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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Stratigraphy and Palaeoenvironment of the Paleocene/Eocene boundary interval in the Indus Basin, Pakistan

Hanif, Muhammad January 2011 (has links)
Marine sedimentary sections across the Paleocene/Eocene (P/E) boundary interval are preserved in the Patala Formation (Upper Indus Basin) and Dungan Formation (Lower Indus Basin), Pakistan. The P/E interval of the Patala Formation is composed of limestone and shale inter-beds indicating deposition on a carbonate platform. The analysis of larger foraminifera across the P/E interval from the Patala Formation (Kala Chitta Ranges), allows the recognition of the Larger Foraminiferal Turnover (LFT). The Larger Foraminiferal Turnover (LFT) observed in the Patala Formation is associated with the PETM (Paleocene Eocene Thermal Maximum) global climatic event and allows the recognition of the P/E boundary in shallow water carbonates of the Indus Basin. This turnover is already reported from other Tethyan sections and from the Salt Range (Upper Indus Basin), Pakistan. The recognition of the LFT allows the inter-basinal and intra-basinal correlation of the P/E interval of the shallow carbonates of the Indus Basin, Pakistan. The available literature on the Paleocene-Eocene Patala and Dungan formations is used to review the planktonic foraminiferal biostratigraphy of the P/E interval. The planktonic foraminiferal zones in the P/E interval of the Indus Basin are identified and reviewed in the light of new international zonations. The planktonic foraminiferal content of the Dungan Formation allows its correlation with the Laki Formation of Rajesthan (India). Four dinoflagellate zones in the P/E interval of the Rakhi Nala section (Lower Indus Basin) are identified and correlated with international and regional zonations. The quantitative analysis of the dinoflagellate cyst assemblages together with geochemical data (i.e., carbon isotopes (organic only), C/N ratio, TOC, carbonate content) is used to reconstruct the palaeoenivronment across the P/E interval. The dinocyst assemblages in general, and the abundance of Apectodinium spp. in particular, indicate the warmer surface water conditions of the global PETM event. The dinocyst assemblages allow the local correlation of the Dungan Formation (part) of the Sulaiman Range with the Patala Formation (part) of the Upper Indus Basin and global correlation of the Zone Pak-DV with the Apectodinium acme Zone of the Northern and Southern hemispheres. The carbon isotopic excursion (CIE) associated with PETM is now globally used to identify the P/E boundary. The CIE in total organic carbon (i.e., δ13CTOC = -28.9‰) and total fine fraction organics (i.e., δ13CFF= 26.4‰) from the Indus Basin is reported for the first time. This CIE record from the Indus Basin is compared with other Tethyan sections from Egypt and Uzbekistan and is also compared with the global sections from USA (Northern hemisphere) and from New Zealand (Southern hemisphere).
182

The Poles of Mars, Past and Present: A High-Resolution Observational Study of the Martian Polar Regions and their Connection to Climate

Becerra, Patricio, Becerra, Patricio January 2016 (has links)
The poles of Mars, much like Earth's polar regions, are covered by kilometer-thick sheets of ice that interact with the Martian atmosphere and can record climatic changes in their stratigraphy. These polar caps are composed of several icy sections that interact with the Martian environment over different timescales. This dissertation describes my investigation of two of these units: The South Polar Residual Cap (SPRC), and the North Polar Layered Deposits (NPLD). The overarching theme of my work is to explore the connections between these caps and the current (SPRC) and past (NPLD) climate of Mars using a wide variety of data from spacecraft missions, and applying numerical models of surface properties and processes to interpret the observations. The SPRC is a ~10 meter thick slab of bright carbon dioxide ice that is covered by pits and scarps formed by differential sublimation. It is unclear whether this cap is in a state of net accumulation or net ablation. During the summer of Mars Year 28 (2006/2007), The High Resolution Imaging Science Experiment (HiRISE) observed an apparent increase in brightness near the edges of these pits that had not been seen before, and was not seen in the few years following. I analyzed hundreds of images from HiRISE and the Mars Orbiter Camera (MOC), as well as data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) to search for compositional and/or grain-size changes in the ice that could explain these "halos". I coupled my observations with numerical modeling of the spectral reflectance of the ice, to explore the effects of different ice grain sizes and minuscule dust inclusions on the observed brightness. I concluded that the features were caused by the occurrence of a global dust storm, after which the depositing dust actually acted to darken the SPRC. The halos were thus areas that had been kept relatively "clean" of the depositing dust, thanks to winds driven by enhanced sublimation from the pit walls. The fact that the halos did not show up in subsequent years means that they had not been exhumed, and that flat areas of the SPRC are in a state of net accumulation. It is likely that events like these result in new flat surfaces formed by snowfall driven by the depositing dust, which could explain the persistence of the cap throughout history. The polar layered deposits (PLD) are kilometer-thick stratified dome structures composed of dusty water ice that make up the bulk of the polar caps. The layers that make up the PLD are thought to record climatic variations over timescales of millions of years, in a similar way to Earth's ice caps. These caps are dissected by deep troughs that allow us to observe outcrops of their internal layers and map the stratigraphy. In the past, researchers have done this using layer brightness. However, remotely observed brightness has been shown to be affected by many external factors and may not represent an intrinsic property of the layers. Using Digital Terrain Models (DTM) made from HiRISE stereo images of NPLD outcrops, I mapped the change with depth of each layer's topographic protrusion from the scarp slope, defining the stratigraphy with a property related to the layers' resistance to erosion. I mapped the protrusion stratigraphy of 16 sites throughout the NPLD, and correlated the stratigraphic profiles from a subset of these sites, with Context Camera (CTX) images and signal-matching algorithms. This correlation combined topographic information with brightness information, resulting in an improvement of the current state of stratigraphic mapping of the NPLD, providing further evidence that layer sequences are continuous across the NPLD, and setting lower limits on relative accumulation rates for large sections of the cap.In order to search for a connection between the Martian paleoclimate and the NPLD stratigraphic record, I identified overlapping periodicities in the stratigraphic structure and compared them to periodicities in the climatic history, represented by the change in insolation with time at the North Pole over the last 5 Myr. I found that the ratio of stratigraphic wavelengths is systematically lower than the ratio between dominant modes of oscillation of the north polar insolation. However, a similar wavelet analysis of synthetic stratigraphic profiles created with a simple climate-driven model of accumulation revealed that a detectable non-linear relationship exists between the variation of insolation on the North Polar region of Mars and the stratigraphic record preserved in the NPLD. The dissertation is organized into four principal chapters and one final chapter with concluding remarks and future directions. Chapter 1 gives an introduction to Mars' polar regions and to the history of research in astronomically forced climate change through cyclostratigraphy, along with a short summary of the scope and main questions of this study. Chapter 2 details my study of the SPRC halos. Chapter 3 deals with the stratigraphic mapping of the NPLD through high-resolution topography, and Chapter 4 presents the results of my search for an astronomical forcing signal in the NPLD stratigraphy. Chapter 2 was published in the journal Icarus, in a special issue on the dynamic geologic processes of Mars and the science learned from continuous monitoring of these processes through remote sensing. Chapter 3 has been accepted for publication in the Journal of Geophysical Research. A modified version of Chapter 4 will be submitted to Nature Geoscience.
183

Applying modern interpretation techniques to old hydrocarbon fields to find new reserves: A case study in the onshore Gulf of Mexico, U.S.A.

Hulsey, Josiah D 13 May 2016 (has links)
This study shows how the use of modern geological investigative techniques can reopen old, “drained” hydrocarbon fields. Specifically, it looks at the White Castle Field in South Louisiana. This field has pay sections ranging from late Oligocene to late Miocene. The late Oligocene package is underexplored and understudied and contains 3 primary reservoirs (Cib Haz (CH), MW, and MR). This study established the depositional history of these reservoirs. During most of the late Oligocene, the White Castle Salt Dome was located in a minibasin on the continental slope. The CH and MW deposited in this minibasin. The CH is an amalgamation of slumped shelfal limestones, sandstones, and shales deposited during a lowstand systems tract (LST). The MW comprises a shelf-edge delta that is part of a LST. The MR is an incised valley fill located in the continental shelf that was deposited during LST after the minibasin was filled.
184

Sedimentation, Climate Change and Tectonics: Dynamic Stratigraphy of the Pliocene-Pleistocene Fish Creek-Vallecito Basin, California

Peryam, Thomas, Peryam, Thomas January 2012 (has links)
In order to better understand the interactions between climate change, landscape erosion and sedimentation, a detailed study was conducted on Plio-Pleistocene non-marine deposits of the Palm Spring Group in the Fish Creek-Vallecito basin, California, USA. Three inter-related studies focused on (1) local response to global climate change in late Pliocene-early Pleistocene time, (2) large-scale evolution of lithofacies architecture, and (3) climate modulation of late Pliocene sediment flux on Milankovitch time scales. Stable isotopes and paleosol classification reveal that between ~4.0 and 0.75 Ma, aridity increased in the study area concurrent with a shift towards a less intense and more winter-dominated precipitation regime. These changes are interpreted to reflect the long-term waning of summer monsoon precipitation in southern California. A dramatic and enigmatic reorganization of basin strata occurred at 2.9 Ma. Detailed basin analysis shows that locally-derived sediment was supplied by the predecessors of two modern drainages, Vallecito and Carrizo creeks. Initial progradation of alluvial deposits from these two sources across the Colorado River delta plain began between 4.0-3.4 Ma. At 2.9 Ma, rapid progradation of these two deposystems was coeval with emplacement of a megabreccia and transgression of Borrego Lake. My data indicate that tectonic realignments at both local and regional scales drove this reorganization. Time series analysis of rock magnetic data from a densely-sampled stratigraphic section of the lacustrine Tapiado Formation reveals that between 2.9 and ~2.75 Ma landscape denudation in the Carrizo Creek catchment was partly modulated by orbital obliquity. Peaks in landscape denudation implied by my data correspond to obliquity highs. More frequent high intensity precipitation events (i.e. monsoons and tropical storms) probably drove increased erosion during these time periods relative to obliquity lows. The breakdown of this relationship at around 2.75 Ma corresponds to a dramatic increase in northern hemisphere glaciation and may reveal a reduction in monsoonal influence in southern California. A geologic map of the Fish Creek-Vallecito basin is included as a supplemental file to this dissertation. This dissertation contains previously published and unpublished coauthored material.
185

VARIACOES TEMPORAIS NA SIDIMENTACAO QUARTENARIA DOS EMBAIAMENTOS DA REGIAO DE UBATUBA, ESTADO DE SAO PAU-LO. / Variations in the quatolnary sedimentation of the coastal embayments of the Ubatuba Region, state of São Paulo

Mahiques, Michel Michaelovitch de 26 May 1992 (has links)
O objetivo do presente trabalho consiste no estudo das características dos sedimentos de superfície de fundo da Baía da Ilha Grande, estado do Rio de Janeiro, e sua correlação com os processos hidrodinâmicos atuais,bem como com a evolução sedimentar do litoral paulista e sul-fluminense a partir do máximo regressivo do Pleistoceno Superior. A baía da Ilha Grande consiste num corpo de água definido pela presença da Ilha Grande. Pode ser dividida em três unidades fisiográficas distintas, a saber: Porção Oeste, Porção Leste e Canal Central. Para o presente estudo, foi coletado um total de 153 amostras de superfície de fundo e realizado um conjunto de análises sedimentológicas constituído por: análise granulométrica, análise morfométrica e de textura superficial, análise de conteúdo em carbonato biodetrítico, analise de conteúdo em matéria orgânica, análise dos constituintes na fração grosseira e analise de assembléias de minerais pesados. Os estudos realizados permitiram identificar quatro fácies sedimentares distintas, caracterizadas como: sedimentos relíquias da Porção Leste, sedimentos atuais do Canal Central e das áreas abrigadas, sedimentos transgressivos da Porção Oeste e sedimentos mistos resultantes da mistura de termos das fácies anteriores.Finalmente, é feita uma proposta de evolução sedimentar da área a partir do máximo regressivo de 18.000 anos A.P. estabelecidas considerações sobre a dinâmica de fundo da baía. / The objective of the present work is to study the characteristics of the surface bottom sediments of Ilha Grande Bay, Rio de Janeiro state, and their correlation with the modern hydrodynamic processes, as well as with the sedimentary evolution of the southeastern brazilian coastal region, since the maximum regression of the Upper Pleistocene. Ilha Grande Bay consista a water body defined by the presence of Ilha Grande island. It can be divided into three distinct fisiographic units: the Western Portion, the Eastern Portion, and the Central Channel. In this work, a total of 153 surface bottom samples were collected, and the sediments were anal zed for: grain size, morphometry and surface texture, carbonate content, organic matter content, coarse fraction constituents, and heavy mineral assemblages. The studies allowed to identify four distinct sedimentary facies, characterized as: relict sediments of the Eastern Portion, modern sediments of the Central Channel and the confined areas, transgressive sediments of the Western Portion, and mixed sediments, resulting from the mixture of the previous facles. Finally, we propose amodel for the sedimentary evolution of the area since the maximum regressive of 18,000 years B.P. and considerate on the bottom dynamic of the bay.
186

Sequence stratigraphy of the arcadia formation, Southeast Florida: an integrated approach

Unknown Date (has links)
The Arcadia Formation is a mixed carbonate-siliciclastic rock unit that existed as a shallow carbonate ramp to platform environment during the Late Oligocene to Early Miocene Epoch. It can be divided into two distinct, informal sections based on lithological properties: the upper Arcadia Formation and lower Arcadia Formation. The sections are part of a major, third-order sequence that can be further divided into four higher-frequency, lower magnitude sequences: ARS1, ARS2, ARS3, and ARS4. The sequence boundary separating ARS2 and ARS3 represents a drastic change in the depositional regime from a high-energy, inner ramp/platform to a lower-energy, deep outer ramp environment. ARS3 represents the period of maximum flooding and constitutes a major portion of the regressive system tract (RST) of the third order depositional sequence. In certain sections, the Arcadia Formation is heavily bioturbated including ichnotaxa from the glossifungites, cruziana, and scolithos inchofacies. Thalassinoides sp. burrows of the glossifungites ichnofacies were found to be commonly associated with firmground substrates and breaks in sedimentation. The lithofacies associations were grouped into paleodepositional environments that ranged from restricted marine to deep outer ramp with lithology ranging from grainstone to wackestone to mudstone with variable amounts of siliciclastic and phosphatic constituents. Each sequence boundary extends regionally south from Broward County to southern Miami-Dade County utilizing gamma-ray geophysical signatures unique to each sequence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
187

VARIACOES TEMPORAIS NA SIDIMENTACAO QUARTENARIA DOS EMBAIAMENTOS DA REGIAO DE UBATUBA, ESTADO DE SAO PAU-LO. / Variations in the quatolnary sedimentation of the coastal embayments of the Ubatuba Region, state of São Paulo

Michel Michaelovitch de Mahiques 26 May 1992 (has links)
O objetivo do presente trabalho consiste no estudo das características dos sedimentos de superfície de fundo da Baía da Ilha Grande, estado do Rio de Janeiro, e sua correlação com os processos hidrodinâmicos atuais,bem como com a evolução sedimentar do litoral paulista e sul-fluminense a partir do máximo regressivo do Pleistoceno Superior. A baía da Ilha Grande consiste num corpo de água definido pela presença da Ilha Grande. Pode ser dividida em três unidades fisiográficas distintas, a saber: Porção Oeste, Porção Leste e Canal Central. Para o presente estudo, foi coletado um total de 153 amostras de superfície de fundo e realizado um conjunto de análises sedimentológicas constituído por: análise granulométrica, análise morfométrica e de textura superficial, análise de conteúdo em carbonato biodetrítico, analise de conteúdo em matéria orgânica, análise dos constituintes na fração grosseira e analise de assembléias de minerais pesados. Os estudos realizados permitiram identificar quatro fácies sedimentares distintas, caracterizadas como: sedimentos relíquias da Porção Leste, sedimentos atuais do Canal Central e das áreas abrigadas, sedimentos transgressivos da Porção Oeste e sedimentos mistos resultantes da mistura de termos das fácies anteriores.Finalmente, é feita uma proposta de evolução sedimentar da área a partir do máximo regressivo de 18.000 anos A.P. estabelecidas considerações sobre a dinâmica de fundo da baía. / The objective of the present work is to study the characteristics of the surface bottom sediments of Ilha Grande Bay, Rio de Janeiro state, and their correlation with the modern hydrodynamic processes, as well as with the sedimentary evolution of the southeastern brazilian coastal region, since the maximum regression of the Upper Pleistocene. Ilha Grande Bay consista a water body defined by the presence of Ilha Grande island. It can be divided into three distinct fisiographic units: the Western Portion, the Eastern Portion, and the Central Channel. In this work, a total of 153 surface bottom samples were collected, and the sediments were anal zed for: grain size, morphometry and surface texture, carbonate content, organic matter content, coarse fraction constituents, and heavy mineral assemblages. The studies allowed to identify four distinct sedimentary facies, characterized as: relict sediments of the Eastern Portion, modern sediments of the Central Channel and the confined areas, transgressive sediments of the Western Portion, and mixed sediments, resulting from the mixture of the previous facles. Finally, we propose amodel for the sedimentary evolution of the area since the maximum regressive of 18,000 years B.P. and considerate on the bottom dynamic of the bay.
188

Facies Analysis, Sedimentary Petrology, and Reservoir Characterization of the Lower Triassic Sinbad Limestone Member of the Moenkopi Formation, Central Utah: A Synthesis of Surface and Subsurface Data

Powell, Kristopher Michael 01 February 2017 (has links)
Lower Triassic strata in the Wellington Flat and Tully cores reflect a lateral transition from shallow water strata (Wellington Flats core) to strata that indicate deposition on a relatively more distal, storm-dominated ramp (Tully core). The Sinbad Member, along with the upper part of the underlying Black Dragon Member and the lower part of the overlying Torrey Member (Moenkopi Formation), are composed of ten carbonate, siliciclastic and mixed carbonate/siliciclastic facies deposited on a west-facing ramp/shelf that reached maximum flooding during Smithian time. Individual beds and facies display a large degree of lateral homogeneity and regional persistence in the study area. The Wellington Flats core contains the three units characteristic of outcropping Sinbad Limestone: a basal skeletal unit, a middle peloidal unit, and an upper, oolitic dolomite unit. The more offshore Tully core is composed of skeletal grainstone, with fewer shallow-water carbonate and siliciclastic deposits. Discontinuity surfaces (hardgrounds, firmgrounds, and change surfaces) are common and indicate that sedimentation was punctuated by short-lived hiatuses accompanied by cementation, scour, and/or encrustation of the sediment-water interface. The Black Dragon, Sinbad, and lower Torrey Members represent at least one 3rd-order depositional sequence bounded below by the Tr-1 unconformity and above by lowstand deposits in the middle Torrey Member. Amalgamated fluvial channels in the middle of the Black Dragon Member may represent an additional 3rd-order sequence boundary that separates a Greisbachian sequence (lower Black Dragon Member) from the Smithian sequence (upper Black Dragon through lower Torrey members), but this is unsubstantiated by biostratigraphic data at present. Diagenesis is strongly controlled by facies. Diagenetic elements include marine fibrous calcite cements, micritized grains, compaction, dissolution and neomorphism of aragonite grains, meteoric cements, pressure dissolution, and dolomitization. The paragenetic sequence progresses from marine to meteoric to burial. Marine and meteoric cements occlude much of the depositional porosity, which ranges from 0 to 10 % in the sample interval. The best reservoir qualities in core (1.0 md) occur in grainstones and quartz-siltstones. Although its relative thinness precludes it from being a major producer, the Sinbad Limestone Member of the Moenkopi Formation bears potential for modest future oil production.
189

Structural Geology of the Central Part of Clarkston Mountain, Malad Range, Utah

Green, Douglas A 01 May 1986 (has links)
The central part of Clarkston Mountain is located in northcentral Utah in the southern part of the Malad Range. It is northwest of Clarkston, Utah. The mapped area measures 2.5 mi. in the north-south direction and 6.5 mi. in the east-west direction. It is within the Basin and Range Province. The Ute Formation of Middle Cambrian age is the oldest exposed stratigraphic unit. Other Cambrian units, in ascending order, are: Blacksmith Formation, Bloomington Formation, Nounan Formation, and St. Charles Formation. These units consist predominantly of limestone, dolostone, and shale. Units of Ordovician age include the Garden City Formation and the Swan Peak Formation. They consist of limestone and orthoquartzite, respectively. The youngest Paleozoic unit is the Fish Haven-Laketown Formation of Ordovician-Silurian age. It is dolostone. Units of Quaternary age include colluvial deposits, Lake Bonneville Group, and alluvial deposits. West-dipping, low-angle normal faults generally trend north and northwest. They were originally thrust faults formed during regional compression. A bedding-plane thrust fault separates the Bloomington and Nounan Formations. Later reversed movement on the west-dipping, low-angle thrust faults changed the stratigraphic relationships across these faults to those characteristic of normal faults. High-angle normal faults trend northwest, north, and northeast. Major normal faults extend along the western and eastern sides of Clarkston Mountain and are responsible for the present topographic relief. The structural features of the mapped area are the result of two major tectonic events. The Sevier orogeny produced eastward directed thrust faults. It began in Late Jurassic and ended in early Eocene. Basin and Range normal faulting caused reversed movement on west-dipping thrust faults, formed by the Sevier orogeny, and also produced many high-angle normal faults. It began in early Eocene and has continued into historic time in the region.
190

Geology of the Deseret Peak East 7.5' Quadrangle, Tooele County, Utah, and Impacts for Hydrology of the Region

Copfer, Torrey J. 01 May 2003 (has links)
Detailed geologic mapping of the Deseret Peak East 7.5' Quadrangle yields new interpretations regarding the stratigraphy of the Oquirrh Basin, fault and fold geometry, and structural evolution of the region. The Stansbury Range consists of the north-southtrending Deseret anticline. Basal Mississippian units rest unconformably on Cambrian beds in the central part of the range. Paleozoic uplift, Mesozoic contraction, and Cenozoic extension have created a series of broad folds, large thrust faults, and several normal faults. The area is dominated by bedrock springs, with the presence of abundant and thick Quaternary deposits unrelated to Pleistocene glaciation, burying drainages, and mantling hillslopes. The influence of bedrock on groundwater flow paths and stream baseflow is suggested by local anecdotal reports that high snowfall in the Deseret Peak region generates high discharge ten miles south in Clover Creek, though they are not in the same drainage basin.

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