Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"Passive Margins"”.
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Evolution of transient topography on passive margins: A study of landscape disequilibrium in the southern Appalachian Mountains
… appropriate, path to present base level. Passive margins may therefore never achieve a topographic steady-state, despite uniformly slow and constant uplift due to isostatic rebound.
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A combination of apatite fission track and (U-Th)/He thermochronometers to constrain the escarpment evolution in south eastern Australia: a case study of high elevation passive margins
… regions of the eastern Australia high elevation passive margin. Two traverses across the coastal lowlands, escarpment and plateau top are used to determine the tempo and styles of response of the landscape to the continental breakup and sea-floor spreading of the Tasman Sea (85 Ma). The three …
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The Significance of Densely Sampled Observations of Mantle Dynamic Topography
… are similar to a more complex numerical model. Passive margins provide an excellent natural laboratory for studying the influence of dynamic topography. Despite tectonic quiescence, topography along passive margins is highly variable. Elevated passive margins are often associated with …
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Post-Orogenic Exhumation and Glacial Erosion on the Flanks of the North Atlantic
Many passive margins experience pulsed exhumation events late in their history as a result of plate boundary distal geodynamic mechanisms or climatic events. The onset of late Cenozoic glaciation, often associated with enhanced rates of erosion, is one such possible cause of passive margin …
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Recalibrating the breakup history of SW Gondwana: the first U-Pb chronostratigraphy for the Uitenhage Group, South Africa
… for initiation and evolution of rift basins and passive margins. The structurally preserved erosional remnants of several rift basins that formed during the Mesozoic breakup of Gondwana are located within the southern Cape region of South Africa. These onshore basins contain the Suurberg and …
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A numerical compaction model of overpressuring in shales
… overpressuring in sediments accumulating along passive margins is nonequilibrium compaction. In general, smectite dehydration and aquathermal pressuring play minor roles in the development and sustenance of overpressuring. Comparison of model cases and Gulf Coast overpressured cases shows that …
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Constraints on passive margin escarpment evolution from river basin reorganization in Brazil
Escarpments are present on passive margins around the world, but their evolution is poorly understood. Some geologists interpret escarpments as stationary features, whereas others have argued that they are retreating inland faster than a kilometer per Myr. I investigate Brazilian escarpments by …
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The Middle Ordovician Knox unconformity, Virginia Appalachians: transition from passive to convergent margin
… shelf carbonate deposition on a passive margin to carbonate and clastic deposition in a foreland basin associated with a convergent margin, possibly during a time of global sea-level lowering. Erosional relief on the unconformity decreases from over 140 m in southwest Virginia to …
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Contractional tectonics : the Himalayan orogen and Perdido fold-thrust belt
… collisional orogenic belts and toe structures of passive margins, which are characterized by fold-thrust belts that are hundreds of kilometer-scale and tens of kilometer-scale, respectively. The Himalayan orogen is an excellent example of collisional orogenic belts along convergent plate …
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Continental Deformation: Collisional Orogenesis to Passive Margin Processes
… the Wilson cycle, intracontinental collision and passive margin development. I present a map of NW Nepal river channel steepness (ksn), a proxy for rock uplift rate over 103-105 years, coupled with a seismotectonic model, and then expand this map and accompanying model to the entire Himalaya; and …
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Deep-marine depositional systems of the western North Atlantic: Insights into climate and passive-margin evolution
… deposits in deep-marine settings, particularly passive margins, provide a unique, long-term record of paleoclimate, paleoceanography, and tectonics affecting the basin in question. Whereas deep-marine strata may be used to answer myriad of questions regarding the evolution and development of …
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The Global Detrital Zircon Database: Quantifying the Timing and Rate of Crustal Growth
… of the host sediment. Rift basins and active margins exhibited smaller offsets from the youngest zircon grain age to host sediment maximum age than observed in samples from passive margins. This study recommends that at least 50 grains need to be age dated on average in order to best constrain …
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Testing the Origins of the Blue Ridge Escarpment
… high-relief escarpments mark many of the world's passive margins. These Great Escarpments have been interpreted to be the result of isostatic flexure, parallel slope retreat, and divide migration which accompanies rifting. It is unclear whether all these escarpments share this origin. Also …
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Cyclostratigraphy of Late Cambrian cyclic carbonates: An interbasinal field and modelling study, U.S.A.
… successions in the Appalachian and Cordilleran passive margins, the Texas cratonic embayment and the southern Oklahoma aulacogen has provided controls on the simultaneous development of peritidal to subtidal meter-scale cycles and the larger scale depositional sequences on which they are …
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Understanding Non-Plume Related Intraplate Volcanism
… can better understand the post-rift evolution of passive margins. This study presents a comprehensive set of geochemical data that includes new 40Ar/39Ar ages, major and trace-element compositions, and analysis of radiogenic isotopes to further constrain their magmatic history. Modeling suggests …
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QUASI STATIC GRAVITY SIGNATURES IN SLOW TECTONIC ZONES: ASSIMILATION OF NOVEL AEROSPACE DATA AND GEOPHYSICAL MODELING
… that the Gulf of Aden developed as a slow passive rift in thin lithosphere with thick crust and that the variations in features along the passive margins could be related to lateral variations in the amount of H2O in the mantle, which determines the different times of mantle melting.
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Evolução tectônica do segmento extremo leste da Margem Equatorial brasileira: contribuição do mapeamento estrutural (onshore) e da modelagem física
… this margin comprises intracontinental rifts and passive margins. In the present work, we investigated the evolution of the ETM, from the application of the structural physical modeling tool and a multiscale analysis of the brittle deformation record in the crystalline basement of the Potiguar and …
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A quantitative approach to the evolution of the central Walvis Basin offshore NW-Namibia : structure, mass balancing, and hydrocarbon potential
… of the South Atlantic and its conjugated pair of passive continental margins. The Walvis Basin offshore NW-Namibia is an Early Cretaceous to recent depositional centre with a typically wedge-shaped postrift sedimentary succession covering an area of 105000km2. A 2D model transect across the …
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Modelling plate kinematics in the Scotia sea
… inversion to reconstruct the west Scotia Sea's margins between its inception at thron C8 (- 26.5 Ma) and extinction at chron C3a (- 6 Ma). The results suggest strongly, and for the first time, that the west Scotia Sea formed as a small ocean basin whose passive margins were Tierra del Fuego and …
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Closure of the Neotethys Ocean in Anatolia : structural, petrologic and geochronologic insights from low-grade high-pressure metasediments, Afyon Zone
… sequences deposited along continental passive margins that were metamorphosed under low-grade, high-pressure conditions, i.e., low temperature/depth ratios (< 15°C/km) with respect to geothermal gradients in tectonically stable regions. Throughout the Mesozoic and Cenozoic (i.e., since …
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