvation in continental basins, with implications for the prediction of hydrocarbon source rocks based on geophysical subsurface data.

In north-western Namibia the fills of the Karoo-Etendeka depositories can be subdivided into (1) a Carboniferous-Permian, (2) a Triassic-Jurassic and (3) a Cretaceous megasequence, each recording extensional periods related to successive rifting phases in the evolving South Atlantic. The tectonic environment of the depositories in north-western Namibia changes successively from the coast towards the continental interior, which is reflected by the facies distribution and the position of time-stratigraphic gaps. Close to the present-day coastline synsedimentary listric faults, trending parallel to the South Atlantic rift (N-S), caused the formation of wedge shaped sediment bodies. Here, the Karoo Supergroup is only represented by the Permian succession in the Huab area. A hiatus within the Permian can be recognised by the correlation with the main Karoo Basin in South Africa and the Brazilian Paraná Basin. This stratal gap correlates with a pre-Beaufort Group unconformity in the main Karoo Basin that might be related to an orogenic pulse in the Cape Fold Belt. The Permian succession itself is unconformably overlain by the Lower Cretaceous Etendeka Group. This hiatus extending from the Upper Permian to the Lower Cretaceous has probably been induced by a combination of rift shoulder uplift and additional crustal doming associated with Etendeka flood volcanism. The enhanced tectonism during the Early Cretaceous controlled accommodation space for the alluvial-fluvial and aeolian deposits of the lower Etendeka Group. Disconformities within those deposits and the overlying lava succession attribute to distinct phases of tectonic and volcanic activity heralding the South Atlantic breakup. Towards the south-east, the Karoo succession becomes successively more complete. In the vicinity of Mt. Brandberg Early Triassic strata (Middle Omingonde Formation) follow disconformably above the Upper Permian/Lowermost Triassic Doros Formation. The sedimentation there was essentially controlled by the SW-NE trending Damaraland Uplift. South of the Damaraland Uplift the SW-NE trending Waterberg-Omaruru Fault zone is interpreted as a sinistral oblique-slip fault that compartmentalised the South Atlantic rift. This fault controlled accommodation space of the entire Triassic Omingonde Formation and the Early Jurassic Etjo Formation in its associated pull-apart and transtension structures. A locally well developed angular unconformity defines a hiatus between the two formations. Correlation with the main Karoo Basin in South Africa confirms that this gap is of a regional extent and not only a local, fault induced feature. Furthermore, it might also correlate with an orogenic pulse of the Cape Fold Belt. In general, the Mesozoic megasequences record the long-lived history of the southern Atlantic rift evolution. Rifting has been controlled by orogenic pulses derived from the Samfrau active margin throughout the Mesozoic. The associated intracratonic E-W extension caused the formation of grabens and conjugated oblique-slip zones. The generation of voluminous flood basalts marks the climax of intracratonic extension that was accompanied by enhanced uplift of the rift shoulders. / Das Mesozoikum in Nordwest-Namibia gliedert sich in (1) eine karbonisch-permische, (2) eine triassisch-jurassische und (3) eine kretazische Megasequenz, welche die Entwicklung des südatlantischen Rifts widerspiegeln. Die tektonische Position der karoo-zeitlichen Ablagerungsräume Nordwest-Namibias verändert sich sukzessive von der Küste bis ins Innere des Kontinents, welches sich in der Verbreitung und Größenordnung mehrerer Hiaten ausdrückt. So dominieren in der Küstenregion listrische Störungen, die dem N-S Trend des südatlantischen Rifts folgen. Dabei zeigen keilförmige Geometrien assoziierter Sedimentkörper den syn-sedimentären Charakter dieser Störungen an. In der küstennahen Region ist die Karoo Abfolge nur durch permische Sedimente in der Huab Region überliefert. Eine Diskordanz innerhalb des Perms läßt sich aus der Korrelation mit zeitäquivalenten Ablagerungen im Großen Karoo Becken Südafrikas und dem Paraná Becken Südamerikas herleiten. Wahrscheinlich hängt dieser Hiatus mit einem orogenen Impuls im Kap-Ventana Faltengürtel zusammen. Die permische Abfolge ist wiederum diskordant überlagert von der unterkretazischen Etendeka Gruppe. Dieser Trias und Jura umfassende Hiatus ist vermutlich durch die Anhebung der südatlantischen Riftschulter verursacht worden. Die damit verbundene hohe tektonische Aktivität drückt sich deutlich in der Fazies- und Mächtigkeitsverteilung der unterkretazischen sedimentären Ablagerungen und Laven aus. Dabei spiegeln mehrere Diskonformitäten einzelne Phasen tektonischer und vulkanischer Aktivität wider, welche die bevorstehende Öffnung des Südatlantiks ankündigen. Südöstlich der Huab Region wird die Karoo Abfolge zunehmend vollständiger. So ist im Bereich des Brandberges bereits die triassische Omingonde Formation vertreten, während noch weiter im Südosten die unterjurassischen Sandsteine des Waterberg Gebietes hinzukommen. Die Sedimentation in diesem Raum wurde maßgeblich durch das SW-NO streichende Damaralandhoch beeinflußt. Südlich des Damaralandhochs stellt die prominente SW-NO streichende Waterberg-Omaruru Störungszone eine Transferzone dar, die das Südatlantikrift unterteilt. Entlang dieser Transferzone erreicht die triassische und jurassische Abfolge ihre höchsten Mächtigkeiten, welches durch eine erhöhte Subsidenz innerhalb verschiedener Extensionsbecken begründet ist. Eine entlang der Transferzone zu beobachtende Diskordanz zwischen der triassischen Omingonde Formation und der unterjurassischen Etjo Formation ist nicht nur von lokaler Bedeutung, sondern korreliert mit einer entsprechenden Diskordanz im Großen Karoo Becken Südafrikas. Letztere läßt sich wiederum einem orogenen Impuls im Kap-Ventana Faltengürtel zuordnen.

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