Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1992. / Title as it appears in the M.I.T. Graduate List, June 1992: Variability of currents in Great South Channel and Georges Bank, observation and modeling. / Includes bibliographical references (leaves 260-270). / by Changsheng Chen. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002. / Includes bibliographical references. / Geochronological, thermochronological and isotopic studies of kimberlite-borne crustal xenoliths have been used to elucidate the architecture and thermal evolution of the continental lithosphere of southern Africa. U-Pb accessory mineral geochronology of lower crustal xenolith assemblages illustrate the youth of granulite-facies metamorphism relative to the ancient stabilization of the craton, and demonstrate two distinct processes for their generation. Granulitic lower crust at the craton margins and in the bounding Proterozoic belts was generated during 1.1 to 1.0 Ga Namaqua-Natal orogenesis, in response to collisional crustal thickening. Ultra-high temperature granulites in the central cratonic lower crust were generated during dramatic advective perturbation of the lithosphere during 2.7 Ga Ventersdorp rifting and magmatism. Utilizing the U-Pb systematics of titanite, apatite and rutile- minerals with closure temperatures for Pb diffusion of 650 to 400ʻC- the thermal evolution of the lower crust and underlying lithosphere has been constrained. Thermal relaxation times for the lithosphere following tectonothermal perturbation indicated by these data (400-600 Ma) are consistent with predictions of simple conductive cooling models, however initial cooling rates in the lithosphere are slower than predicted. Closure of the U-Pb system in rutile, heralding the establishment of cratonic geotherms in the Proterozoic belts of southern Africa by 700 Ma, demands lithospheric thickness comparable to that beneath the Archean cratons. / (cont.) Lower crustal thermochronology also reveals the influence of a thermal perturbation to the southern African lithosphere in the Late Mesozoic, consistent with a broad upper mantle thermal anomaly associated with southern Gondwana breakup. The patterns of lower crustal heating are spatially and temporally complex, suggesting the importance of pre-existing lithospheric structure as a control on advective focussing. U-Pb zircon geochronology of basement lithologies from the western Kimberley domain of the Kaapvaal craton constrain a model for Neoarchean accretion of the Kimberley block to the eastern Kaapvaal shield at 2.9 Ga. The timing of this convergence through subduction beneath the western domain is correlated with a variety of Re-Os model ages for the underlying lithospheric mantle of the western craton, including peridotite depletion ages, eclogite formation ages and sulfide diamond inclusion ages, and suggests significant coupling of continental crust and lithospheric mantle formation and modification during convergent margin processes. / by Mark D. Schmitz. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001. / Includes bibliographical references (leaves 77-79). / Thermodynamic analysis and numerical modeling of hurricane intensity has shown that its is controlled by the enthalpy transfer from the ocean surface and by drag. Direct measurements of drag, evaporation, and sensible heat transfer are not easily performed on the high seas. Therefore, a wind wave tank has been constructed in which a few aspects of a tropical storm are simulated. The air velocity inside the annular tank is comparable to that of hurricane. However, the three dimensionality of the tank obscures the quantitative comparison between experiments and actual conditions over the surface of the ocean at high wind speeds. The design of the wind wave tank and the initial experiments create a foundation for future and more comprehensive experimental programs. This thesis focuses mainly on the design and engineering of the tank, and on the fluid mechanics of the rotational flow in the tank. It also provides preliminary experimental data on the drag at high wind speeds obtained by using spindown experiments. / by Moshe Alamaro. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references. / by Glenn Allan Gaetani. / Ph.D.

Thesis (S.M. in Geophysics)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 92-97). / Pressure solution is a naturally occurring deformation process in fluid-bearing rocks, with implications for sediment consolidation rates and deformation in the mid to upper crust. The process involves dissolution at asperities under load; diffusion along grain-to-grain contacts; and precipitation in the pore space. The kinetics of the process and the identity of the rate-limiting step in quartzose rocks are still a subject of debate and depend critically upon the structure of the inter-granular boundary during deformation. To investigate the mechanisms and kinetics of pressure solution and the effects of changes in boundary morphology, we continuously monitored deformation and the evolution of boundary morphology at a Y-cut convex quartz lens that was pressed against a flat surface of Y-cut quartz under hydrothermal conditions (425 0C, 150 MPa fluid pressure, 80-435 MPa effective normal stress) in a see-through optical pressure vessel. The pore fluid was de-ionized water, which became saturated with quartz during the initial heat-up period. Several different boundary morphologies were used, including polished flats, etched and roughened flats, and an island-channel structure fabricated by plasma etching. The island-channel structure had square pillars of quartz, either 4 micro meter or 8 micro meter on a side, surrounded by an inter-connected grid of open channels of comparable width. Deformation at the interface between the quartz flat and lens (i.e., inter-granular convergence) was observed in only one case: the 4pum island-channel structure. In that instance, pillars within the contact region were eroded at a rate that decreased with time, and SEM photomicrographs after the experiment showed significant cataclasis within and adjacent to the pillars. The total transient convergence (0.15i0.02pum) observed during the 472 hour period was less than the original pillar height (0.55±0.005pim). For all surface morphologies, the shapes of the surface structures in both the loaded and unloaded regions evolved, perhaps owing to capillarity forces. Although an inter-connected island-channel structure was initially imposed upon some of the experiments, this open, fluid-filled boundary structure was seen to be a transient phenomenon that was largely destroyed during convergence. Thus, there was no evidence for a dynamically stable interface, as previously suggested. / by Sudhish Kumar Bakku. / S.M.in Geophysics

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 41-43). / Mercury pollution can cause harmful impacts on human health and the environment, a concern that is magnified in marine environments like the Great Lakes. While there are many local, national, and global efforts to track emissions, one key complication to accurately estimating atmospheric mercury is the disagreement between the two national EPA inventories, the National Emissions Inventory (NEI) and Toxics Release Inventory (TRI), which differ in both location and magnitude of emissions. By comparing the NEI and TRI datasets from 2008 and 2011 in the states bordering Lake Superior, this study aims to uncover potential biases in each inventory and determine when a given inventory is more accurate. Additionally, year-to-year TRI emission totals since 2000 are studied to produce a more precise visualization of mercury trends in the Lake Superior Basin. The most notable difference between the two inventories was the absence of mining in TRI, one of the most significant sectors in NEI for both years studied. The utilities sector, however, showed more agreement between the two inventories. The relationship between the NEI and TRI numbers for the facilities within the utilities sector that were found in both datasets was found to be TRI = (1.206)NEI, matching the results from a previous study. Additionally, the study of the yearly TRI data from 2000 to 2014 showed that while average emissions per facility have been declining since 2000, particularly in the manufacturing sector, there is a surprising degree of variability in yearly totals than expected, exposing a potential topic of future research. / by Elizabeth Berg. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993. / Includes bibliographical references (p. 249-254). / by Joseph R. Materese. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 197-209). / by Mark Simons. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998. / Includes bibliographical references (p. 169-180). / by John J. Graham, Jr. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (leaves 227-234). / by Zhongxiang Wu. / Ph.D.