Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"Shelf sediments"”.
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Microbial ecology of anaerobic carbon mineralization in Namibian shelf sediments
… and into the water column on the Namibian shelf, which is one of the most productive upwelling systems on Earth. Organic matter degradation in the sediment drives hydrogen sulfide production, the maintenance of anoxia, and methane formation. Therefore, the primary aims of the thesis are to …
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Organic Carbon Cycling in East China Sea Shelf Sediments: Linkages with Hypoxia
… and plant pigment, black carbon (BC) on ECS sediments sampled in winter 2009 and 2010 in order to study the OC cycling under the influence of natural and anthropogenic disturbance. Low-oxygen tolerant foraminiferal microfossils were analyzed in another two sediment cores to study the …
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The geochemistry and sedimentology of quaternary shelf sediments of the Tugela River, Natal, South Africa
… sediment samples recovered from the continental shelf off the Tugela River Mouth, Natal, South Africa, and nine samples taken from the Lower Tugela River. The purpose of the research was to examine the geochemical nature of the sediments in relation to their particle size distributions and the …
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High-Resolution Sequence Stratigraphy of Paleogene, Nontropical Mixed Carbonate/Siliciclastic Shelf Sediments, North Carolina Coastal Plain, U. S. A.
… and shell beds (estuarine/lagoon/protected inner shelf facies); clean quartz sands and sandy mollusk-fragment grainstones (shoreface/shallow shelf); phosphatic hardgrounds (current and wave-swept shoreface and shallow shelf); bryozoan and echinoderm grainstones/packstones (storm reworked middle …
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Sedimentological and geochemical evidence for late quaternary environmental changes in southern Africa : a case study of the mudbelt deposits off Namaqualand
… and geochemical studies of seven 7m core sediments retrieved from the Namaqualand Mudbelt, South Africa. The purpose of this research is to contribute to the evidence for environmental change during the late Quaternary in the southern Africa from the analyses of continental shelf sediments …
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Iron inputs from sediments to the oceans
… the nature and ubiquity of iron (Fe) inputs from sediments to the<br/>oceans. In the last 10 years continental shelf sediments have become widely recognised<br/>as important vectors for dissolved Fe inputs to the oceans, where bacterial dissimilatory<br/>Fe-reduction (DIR) promotes the flux of Fe …
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Thrust sheet evolution in the Kinlochewe region of the Moine Thrust Zone, N.W. Scotland and the Pelvoux-Brianconnais, French Alps
… from basement (Lewisian gneiss) to Cambrian shelf sediments parallel to the ESE-WNW movement direction. Cut-off relationships and fold geometries within the Pelvoux-Brianconnais suggest a change in move-ment direction of thrust sheets during the evolution of the French Alps from ENE-WSW for …
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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
… the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance exists between ²³⁰Th production and burial in the Central Arctic basins, based …
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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
… the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance exists between 230Th production and burial in the Central Arctic basins, based …
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Cretaceous Nerineacean gastropods
… Mesozoic Tethyan macrofaunas. They occur in shelf sediments deposited in tropical regions during the Jurassic and Cretaceous. The group first appears in the early Jurassic and high diversity levels had developed by late Jurassic and early Cretaceous times. A major extinction episode occurred …
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The marine biogeochemistry of chromium isotopes
… oxic bottom waters of the shallow Arctic Chukchi shelf, while Cr concentrations decreased. This extreme isotope signal may result from Cr reduction by a reduced species (e.g. Fe(II)), which was released from the underlying anoxic shelf sediments. Cr in the Atlantic layer and in the bottom water of …
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Trace Metal Biogeochemistry in the Western North Pacific
… material beyond the immediate continental shelf. Elevated particulate Mn and Fe concentrations originating from the Kuril-Kamchatka margin are found in the central North Pacific as well as across the Kuroshio-Oyashio front.</p> <p>Dissolved trace metal concentrations in the surface waters …
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Sedimentology and micropalaeontology of gravity cores from the N.E. Atlantic continental slope south west of Ireland
… evolution of the adjacent European shelf. Sediments deposited during Late Pleistocene glacial conditions show the following characteristics when compared to the surface sediments deposited under Holocene interglacial conditions: an increase in the quantity of ice-rafted debris and …
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The marine biogeochemistry of chromium isotopes
… oxic bottom waters of the shallow Arctic Chukchi shelf, while Cr concentrations decreased. This extreme isotope signal may result from Cr reduction by a reduced species (e.g. Fe(II)), which was released from the underlying anoxic shelf sediments. Cr in the Atlantic layer and in the bottom water of …
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Nearshore and inner shelf sedimentation on the east Coromandel coast, New Zealand
… for possible use of the adjacent continental shelf as a repository for dredge and mining tailings, and extraction of commercial aggregate and mineral deposits. This has raised the question of dynamic links between the continental shelf and local beach systems I and resulting impacts on the …
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FORAMINIFERAL COMMUNITY DYNAMICS OF THE CHESAPEAKE GROUP, CALVERT CLIFFS, MARYLAND, USA
… response of benthic foraminiferal communities in shelf sediments of the Calvert and Choptank formations from the Calvert Cliffs, Maryland.to the MMCO, the MMCT, and sea-level cycles. To accomplish these objectives, 21 laterally equivalent samples in each of three vertical, composite transects were …
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Neogene to quaternary foraminifera from the western margin of southern Africa
… during the Neogene. Microfossils in marine sediments provide key proxies in our understanding of how the margin evolved. Fossil shells (tests) of foraminifera (singlecelled protists) from twenty cores from the Namibian shelf (199 to 309 m water depth) and three cores from the western slope …
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Dredge spoil dispersion from an inner shelf dump-mound
… of dredge spoil from a dump-mound on the inner shelf in 11-17 m water depth, 3 km offshore from Tauranga Harbour, New Zealand. Graphic and volumetric analysis of bathymetric changes over the dump-mound and its near vicinity, between 1978 and 1988, showed that based on echo-sounding surveys a …
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Distribution of Dehalococcoidia in marine sediments and strategies for their enrichment
… role are unknown. In this study, marine sediments were cultivated with various potential electron acceptors to explore respiration modes catalysed by Dehalococcoidia. The cultivation revealed that Dehalococcoidia can be cultivated in an anoxic minimal medium amended with hydrogen and …
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Tephrostratigraphy, petrography, geochemistry, age and fossil record of the Ganigobis Shale Member and associated glaciomarine deposits of the Dwyka Group, Late Carboniferous, southern Africa
… dominated, Carboniferous Dwyka Group and the shelf sediments of the overlying Permian Ecca Group. The Dwyka Group can be subdivided into four upward-fining deglaciation sequences, each capped by relatively fine-grained glaciolacustrine or glaciomarine deposits. The uppermost part of the second …
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