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In contrast to early work establishing the importance of earthquake-induced liquefaction in producing soft-sediment deformation (SSD) of the Navajo Sandstone, this report advances the use of SSD analysis to: characterize wet climatic conditions and flood events during the depositional history of ancient eolianites; discriminate the signatures of multiple deformation events from those of complex deformation features formed in a single event; and to document the occurrence of liquefaction features unrepresented in modern Earth analogues. The diversity of deformation styles, presented here, is very unusual in a report from a single formation; yet the high resolution of interpreted time relationships between various processes of deposition, erosion, water table fluctuation, and deformation is even more notable. These exceptional features derive from the extraordinary outcrops of the Colorado Plateau, which expose many large-scale (tens of meters) features throughout their entire extent and reveal an extended history of episodic deformation through thick (hundreds of meters) sections of cross-bedded units, which frequently continue along several kilometers of cliff face. Prior studies of fluid escape from unconsolidated sand that support the present work are outlined in Chapter II. These include laboratory simulations of liquefaction and fluidization as well as analyses of analogous deposits, both ancient and modern. Chapter III provides an overview of outcrop evidence, gathered during the course of this study, for dramatic alterations in the topography and sedimentation patterns of the Navajo erg. Interpreted perturbations include: the foundering of active dunes; sediment eruptions; and the subsidence of interdune surfaces. Chapter IV constitutes an example of the detailed analyses that support the overview of Chapter III. Outcrop features from a site in West Canyon, Arizona provide the basis for interpreting the subsidence of a dry interdune surface to a position several meters below the contemporary water table, followed by the filling of this depression with a succession of mass flow, lacustrine, and eolian deposits. Chapter V outlines the implications of various outcrop features for the prevailing model of soft-sediment deformation in the Navajo Sandstone. Proposed modifications of this model accommodate a broader range of deformation dynamics and specifically incorporate the impact of wet climates.

In contrast to early work establishing the importance of earthquake-induced liquefaction in producing soft-sediment deformation (SSD) of the Navajo Sandstone, this report advances the use of SSD analysis to: characterize wet climatic conditions and flood events during the depositional history of ancient eolianites; discriminate the signatures of multiple deformation events from those of complex deformation features formed in a single event; and to document the occurrence of liquefaction features unrepresented in modern Earth analogues. The diversity of deformation styles, presented here, is very unusual in a report from a single formation; yet the high resolution of interpreted time relationships between various processes of deposition, erosion, water table fluctuation, and deformation is even more notable. These exceptional features derive from the extraordinary outcrops of the Colorado Plateau, which expose many large-scale (tens of meters) features throughout their entire extent and reveal an extended history of episodic deformation through thick (hundreds of meters) sections of cross-bedded units, which frequently continue along several kilometers of cliff face. Prior studies of fluid escape from unconsolidated sand that support the present work are outlined in Chapter II. These include laboratory simulations of liquefaction and fluidization as well as analyses of analogous deposits, both ancient and modern. Chapter III provides an overview of outcrop evidence, gathered during the course of this study, for dramatic alterations in the topography and sedimentation patterns of the Navajo erg. Interpreted perturbations include: the foundering of active dunes; sediment eruptions; and the subsidence of interdune surfaces. Chapter IV constitutes an example of the detailed analyses that support the overview of Chapter III. Outcrop features from a site in West Canyon, Arizona provide the basis for interpreting the subsidence of a dry interdune surface to a position several meters below the contemporary water table, followed by the filling of this depression with a succession of mass flow, lacustrine, and eolian deposits. Chapter V outlines the implications of various outcrop features for the prevailing model of soft-sediment deformation in the Navajo Sandstone. Proposed modifications of this model accommodate a broader range of deformation dynamics and specifically incorporate the impact of wet climates.

Soft-sediment ecosystems can be degraded through anthropogenic development, leading to reduced habitat suitability for biological communities. On the North Coast of British Columbia, Canada, intensive industrial activity and coastal development has occurred, specifically around the Skeena and Kitimat River Estuaries. In addition to current development, both regions have the potential for further development, while also undergoing passive restoration from historical disturbances. Therefore, I aimed to broaden our understanding of passive restoration and non-invasive monitoring of intertidal soft-sediment ecosystems, by carrying out experiments at mudflats in both estuaries during the summer of 2017. Specifically, I aimed to expand the use of a non-invasive population assessment technique to novel species in soft-sediment ecosystems. Relationships between burrowing decapod abundance and burrow openings have been successfully used to estimate population sizes, but this technique has yet to be applied to large burrowing polychaetes, bivalves, or in regions of high macrofaunal diversity. As such, I assessed mudflats in regions of low (n = 1 species) and high (n = 8 species) biodiversity to determine if macrofauna abundances could be estimated from burrow openings on the sediment surface. Where only one burrowing bivalve species was present, a relationship between burrow openings and population abundance was not feasible, but burrow openings were useful in estimating total macrofaunal community abundance at a high diversity mudflat. This suggests that monitoring through burrow opening counts has the ability to detect overall changes in population abundance. Next, I examined the infaunal community, sediment conditions, and nutrient availability at one intertidal mudflat in the Skeena River Estuary following the cessation of heavy industrial activities (i.e. a salmon cannery and pulp mill) to determine the capacity for passive restoration. Sediment conditions varied spatiotemporally, and nutrient availability showed temporal variation but trends were difficult to relate to historical or current potential disturbances. The legacy of past development is still apparent on the infaunal community in the form of patchy distributions of disturbance-indicating taxa, but the mudflat appears to be in an overall healthy state with a diverse and functioning food web, indicating community recovery from historical activities. Results from these studies indicate passive restoration can be appropriate for estuarine soft-sediment ecosystems, while monitoring population abundance through burrow openings could be a method of detecting disturbances or tracking recovery of macrofaunal populations. / Graduate / 2020-06-28

Due to intensive coastal development, a combination of local (e.g. pollution, fishing) and global pressures (such as climate change) is affecting marine habitats worldwide. This is a pressing issue in Saudi Arabia, particularly considering the plans for the expansion of sea-related activities within the Saudi Arabia's Vision 2030 framework. Sustaining some of those activities, such as tourism, is dependent upon the maintenance of good ecosystem health. National monitoring programs in Saudi Arabia are scarce and a lack of sound knowledge on how marine organisms change in space and time and what the main factors driving their responses are, limits the contribution of scientists to the management and conservation of the Red Sea. Here we provide baseline knowledge, that can be critical for assessing changes associated with current and future coastal development as well as climate change by collecting data across multiple spatial (including multiple habitats) and temporal scales for the analysis of macroinvertebrate organisms and environmental drivers. One of the most striking findings is related to the low densities observed for macroinvertebrates, making populations potentially vulnerable to disturbance. We also highlight the contribution of different habitats within the seascape and the need to prioritize the features of the bottoms for management and conservation purposes. Each habitat has a unique ecological signature but they are connected to adjacent habitats through a subset of species able to utilize different biotopes within the seascape. Disrupting this ecological network may affect biodiversity patterns from local to regional levels. Within each habitat, temporal variability should be taken into account as patterns change on a seasonal and annual scale. The aim of the thesis is to contribute to the sustainable development of the Red Sea, a unique resource shared among several countries, which will result in a long-term benefit to the Kingdom of Saudi Arabia, and other countries. Information provided is critical as previous knowledge for the region was almost inexistent and allows for future studies to investigate and predict the impacts of intense coastal development and inform conservation and management decisions.

When multiple predators foraging together have different individual consumption rates than predators foraging in isolation, they exhibit non-independent multiple predator effects on prey. I examined multiple predator effects in a system consisting of invasive green crabs (Carcinus maenas L.), native rock crabs (Cancer irroratus Say) and benthic macrofauna prey. First, I examined multiple predator effects when green crabs and rock crabs forage on soft-shell clams (Mya arenaria L.) in different habitat types (sand, sand with artificial seagrass) and assessed the behavioural mechanisms responsible for the observed predation effects. Independent multiple predator effects on prey were detected for most conspecific and heterospecific pairs in both habitat types. In general, crab foraging behaviours were not affected by the presence of another predator. Interactions between predators did not influence foraging behaviours because encounters were infrequent, short in duration and predominantly non-aggressive. A non-independent multiple predator effect on prey (marginally significant) was observed when green crabs foraged with rock crabs in artificial seagrass. This effect, however, could not be explained by the observed crab behaviours. Second, I investigated multiple predator effects when green crabs and rock crabs forage on a soft-sediment macrofauna community. Because crabs did not have significant predation effects on the community throughout the experiment, I did not evaluate multiple predator effects on prey. It is possible that crab predation was not important in regulating the macrofauna community, in which case multiple predator effects were non-existent. Predation may have been suppressed due to a combination of factors, including interactions between predators, harsh environmental conditions or a sub-optimal prey field. Alternatively, my ability to detect significant predation effects may have been hindered because of prey movement in and out of cages or low statistical power. Overall, results from this thesis demonstrate that multiple predator effects on prey may differ with habitat and highlights the importance of conducting behavioural observations to better understand interactions between predators and the resulting consequences for prey. Multiple predator effects on a soft-sediment community should be re-evaluated to assess the importance of these crab species in regulating benthic macrofauna under natural conditions.

Le but de cette thèse est d'étudier les structures sédimentaires de déformations produites par liquéfaction en subsurface des sédiments marins (soft sediment deformations) lors d'événements sismiques. Une caractérisation de différents niveaux de séismites est menée afin de mettre en relation la formation des SSDs et la tectonique régionale au moment de la déstabilisation à l'aide des directions de structures, et de discuter de l'impact de la lithologie sur la forme et la localisation des SSDs dans la pile sédimentaire. Ce travail est réalisé à partir d'observations de terrain et de mesures statistiques de la direction des structures sur des objets de dimensions variables. Le premier exemple s'est portée sur les SSDs qui affectent les dépôts du Penarth group (limite Trias-Jurassique) dans les îles Britanniques au début de la phase de dislocation de la Pangée. Le second exemple s'est appliqué à la caractérisation des parties amont de quatre grands mass transport deposits présents dans le bassin néogène de Tabernas, (cordillères Bétiques, Espagne). Cette étude a mis en évidence le lien très fort entre la déformation de surface et la tectonique et l'intérêt d'étudier ces objets pour mieux définir le contexte du bassin au moment de la déstabilisation. La lithologie du sédiment et son taux d'induration ont un impact fort sur le type de SSDs observées. Les paramètres favorisant le déclenchement de la déstabilisation gravitaire au-dessus d'un niveau liquéfié sont 1) un faible taux d'induration sédimentaire 2) un temps de liquéfaction important et des fortes magnitudes de séisme 3) l'absence de failles qui traversent le niveau liquéfié susceptibles d'ancrer la déformation. / The aim is to study the sedimentary structures of deformation produced by liquefaction in subsurface of marine sediments (soft sediment deformations) during seismic events. A characterization of different levels of seismites is carried out in order to (1) establish links between the formation of SSDs and the regional tectonics with the time of destabilization using structural directions of deformation; (2) to discuss the impact of lithology on the shape and location of deformation structures in the sedimentary pile. The characterization of SSDs is realized from: (1) field observations and (2) statistical measurements of the direction of structures on objects of variable dimensions. The first studied case concerns the characterization of the SSDs that affect the Penarth group (Triassic-Jurassic boundary) deposits in the British Isles at the beginning of the break-up phase of the Pangea. The second example present the characterization of upstream areas of four major mass transport deposits, located in the intramontane basin of Tabernas, in the Betic Cordilleras (Spain). Sediment lithology and induration rates with depth, have a strong impact on the type of observed deformation structures. The parameters that encourage the triggering of the gravity destabilization above a liquefied level are (1) a low sedimentary induration rate which does not limit the liquefaction process (2) a high liquefaction duration which requires a high magnitude of the seismic event (3) the absence of faults which cross the liquefied level and can anchor the deformation in the underlying bed by forming relief.

Orientador: Lucas Veríssimo Warren / Resumo: O evento de ruptura do Gondwana no Cretáceo foi responsável pela reativação de estruturas do Pré-Cambriano e geração de diversas bacias interiores do tipo rifte no Nordeste do Brasil. Nesse contexto, a sucessão sedimentar da Bacia do Araripe registra as sequências pré-, sin- e pós-rifte formadas durante os distintos estágios tectono-sedimentares envolvidos na formação do Oceano Atlântico Sul. A Formação Araripina do Albiano Médio faz parte da sequência pós-rifte, é limitada na base por discordância litológica com rochas do embasamento ou por discordância angular com a Formação Romualdo, marinha. No topo, é limitada por discordância erosiva ou angular com os depósitos fluviais da Formação Exu. A Formação Araripina é composta principalmente de intercalações rítmicas de arenitos e lamitos, e a sucessão sedimentar é dividida em duas sequências deposicionais, SD1 e SD2, por uma superfície de truncamento regional. Sob essa superfície tectônica, em SD1, a associação de fácies mostra que a sedimentação foi em planícies intermediárias a distais de sistemas fluviais distributivos sujeitas a inundações episódicas associadas a canais efêmeros e à fluxos laminares, com evidências de complexos de splays terminais e laterais, pequenos lagos efêmeros e tectônica ativa. Acima da superfície, a SD2 apresenta menor evidência de tectonismo e de aporte sedimentar. O ambiente deposicional imediatamente após a superfície é compatível com depósitos de playa lake em diversos afloramentos estudados, pr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Cretaceous Gondwana breakup event was responsible for the reactivation of Precambrian structures producing several interior rift basins in the Northeast Brazil. In this context, the sedimentary succession of the Araripe Basin record the pre, syn and post-rift sequences formed during the distinct tectono-sedimentary stages involved in the formation of the South Atlantic Ocean. The Middle Albian Araripina Formation is part of the post-rift sequence, bounded at base by basement rocks (nonconformity) or by the marine Romualdo Formation (angular unconformity). It is bounded at the top by a disconformity/angular unconformity with the fluvial deposits of the Exu Formation. The Araripina Formation is mainly composed of rhythmically interbedded sandstones and mudstones, and the succession is divided in two (DS1 and DS2) by a major truncating surface. Under this tectonic surface, in DS1, facies association shows that sedimentation was likely in a plain with medial to distal distributive fluvial systems. This plain was subjected to episodic inundations associated with ephemeral channels and sheetfloods, with evidences of terminal splays complexes, lateral splays, small playa lakes and active tectonics. Above the surface, the DS2 presents a more lenient tectonic setting and less sediment suppy. The depositional environment immediately after the surface is compatible with playa lake deposits in several studied places, probably in response to the previous tectonic activity. Overall, it... (Complete abstract click electronic access below) / Mestre

O Lineamento Transbrasiliano é uma das principais estruturas da Plataforma Sul-Americana, estendendose em território brasileiro por cerca de 2700km. Desde sua instalação, no Neoproterozóico, o lineamento sofreu diversas reativações, e evidências geofísicas mostram que este se constitui numa importante descontinuidade litosférica. O Lineamento Transbrasiliano e outras estruturas do embasamento exerceram grande influência na instalação e história deposicional das bacias sedimentares da Província Parnaíba. Zonas de fraqueza litosférica importantes, como o Lineamento Transbrasiliano, tendem a concentrar esforços remotos gerados na borda das placas, e dessa forma a ser foco de atividade tectônica e sismicidade intraplaca. Sismos intraplaca, embora pouco comuns, podem atingir magnitudes consideráveis e afetar grandes áreas, como o atestam os sismos ocorridos no início do século XIX em New Madrid, EUA. Tectônica e sismicidade intraplaca podem gerar diversos tipos de registro em bacias intracratônicas. Entre eles, se destacam os sismitos: estruturas de liquidificação produzidas em sedimentos inconsolidados submetidos a choque sísmico. Sismitos são ferramentas particularmente úteis para a reconstrução da história tectônica de bacias sedimentares; no entanto, sua caracterização e interpretação podem ser problemáticas, visto que processos não sísmicos podem induzir a formação de estruturas similares às produzidas por terremotos. Foram identificados horizontes com estruturas de deformação sinsedimentares em cinco unidades litoestratigráficas na área estudada, no sudoeste da Província Parnaíba: as formações Pimenteiras, Cabeças, Longá e Piauí (Bacia do Parnaíba) e o Grupo Areado (Bacia do Espigão-Mestre). Foi aplicada a estas feições uma metodologia para a caracterização de estruturas de deformação sinsedimentar geradas por abalos sísmicos, desenvolvida a partir de uma ampla revisão da literatura sobre o tema. A partir de sua caracterização como possíveis sismitos, as estruturas foram analisadas, visando determinar intervalos de atividade tectônica sinsedimentar, possíveis campos de paleotensões à época de sua formação e que estruturas do embasamento foram reativadas. Os resultados obtidos, embora ainda preliminares, sugerem atividade tectônica sinsedimentar em quatro episódios: no Neodevoniano (formações Pimenteiras e Cabeças), com o esforço horizontal máximo (\'Sh IND.máx\') do campo de paleotensões associado orientado segundo N-S; no Neodevoniano - Eocarbonífero (Formação Longá), com \'Sh IND.máx\' orientado segundo N60-65E; no Neocarbonífero (Formação Piauí), com \'Sh IND.máx\' orientado segundo N40E; e no Eocretáceo (Grupo Areado). Reativações do Lineamento Transbrasiliano parecem ser responsáveis pela atividade tectônica sinsedimentar, embora os lineamentos de Senador Pompeu e do Rio das Balsas possam ter sido responsáveis por parte desta atividade. / The Transbrasiliano Lineament is one of the main structures in the South American Platform, with a lenght of ca. 2700km in brazilian territory. Since its formation, in the Neoproterozoic, the lineament was reactivated several times, and geophysical evidence shows that it is a major lithospheric discontinuity. The Transbrasiliano Lineament and other basement structures played a major role on the formation and depositional history of the sedimentary basins of the Parnaíba Province. Major zones of lithospheric weakness, such as the Transbrasiliano Lineament, may concentrate remote stresses originated on the edges of tectonic plates, and so may be focus of intraplate tectonics and seismicity. Intraplate earthquakes, although uncommon, can reach large magnitudes and affect large areas, as shown by the New Madrid (USA) earthquakes, in the beginning of the XIXth century. Intraplate tectonics and seismicity may leave several types of records in intracratonic basins. Of great significance among them are seismites: liquidization structures produced in soft-sediments under seismical shock. Seismites are particularly useful in the reconstruction of the tectonic history of sedimentary basins. However, identifying and interpreting seismites can be troublesome, since non-seismical processes can generate structures similar to those produced by earthquakes. Horizons with soft-sediment deformation structures were identified in five lithostratigraphic units in the study area, on the southwest of Parnaíba Province: the Pimenteiras, Cabeças, Longá and Piauí formations (Parnaíba Basin) and the Areado Group (Espigão-Mestre Basin). A methodology for distinguishing soft-sediment deformation structures generated by seismical shock was developed from a review of the literature concerning seismites, and applied to the described strutures. Structures interpreted as seismites were analised in order to identify intervals of sinsedimentary tectonic activity, possible paleostress fields at the time of their formation and which basement strutures were reactivated. The results obtained, although still preliminary, suggests four intervals of sinsedimentary tectonic activity: during the Neodevonian (Cabeças and Pimenteiras formations), with maximum horizontal stress (\'Sh IND.max\' ) of the associated paleostress field oriented N-S; Neodevonian-Eocarboniferous (Longá Formation), with an N60-65Eoriented \'Sh IND.max\' ; Neocarboniferous (Piauí Formation), with an N40E-oriented \'Sh IND.max\'; and on Eocretaceous (Areado Group). Transbrasiliano Lineament reactivations seem to be responsible for the sinsedimentary tectonic activity, although the Senadour Pompeu and Rio das Balsas lineaments may also have played some role on these deformations.

O Lineamento Transbrasiliano é uma das principais estruturas da Plataforma Sul-Americana, estendendose em território brasileiro por cerca de 2700km. Desde sua instalação, no Neoproterozóico, o lineamento sofreu diversas reativações, e evidências geofísicas mostram que este se constitui numa importante descontinuidade litosférica. O Lineamento Transbrasiliano e outras estruturas do embasamento exerceram grande influência na instalação e história deposicional das bacias sedimentares da Província Parnaíba. Zonas de fraqueza litosférica importantes, como o Lineamento Transbrasiliano, tendem a concentrar esforços remotos gerados na borda das placas, e dessa forma a ser foco de atividade tectônica e sismicidade intraplaca. Sismos intraplaca, embora pouco comuns, podem atingir magnitudes consideráveis e afetar grandes áreas, como o atestam os sismos ocorridos no início do século XIX em New Madrid, EUA. Tectônica e sismicidade intraplaca podem gerar diversos tipos de registro em bacias intracratônicas. Entre eles, se destacam os sismitos: estruturas de liquidificação produzidas em sedimentos inconsolidados submetidos a choque sísmico. Sismitos são ferramentas particularmente úteis para a reconstrução da história tectônica de bacias sedimentares; no entanto, sua caracterização e interpretação podem ser problemáticas, visto que processos não sísmicos podem induzir a formação de estruturas similares às produzidas por terremotos. Foram identificados horizontes com estruturas de deformação sinsedimentares em cinco unidades litoestratigráficas na área estudada, no sudoeste da Província Parnaíba: as formações Pimenteiras, Cabeças, Longá e Piauí (Bacia do Parnaíba) e o Grupo Areado (Bacia do Espigão-Mestre). Foi aplicada a estas feições uma metodologia para a caracterização de estruturas de deformação sinsedimentar geradas por abalos sísmicos, desenvolvida a partir de uma ampla revisão da literatura sobre o tema. A partir de sua caracterização como possíveis sismitos, as estruturas foram analisadas, visando determinar intervalos de atividade tectônica sinsedimentar, possíveis campos de paleotensões à época de sua formação e que estruturas do embasamento foram reativadas. Os resultados obtidos, embora ainda preliminares, sugerem atividade tectônica sinsedimentar em quatro episódios: no Neodevoniano (formações Pimenteiras e Cabeças), com o esforço horizontal máximo (\'Sh IND.máx\') do campo de paleotensões associado orientado segundo N-S; no Neodevoniano - Eocarbonífero (Formação Longá), com \'Sh IND.máx\' orientado segundo N60-65E; no Neocarbonífero (Formação Piauí), com \'Sh IND.máx\' orientado segundo N40E; e no Eocretáceo (Grupo Areado). Reativações do Lineamento Transbrasiliano parecem ser responsáveis pela atividade tectônica sinsedimentar, embora os lineamentos de Senador Pompeu e do Rio das Balsas possam ter sido responsáveis por parte desta atividade. / The Transbrasiliano Lineament is one of the main structures in the South American Platform, with a lenght of ca. 2700km in brazilian territory. Since its formation, in the Neoproterozoic, the lineament was reactivated several times, and geophysical evidence shows that it is a major lithospheric discontinuity. The Transbrasiliano Lineament and other basement structures played a major role on the formation and depositional history of the sedimentary basins of the Parnaíba Province. Major zones of lithospheric weakness, such as the Transbrasiliano Lineament, may concentrate remote stresses originated on the edges of tectonic plates, and so may be focus of intraplate tectonics and seismicity. Intraplate earthquakes, although uncommon, can reach large magnitudes and affect large areas, as shown by the New Madrid (USA) earthquakes, in the beginning of the XIXth century. Intraplate tectonics and seismicity may leave several types of records in intracratonic basins. Of great significance among them are seismites: liquidization structures produced in soft-sediments under seismical shock. Seismites are particularly useful in the reconstruction of the tectonic history of sedimentary basins. However, identifying and interpreting seismites can be troublesome, since non-seismical processes can generate structures similar to those produced by earthquakes. Horizons with soft-sediment deformation structures were identified in five lithostratigraphic units in the study area, on the southwest of Parnaíba Province: the Pimenteiras, Cabeças, Longá and Piauí formations (Parnaíba Basin) and the Areado Group (Espigão-Mestre Basin). A methodology for distinguishing soft-sediment deformation structures generated by seismical shock was developed from a review of the literature concerning seismites, and applied to the described strutures. Structures interpreted as seismites were analised in order to identify intervals of sinsedimentary tectonic activity, possible paleostress fields at the time of their formation and which basement strutures were reactivated. The results obtained, although still preliminary, suggests four intervals of sinsedimentary tectonic activity: during the Neodevonian (Cabeças and Pimenteiras formations), with maximum horizontal stress (\'Sh IND.max\' ) of the associated paleostress field oriented N-S; Neodevonian-Eocarboniferous (Longá Formation), with an N60-65Eoriented \'Sh IND.max\' ; Neocarboniferous (Piauí Formation), with an N40E-oriented \'Sh IND.max\'; and on Eocretaceous (Areado Group). Transbrasiliano Lineament reactivations seem to be responsible for the sinsedimentary tectonic activity, although the Senadour Pompeu and Rio das Balsas lineaments may also have played some role on these deformations.