Ancient basin-floor strata are exceptionally well exposed in the Neoproterozoic Windermere Supergroup in the southern Canadian Cordillera. Data from the Castle Creek outcrop, where strata of the upper Kaza Group crop out, and the Mt. Quanstrom outcrop, where the middle Kaza is exposed, form the main dataset for this study. The aim of this study is to describe and interpret the strata starting at the bed scale, followed by stratal element scale, lobe scale and ultimately fan scale. Strata of the Kaza Group comprise six sedimentary facies representing deposition from a variety of fluid and cohesive sediment gravity flows. These, in turn, populate seven stratal elements that are defined by their basal contact, cross-sectional geometry and internal facies distribution. The lithological characteristics of stratal elements vary little from proximal to more distal settings, but their relative abundance and stacking pattern do, which, then, forms the basis for modeling the internal architecture of lobes. Lobes typically comprise an assemblage of stratal elements, which then are systematically and predictably arranged in both space (along a single depositional transect) and time (stratigraphically upward). Lobes typically became initiated by channel avulsion. In the proximal part of the system scours up to several meters deep, several tens of meters wide are interpreted to have formed by erosion downflow of the avulsion node. Erosion also charged the flow with fine-grained sediment and on the lateral margins and downflow avulsion splays were deposited. Later flows then exploited the basin-floor topography and on the proximal basin-floor carved a feeder channel, which then fed a downflow depositional lobe. At the mouths of feeder channels flows became dispersed through a network of distributary channels that further downflow shallow and widen until eventually merging laterally in sandstone-rich terminal splays. During the lifespan of a single lobe the feeder channel remains fixed, but the distributary channel network and its associated terminal splays wander, causing them to stack and be intercalated laterally and vertically. Eventually an upstream avulsion terminates local sediment supply, causing a new lobe to be initiated elsewhere on the fan, and the process repeats.

The Guará Formation (Upper Jurassic) crops out in the western portion of Rio Grande do Sul along a track with north-south orientation, of which the northern part essentially consists of fluvial deposits with paleocurrent to southwest. Despite the existence of outcrops with good vertical exposure and high lateral continuity, had not yet been carried out detailed studies of fluvial architecture of this unit. Through facies analysis, with vertical logs and lateral sections data, 9 lithofacies composing 8 architectural elements were described and interpreted. These elements are grouped in sandstone bodies of two fluvial styles: (1) Deep perennial braided rivers – composed by simple and composed downstream-accretion elements, small and large-sized hollows, trough cross-stratified sets and overbank sand and fine facies – and (2) Poorly channelized ephemeral braided rivers - characterized by horizontally stratified sandstones and trough cross-stratified sets. Two or more sandstone bodies of same style amalgamate into 10 to 15 m packages representing time intervals with the domain of a river style. These packages alternate vertically separated by hundreds of meters lateral extent surfaces, reflecting intervals with larger and more continuous water discharge (sandstone bodies of deep perennial rivers) or with high energy episodic discharge (with sandstone bodies of poorly channelized ephemeral rivers). The river systems of the proximal portion of the Guará Formation reflects low frequency discharge variations, controlled by the climate. / A Formação Guará (Jurássico Superior) aflora na porção oeste do Rio Grande do Sul ao longo de uma faixa com orientação norte-sul, sendo a sua porção setentrional constituída essencialmente por depósitos fluviais com paleocorrente para sudoeste. Apesar da existência de afloramentos com boa exposição vertical e uma alta continuidade lateral, não haviam sido realizados até o presente momento estudos detalhados da arquitetura fluvial desta unidade. Por meio da análise de fácies, com a elaboração de perfis verticais e seções laterais, foram descritos e interpretados 9 litofácies que compõem 8 elementos arquiteturais. Estes elementos se agrupam em corpos arenosos de dois estilos fluviais: (1) Rios entrelaçados perenes profundos – compostos por elementos de acresção frontal simples e compostas, hollows de pequeno e grande porte, sets isolados com estratificações cruzadas e fácies arenosas e finas externas aos canais – e (2) Rios entrelaçados efêmeros fracamente canalizados – caracterizados por arenitos horizontalmente estratificados e sets isolados com estratificações cruzadas. Dois ou mais corpos arenosos de mesmo estilo se amalgamam em pacotes de 10 a 15 m que representam intervalos de tempo com o domínio de um estilo fluvial. Estes pacotes se alternam verticalmente separados por superfícies de centenas de metros de extensão lateral, refletindo intervalos com descarga aquosa maior e mais contínua (com corpos arenosos de rios perenes e profundos) ou com descarga episódica e de alta energia (com corpos arenosos de rios efêmeros fracamente canalizados). Os sistemas fluviais da porção proximal da Formação Guará refletem variações de descarga de baixa frequência, de controle climático.

The Guará Formation (Upper Jurassic) crops out in the western portion of Rio Grande do Sul along a track with north-south orientation, of which the northern part essentially consists of fluvial deposits with paleocurrent to southwest. Despite the existence of outcrops with good vertical exposure and high lateral continuity, had not yet been carried out detailed studies of fluvial architecture of this unit. Through facies analysis, with vertical logs and lateral sections data, 9 lithofacies composing 8 architectural elements were described and interpreted. These elements are grouped in sandstone bodies of two fluvial styles: (1) Deep perennial braided rivers – composed by simple and composed downstream-accretion elements, small and large-sized hollows, trough cross-stratified sets and overbank sand and fine facies – and (2) Poorly channelized ephemeral braided rivers - characterized by horizontally stratified sandstones and trough cross-stratified sets. Two or more sandstone bodies of same style amalgamate into 10 to 15 m packages representing time intervals with the domain of a river style. These packages alternate vertically separated by hundreds of meters lateral extent surfaces, reflecting intervals with larger and more continuous water discharge (sandstone bodies of deep perennial rivers) or with high energy episodic discharge (with sandstone bodies of poorly channelized ephemeral rivers). The river systems of the proximal portion of the Guará Formation reflects low frequency discharge variations, controlled by the climate. / A Formação Guará (Jurássico Superior) aflora na porção oeste do Rio Grande do Sul ao longo de uma faixa com orientação norte-sul, sendo a sua porção setentrional constituída essencialmente por depósitos fluviais com paleocorrente para sudoeste. Apesar da existência de afloramentos com boa exposição vertical e uma alta continuidade lateral, não haviam sido realizados até o presente momento estudos detalhados da arquitetura fluvial desta unidade. Por meio da análise de fácies, com a elaboração de perfis verticais e seções laterais, foram descritos e interpretados 9 litofácies que compõem 8 elementos arquiteturais. Estes elementos se agrupam em corpos arenosos de dois estilos fluviais: (1) Rios entrelaçados perenes profundos – compostos por elementos de acresção frontal simples e compostas, hollows de pequeno e grande porte, sets isolados com estratificações cruzadas e fácies arenosas e finas externas aos canais – e (2) Rios entrelaçados efêmeros fracamente canalizados – caracterizados por arenitos horizontalmente estratificados e sets isolados com estratificações cruzadas. Dois ou mais corpos arenosos de mesmo estilo se amalgamam em pacotes de 10 a 15 m que representam intervalos de tempo com o domínio de um estilo fluvial. Estes pacotes se alternam verticalmente separados por superfícies de centenas de metros de extensão lateral, refletindo intervalos com descarga aquosa maior e mais contínua (com corpos arenosos de rios perenes e profundos) ou com descarga episódica e de alta energia (com corpos arenosos de rios efêmeros fracamente canalizados). Os sistemas fluviais da porção proximal da Formação Guará refletem variações de descarga de baixa frequência, de controle climático.

The Guará Formation (Upper Jurassic) crops out in the western portion of Rio Grande do Sul along a track with north-south orientation, of which the northern part essentially consists of fluvial deposits with paleocurrent to southwest. Despite the existence of outcrops with good vertical exposure and high lateral continuity, had not yet been carried out detailed studies of fluvial architecture of this unit. Through facies analysis, with vertical logs and lateral sections data, 9 lithofacies composing 8 architectural elements were described and interpreted. These elements are grouped in sandstone bodies of two fluvial styles: (1) Deep perennial braided rivers – composed by simple and composed downstream-accretion elements, small and large-sized hollows, trough cross-stratified sets and overbank sand and fine facies – and (2) Poorly channelized ephemeral braided rivers - characterized by horizontally stratified sandstones and trough cross-stratified sets. Two or more sandstone bodies of same style amalgamate into 10 to 15 m packages representing time intervals with the domain of a river style. These packages alternate vertically separated by hundreds of meters lateral extent surfaces, reflecting intervals with larger and more continuous water discharge (sandstone bodies of deep perennial rivers) or with high energy episodic discharge (with sandstone bodies of poorly channelized ephemeral rivers). The river systems of the proximal portion of the Guará Formation reflects low frequency discharge variations, controlled by the climate. / A Formação Guará (Jurássico Superior) aflora na porção oeste do Rio Grande do Sul ao longo de uma faixa com orientação norte-sul, sendo a sua porção setentrional constituída essencialmente por depósitos fluviais com paleocorrente para sudoeste. Apesar da existência de afloramentos com boa exposição vertical e uma alta continuidade lateral, não haviam sido realizados até o presente momento estudos detalhados da arquitetura fluvial desta unidade. Por meio da análise de fácies, com a elaboração de perfis verticais e seções laterais, foram descritos e interpretados 9 litofácies que compõem 8 elementos arquiteturais. Estes elementos se agrupam em corpos arenosos de dois estilos fluviais: (1) Rios entrelaçados perenes profundos – compostos por elementos de acresção frontal simples e compostas, hollows de pequeno e grande porte, sets isolados com estratificações cruzadas e fácies arenosas e finas externas aos canais – e (2) Rios entrelaçados efêmeros fracamente canalizados – caracterizados por arenitos horizontalmente estratificados e sets isolados com estratificações cruzadas. Dois ou mais corpos arenosos de mesmo estilo se amalgamam em pacotes de 10 a 15 m que representam intervalos de tempo com o domínio de um estilo fluvial. Estes pacotes se alternam verticalmente separados por superfícies de centenas de metros de extensão lateral, refletindo intervalos com descarga aquosa maior e mais contínua (com corpos arenosos de rios perenes e profundos) ou com descarga episódica e de alta energia (com corpos arenosos de rios efêmeros fracamente canalizados). Os sistemas fluviais da porção proximal da Formação Guará refletem variações de descarga de baixa frequência, de controle climático.

Ancient basin-floor strata are exceptionally well exposed in the Neoproterozoic Windermere Supergroup in the southern Canadian Cordillera. Data from the Castle Creek outcrop, where strata of the upper Kaza Group crop out, and the Mt. Quanstrom outcrop, where the middle Kaza is exposed, form the main dataset for this study. The aim of this study is to describe and interpret the strata starting at the bed scale, followed by stratal element scale, lobe scale and ultimately fan scale. Strata of the Kaza Group comprise six sedimentary facies representing deposition from a variety of fluid and cohesive sediment gravity flows. These, in turn, populate seven stratal elements that are defined by their basal contact, cross-sectional geometry and internal facies distribution. The lithological characteristics of stratal elements vary little from proximal to more distal settings, but their relative abundance and stacking pattern do, which, then, forms the basis for modeling the internal architecture of lobes. Lobes typically comprise an assemblage of stratal elements, which then are systematically and predictably arranged in both space (along a single depositional transect) and time (stratigraphically upward). Lobes typically became initiated by channel avulsion. In the proximal part of the system scours up to several meters deep, several tens of meters wide are interpreted to have formed by erosion downflow of the avulsion node. Erosion also charged the flow with fine-grained sediment and on the lateral margins and downflow avulsion splays were deposited. Later flows then exploited the basin-floor topography and on the proximal basin-floor carved a feeder channel, which then fed a downflow depositional lobe. At the mouths of feeder channels flows became dispersed through a network of distributary channels that further downflow shallow and widen until eventually merging laterally in sandstone-rich terminal splays. During the lifespan of a single lobe the feeder channel remains fixed, but the distributary channel network and its associated terminal splays wander, causing them to stack and be intercalated laterally and vertically. Eventually an upstream avulsion terminates local sediment supply, causing a new lobe to be initiated elsewhere on the fan, and the process repeats.

This thesis investigates how architectural element analysis (AE) can be utilized to deconstruct the sedimentary architecture of glacial sedimentary successions, and its significance for paleoenvironmental reconstruction, understanding depositional histories, and providing insight to the hydrostratigraphy of glaciated terrains. The first component of this thesis explores the applicability of AEA to the local-scale analysis of a till succession exposed in outcrop sections in order to understand the significance of the bounding surface hierarchy and architectural elements in sediments deposited in a subglacial depositional environment. Fieldwork was conducted at two outcrop sites in north-central Illinois, U.S.A., which expose Late Wisconsin-age till of the Tiskilwa Formation, in order to test the local-scale applicability of AEA to the architectural analysis of a subglacial succession (Chapter 2). A major finding of this study was that fifth-order bounding surfaces delineate ‘element associations’ which can be mapped across the local study area, and utilized for detailed paleoenvironmental reconstruction of the ‘subglacial bed mosaic’ and local-scale reconstruction of the depositional history of the till sheet, including periods of separation and reattachment of the ice and its bed. The second part of this research explores AEA at Sólheimajökull (Iceland), specifically to test the validity of AEA for the analysis of glacial successions, and to better understand the environmental significance of unit contacts (bounding surfaces) and sedimentary geometries in a modern glacial landscape. Fieldwork was conducted at Sólheimajökull and basic principles of AEA and landsystems analysis were integrated in order to facilitate delineation of the sedimentary architecture and allostratigraphy of the Sólheimajökull landsystem (Chapter 3). Fifth-order surfaces delineate landsystem tract components, which can be utilized to characterize the heterogeneity and sedimentary architecture, delineate allostratigraphic units, and reconstruct the depositional hist¬ory of the Sólheimajökull landsystem. Data from Sólheimajökull (Chapter 3) and Illinois (Chapter 2) were utilized as a modern and outcrop analogue, respectively, to provide insight to the sedimentary architecture of subsurface Quaternary glacial deposits in Georgetown, southern Ontario (Canada; Chapter 4). Basic concepts of AEA were applied to the analysis of sediments recovered from fully-cored boreholes. A major finding of this study is that AEA can be effectively utilized for delineation of subsurface architectures from the analysis of core, and the hierarchies of bounding surfaces and units of AEA can be utilized to organize the sedimentary heterogeneity into a ‘nested’ architectural framework. The geometry and spatial relationship of architectural units (sixth-order surfaces) and architectural components (fifth-order surfaces) provides insight to the hydrostratigraphy of Georgetown. AEA, as utilized in this thesis, provides a systematic methodology with which to deconstruct glacial successions into their basic architectural building blocks at various scales of resolution. AEA enhances traditional facies models by facilitating site-specific delineation, visualization, and characterisation of the sedimentary geometry of facies associations, which in turn, allows direct comparison of sedimentary architectures at different study sites; this has significant implications for analogue selection for the purpose of reservoir analysis. The architectural framework of glacial deposits and its potential significance to hydrostratigraphic models (as discussed in this thesis) may help to facilitate communication and translation of data between the disciplines of ‘geology’ and ‘hydrogeology’. The results of this project can be utilized as a framework to better understand the sedimentary geometry and hydrostratigraphy of modern and Quaternary glacial deposits in southern Ontario, previously glaciated terrains elsewhere, and other modern glacial landsystems, and provide insight into other applications such as civial engineering projects, aggregate resources, placer mining exploration, and land use planning. / Thesis / Doctor of Philosophy (PhD)

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