Thesis (Ph.D.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Mar. 25, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Earth and Atmospheric Sciences, University of Alberta. Includes bibliographical references.

The Mackenzie Mountains of NW Canada contains a superb record of biotic evolution through the late Ediacaran-early Cambrian that is ideal for studying the biological, ecological, behavioural, and environmental innovations that occurred during the Ediacaran and basal Cambrian. Newly discovered Ediacara-type megafossils in the uppermost Blueflower Formation at Sekwi Brook include tubes possibly attributable to suspension-feeding annelids, the preserved top of a large frond holdfast, and several problematica. These fossils represent the youngest and shallowest Ediacaran fossils known from NW Canada, and differ significantly from the communities of deep-water rangeomorphs preserved lower in the succession. Behavioural evolution of the infauna through the Ediacaran and earliest Cambrian can be observed in the rich trace fossil records of the Blueflower and Ingta formations. Trace fossils in the lower part of the Blueflower Formation are characterized by millimeter-diameter, simple, horizontal burrows of microbial grazers and deposit feeders that demonstrated very primitive and inconsistent two-dimensional avoidance strategies. Upper Blueflower trace fossils additionally include three-dimensional avoidance burrows and oblique burrows of filter-feeders or predators, reflecting new behavioural innovations and increased three-dimensional use of the substrate. The Cambrian strata of the Ingta Formation further include probing, U-shaped, and radiating burrows, irregular networks, and arthropod trails. These new feeding strategies were accompanied by increasingly more systematic grazing burrows. The development of more diverse feeding styles upwards through the succession both caused and reflected the spatial and temporal disappearance of Proterozoic matgrounds and their replacement by Phanerozoic mixgrounds. Avoidance strategies among grazing burrows became more consistent and complicated upward throughout this succession, increasingly resembling the guided meanders of Phanerozoic trace fossils. This implies that, while the first avoidance burrows probably reflected the responses of individual burrowers to individual stimuli, genetically-coded programmed behaviour developed and became dominant in the earliest Cambrian. These observations imply that increases in sensory and neural capacity accompanied skeletonization as a major factor in the Cambrian explosion of animal life. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2014-01-27 12:37:17.741

Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 2, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Earth and Atmospheric Sciences, University of Alberta. Includes bibliographical references.

No description available.

The currently unnamed early Cambrian (Series 2, Stage 4) sandstone unit is exposed in the Minto Inlier of western Victoria Island, Canadian Arctic Islands, and forms the base of the Phanerozoic succession. Coeval with other sandstones of this age in Laurentia, it was deposited in a shallow-marine embayment on the passive margin during the initial phase of the early Paleozoic transgression. Four facies associations are recognized: (1) outer embayment sand dune complex characterized by laterally continuous, planar cross-stratified, medium- to coarse-grained sandstone; (2) inner embayment sand flat consisting dominantly of fine- to medium-grained bioturbated sandstone and fine- to medium-grained sandstone interbedded with laminated mudstone; (3) coastal lagoon characterized by laterally continuous, medium-grained oolitic ironstone and fine- to medium-grained bioturbated sandstone; and (4) offshore muddy shelf consisting dominantly of laminated mudstone with discontinuous seams of medium- to coarse sand. Bioturbation in the form of a typical early Cambrian suite of shallow-subtidal ichnofossils predominated in the inner embayment and coastal lagoon settings, representing a low-diversity Cruziana ichnofacies. Oolitic ironstone horizons in the coastal lagoon setting mark periods of low sedimentation rates when iron became concentrated and calcite was the primary cementing agent. Dunes are, for the most part, non-bioturbated or contain just a few individual burrows belonging to Skolithos, representing the Skolithos ichnofacies. The dominantly tabular, sheet-like geometry of the sandstones characterizes a comparatively lower energy regime than what has been found in typical complex dune geometries in modern and ancient examples and is attributed to sediment deposition under essentially uniform current speeds at consistent water depth conditions on a low-gradient shelf. Paleocurrent measurements and thickness variation suggest that deposition was affected by undulating topography on the Proterozoic basement within facies association 1 and 2, as well as by syndepositional faulting in some areas. The coastline is envisaged as a complex of bays and lagoons. The embayment opened to the northwest where sandbars developed offshore; stratigraphic thinning towards both the south and northeast indicates the direction of the paleoshoreline. Approximately shoreline orthogonal paleocurrents are considered indicative of a tidal origin. The lack of hummocky cross-stratification suggests there was no influence of major storms in this region.

No description available.

Middle-Upper Eocene successions were studied in the Fayum Depression in order to establish depositional and paleoenvironmental models that link the ichnological and sedimentologic data to relative sea-level changes in a sequence stratigraphic framework. Five facies associations (FA1- FA5) are identified. The facies depositional models show overall progradation from quiescent open-marine bay (FA1-2: Gehannam and Birket Qarun formations) to lagoon/distributary channel/estuary sedimentary environments (FA3-5: Qasr El-Sagha Formation). The facies successions and their stratigraphic evolution are controlled by a regional, second-order cycle associated with the northward regression of the Tethys, which is overprinted by subordinate third- and higher-order cycles. Whale-bearing FA1 and FA2 are subdivided into five sedimentary facies. Seventeen ichnospecies belonging to thirteen ichnogenera, as well as rhizoliths are observed within these facies. Facies Association 1 accumulated in a low-energy fullymarine bay, whereas FA 2 represents a bay margin / supratidal paleoenvironments. Clastic point-sources are dominantly hypopycnal although eolian sand may represent an important source locally. The quiescent marine bay is a typical environment and biome for the Eocene whales. Preservation of these fossil whales must occur in association with rapid sedimentation rates, but sufficiently that bioturbation eradicates the physical sedimentary structures. Unusual, large-sized sedimentary structures are examined along the parasequence-bounding surfaces of the Birket Qarun Sandstone. Ichnological data, petrography and stable-isotope analysis are integrated to propose a bio-sedimentologic/diagenetic model, interpreting the origin of these structures as concretion growths around ichnofossils. The marine pore-water carbon was influenced by organic carbon and mixing of meteoric groundwater under eodiagenetic conditions. These conditions led to the precipitation of pervasive authigenic calcite-dominated cement in and around the burrows. More than twenty-five Glossifungites Ichnofaciesdemarcated discontinuities are examined in the study area. These surfaces are grouped into those of autocyclic and those of allocyclic origin. Occurrences of the allocyclically significant Glossifungites Ichnofacies can be classified into sequence-bounding, systems tract-bounding and parasequence-bounding surfaces. Sequence-bounding Glossifungites Ichnofacies-demarcated surfaces divide the studied successions into four third-order sequences. Systems tract-bounding and parasequence-bounding Glossifungites Ichnofacies-demarcated surfaces display higher-order cycles, overprinting the third-order cycles.

<p>The architecture, distribution and facies of sandstone bodies in the Gog Group of the southern Rocky Mountains of western Canada record the dynamics of sand movement on the broad continental shelf of West Laurentia during the Early Cambrian phase of worldwide transgression. This study focuses on the stratigraphy, sedimentology and ichnology in the Bow Valley region, specifically the sector from Mount Assiniboine northwest to the North Saskatchewan River. The objectives of this project were several-fold: (1) revise the existing stratigraphic nomenclature; (2) document the sedimentary facies; (3) identify facies assemblages and interpret them in terms of sedimentary processes and environments; (4) characterize sandstone body geometries; (5) develop a sequence-stratigraphic framework; (6) document trace-fossil occurrences; and (7) characterize different trace-fossil assemblages in terms of colonization trends and prevailing paleoenvironmental conditions.</p> <p>The Gog Group in this area has historically comprised four units, the Fort Mountain, Lake Louise, St. Piran and Peyto formations. North of Bow Pass an additional unit, the Jasper Formation, occurs below the Fort Mountain Formation and is related to accommodation created by active rift-faulting during the latest Neoproterozoic. In the Lake Louise and Lake O'Hara area, four new formal subdivisions within the St. Piran Formation are proposed: Lake O'Hara, Lake Oesa, Lake Moraine and Wiwaxy Peaks members.</p> <p>The sequence stratigraphy of tide-dominated setting has yet not been fully explored. The stratal architecture of the Lake O'Hara and Lake Oesa members reveals a new mechanism for the formation of the regressive surface of marine erosion landward of the lever point of balance between sedimentation and erosion in the subtidal environment. As the shoreline is forced to regress with falling sea level, the laterally continuous tidal flats advance and the preexisting shallow-subtidal compound dunes are scoured by strong tidal currents that carve gradually a new equilibrium profile. We argue that the accretion of intertidal flats on top of subtidal sands is an overlooked yet predictable component of falling-stage systems tracts in tide-dominated settings.</p> <p>The Gog Group also offers an opportunity to explore animal-sediment relationships in a high-energy setting, during the early phase of Phanerozoic diversification. The presence of constrasting ichnofabrics within a single Early Cambrian sand-sheet complex illuminates how the colonisation trends of suspension and detritus feeders were controlled by factors specific to the various subenvironments.<p> <p>The variety of sandbody types in the Gog Group reflects varying sediment supply and location on the inner continental shelf. Five types of compound cross-stratified sandstone are distinguished based on foreset geometry, sedimentary structures and internal heterogeneity. These represent five broad categories of subtidal sandbodies: (1) compound-dune fields; (2) sand sheets; (3) sand ridges; and (4) patchy dunes. Trace-fossil distribution in these tide-dominated sand bodies and adjacent sediments is mostly controlled by an interplay of substrate mobility, grain size, turbidity, water-column productivity, and sediment organic matter. Salinity is a critical factor in marginal-marine locations but played no role in this region of the shelf.</p>

Actualistic, sedimentological, and experimental approaches to the study of vertebrate trace taphonomy in the Kenya Rift Valley have permitted the characterization and even quantification of factors that influence trace morphology and preservation potential in semi-arid lake margins. Several important taphonomic factors were identified from the modern lake-marginal sediments of saline, alkaline Lake Bogoria and freshwater Lake Baringo in the Baringo-Bogoria basin (1º N and 36º E). The investigation of these factors, considering vertebrate ecology and sedimentology of the deposits, together with the study of early and later diagenetic processes that cement substrates, provided a framework for the paleoecological interpretation of three Pleistocene fossil footprint localities, also in the Baringo-Bogoria basin. The most important taphonomic factors appear to be related to the semi-arid climate (e.g., high evaporation:precipitation ratio), frequent lake level changes, the closed nature of the lake basins, bedrock geology (mainly volcaniclastic) within the catchment, and the chemical composition of lake and pore waters. Notable factors that cause the alteration, destruction, and stabilization of traces include efflorescent salt crystallization, which may temporarily cement substrates or destroy traces during crystal growth in the capillary fringe; substrate wetting and drying, which can induce soil-crusting and the shrinking and swelling of smectitic clays; and the presence of benthic microbial mats and biofilms, which may temporarily stabilize substrates or contribute to their early cementation by mediating carbonate precipitation. Experiments to quantitatively and statistically test the effects of salt efflorescence, the rate and temperature of substrate drying (e.g., sun-baking), and swelling and non-swelling clays supported field observations. Preservational processes interpreted from Pleistocene footprint-bearing sediments include the early cementation of substrates by carbonates (e.g., calcite), and during prolonged, stable dry phases, the precipitation of zeolitic cements and Mn- and Fe-oxide minerals. ****PLEASE NOTE: This thesis is formatted to be printed double-sided.

<p>The architecture, distribution and facies of sandstone bodies in the Gog Group of the southern Rocky Mountains of western Canada record the dynamics of sand movement on the broad continental shelf of West Laurentia during the Early Cambrian phase of worldwide transgression. This study focuses on the stratigraphy, sedimentology and ichnology in the Bow Valley region, specifically the sector from Mount Assiniboine northwest to the North Saskatchewan River. The objectives of this project were several-fold: (1) revise the existing stratigraphic nomenclature; (2) document the sedimentary facies; (3) identify facies assemblages and interpret them in terms of sedimentary processes and environments; (4) characterize sandstone body geometries; (5) develop a sequence-stratigraphic framework; (6) document trace-fossil occurrences; and (7) characterize different trace-fossil assemblages in terms of colonization trends and prevailing paleoenvironmental conditions.</p> <p>The Gog Group in this area has historically comprised four units, the Fort Mountain, Lake Louise, St. Piran and Peyto formations. North of Bow Pass an additional unit, the Jasper Formation, occurs below the Fort Mountain Formation and is related to accommodation created by active rift-faulting during the latest Neoproterozoic. In the Lake Louise and Lake O'Hara area, four new formal subdivisions within the St. Piran Formation are proposed: Lake O'Hara, Lake Oesa, Lake Moraine and Wiwaxy Peaks members.</p> <p>The sequence stratigraphy of tide-dominated setting has yet not been fully explored. The stratal architecture of the Lake O'Hara and Lake Oesa members reveals a new mechanism for the formation of the regressive surface of marine erosion landward of the lever point of balance between sedimentation and erosion in the subtidal environment. As the shoreline is forced to regress with falling sea level, the laterally continuous tidal flats advance and the preexisting shallow-subtidal compound dunes are scoured by strong tidal currents that carve gradually a new equilibrium profile. We argue that the accretion of intertidal flats on top of subtidal sands is an overlooked yet predictable component of falling-stage systems tracts in tide-dominated settings.</p> <p>The Gog Group also offers an opportunity to explore animal-sediment relationships in a high-energy setting, during the early phase of Phanerozoic diversification. The presence of constrasting ichnofabrics within a single Early Cambrian sand-sheet complex illuminates how the colonisation trends of suspension and detritus feeders were controlled by factors specific to the various subenvironments.<p> <p>The variety of sandbody types in the Gog Group reflects varying sediment supply and location on the inner continental shelf. Five types of compound cross-stratified sandstone are distinguished based on foreset geometry, sedimentary structures and internal heterogeneity. These represent five broad categories of subtidal sandbodies: (1) compound-dune fields; (2) sand sheets; (3) sand ridges; and (4) patchy dunes. Trace-fossil distribution in these tide-dominated sand bodies and adjacent sediments is mostly controlled by an interplay of substrate mobility, grain size, turbidity, water-column productivity, and sediment organic matter. Salinity is a critical factor in marginal-marine locations but played no role in this region of the shelf.</p>