The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation. In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr. In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth. In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.

Campaign GPS measurements during 2001-2003 in the transition between subduction and collision of the Banda arc reveal how strain is partitioned away from the trench and distributed to other parts of the arc-trench system. Genrich, et. al. (1996) conducted a GPS campaign (1992-1994) throughout the Eastern Sunda and Banda arcs that demonstrated partial accretion of the arc to the Australian plate. We reoccupied many of the sites from this earlier study and 7 additional stations, 3 of which are new benchmarks. Our study shortened many baselines and extended the observation epoch to ten years for many key stations. The resulting GPS velocity field for the active Banda arc-continent collision reveals: 1) several mostly rigid crustal blocks exist in the transition from subduction to collision, 2) relative to an Asian reference frame, most of these blocks move in the same direction as the Australian lower plate, but at different rates, 3) block boundaries may exist between the islands of Lombok and Komodo, Flores and Sumba, Savu and West Timor, and between Timor and Darwin, 4) the Timor Trough may account for at least 20 mm/yr of motion between Timor and Darwin, 5) a major transverse fault off the coast of West Timor separates the Savu/Flores/Sumba block from the Timor/Wetar Block and may account for variations in movement in Rote, 6) the Flores thrust moves the eastern Sunda arc north relative to Asia by decreasing amounts to the west, 7) the back-arc Wetar Thrust system takes up the majority of plate convergence between Australia and Asia, and 8) fault boundaries are not found between many blocks, such as various islands of the Sunda arc and forearc with different amounts of motion.

Triple junctions form at the intersection of three tectonic plates and are a necessary consequence of new microplate formation. The splitting of a plate into two smaller plates always results in the formation of two triple junctions. As a result, they are fundamental structural elements of ocean floor geodynamics. Their evolution is influenced by the complex interplay of near- and far-field plate dynamics, crustal types, and mantle processes, and they include a wide range of boundary types. The long-term stability and evolution of triple junctions are influenced by continuous plate reorganization, such as in the complex microplate mosaics of the Western Pacific margin. To better understand how triple junctions form and respond to near- and far-field stresses, this study presents a detailed examination of the North Fiji Basin Triple Junction (NFBTJ), which is located within one of the largest and most mature back-arc basins of the Pacific margin. A new geological map of the NFBTJ at a 1:500,000 scale is presented. The mapping provides insight into the factors controlling plate fragmentation and crustal growth during triple junction formation. The map is based on a compilation of more than 50 years of ship-based bathymetry, backscatter data, gravity and magnetics used to reconstruct the spreading history, magmatic productivity, tectonic fabric and origin of geological formations of the basin. These aspects also have important implications for understanding the origins and evolution of large-scale back-arc basin hydrothermal systems. Crustal growth in the NFB is recorded by the area-age relationships of different geological formations identified in the new geological map. The triple junction is the site of volume addition related to enhanced magmatic productivity, with a large Central Volcanic Complex (CVC) (shield volcano and inflated ridge) at its centre and a well-developed spreading ridge along the SW limb. Extensive lava flows emanating from the CVC covers early spreading-related fabric in the NE and NW limbs. The large shield volcano, which is 0.5 km high and occupies an area of at least 62.3 km², has a distinctive 2.5-km diameter summit caldera with extensive hydrothermal activity in the south. The CVC and surrounding lava flows are estimated to have grown in place at a rate of 3,000 m²/yr, thus dominating the recent history of the NFBTJ. By contrast, earlier crustal growth along the SW and NW spreading segments, prior to the emergence of CVC, is estimated to have been ~1,650 m²/yr and 200 m²/yr respectively. The quantitative analysis of rifting and the eruptive history highlight previously unrecognized near and far-field geodynamic influences on the triple junction formation. In particular, the pulse of crustal growth at the NFB beginning at 3 Ma was related to rift propagation from the south in response to rotation of the NFB that produced some of the fastest growing crust in the oceans. Comparisons with a global database of triple junctions show that the evolution of the NFBTJ shares many features with other microplate mosaics and that processes related to triple junction formation is associated with crustal growth wherever triple junctions occur. The high heat flow and voluminous mafic magmatism has been compared to rapid crustal growth in some ancient greenstone belts, such as the Archean Abitibi Greenstone Belt in the Superior Province of Canada. In particular, the NFBTJ is a possible modern analog of large central volcanic complexes that characterize ancient greenstone-belt development.

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<p>Magnetic surveys are one of the principal geophysical methods employed to map the structure of basement rocks deeply buried below cover strata. In resource studies, aeromagnetic surveys are commonly acquired at regional scales (100-1000’s km2) while very few studies have attempted to resolve basement structures at site-scale (<10 >km2). In this study, high-resolution lake-based magnetic survey methods were evaluated for mapping of deeply-buried basement faults (Küçükçekmece Lagoon, Turkey; 6 km2) and a suspected meteorite impact crater (Charity Shoal, Lake Ontario; 9 km2). Total magnetic intensity (TMI) surveys were acquired using a single Overhauser magnetometer with 50-150 m line spacing. Interpretation of the magnetic data was aided by forward modelling of TMI data and depth to basement estimates using Euler and analytic signal methods. Total magnetic intensity (TMI) maps of Küçükçekmece Lagoon identify several north-northwest trending (340-350°) magnetic lineaments that are aligned with strike-slip faults mapped from offshore seismic data. The pattern of magnetic anomalies in the lagoon is consistent with extensional normal faulting of bedrock and lake sediments. Magnetic results from Charity Shoal reveal a large (>1400 nT) parabolic-shaped magnetic anomaly centered over the crater basin and an annular magnetic high (40-50 nT) corresponding with the basin rim. Modelling results exclude the origin of the CSS as a shallow glacial erosional or karst sinkhole feature and are most consistent with a pre-Paleozoic meteorite impact in the Precambrian basement.</p> / Master of Science (MSc)

The late Mississippian carbonates in the Appalachian Basin, U.S.A., were deposited on a huge, south-facing ramp during long-term Mississippian transgression that formed the Mississippian supersequence. The St. Louis- to Glen Dean interval consists of up to twelve fourth-order depositional sequences (300 to 400 k.y. average duration). The sequences (a few meters to over a hundred meters thick) consist of eolianites, lagoonal carbonate muds, ooid shoals, and skeletal banks, and open marine skeletal wackestone and basinal marion the ramp-slope and basin margin. Sequence boundaries are at the top of prograding red-beds, eolianites, and shoal water facies on the ramp, and beneath lowstand sand bodies and quartzose calcisiltite wedges on the ramp margin and slope. Maximum flooding surfaces are difficult to map regionally, therefore it is difficult to separate the TST from the HST of these fourth-order sequences. / Ph. D.

Like Art, Architecture has the potential to impact people. Art is often considered the process of consciously arranging elements in a way that appeals to the senses or emotions. Architecture can also be described similarly. However, the key difference between Art and Architecture is that while Art is pure personal expression, Architecture carries with it a certain accountability towards its immediate context and inhabitants. While a painting begins and ends on a canvas, Architecture cannot stop at a whim; it must transform from imagination to tangible reality. This process brings with it, a set of constraints imposed by structural, climatic, socio-economic aspects, construction methodologies and material properties, amongst others. These constraints call for fine-tuning of the design. The sophistication and elegance used to handle these constraints differentiate a "building" that poses as a mere visual sculpture in isolation, from "architecture" that evolves as a response to its context and people. Matthew Frederick (2007) says, "being genuinely creative requires something different from conventional, authoritarian control; a loose velvet tether". The "velvet tether" possibly represents the constraints that need to be navigated through, during the realization of the project. The central focus of this thesis is to explore how to address some of those constraints, through the design of a school campus for students of music and dance. The program includes practice, rehearsal and classroom spaces for music and dance, administrative spaces and a library. Themes explored as part of the design development process include architectural form, materiality and detailing. / Master of Architecture

Increasingly, teachers are encouraged to use data resources in their classrooms, which are becoming more widely available on the web through organizations such as Digital Library for Earth System Education, National Science Digital Library, Project Kaleidoscope, and the National Science Teachers Association. As "real" data becomes readily accessible, studies are needed to assess and describe how to effectively use data to convey both content material and the nature of scientific inquiry and discovery. In this study, we created two introductory undergraduate physical geology lab modules for calculating plate motion. One engages students with a model-driven approach using contrived data. Students are taught a descriptive model and work with a set of contrived data that supports the model. The other lab exercise uses a data-driven approach with real data. Students are given the real data and are asked to make sense of it. They must use the data to create a descriptive model. Student content knowledge and understanding of the nature of science were assessed in a pretest-posttest experimental design using a survey containing 11 Likert-like scale questions covering the nature of science and 9 modified true/false format questions covering content knowledge. Survey results indicated that students gained content knowledge and increased their understanding of the nature of science with both approaches. Lab observations and written interviews indicate these gains resulted from students experiencing different pedagogical approaches used in each of the two labs. / Master of Science