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1
Kingsford, Smith E. D. "Marginal Seal Of Cervical Restorations." Thesis, The University of Sydney, 1988. http://hdl.handle.net/2123/5099.
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Serhat, Koken. "Clinical and laboratory investigations on cervical margin relocation." Doctoral thesis, Università di Siena, 2020. http://hdl.handle.net/11365/1096029.
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In the presence of subgingival proximal margins, close to or below the cemento-enamel junction (CEJ), impression taking and adhesive luting procedures for indirect restorations are hampered; surgical crown lengthening or orthodontic eruption are viable options. However, the placement of a small amount of composite, so-called cervical margin relocation (CMR), was proposed as an alternative technique.
To date, literature about CMR is scarce and the aim of this PhD thesis was to perform laboratory and clinical investigations to shed light on some crucial missing points.
The thesis consists of 5 studies. The first study is a literature review summarizing the existing scientific literature on CMR technique performed prior to the adhesive cementation of indirect restorations. The second study is an in vivo randomized controlled clinical trial assessing the possible influence of CMR on periodontal health, after 12- month of clinical service. The third study is an in vitro study evaluating the marginal sealing of relocated mesio-occluso-distal overlays. The fourth study is an in vitro study analyzing the influence of cervical margin relocation and adhesive system on microleakage of indirect composite restorations. The fifth study is an in vitro study evaluating the possible correlation between two methodological approaches applied to evaluate cervical margin relocation.
Different methodological approaches were used to perform the above-reported investigations, such as scanning electron microscopy (SEM) and microleakage analyses.
The principal investigator was calibrated and trained before performing the operative procedures and laboratory investigations. All the recorded data were statistically analyzed with dedicated software.
CMR is a relatively new restorative procedure and information on its performance is limited. Within the limitations of the performed laboratory and clinical studies, the present PhD thesis allowed to draw the following conclusions:
1. On the basis of the reviewed literature, currently, there is no strong scientific evidence that could either support or discourage the use of CMR technique prior to restoration of deep subgingival defects with indirect adhesive restorations; further randomized controlled clinical trials are necessary to provide reliable evidence on the influence of CMR technique on the clinical performance, especially on the longevity of restorations and periodontal health.
2. A higher incidence of bleeding on probing can be expected around teeth treated with CMR and in coincidence with deep margins placed at or closer than 2 mm from the bone crest; consequently, CMR should be considered as a clinically sensitive-technique, especially when performed on deep subgingival margins.
3. The marginal sealing ability of flowable and microhybrid resin composites is comparable for CMR; furthermore, luting overlays directly onto dentin without CMR appears to be a better method for limiting marginal leakage underneath CAD/CAM overlays.
4. CMR technique and the adhesive system employed for luting indirect restorations might represent a significant factor affecting microleakage at the interface below CEJ.
5. CMR seems to provide less adequate seal of the margin than the one achieved by cementing the restoration directly to dentin without CMR. The sealing ability of the marginal interface depends on the adhesive materials used for performing CMR. Differences in the quality of the marginal adaptation between two different materials used for CMR could not be detected by SEM observations. SEM examination of the marginal adaptation does not allow for the predictions of the functional sealing of the margins.
Future in vitro and in vivo studies should evaluate the effectiveness of CMR technique and the marginal seal of different bonding systems and luting cements in combination with CMR. Particularly, randomized controlled clinical trials should investigate the durability of CMR and the response of periodontal tissues.
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Matthiesen, Stephan. "The feedback between basin and strait processes in the Mediterranean Sea and similar marginal seas : a process study." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/15290.
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The Strait of Gibraltar limits the exchange between the Atlantic and the Mediterranean Sea and therefore plays an important role in determining the water properties of the evaporation-dominated Mediterranean Sea. On the other hand, the strait dynamics depends on the boundary conditions set by the basin. To investigate this fundamental feedback between strait and basin processes, a 3-box model of the Mediterranean with a hydraulically controlled strait was programmed. It accommodates both maximal and submaximal strait exchange and does not impose steady state budget constraints, making it particularly useful for investigating transitional and non-equilibrium situations. The model is used in an explorative study to find new dynamical aspects of the system. First, the response of the system to changing air-sea-fluxes is modelled. Increasing evaporation shifts the steady state of the system to a more saline and - as a secondary effect - slightly warmer state. Increased heat loss leads to a colder and slightly less saline basin. Besides shifting the steady state, changes in heat flux and net evaporation can also lead to a nonlinear response in which the pycnocline deepens considerably for a transitional period of decades or centuries before returning to its steady state depth. Second, the effect of rising sea levels since the Last Glacial Maximum (18kyr BP) was modelled. At times of rapid sea level rise, the long residence time leads to stronger stratification and reduced circulation in the basin, providing a possible mechanism for the formation of sapropel S1. Finally the effect of mixing in the hydraulic jump between the Mediterranean and the Strait of Gibraltar is included in the model. The entrainment of inflowing water into the outflow reduces the effective exchange between Atlantic and Mediterranean, and the system develops multiple equilibria. After a comparatively short perturbation (e.g. a 20% larger evaporation for 10 years), the system can move from the stable, well-ventilated state to an almost stagnant meta-stable state which persists for centuries before the well-ventilated state is reestablished.
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Boutin, Guillaume. "Interactions vagues-banquise en zones polaires." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0050/document.
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La banquise, qui couvre de larges étendues de l’océan près des pôles, est une composante majeure du climat. Le réchauffement de la planète entraîne sa fonte massive, en particulier en Arctique.Là où l’extension de la banquise diminue, l’augmentation du fetch est associée à une élévation de la hauteur des vagues, laissant penser que les effets liés aux interactions vagues-glace pourraient s’accroître dans le futur. L’évolution rapide de la banquise associée à l’intensification des activités humaines dans les régions polaires pressent à améliorer notre connaissance de ces interactions.La banquise atténue les vagues. Elles peuvent néanmoins s’y propager et briser la glace sur de longues distances. L’atténuation dépend des propriétés de la glace comme l’épaisseur, la taille des plaques... Les plaques de glace une fois cassées sont plus susceptibles de dériver et de fondre. En outre, lors de l’atténuation, les plaques sont poussées dans la direction de propagation des vagues.Une représentation simple de la banquise dans un modèle de vagues intégrant une distribution de la taille des plaques nous a permis de montrer l’importance des mécanismes dissipatifs dans l’atténuation, notamment ceux induits par la flexion de la glace.Après avoir été validé, ce modèle a été couplé à un modèle de glace. La taille des plaques est échangée et utilisée dans le calcul de la fonte latérale. La force exercée par les vagues sur la banquise est également envoyée depuis le modèle de vagues. En été, cette force compacte la glace et tend à diminuer la fonte, augmentant significativement la température et la salinité des eaux de surface au bord de la banquiseSea ice, which covers most of the ocean near the poles, is a key component of the climate system. Global warming is driving its massive melting, especially in the Arctic. Where sea ice cover decreases, fetch increases leading to more energetic sea states. This means potentially enhanced wavesice interactions effects in the future. The quick evolution of sea ice extent and volume combined with the intensification of human activities in polar regions urge us to improve our understanding of waves-ice interactions.Sea ice attenuates waves. They can however propagate through it and break it far into the ice cover. Attenuation depends on ice properties such as floe size, thickness, etc. Once broken, resulting floes are more likely to drift and melt. In addition, wave attenuation yields a force which pushes the floes in the direction of wave propagation.A simplified representation of sea ice, including a floe size distribution, has been incorporated in a wave model.It allows us to show the important contribution of dissipative mechanisms in the wave attenuation, especially those induced by the bending of the ice plates. After validation, the modified wave model is coupled to an ice model. The floe size distribution is exchanged in the coupled framework and used in ice lateral melt computation. The force exerted by the waves on the ice floes is sent from the wave model and is shown to compact sea ice in summer. This reduces the melting and significantly increases the temperature and salinity in the surface ocean close to the ice edge
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Roth, Michael J. "A coastal air-ocean coupled system for the East Asian marginal seas." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA406235.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, Sept. 2001.Thesis advisor, Chu, Peter C. "September 2001." Includes bibliographical references (p. 567-570). Also available in print.
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Di, Noto Giacomo. "Observations and modeling of the Marginal Ice Zone." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10228/.
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Global climate change in recent decades has strongly influenced the Arctic generating pronounced warming accompanied by significant reduction of sea ice in seasonally ice-covered seas and a dramatic increase of open water regions exposed to wind [Stephenson et al., 2011]. By strongly scattering the wave energy, thick multiyear ice prevents swell from penetrating deeply into the Arctic pack ice. However, with the recent changes affecting Arctic sea ice, waves gain more energy from the extended fetch and can therefore penetrate further into the pack ice. Arctic sea ice also appears weaker during melt season, extending the transition zone between thick multi-year ice and the open ocean. This region is called the Marginal Ice Zone (MIZ).
In the Arctic, the MIZ is mainly encountered in the marginal seas, such as the Nordic Seas, the Barents Sea, the Beaufort Sea and the Labrador Sea. Formed by numerous blocks of sea ice of various diameters (floes) the MIZ, under certain conditions, allows maritime transportation stimulating dreams of industrial and touristic exploitation of these regions and possibly allowing, in the next future, a maritime connection between the Atlantic and the Pacific. With the increasing human presence in the Arctic, waves pose security and safety issues. As marginal seas are targeted for oil and gas exploitation, understanding and predicting ocean waves and their effects on sea ice become crucial for structure design and for real time safety of operations. The juxtaposition of waves and sea ice represents a risk for personnel and equipment deployed on ice, and may complicate critical operations such as platform evacuations. The risk is difficult to evaluate because there are no long-term observations of waves in ice, swell events are difficult to predict from local conditions, ice breakup can occur on very short time-scales and wave-ice interactions are beyond the scope of current forecasting models [Liu and Mollo-Christensen, 1988,Marko, 2003].
In this thesis, a newly developed Waves in Ice Model (WIM) [Williams et al., 2013a,Williams et al., 2013b] and its related Ocean and Sea Ice model (OSIM) will be used to study the MIZ and the improvements of wave modeling in ice infested waters. The following work has been conducted in collaboration with the Nansen Environmental and Remote Sensing Center and within the SWARP project which aims to extend operational services supporting human activity in the Arctic by including forecast of waves in ice-covered seas, forecast of sea-ice in the presence of waves and remote sensing of both waves and sea ice conditions. The WIM will be included in the downstream forecasting services provided by Copernicus marine environment monitoring service.
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Lipka, Marko [Verfasser], Michael E. [Akademischer Betreuer] Böttcher, Michael E. [Gutachter] Böttcher, and Jens [Gutachter] Hartmann. "Current biogeochemical processes and element fluxes in surface sediments of temperate marginal seas (Baltic Sea and Black Sea) / Marko Lipka ; Gutachter: Michael E. Böttcher, Jens Hartmann ; Betreuer: Michael E. Böttcher." Greifswald : Ernst-Moritz-Arndt-Universität, 2018. http://d-nb.info/1171425538/34.
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Lipka, Marko Verfasser], Michael Ernst [Akademischer Betreuer] [Böttcher, Michael E. [Gutachter] Böttcher, and Jens [Gutachter] Hartmann. "Current biogeochemical processes and element fluxes in surface sediments of temperate marginal seas (Baltic Sea and Black Sea) / Marko Lipka ; Gutachter: Michael E. Böttcher, Jens Hartmann ; Betreuer: Michael E. Böttcher." Greifswald : Ernst-Moritz-Arndt-Universität, 2018. http://d-nb.info/1171425538/34.
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Lipka, Marko Verfasser], Michael Ernst [Akademischer Betreuer] [Böttcher, Michael Ernst [Gutachter] Böttcher, and Jens [Gutachter] Hartmann. "Current biogeochemical processes and element fluxes in surface sediments of temperate marginal seas (Baltic Sea and Black Sea) / Marko Lipka ; Gutachter: Michael E. Böttcher, Jens Hartmann ; Betreuer: Michael E. Böttcher." Greifswald : Ernst-Moritz-Arndt-Universität, 2018. http://d-nb.info/1171425538/34.
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Hill, Jenna Catherine. "Continental margin architecture sea level and climate /." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3258373.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed May 29, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Gupta, Mukesh. "On the estimation of physical roughness of a marginal sea ice zone using remote sensing." John Wiley and Sons, Ltd, 2013. http://hdl.handle.net/1993/23836.
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This thesis provides insight into techniques for the detection and classification of various marginal ice zone roughnesses in the southern Beaufort Sea using in situ and satellite-based microwave remote sensing. A proposed model of surface roughness shows the dependence of circular coherence, a discriminator of roughness, on the roughness and dielectrics. A relationship between ice slopes in azimuth and range direction is derived. Microwave brightness temperature of open water is significantly correlated with wave height but not with the wind speed, having the strongest correlations for the H-polarization at both 37 and 89 GHz. A modified formula for the relationship between non-dimensional form of energy and wave age at wind speeds 0−10 m/s is obtained. The brightness temperature (April−June) of sea ice at H-polarization of 89 GHz is found to decrease with increasing roughness, and is attributed to the dominant contributions from rapidly varying thermodynamic properties of snow-covered sea ice.
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Thrasher, Ian Mark. "Optically Stimulated Luminescence dating of ice-marginal palaeosandar from the last Irish Sea Ice-Stream." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507501.
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Alagarsamy, R. "Trace metals and organic matter diagenesis at the Oman Margin." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243212.
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Hillier, Robert David. "Siliciclastic shelf margin sedimentology and relative sea-level changes." Thesis, University of Aberdeen, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386359.
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The effects of changes in relative sea-level on clastic shelf margins are examined utilizing two case studies, the passive Quaternary to Recent of Sable Island Bank, Nova Scotia, and the active Silurian shelf of Dyfed, southwest Wales. Within the overall transgressive systems tract of the Sable Island Sand and Gravel Formation, siliciclastic material is continually reworked in shallow water by modern storm-dominated, tidally-modulated flows in an attempt to reach equilibrium and textural grade with the bank-top hydrodynamics. Over the past 11,000 years marked transgressive marine ravinement of the bank-top has cannibalised considerable volumes of sediment into the dynamic realms of eustatically produced accommodation space. Sediment transport, together with bedform and grain-size variations reflect both progressive sorting and the depth dependent fluid power relationship. Bedload sediment transport is predominantly geostrophic, and is seen to be topographically steered at shelf-edge breaks in slope, a process related to the hydraulic fence concept. Through this process, sediment by-pass into deep water is hindered, and spatially significant upward coarsening/thickening sandbodies are developing, most notably at East Bar. Taken a stage further, shoal aggradation of this sediment supply dominated coastal system has enabled the emergence of the cuspate/elongate shelf-edge Sable Island. The effects of changes in relative sea-level on various scales is described from the Coralliferous and Gray Sandstone Groups of southwest Wales. Six Vailian sequences are recognised within a thick basinward prograding clastic wedge. During lowstands of relative sea-level, shelfal incision and sediment by-pass occurred, with sediment supplying deep water fan systems immediately to the north of the study area. Valley-fills vary in depositional environment from low sinuosity fluvial channels (Sequence I), estuarine tidal channels (Sequences II to V), and mixed estuarine/high sinuosity fluvial channels of Sequence VI.
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Jemsek, John P. "Heat flow and tectonics of the Ligurian Sea basin and margins." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/44596.
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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1988.Vita.
Includes bibliographical references.
by John P. Jemsek.
Ph.D.
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Dinkler, Karl L. "The variability of the marine atmospheric boundary layer in the Greenland Sea marginal ice zone a case study." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23443.
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Ståhl, Henrik. "Carbon-cycling in deep-sea and contrasting continental margin sediments /." Göteborg : Göteborg university, 2001. http://catalogue.bnf.fr/ark:/12148/cb401108738.
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Cates, Charles C. "A Computational Study of Axial Compressor Rotor Casing Treatments and Stator Land Seals." VCU Scholars Compass, 2006. http://hdl.handle.net/10156/1579.
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Groters, Douglas J. "The temporal and spatial variability of the marine atmospheric boundary layer and its effect on electromagnetic propagation in and around the Greenland Sea marginal ice zone." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23422.
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Approved for public release; distribution is unlimitedVariability of the MABL and its effect on the electromagnetic (EM) refractive structure around the Greenland Sea marginal ice zone were examined. Rawinsonde profiles and surface observations collected from 3 ships during MIZEX-87(20 March-11 April) served as the data set. A program, developed to calculate the refractivity at each vertical level of the rawinsonde profiles, also identified the levels at which trapping, superrefraction and subrefraction occurred. Temporal studies showed that a higher incidence of anomalous refractive layers occurred during periods when the region was under the influence of high pressure. More than 50% of the time, trapping and super-refractive layers were attributed to development of a capping inversion just above the MABL during these periods. Spatial studies showed that the refractive structure varied relative to distance from the ice edge as did the depth of the MABL. An upward slope in refractive layer heights was observed from the ice toward the open water. Significant spatial inhomogeneity was observed over horizontal ranges of less than 100 km. This was attributed to both the large-scale synoptic forcing affecting the region and to variations in the surface fluxes of heat and moisture over the ice and over the water. A range-dependent ray trace model developed at the Naval Ocean Systems Center was used to show how the ray paths of EM waves vary with a changing refractive structures. Keywords: Air water interactions, Greenland Sea, Atmospheric refraction, Electromagnetic wave propagation, Heat flux, Sea ice. Theses. (EDC)
http://archive.org/details/temporalspatialv00grot
Lieutenant, United States Navy
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Waterstrat, Willapa James. "Morphometric Differentiation of Flank Margin Caves and Littoral, or Sea Caves." MSSTATE, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04052007-150907/.
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Caves on carbonate islands are useful indicators of past sea level because cave formation is dependent on sea-level controlled freshwater lens position (flank margin caves), or form in direct contact with coastal processes (sea caves). Sea-level curves present a useful proxy for glacioeustatic and paleoclimate studies, so caves offer useful data. Once a flank margin cave is breached, it may be modified and eroded by waves. This overprinting leads to morphology similar to that of sea caves. While both indicate past sea level, they reveal differing information about the amount of denudation that has occurred to expose them (a paleoclimate indicator), so differentiation of these cave types is important. This study presents some of the first sea cave data from carbonate islands, and makes morphological comparisons between flank margin caves and sea caves from the Bahamas, California, and Maine. Using morphometric techniques, these caves can be distinctly identified.
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Batchelor, Christine Louise. "Reflection seismic investigations of the Canadian Beaufort Sea margin, Arctic Ocean." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/268049.
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The seismic stratigraphy and sedimentary architecture of the Canadian Beaufort Sea margin are investigated using a comprehensive grid of two-dimensional seismic reflection data. Three cross-shelf troughs, representing locations of former ice streams draining a 1000 km-long section of the Laurentide Ice Sheet (LIS), are examined: the Mackenzie, Amundsen Gulf and M'Clure Strait systems. These palaeo-ice streams operated during the last, Late Wisconsinan glacial maximum, as well as during a hitherto unknown number of earlier Quaternary glaciations. Their dynamics influenced past ice-sheet configuration and may have forced abrupt climate change through transport of ice and freshwater to the Arctic Ocean. The objectives of this work are to constrain the number of ice advances through each trough, to discuss the possible timing of these events, and to examine the impact of Quaternary glaciation on the continental shelf and slope. The implications of these data are discussed in relation to ice dynamics at the northwest LIS limit, the glacial history of the Canadian Beaufort Sea margin, and the geomorphological imprint of palaeo-ice streams. The number of Quaternary ice advances across the Canadian Beaufort Sea margin varies markedly between the Mackenzie Trough (two) and the Amundsen Gulf Trough (at least nine). The Mackenzie Trough was probably occupied by an ice stream during the Late Wisconsinan and either the Illinoian or Early Wisconsinan glaciation. The Amundsen Gulf ice stream was initiated earlier in the Quaternary. The architecture of the slope beyond the Mackenzie Trough reflects this comparatively short history of ice advance and lacks the progradational architecture and major glacialsedimentary depocentre that is characteristic of slopes seaward of high-latitude cross-shelf troughs. In contrast, trough-mouth fans ( of volumes -10,000 km.3 and -60,000 km3) are present beyond Amundsen Gulf and M'Clure Strait, respectively. The location of 75 High Arctic cross-shelf troughs is presented together with a synthesis of their key physiographic characteristics and available glacial-geological evidence of past occupation by ice streams. The dimensions and architecture of the three troughs on the Canadian Beaufort Sea margin are compared to those of other High Arctic troughs. The Amundsen Gulf and M'Clure Strait troughs were probably two of the most significant cross shelf troughs in the High Arctic, in terms of their dimensions and palaeo-drainage basin areas. A number of buried glacigenic landforms, including grounding-zone wedges and lateral moraines, are identified from the Canadian Beaufort Sea shelf, recording the former positions of still-stands or re-advances in the ice margin. The youngest sequence of sediment in the Amundsen Gulf Trough is interpreted to have been deposited by a subsidiary ice stream, the Anderson ice stream, subsequent to Late Wisconsinan ice retreat through the Amundsen Gulf. This provides evidence of dynamic ice-stream behaviour and the reorganisation of the north west sector of the LIS during the last de glaciation.
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Ivanochko, Tara S. "Sub-orbital scale variations in the intensity of the Arabian Sea Monsoon." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/760.
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A high-resolution multi-proxy reconstruction of the Arabian Sea Summer Monsoon (ASSM) intensity over the past 90,000 years has been determined using two marine sediment cores: one from the Somali margin and one from the Indian margin. This reconstruction indicates that changes in monsoon- induced upwelling, primary productivity and denitrification have varied in synchrony with Dansgaard-Oeschger (D-O) cycles. Increased monsoon intensity correlates with warm climate events (interstadials) and decreased monsoon intensity, which coincides with stadials and Heinrich Events, is confirmed by elevated dust concentrations in the marine cores. A comparison of the Somali and Indian margin cores with previously reported studies from the Northern and Western Basin allows the identification of discrete sediment signals from the Indus River, the Arabian Peninsula and from local riverine runoff. Sedimentary deposition on the Indian margin during interglacials is dominated by local terrestrial runoff, whereas during glacial periods increased dust input from the Arabian Peninsula is evident. Both signals are related to changes in the intensity of the ASSM. Monsoon intensity has decreased during the Holocene as the Intertropical Convergence Zone (ITCZ) has moved to a more southerly position. The ASSM-ITCZ relationship (increased ASSM intensity and a northern ITCZ, decreased ASSM intensity and a southern ITCZ) has remained consistent over the last glacial cycle suggesting that global millennial scale climatic variability is in part driven by modulations in tropical hydrological cycle. This ASSM reconstruction provides evidence that rearrangements in the tropical convection system affected atmospheric dust concentrations as well as the concentration and location of atmospheric water vapour. In addition to modulating terrestrial and marine emissions of greenhouse gases, variation in the tropical hydrological cycle provides a mechanism of amplifying and perpetuating millennial-scale climatic changes.
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Pak, Ŭn-ju. "Cenozoic geohistory of the southwestern margin of the Ulleung basin, East Sea." [S.l. : s.n.], 1986. http://catalog.hathitrust.org/api/volumes/oclc/53229626.html.
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Handayani, Lina. "Seismic tomography constraints on reconstructing the Philippine Sea Plate and its margin." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1497.
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The Philippine Sea Plate has been surrounded by subduction zones throughout Cenozoic time due to the convergence of the Eurasian, Pacific and Indian-Australian plates. Existing Philippine Sea Plate reconstructions have been made based primarily on magnetic lineations produced by seafloor spreading, rock magnetism and geology of the Philippine Sea Plate. This dissertation employs seismic tomography model to constraint the reconstruction of the Philippine Sea Plate. Recent seismic tomography studies show the distribution of high velocity anomalies in the mantle of the Western Pacific, and that they represent subducted slabs. Using these recent tomography data, distribution maps of subducted slabs in the mantle beneath and surrounding the Philippine Sea Plate have been constructed which show that the mantle anomalies can be related to the various subduction zones bounding the Philippine Sea Plate.
The high velocity mantle anomalies are clearly coincident with Wadati-Benioff zones in the upper mantle. The lower mantle anomalies, although distributed in the transition zone (500-1000 km) as stagnant slabs in some cases, can clearly be mapped as continuations of upper mantle subduction zones. Reconstructing the subduction of the slabs now in the mantle best fits Philippine Sea Plate reconstructions that involve the minimal or simplest rotations. Northward movement of the Philippine Sea Plate, WNW subduction of the Pacific Plate since Eocene time (~50 Ma), and northward subduction of the Indian/Australian Plate along Indonesia best explain the subducted slab mantle anomalies. The origin of the eastern plate boundary was a transform zone that evolved into a subduction zone a few million years before the Pacific Plate changed its movement. In addition, the initiation of this subduction zone might possibly be one of the triggers of the Pacific Plate motion changes.
The 90 degree rotation of the Philippine Sea Plate including southward plate subduction at its northern boundary proposed in the reconstruction by Hall (2002) is not supported by seismic tomography evidence for slab distribution in the mantle beneath the Philippine Sea region. A hypothesis of minimal rotation of the Philippine Sea Plate, supported by the seismic tomography, guides the reconstruction model presented.
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MacDonald, Alister C. "Kimmeridgian and Volgian fault-margin sedimentation in the northern North Sea area." Thesis, University of Strathclyde, 1985. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24323.
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The Upper Jurassic sediments of the East Coast of Sutherland and the South Brae Oilfield were deposited during the late Jurassic taphrogenic episode in which there was rapid subsidence in the grabens and uplift of the adjacent areas. The initiation of coarse-grained sedimentation in the grabens was directly related to an increase in subsidence rates. At Sutherland the most sand-rich sequences were deposited during the cymodoce zone of the Kimmeridgian, immediately after the increase in subsidence rates. Depositional environments varied from a relatively shallow water and sand-rich submarine slope during the early Kimmeridgian to a deeper water sediment starved submarine slope during the early Volgian. The sediments of the South Brae Oilfield were deposited in the channelised part of a submarine fan system which was sourced from a point which lay to the west of the 16/7a-8 well and to the southwest of the 16/7a-12 well. The South Brae sequences are part of a much larger complex which was composed of at least seven different submarine fan systems. Sediment entry points occurred along the western margin of the South Viking Graben from the T-Block in the south to East Brae in the north and each of these fed a submarine fan system. The reservoir sequences will tend to be vertically stacked and spatially restricted in proximal areas and will become less stacked and less restricted distally. Stratigraphically trapped "Brae-like" plays probably exist at the margins of many North Atlantic Continental Shelf grabens. The eastern margins of the Vøring and Træna Basins have especially high prospectivity.
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Wolfenden, Ellen. "Evolution of the southern Red Sea Rift : birth of a magnetic margin." Thesis, Royal Holloway, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405194.
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Rovelli, Lorenzo [Verfasser]. "Physical and geochemical controls on oxygen dynamics at continental margins and shelf seas / Lorenzo Rovelli." Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/1048558363/34.
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Shields, Mark Aiden. "Gradients in benthic community structure and bioturbation potential along the Nordic Seas continental margin." Thesis, University of the Highlands and Islands, 2008. https://pure.uhi.ac.uk/portal/en/studentthesis/gradients-in-benthic-community-structure-and-bioturbation-potential-along-the-nordic-seas-continental-margin(ec1e3a76-38af-443f-b33b-1219e52e817f).html.
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The Nordic Seas region marks a transitional zone between the temperate North Atlantic Ocean and the polar Arctic Ocean. The influence of contrasting fluxes of organic matter on benthic community structure and function within the deep waters of the region were investigated. Samples of the macrofaunal community were collated throughout the region employing a standardised method. In the summer of 2002, during the RRS James Clark Ross 75 cruise, replicated samples were obtained with the SMBA multiple corer and the USNEL boxcorer from four stations located at similar sampling depths along a latitudinal transect at the Norwegian Sea continental margin. Additional replicated samples were obtained with a megacorer at six stations located along two bathymetric transects across the Norwegian Sea continental margin in the summer of 2005 during the RRS James Clark Ross 127 cruise. Contrasting fluxes of organic matter influenced benthic community structure, functional ecology and bioturbation potential. Species known to adopt the feeding strategy of the sub-surface storage of organic matter occurred in areas characterised by a seasonal input of organic matter. Species richness and diversity was highest at the Svalbard Margin, located within the marginal ice zone. Bathymetric patterns of macrofaunal biomass were comparable with previously reported global patterns. However, bathymetric patterns of macrofaunal abundance were higher than global patterns. The previously reported rapid subduction of organic matter by the sipunculan Nephasoma sp. and associated deep burrow networks on the Voring Plateau was linked to the species Nephasoma lilljeborgi. It is proposed that N. lilljeborgi is an ecosystem engineer.
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Russell, Simon Mark. "A magnetic study of the west Iberia and conjugate rifted continental margins : constraints on rift-to-/drift processes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4358/.
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The analysis and modelling of magnetic anomalies at the conjugate rifted continental margins of the southern Iberia Abyssal Plain (TAP) and Newfoundland Basin have revealed that the sources of magnetic anomalies are distinctly different across both each margin and between the two margins. Analyses of synthetic anomalies and gridded sea surface magnetic anomaly charts west of Iberia and east of Newfoundland were accomplished by the methods of Euler deconvolution, forward and inverse modelling of the power spectrum, reduction-to-the-pole, and forward and inverse indirect methods. In addition, three near-bottom magnetometer profiles were analysed by the same methods in addition to the application of componental magnetometry. The results have revealed that oceanic crust, transitional basement and thinned continental crust are defined by magnetic sources with different characteristics. Over oceanic crust, magnetic sources are present as lava-flow-like bodies whose depths coincide with the top of acoustic basement seen on MCS profiles. Top-basement source depths are consistent with those determined in two other regions of oceanic crust. In the southern IAP, oceanic crust, ~4 km thick with magnetizations up to +1.5 A/m, generated by organized seafloor spreading was first accreted -126 Ma at the position of a N-S oriented segmented basement peridotite ridge. To the west, seafloor spreading anomalies can be modelled at spreading rates of 10 mm/yr or more. Immediately to the east, in a zone -10-20 km in width, I identify seafloor spreading anomahes which can only be modelled assuming variable spreading rates. In the OCT, sources of magnetic anomalies are present at the top of basement and up to -6 km beneath. I interpret the uppermost source as serpentinized peridotite, and the lowermost source as intruded gabbroic bodies which were impeded, whilst rising upwards, by the lower density serpentinized peridotites. Intrusion was accompanied by tectonism and a gradual change in conditions from rifting to seafloor spreading as the North Atlantic rift propagated northwards in Early Cretaceous times. Within thinned continental crust, sources are poorly lineated, and distributed in depth. Scaling relationships of susceptibility are consistent with the sources of magnetic anomalies within continental crust. OCT-type intrusions may be present in the mantle beneath continental crust. At the conjugate Newfoundland margin, seafloor spreading anomalies can be modelled at rates of 8 and 10 mm/yr suggesting an onset age consistent with that of the IAP. In the OCT there, I propose that magnetic anomalies are sourced in near top-basement serpentinized peridotites. An absence of magmatic material and the differences in basement character (with the IAP) suggest that conjugate margin evolution may have been asymmetric.
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Brothers, Richard John. "The mechanical formation of vein structures as fluid flow pathways in Peru margin sediments and the Monterey formation, California." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262451.
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LaRiviere, Jonathan. "California Margin sea surface temperature and paleoproductivity records at Ocean Drilling Program site 1012 /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1324373241&sid=18&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Warren, Jeffrey Dennis Bartek Louis Robert. "The sequence stratigraphy of the East China Sea continental margin (late Pleistocene to present)." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,171.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Geological Sciences." Discipline: Geology; Department/School: Geological Sciences.
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Morgan, Susan K. "Petrology of Passive Margin-Epeiric Sea Sediments: the Garden City Formation, North-central Utah." DigitalCommons@USU, 1988. https://digitalcommons.usu.edu/etd/5623.
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The Lower Ordovician Garden City Formation is part of the thick sequence of Lower Paleozoic limestones, dolostones, and minor siliciclastic sedimentary rocks of the western United States. The carbonate rocks were formed predominantly by shallow water deposition in tropical, passive-margin epeiric seas.
The Garden City Formation is composed of nine lithotypes which represent the various environments. The formation is a storm-influenced transgressive sequence which may be divided into innershelf shallow subtidal and outer-shelf deep subtidal environments separated by a skeletal accumulation. The skeletal accumulation, formed by storm initiation, was a submerged topographic high, below normal wave base. The inner shelf includes the initial peritidal transgressive and shoreface material, which was extensively reworked by storm action, and a patchy distribution of shallow subtidal deposits. It is characterized by shoreward fossil banks and mud mounds, a restricted fauna, large amounts of terrigenous material and repeated occurrences of storm-created intraclastic layers within a nodular limestone.
The outer shelf sediments have a diverse fauna, are extensively burrowed and bioturbated, and have significant amounts of chert. Uncommon intraformational conglomerate layers signify deposition below mean storm-wave base.
The Garden City Limestone facies were deposited in broad, energy-related zones parallel to the ancient shoreline. These facies were compared to the model of epeiric sea deposition presented by Shaw (1964) and Irwin (1965). There was a lack of evidence within the Garden City sediments to support the existence of an extensive, shoreward, tideless low-energy zone as predicted by the model. The inner shallow subtidal environments remained near normal marine conditions, with water circulation provided by tidal action.
Early diagenetic features of the Garden City Formation include compaction, micritization, cementation and neomorphism. Chert formation preceded pressure solution and probably represents silicification of burrows.
Dolomitizing fluids moved along faults, unconformities, and bedding planes to selectively dolomitize the formation. Near-surface weathering resulted in dedolomitization and the oxidation of pyrite to hematite.
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Alexander, Ian T. "Late Quaternary sedimentation off the Queensland continental margin (northeast Australia) in response to sea level fluctuations." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/8161.
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Drilling during ODP Leg 133 offshore Cairns, northeast Queensland, provided a unique opportunity to document carbonate production and facies development on a mixed carbonate-siliciclastic margin. Recent studies have shown that variations in the sedimentology of Late Quaternary and Pliocene periplatform sediments (Schlager and James, 1978), deposited on continental slopes and in deep basins surrounding shallow carbonate platforms, are linked to changes in sea-level (Droxler et al., 1993; Schlager et al., 1994). However, considerable debate has arisen to the timing of the production and export of shallow water carbonate material, with respect to sea level change. Two main hypotheses have been proposed to explain the response of shallow water carbonate platforms to variation in Late Quaternary sea level: I) 'highstand shedding' and 2) 'lowstand shedding'. Proponents of highstand shedding argue that depositional systems shed most of its carbonate sediments onto the platform slopes during highstands of sea level. Conversely, during lowstands of sea level bank top production and export of carbonate material is restricted, and platform slopes are largely starved of bank derived carbonate (Schlager, 1992; Schlager et al., 1994 ). Supporters of lowstand shedding maintain that significant carbonate production and export of shallow water carbonate material occurs during lowstands (and highstands) of sea level (Bosellini, 1989; Goldhammer and Harris. 1989; Grammer and Ginsburg. 1992). In order to investigate the response of mixed carbonate-siliciclastic systems to variations in Late Quaternary sea level and climate change, core material was collected from Ocean Drilling Program (ODP) Leg 133, Sites 819 and 823 (northeast Australian margin). These two sites form part of an eastward extending transect of drill localities, offshore Cairns, Queensland, from the outershelf/upper-slope of the Great Barrier Reef (Sites 821 /820/819), into the Queensland Trough (Site 823) and ultimately onto the flanks of the Queensland Plateau (Sites 824 and 811 /825). Pelagic to hemipelagic sediments collected from these two sites were examined for the downcore distribution of grain size, magnetic susceptibility, carbonate content, variations in carbonate mineralogy (XRD), and major and minor element (XRF) geochemistry. Using high resolution foraminiferal stable oxygen isotopes, coupled with biostratigraphic and magnetostratigraphic datums, well defined age models for Hole 819A and Hole 823A have been constructed, although it was not an easy task as hiatuses occur in these records. Age models for the sequences recovered from Hole 819A and Hole 823A have been further refined using correlation with existing isotopic stratigraphies in the Pacific Ocean (ODP Hole 677, Raymo et al., 1989), and comparison with high resolution sedimentologic records from other ODP Leg 133 marine sequences. Analysis of the mineralogical, sedimentological and geochemical records from Holes 819A and 823A indicate that, over the last 1.1 million years, highstands of sea level (and during the early regression) are characterized by increased shallow water carbonate production, and deposition on the upper slope. This pattern of carbonate deposition is consistent with the highstand carbonate shedding scenario outlined by Schlager et al. (1992), and Schlager et al. ( 1994 ). Lowstands of sea level (and particularly the early transgression) are characterized by increased deposition of non-carbonate (mainly terrigenous) material and/or were not diluted by shallow water carbonate platform material. During the lowstands of sea level the shallow water carbonate factories were switched off. Therefore, the sediments deposited during lowstands of sea level tend to record the greater influence of pelagic driven carbonate. Although the above mentioned scenario of highstand shedding applies to the entire record of 1.1 million years. mineralogical and geochemical data indicate that shallow burial diagenesis, and dissolution of solution sensitive carbonate, occurred in the lower part of the records. The diagenesis and dissolution, however, have played only a minor role in determining the composition of the Queensland margin sediments. Variations in the terrigenous input (Cr/Al and Ti/AI ratios) in Queensland margin sediments indicate that interglacial periods were generally wetter than corresponding glacials or lowstands of sea level, during the Late Quaternary.
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Lago, Cameselle Alejandra. "Sedimentary processes and resulting continental margin configuration during large-scale sea-level drawdown: The Messinian Salinity Crisis in the Western Mediterranean Sea." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/334404.
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At the end of the Miocene (5.97-5.33 Ma), the Mediterranean basins underwent deep morphological and sedimentological changes as a result of the large-scale sea-level fall during the so-called Messinian Salinity Crisis (MSC) and subsequent fast sea-level rise in the 3 Zanclean. Whereas deep basins accumulated more than 1 million km of evaporites, continental margins recorded several erosion surfaces. Through the analysis of 2D and 3D seismic reflection data and 2D numerical modelling, this Thesis attempts to contribute to better understand the sedimentary processes and resulting continental margin configuration during the large-scale Messinian sea-level drawdown. Detailed mapping of the seismic stratigraphy from the continental margin to the deepwater basin of the Valencia Trough (Western Mediterranean) has revealed two Messinian depositional units (Complex and Upper Units) and four erosional surfaces (Margin Erosion Surface, and Bottom, Top and Intermediate Surfaces). The stratigraphic relationship and margin configuration of these ‘Messinian seismic markers’ suggest that during the Miocene and until late Tortonian, the Mediterranean passive margins were characterized by prograding depositional sequences in the context of a Highstand System Tract. At that time, a sedimentary- active continental slope and delta progradation developed in a normal regressive in the Ebro margin, suggesting context associated to a pre-Messinian Ebro River.
During late Messinian, the large-scale sea-level drawdown resulted in the initial development of a Falling Stage System Tract. The subaerial exposure of the shelf and upper slope of the Valencia continental margin at the beginning of the sea-level drawdown – probably in combination with local factors – induced destabilization of the continental slope and deposition of major Mass-transport Deposits (MTD). Results obtained from 2D numerical modeling of coupled transient seepage and deformation analysis and stability analysis suggest a decrease in hydrostatic pore pressures and development of seepage and stress-induced excess pore pressures. As the sea-level dropped, depocenters displaced offshore, major Mediterranean rivers incise to adapt to the base level, and high sediment supply contributed to the development of submarine channels. Concurrently, a submarine paleo-Valencia channel formed in the deepwater Valencia Trough. The gradually slow-down of the sea-level fall allowed the development of a smooth surface at the top of the Lowstand System Tract, whereas the long- time exposure of the proximal shelf and upper slope resulted in a rough erosional surface deeply carved by drainage networks. The Margin Erosion Surface (MES) attained full development on the margins and the MTDs were partially eroded. The development attained by the Messinian Ebro network during the MSC corroborates that the capture of the Ebro Basin occurred prior to the MSC. A slow transgressive phase before the final rapid re-flooding, together with high evaporation rate, favored aggradational deposition of the Upper Unit in a shallow-water basin. At the end of the MSC, the reestablishment of the Mediterranean-Atlantic connection triggered the rapid sea-level rise and the return marine conditions, supported by the outstanding preservation of the fluvial deposits on the main valleys of the MES.Ó final do Mioceno (5.97-5.33 Ma) a Cuenca Mediterránea sufriu importantes cambios morfolóxicos e sedimentarios como consecuencia dunha baixada do nivel do mar duns 1500 m durante o evento coriecido coma Crise Salina Messiniense. A través da análise de datos de sísmica de reflexión 2D e 3D e do modelado numérico, esta Tese quere contribuír a un mellor entendemento dos procesos sedimentarios e a configuración resultante da marxe continental durante unha Baixada do nivel do mar a gran escala. A mostraxe detallada da estratigafía sísmica do Surco de Valencia (Mediterráneo Occidental) revelou a existencia de dúas unidades deposicionais (Complex and Upper Units) e catro superficies limitantes (Margin Erosion Surface, and Bottom, Top and Intermediate Surfaces). Ás relación estratigráficas suxiren que durante o Mioceno e ata o Tortoniense, a marxe estivo caracterizada por un Sistema deposicional progradante asociado ós aportes dun proto-rio Ebro. Ó final do Messiniense, unha Baixada do mar a gran escala provocou a exposición subaérea das marxes continentais e a desestabilización dos taludes da marxe de Valencia que, posiblemente en combinación con factores locais, ocasionou desprendementos submarinos que depositáronse ó pé do talude. A medida que o nivel do mar descendía, a sedimentación desprazouse cara o mar e os grandes ríos Mediterráneos incidíronse nas plataformas continentais para adaptarse ó novo nivel de base do mar. Ó mesmo tempo, o gran transporte de sedimentos xerado facilitou o desenvolvemento de canóns e sistemas de canles submarinas como o paleo-Canle de Valencia. Unha diminución da taxa de baixada do mar facilitou a formación dunha plataforma de erosión no teito do Lowstand System Tract, mentras a zona proximal da marxe – moito máis tempo exposta á erosión – transformouse nunha superficie moi irregular e amplamente escarvada por sistemas fluviais.. O nivel de madurez que caracteriza ó proto-rio Ebro suxire que a súa captura foi previa á Crise Salina Messiniense. Unha fase transgresiva lenta, previa á inundación, unida cunha alta taxa de evaporación, favoreceu a deposición das evaporitas na conca profunda. Ó final da Crise Salina Messiniense, o restablecemento da conexión do Mar Mediterráneo có Océano Atlántico permitiu á volta as condicións mariñas normais.
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Mea, Marianna. "Temporal variability and impact of dense water cascading events on deep-sea biodiversity and ecosystem functioning in the Catalan margin (Mediterranean sea)." Doctoral thesis, Università Politecnica delle Marche, 2011. http://hdl.handle.net/11566/242222.
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Negli ultimi decenni si sono raccolte prove a dimostrazione del fatto che gli ambienti marini profondi non siano stabili come creduto in precedenza. Ad oggi studi quantitativi di ecologia degli ambienti profondi sono stati condotti in tutti i maggiori bacini oceanici e sono stati descritti i principali pattern ecologici e biogeografici degli oceani profondi. Nonostante ciò, la maggior parte di questi studi si sono focalizzati su gradienti batimetrici basati o su un singolo sito di campionamento. Le indagini a lungo termine sono vitali per comprendere la varietà e la complessità dei processi che avvengono negli ambienti profondi. In particolare, non sono state finora analizzate le variazioni stagionali e annuali delle comunità profonde e se tali cambiamenti possano dipendere da un gradiente batimetrico o dalla tipologia di habitat.
Le conoscenze sulla relazione fra abbondanza, biomassa, diversità delle comunità profonde e disponibilità delle risorse trofiche e condizioni ambientali è determinata dalla mancanza di informazioni sufficienti sull’effetto della variabilità spaziale e temporale.
Nella presente tesi di dottorato ho provato a far fronte alla necessità di integrare le informazioni relative agli effetti della variabilità temporale degli ambienti marini profondi e la loro biodiversità. Ho utilizzato la meiofauna come modello di studio per investigare gli effetti dei cambiamenti temporali su variabili biotiche quali la struttura di comunità, la diversità (livello tassonomico superiore e diversità di specie dei nematodi) e il loro legame con le variabili ambientali (e.g., input stagionali di materia organica provenienti dalla zona fotica). Ho analizzato con cadenza regolare (biennale quando possibile) la variabilità temporale (intra- e inter- annuale) delle variabili ambientali, delle condizioni trofiche (contenuto in materia organica e composizione biochimica dei sedimenti) e della comunità della meiofauna (abbondanza, biomassa, numero di taxa e diversità dei nematodi). I campioni di sedimento sono stati raccolti lungo il margine continentale Catalano, nel Mar Mediterraneo nord-occidentale, a profondità comprese tra 1000 e 2400m nel canyon Cap de Creus e nella scarpata adiacente durante 6 campagne oceanografiche da Aprile 2005 a Ottobre 2009.
La regione studiata è frequentemente sottoposta a eventi episodici di sprofondamento di acque dense superificiali, che si sono formate a seguito del raffreddamento e/o evaporazione delle acque costiere. Questi eventi, generando forti correnti di fondo con trasporto di sedimento, possono causare un’abrasione del substrato e determinare un potenziale disturbo sulle comunità bentoniche presenti lungo le scarpate e i canyon nell’area interessata da tale fenomeno. Analisi oceanografiche e sedimentologiche hanno rivelato come nell’inverno 2004-2005 questo evento è stato particolarmente drammatico. I risultati della presente tesi dimostrano che questo evento ha causato, a partire da 1000m fino alla porzione più profonda del bacino (2400m) un trasporto elevato di sostanza organica e una evidente diminuzione di abbondanza, biomassa e diversità della meiofauna. I risultati mettono inoltre in evidenza che la comunità bentonica ha mostrato una rapida resilienza a seguito del fenomeno di disturbo, nonostante i più alti livelli di biodiversità si raggiungano soltanto dopo 4-5 anni dall’evento di cascata di acque dense.
I risultati di questa tesi evidenziano che la principale variabilità temporale in termini di quantità e qualità della sostanza organica, abbondanza, biomassa e biodiversità della meiofauna si verifica su scala inter-annuale con andamenti diversi al variare della diversa tipologia di habitat considerata. L’effetto della profondità del campionamento è apparentemente più forte della scala temporale intra-annuale nel determinare il cambiamento delle variabili investigate. Allo stesso tempo, la variabilità della comunità di meiofauna e della diversità dei nematodi è più forte nella porzione superficiale della scarpata continentale e si riduce nella piana abissale.
I risultati di questa tesi pongono le basi per una migliore comprensione dell’importanza della variabilità temporale nell’analizzare il benthos profondo e dei limiti associati alle analisi basate su singoli tempi di campionamento.In last two decades, a strong evidence is accumulating that the deep-sea environments are not as stable as previously thought. Quantitative studies of deep-sea ecology have been now conducted in all major oceanic basins and the main deep-sea biogeographic and ecological patterns are being disclosed. However, most of these investigations have been focused on the analysis of bathymetric gradients based on a single sampling. Long-term studies are vital to understand the diverse range of processes which occur in the deep sea. In particular, is still unknown whether deep-sea assemblages display significant seasonal or inter-annual variations, if these changes occur at all depths or are dependent on bathymetric gradients and whether they are more variable in different habitat types. The picture we have on the abundance, biomass and diversity of deep-sea assemblages and of their relationships with food availability and other environmental factors is therefore constrained by the lack of sufficient information on the effect of spatial and temporal variability. In the present PhD thesis I tried to partly cope with the need of integrating the information of the effects of temporal variability of deep-sea ecosystems and their biodiversity. I used deep-sea meiofauna as a model for investigating the effects of temporal changes on assemblage structure, higher taxa, species diversity and on several attributes as well as their links with environmental variables (e.g., the seasonal pulses of organic matter from the photic zone). I investigated on a regular basis (biannual when possible) the temporal (intra- and inter- annual) variability of environmental variables, trophic condition (organic matter content and biochemical composition of sediments) and meiofaunal assemblage (abundance, biomass, number of taxa of meiofaunal assemblage and nematode biodiversity). Sediments samples were collected along a continental margin (Catalan margin in the North-Western Mediterranean) at depth from 1000 to 2400m in Cap de Creus Canyon and in the adjacent slopes during 6 oceanographic cruises from April 2005 to October 2009. The investigated region is frequently subjected to episodic events of dense shelf water cascading, because of the formation of dense water due to cooling and/or evaporation of coastal shallow waters. These events by generating strong bottom currents and associated sediment transport can cause the physical abrasion of the deep-sea floor and determine a potential disturbance on the benthic assemblages inhabiting the open slopes and canyons of this margin. Oceanographic and sedimentological analyses revealed that in the winter 2004-2005 this event was particularly dramatic. I show here that this event caused, from 1000 down to the deepest part of the basin (2400 m depth), a major transport of organic matter and the collapse of meiofaunal abundance, biomass and diversity. I also demonstrated that the benthic assemblages displayed a rapid resilience after the cessation of the disturbance event, but the highest levels of biodiversity were reached only 4-5 years after. The analysis of the temporal changes revealed the presence of the highest variability in terms of quantity and quality of organic matter, total meiofaunal abundance, biomass and diversity over the inter-annual scale. The second source of variability was provided by the differential response of the different habitat types (e.g., canyons vs slopes) to changes in the environmental conditions. Interestingly, the effect of sampling depth was apparently stronger than that of intra-annual temporal scale in determining the variability of the investigated variables. At the same time the variability in meiofaunal and nematode biodiversity was stronger in the upper part of the slope and much reduced in the bathyal plain. Our results pose the basis for a better understanding of the importance of temporal variability in the analysis of deep-sea benthos and on the comprehension of the limits associated to the analyses based on single sampling times.
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Wang, Dong 1963. "Continental-slope sedimentation adjacent to an ice-margin, Labrador sea : depositional facies and glacial cycles." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56949.
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Analyses of 13 sediment cores and 2800 km of 3.5 kHz seismic profiles reveal that the majority of the sediments on the Labrador continental slope was deposited by hemipelagic settling and ice-rafting (53%), debris flows (7%) and turbidity currents (34%) during the Wisconsinan Glaciation. Only minor amounts (6%) are attributed to contour current activity and related processes. Eight sedimentary facies were differentiated which include (1) hemipelagic (H); (2) hemipelagic (HI) with ice-rafted detritus (IRD); (3) debris-flow deposits (subfacies D1, D2, D3), spill-over turbidite (T), headspill turbidite (TH), turbidite (TI) alternating with IRD; and (4) contourite (C) and nepheloid-flow deposits (N).Six major glacial advances were identified in Mid- to Late-Wisconsinan (64-10 ka) slope sediments by 6 very dark hemipelagic units containing abundant sinistral-coiling, cold-water foraminifera. The associated ice-retreat phases are characterized by the occurrence of turbidites, debris-flow deposits, nepheloid-flow deposits, and ice-rafted debris (IRD).
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Olobayo, Oluwatobi Anastasia. "Deposition, remobilization and fluid flow in sedimentary basins : case studies in the northern North Sea and Nigeria Transform Margin." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/deposition-remobilization-and-fluid-flow-in-sedimentary-basins--case-studies-in-the-northern-north-sea-and-nigeria-transform-margin(c95cfa22-8437-42d0-a79d-bf2d5c2440fb).html.
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Soft-sediment remobilization and fluid flow processes and their products such as sand injectites, mud volcanoes, pipes, pockmarks and authigenic carbonates constitute a key, but under-appreciated component of sedimentary basins. The structures are evidence of and provide focused fluid pathways bypassing the stratigraphic and structural framework and thus have numerous implications for hydrocarbon exploration and production by influencing sediment and fluid distributions. Recent advances in subsurface imaging using high-resolution 3D seismic data, integrated with well data, geochemical data and outcrop data have greatly improved the understanding of subsurface sediment remobilization and fluid flow processes in sedimentary basins. This study presents substantial new results from the description, analysis and interpretation of products of subsurface remobilization processes and fluid flow based on all available data from the Northern North Sea and the Nigeria Transform Margin. The studied intervals, which encompass the entire Cenozoic and Cretaceous succession, have undergone repeated, large-scale remobilization and deformation of sediments through time. The North Sea is the archetype Giant Injected Sand Province (GISP) with kilometre-scale sandstone intrusions observed within multiple stratigraphic intervals, but this is the first time the northern North Sea has been systematically studied on a regional scale. Seismic-scale sandstone intrusions are well documented along the Atlantic Margin from the South Viking Graben, Outer Moray Firth, Norwegian-Danish Basin, Faroe-Shetland Basin and Barent Sea but primarily emplaced during one or two episodes. Results from the NNS show evidence for five major episodes of emplacement. These sandstones, believed to be sourced from different stratigraphic levels, have intruded thick polygonally-faulted, diatomaceous and smectite-rich mudstones; probably facilitated by hydrocarbons and diagenetically-released water in spatio-temporally varying proportions. The Cenozoic section of the Nigeria Transform Margin comprises up to 2 km of sediments, including recurrent mass transport deposits ranging between a few to tens of kilometres in length and constituting up to 25 % of the stratigraphic section. A series of fluid flow features such as pockmarks, pipes, bottom simulating reflections, polygonal faults and mound have been interpreted on the seabed and in the overburden; all of which provide evidence of focused fluid movement in the subsurface becoming more abundant towards the Niger Delta. Our study provides details on the geometries, scale, spatial distribution, potential causative mechanisms and implications of these soft-sediment remobilized and fluid flow products; as well as their relationships with other depositional and structural elements within the basin. It also reveals the extent by which sedimentary basins can be affected by these processes and therefore be incorporated into present stratigraphic frameworks and improve reservoir models.
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Leinweber, Volker Thor. "Geophysical study of the conjugate East African and East Antarctic margins." Brest, 2011. http://www.theses.fr/2011BRES2017.
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The study deals with the relative movements between Africa and Antarctica in Middle Jurassic to Lower Cretaceous times using new data from four campaigns (2006-2010). Aeromagnetic measurements in the 5W Enderby Basin clearly image the continent-ocean-transition east of the Gunnerus Ridge. Spreading anomalies are absent, pointing to a formation of the oceanic crust during Cretaceous Normal superchron times. Velocity and density modelling of two wide-angle seismic profiles across the Central Mozambique continental margin reveal continental crust, thinning seawards by 50% over a distance of ~130 km. Farther south, oceanic crust is overlain by sediments with high P-wave velocities around 4. 8 km/s. An extensive lower crustal high-velocity-body has been found in both profiles. Identifications of magnetic spreading anomalies reveal that the COT is located closer to the coast than supposed so far. M41 n is interpreted as oldest existing spreading anomaly. New magnetic and gravity data across the Mozambique Ridge and the Northern Natal Valley and their similarity to potential field data on the Mozambique Coastal Plains point to a mainly oceanic nature from the plains south and two southward jumps of the spreading centre. The Astrid Ridge is subdivided by the Astrid Fracture Zone into a northern and a southern part with different magnetic signatures and is interpreted to consist of oceanic crust. The regional results were implemented into a new kinematic model between Africa and Antarctica, postulating a tight continental Gondwana fit, a two-stage breakup and a southward movement of the Grunehogna Craton east of the Mozambique Ridge during the second stage of breakupL’étude traite des mouvements relatifs de l’Afrique et de l'Antarctique, du Jurassique moyen jusqu’à la fin du Crétacé inférieur, en utilisant les données de quatre campagnes (2006-2010). Des mesures aéromagnétiques dans le bassin Enderby Sud-Ouest montrent la COT à l’est de la dorsale de Gunnerus. Il n’y a pas d’anomalie évidente dans les données, ce qui indique une formation de croûte océanique durant le superchron normal du Crétacé. La modélisation de deux profils sismiques grand-angles à travers la marge continentale du Mozambique central révèle une croûte continentale qui s’amincit ~50% sur une distance de ~130 km vers le large. Plus au sud, de la croûte océanique se trouve sous des sédiments à hautes vitesses d’ondes P autour de 4,8 km/s. Dans la croûte inférieure se retrouve un vaste corps de grande vitesse d’ondes. Des identifications des anomalies (M41n étant interprétée comme la plus vieille) révèlent que la COT est plus proche de la côte qu’on ne le croyait. De nouvelles données magnétiques et gravimétriques à la ride du Mozambique et au bassin nord du Natal et leur similitude avec les données des plaines de la côte du Mozambique indiquent une nature de croûte océanique majoritaire des plaines vers le sud ainsi que deux sauts du centre d’écartement vers le Sud. La ride d’Astrid est scindée en deux parties magnétiquement différentes, interprétées en croûte océanique. Les résultats régionaux ont été implémentés dans un nouveau modèle cinématique, qui postule un ajustement étroit des continents du Gondwana, une fracturation diphasée et un mouvement du Craton Grunehogna vers le sud à l’est de la ride du Mozambique pendant la deuxième phase de la fracturation
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Mathew, Johan. "Margins of the Market: Trafficking and the Framing of Free Trade in the Arabian Sea, 1870s to 1960s." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10535.
Full textAbstract:
My dissertation traces how the interplay of trafficking and regulation shaped free trade in the Arabian Sea. It explores trafficking in the littoral region stretching from western India to the Swahili Coast, as it evolved under colonial regulation. British officials wanted commercial practices in the Arabian Sea to conform to their perception of free trade, but their dedication to laissez-faire policies prevented them from intervening directly in trade. But smuggling provided the perfect justification for intervention. Colonial regulation focused on four illicit arenas that structured free trade: labor, security, finance and transportation. The suppression of the slave trade would produce wage labor. The suppression of the arms traffic would eliminate violence from trade. The regulation of currency arbitrage would create a stable monetary standard. Finally, the regulation of shipping would develop a transportation system which could incorporate distance into the calculation of price. Yet these regulatory efforts were frustrated by merchant networks which exploited the gaps in the enforcement of these regulations. Merchants co-opted regulators, circumvented regulations and evaded policing in order to structure transactions to their own advantage. Thus my dissertation demonstrates how free trade in the Arabian Sea was framed through this intricate interplay of trafficking and regulation.History
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Kong, Fanchen. "Continental margin deformation analysis and reconstruction : evolution of the East China Sea basin and adjacent plate interaction /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Callihan, Laura Dawn Bartek Louis Robert. "Relative roles of sea level and climate change in the evolution of the stratigraphic architecture of the northeastern continental margin of the South China Sea." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1846.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Geological Sciences." Discipline: Geology; Department/School: Geological Sciences.
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Birnbaum, Gerit. "Numerische Modellierung der Wechselwirkung zwischen Atmosphäre und Meereis in der arktischen Eisrandzone = Numerical modelling of the interaction between atmosphere and sea ice in the Arctic marginal ice zone /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 1998. http://www.gbv.de/dms/bs/toc/245351841.pdf.
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Ramos, Diana Gouveia. "Taxonomy, distribution and ecology of the order Phyllodocida (Annelida, Polychaeta) in deep-sea habitats of the Iberian margin." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/15380.
Full textAbstract:
Mestrado em Biologia MarinhaThe polychaetes are mostly marine annelids, with a worldwide distribution, which constitute a food source of benthic and demersal communities, representing this way a relevant importance in an ecological approach. Most species are typical from marine ecosystems, and they are usually distributed from the intertidal zone to abyssal depths occupying a huge variety of habitats, from estuarine and sandy muds to coral reefs and deep-sea muds (Glasby et al., 2000). They live frequently associated with marine chemosynthetic ecosystems, such as hydrothermal vents, mud volcanoes, or cold seeps, that host a high biodiversity of fauna. The present work represents a taxonomic review of the polychaetes belonging to the order Phyllodocida, sampled in many oceanographic cruises from 2002 to 2012, in the Bay of Biscay, Gorringe Bank, Atlantis seamount, Alboran Sea and eastern Mediterranean, in several ecosystems such as mud volcanoes, cold seeps, submarine mounds and deep sea corals. This work includes a detailed knowledge of the biodiversity in deep sea ecosystems, made by a morphological study using identification keys, diagnosis and descriptions of the families, genera and species of the order Phyllodocida using the available bibliography, and also an ecological study of the order. In some cases, a determination to a species level was not possible but taxonomic remarks are given which will be a basis for further study of those specimens, preferably including the use of molecular tools, in order to achieve more clear results.
Os poliquetas são anelídeos maioritariamente marinhos, com ampla distribuição global, que constituem uma fonte de alimento para as comunidades bentónicas e demersais representando assim uma relevante função ecológica. A maioria das espécies é típica de ambientes marinhos distribuindo-se de um modo geral desde a zona intertidal até profundidades abissais, e ocupando uma grande variedade de habitats, como sedimentos lodosos e/ou arenosos das zonas estuarinas, costeiras e profundas, recifes de coral, entre outros (Glasby et al., 2000). Vivem frequentemente associados a ecossistemas quimiossintéticos marinhos, tais como fontes hidrotermais, vulcões de lama ou fontes frias, os quais albergam uma enorme diversidade de seres vivos. O presente trabalho consiste numa revisão taxonómica dos poliquetas pertencentes à ordem Phyllodocida, colhidos em diversas campanhas oceanográficas decorrentes desde 2002 a 2012, em diversas áreas da margem Ibérica desde o Golfo da Biscaia ao Golfo de Cádis (Oceano Atlântico) e Mar de Alborão (Mediterrâneo Ocidental), em diferentes habitats batiais, mas principalmente em vulcões de lama, e recifes de coral de profundidade. Adicionalmente, foram analisadas algumas amostras colhidas em montes submarinos do Atlântico e na região Oriental do Mar Mediterrâneo. O estudo pretende contribuir para o conhecimento da biodiversidade em ecossistemas marinhos profundos, a partir do estudo morfológico e taxonómico de espécies da Ordem Phyllodocida (Polychaeta). São referidos aspetos de habitat e distribuição através do uso de bibliografia disponível, e ainda a partir de um estudo ecológico da ordem. Em alguns casos não foi possível a determinação ao nível de espécie apresentando-se apenas considerações taxonómicas que servirão de base a um estudo futuro mais detalhado, preferencialmente com base em análises moleculares, de forma a obter uma identificação mais precisa dos mesmos.
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Greenhalgh, Erica. "A geodynamic model for continental breakup and sea-floor spreading initiation : implications for post-breakup rifted margin hinterland uplift." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539517.
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Elkhashab, Mohamed. "Tectonogeomorphological and satellite image analysis of the Red Sea passive margin at the latitude of Wadi Siatin, Northern Quseir, Egypt." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-170717.
Full textAbstract:
Remote sensing has become an essential tool to improve data collection and spatial
analysis in the geosciences. Identification of passive margin structures that are exposed along
the Egyptian coast of the Red Sea, and their control on landforms has been hampered by
limited data resolution and restricted access to this arid and inaccessible region. A major
challenge lies in distinguishing features in the landscape that formed due to long-term tectonic
activity and erosion from those features that modified the landscape recently. The goals of this
thesis were to determine to what degree the study area is currently tectonically active, and
what major hazards might affect the touristically developing coastal region.
This study deals with the structural and geomorphological evolution of the rift-related
structures and their impact on the sediment distribution and landforms variation in the
northern Quseir area. In such a remote desert area, field and remote morphostructural analysis
are needed to understand the structural and geomorphological evolution. The current study is
mainly based on high-resolution QuickBird image analysis and field investigation. Field
mapping was limited to one season, owing to acute safety concerns in the Eastern Desert.
In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by
pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift
clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional
patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted,
amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the
Red Sea: the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are
perfectly exposed as tilted fault blocks.
The results of my field mapping and structural analysis show that the fault architecture of
the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal
faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping
detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS-
striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross
faults as previously proposed in a neighboring area. Thus seismic activity is more likely to
occur on the large NW-striking normal faults, leading to potentially larger Magnitude
earthquakes than previously recognized in the area. The left-step may act as a barrier to
rupture propagation and should be examined in more detail.
The northwestern Red Sea coast is part of the straight coastal segment that is generally
characterized as seismically inactive. However, during the geological field mapping, I found
evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal
and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and
earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces
implies that at least some of the coastal uplift was seismogenic, because terraces of the same
age can be found at different elevations along strike. Presumably, some of the seawarddipping,
N-S-striking normal faults are active today, despite the lack of recent instrumental
seismicity. These findings imply long recurrence intervals for active faults in the northern
Quseir area. These results differ from previously published results for the adjacent Quseir-Um
Gheig sub-basin area, were E-W-striking strike-slip faults were mapped to offset the N-Sstriking
faults, and had been inferred as earthquake-generating faults by Abd El-Wahed et al.
(2010). Based on our mapping, we postulate that the large rift-parallel normal faults are
seismogenic.
Drainage network evolution within the study area is often structurally controlled and the
nature of these controls was examined in this study. The Wadi Siatin stream channel network
is classified in a relatively simple way, based on the high-resolution satellite data, with
dendritic, and rectangular considered the most fundamental channel geometries.
It was possible to distinguish the different morphological elements of the network, as well as
the anomalies that affect the patterns. This analysis revealed, in the northern Red Sea area
basins, the existence of old structures whose successive reactivations have left their mark on
the drainage network. Comparison of joint systems direction with the directions of the main
trunk stream channel of Wadi Siatin shows that the channel is highly affected by tectonic
jointing. First-order channels follow easily erodable faults.
Investigations concerning the relationship of stream-flow orientation with geological
structure in the Wadi Siatin Basin shows that, generally, the least influenced flows are those
of first-order which are governed simply by the valley side slopes on which they developed.
However, in certain geological and geomorphological situations, there are clear exceptions to
this generalization. Certainly, locally, geological control of these small streams may be even
higher than in many streams of higher order. In the peripheral parts of the Basin, expansion of
drainage into the available space has obviously been easiest along lines of weakness and, as a
consequence of this, streams of the first order come to exhibit a high degree of adjustment to
the underlying structure. The maximum structural control is reached by the streams of the
third order. Towards the higher orders, the influence of local structure becomes weaker.
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Schwab, Julia [Verfasser]. "Sediment dynamic, slope instability and potential tsunami hazard at the outer Thai shelf margin, Mergui Ridge, Andaman Sea / Julia Schwab." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1150704381/34.
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Major, Josef. "Controls on mid-Holocene fringing reef growth and termination in a high latitude, estuarine setting, Wellington Point, Southeast Queensland." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/63964/1/Josef_Major_Thesis.pdf.
Full textAbstract:
Several fringing coral reefs in Moreton Bay, Southeast Queensland, some 300 km south of the Great Barrier Reef (GBR), are set in a relatively high latitude, estuarine environment that is considered marginal for coral growth. Previous work indicated that these marginal reefs, as with many fringing reefs of the inner GBR, ceased accreting in the mid-Holocene. This research presents for the first time data from the subsurface profile of the mid-Holocene fossil reef at Wellington Point comprising U/Th dates of in situ and framework corals, and trace element analysis from the age constrained carbonate fragments. Based on trace element proxies the palaeo-water quality during reef accretion was reconstructed. Results demonstrate that the reef initiated more than 7,000 yr BP during the post glacial transgression, and the initiation progressed to the west as sea level rose. In situ micro-atolls indicate that sea level was at least 1 m above present mean sea level by 6,680 years ago. The reef remained in "catch-up" mode, with a seaward sloping upper surface, until it stopped aggrading abruptly at ca 6,000 yr BP; no lateral progradation occurred.
Changes in sediment composition encountered in the cores suggest that after the laterite substrate was covered by the reef, most of the sediment was produced by the carbonate factory with minimal terrigenous influence. Rare earth element, Y and Ba proxies indicate that water quality during reef accretion was similar to oceanic waters, considered suitable for coral growth. A slight decline in water quality on the basis of increased Ba in the later stages of growth may be related to increased riverine input and partial closing up of the bay due to either tidal delta progradation, climatic change and/or slight sea level fall. The age data suggest that termination of reef growth coincided with a slight lowering of sea level, activation of ENSO and consequent increase in seasonality, lowering of temperatures and the constrictions to oceanic flushing. At the cessation of reef accretion the environmental conditions in the western Moreton Bay were changing from open marine to estuarine. The living coral community appears to be similar to the fossil community, but without the branching Acropora spp. that were more common in the fossil reef. In this marginal setting coral growth periods do not always correspond to periods of reef accretion due to insufficient coral abundance. Due to several environmental constraints modern coral growth is insufficient for reef growth. Based on these findings Moreton Bay may be unsuitable as a long term coral refuge for most species currently living in the GBR.
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Woulds, Clare. "Investigating the links between faunal activity and organic geochemistry in continental margin sediments : tracer studies across the Arabian Sea oxygen minimum zone." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/14707.
Full textAbstract:
The objectives of this study were to investigate the role that fauna play in short-term OM processing, how this varies with OM supply and quality, oxygen availability and faunal community structure, and how faunal activity is linked to sediment organic geochemistry. This was achieved through experiments and organic geochemical sampling, at sites spanning the OMZ on the Pakistan margin. The steep gradients in OM quantity and quality, oxygen, and faunal communities, and seasonal changes in OM supply, provided an exceptional natural setting to assess these relationships. Incubation studies were conducted on intact sediments containing whole faunal communities, aboard ship and in situ and using a novel system to maintain ambient oxygen levels. 13C-labelled algae were added to the sediments and traced into organisms, sediments, and respired pools. The resulting carbon budgets are some of the most complete to date, and allowed direct comparison among an unprecedented range of site conditions. Where macrofauna and higher-quality OM were present, OM uptake by fauna was greater; at one site macrofaunal uptake equalled total respiration, illustrating the key significance of fauna. Oxygen had a threshold effect on the faunal groups responsible for OM processing, with foraminifera and macrofauna dominating OM processing below and above the threshold, respectively. Notably, a new technique was developed for the quantitative tracing of labelled amino acids, which allowed the first molecular level tracing of OM in whole community and in situ experiments, and provided among the first direct links between faunal digestive activity and sediment OM composition. Compound-selective assimilation and OM alteration were observed, the patterns of which were taxon-specific.
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Chu, Fang-Yi, and 朱芳儀. "Variations of Sea Surface Temperature in the Asian Marginal Seas." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/y44wg6.
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碩士國立臺灣海洋大學
海洋環境資訊系
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This study used satellite sea surface temperature (SST) data from 1982 to 2017 to explore the SST trends in seven Asia marginal seas, including the Japan Sea, the Yellow Sea, the East China Sea, the South China Sea, the Gulf of Thailand, the Andaman Sea, and the Bay of Bengal. The SST data are derived using nonlinear algorithms derived from the Advanced Very High Resolution Radiometer onboard the US Oceanic and Atmospheric Administration (NOAA) series of satellites. Research results show the SST trends are related to latitude. The SST is rising at each marginal sea with a rate about 0.0384 ℃/year for the Sea of Japan, 0.0240 ℃/year for the Yellow Sea, 0.0288 ℃/year for the East China Sea, 0.0192 ℃/year for the South China Sea, 0.0108 ℃/year for the Gulf of Thailand, 0.0120℃/year for the Andaman Sea, and 0.0144 ℃/year for the Bay of Bengal. Generally, the SSTs rise faster in the marginal seas at mid-latitude than that at low-latitude. The same phenomenon also occurs in the trend of the annual highest SST and the annual lowest SST. The SST rising trends are higher with the annual highest SST at mid-latitude marginal seas, while are higher with the annual lowest SST at low-latitude marginal seas. However, the rising trend of the annual highest SST is more obvious. Comparing the average rising trend in summer and winter, the marginal seas at mid-latitude have a higher value of average SST trend in summer, while the marginal seas at low-latitude have a higher value of average SST trend in winter.