Thesis (Ph.D.)--McMaster University (Canada), 1987. / Source: Dissertation Abstracts International, Volume: 49-02, Section: B, page: 0341.

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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.

The Gharian area is used as a case study to examine the sedimentary succession, structural evolution and timing of sedimentary and structural events during basin development in the Early Mesozoic. These sediments (Kurrush, Al Aziza and Abu Shaybah Formations) are examined in order to provide palaeonvironmental and palaeogeographic reconstructions for the study area. The formations are described using facies analysis. The Kurrush is probably deposited in delta plain environment. A complete section (140 m) has been logged and seven facies from the Al Aziza Formation represent a shallow shelf platform area (inner ramp: an intertidal-subtidal carbonate flat to shelf lagoonal environment), which was deposited during the opening of the Early Triassic Neo-Tethys Ocean. Eleven localities from the Abu Shaybah Formation have been investigated with a cumulative thickness of 125 m. Ten facies from the Abu Shaybah Formation represent deposition in a shallow marine environment as part of low gradient continental margin, succeeded by sand deposition in braided and meandering fluvial systems. Regional tectonic activity, regional relative sea-level fluctuations and climatic conditions led to control of the sedimentary megasequences (266 m coarsening upward and fining upward megasequence). A magnetostratigraphic analysis was undertaken in the above units as their depositional age is poorly constrained and currently based on limited fossil evidence. Most of these samples convey a weak but stable remanent magnetization. The Al Aziza Formation yielded a primary remanence that has suffered a substantial post-acquisition clockwise rotation (~50˚). Restoration of the rotation about a simple vertical axis would place the pole on the APW path at an appropriate point in time. The palaeomagnetic data from the studied formations yield a distinct series of polarity zones that provide clear local and regional correlation and are readily tied to a recently compiled global magnetostratigraphic time scale. The Al Aziza Formation at Gharian is latest Ladinian in age, whilst the Abu Shaybah Formation is earliest Carnian in age. The Abu Shaybah Formation at Gharian suggests that the stratigraphic equivalence with the Aziza Formation at Azizyah and Kaf Bates (Jafarah Plain). The study established that the Gharian area is the expression of major normal faults (NNE-SSW, WNW to ESE, NW to NNW and NE-SE) in a system of half-grabens which formed as part of the African extensional margin on the southern Tethyan margin in Latest Early Cretaceous.

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The Dinantian West Lothian Oil-Shale Formation of the Midland Valley, Scotland, is a laterally variable lacustrine sequence, deposited in an overall humid climatic period. The sequence comprises non-marine limestones, dolostones, oil-shales, mudrocks and deltaic sandstones. Thin marine bands and the thick freshwater Burdiehouse Limestone are the most reliable stratigraphic markers. Eight individual outcrops of microbial carbonatesa, ll stratigraphically close to the Burdiehouse Limestone, are correlatable, and therefore important in helping to clarify the Asbian stratigraphy of the eastern Midland Valley of Scotland. The microbial carbonates were deposited in varied shallow lake settings. Lake waters had a long residence time, suggested by fairly positive stable carbon and oxygen isotope ratios. Petrography and geochemistry suggest the primary carbonate was high-Mg calcite. Isotopic variations are mainly controlled by depositional water depth, diagenetic fluid temperaturesl,o calised magmatica ctivity and in-situ organicm atterd ecay. A regional dolornitisation event affected the lithologies, with high Fe" and Mg2+ concentrations suggesting early diagenetic dolomitisation under phreatic conditions. High Sr dolomite suggestst hat the lake and / or regional groundwaters were Sr enriched. Both the Sr ions and the Mg ions for dolomitisation were probably derived from chemically-enriched, seaward flowing groundwaters, that originated on a westerly situated volcanic plateau. The microbial carbonates represent regional and localised regressive sequences, lake, and in volcanically-isolated depositional sub-basins. The carbonates probably correspond to a regionally-significant period of aridity within the Asbian of south-east Scotland, similar to fluctuating seasonal semi-arid and humid conditions identified in the Dinantian of England and Wales.

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Made available in DSpace on 2015-03-05T12:15:33Z (GMT). No. of bitstreams: 0 Previous issue date: 15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A análise integrada entre a sedimentologia e a paleoicnologia da Formação Rio Bonito e da base da Formação Palermo (bacia do Paraná) na região de Cachoeira do Sul (RS) vem demonstrando a presença de depósitos flúvio-estuarinos dominados por marés na porção inferior da Formação Rio Bonito, passando a estuarinos dominados por ondas no topo e rapidamente dando lugar a depósitos marinhos rasos (base da Formação Palermo). Visando validar e, se possível, refinar essas interpretações, foi realizada uma análise paleopalinológica de alta resolução dos depósitos bioturbados. Para tanto, foram selecionadas 26 amostras nos testemunhos de sondagem IC-07-RS, IC-44-RS, IC-03-RS e IC-12-RS, pertencentes ao bloco central da jazida carbonífera de Iruí (Cachoeira do Sul, RS), quando da análise paleoicnológica. Das amostras inicialmente coletadas, foram utilizadas para a análise paleopalinológica apenas as de natureza pelítica, de forma a homogeneizar possíveis disparidades na assembléia orgânica decorrentes de granulometri / The integrated analysis of sedimentology and paleoichnology of the Rio Bonito Formation and the lower part of Palermo Formation (Paraná Basin) in Cachoeira do Sul region (Rio Grande do Sul State, south Brazil) revealed that the Rio Bonito Formation are characterized at the base by tide-dominated fluvio-estuarine deposits, changing upward to wave-dominated estuarine deposits, which are overlapped by the shallow marine deposits of the Palermo Formation. With the aim of refine such interpretations, a high-resolution paleopalynologic analysis of the bioturbed deposits is conducted in this study. Thus, 26 samples were selected from the cores IC-07-RS, IC-44-RS, IC-03-RS and IC-12-RS, from the central area of the Iruí Quarry (Cachoeira do Sul). Only mudstones and siltstones samples were used for the paleopalynologic analysis, in order to homogenize possible disparities in the organic assemblage due to the grain-size. Paleopalynomorph and palynofacies samples were prepared following the traditional methods for Pa