Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references. / This thesis primarily investigates how the conditions of crystallization affect the chemical evolution of magmas. A major focus is the effect of water on the stability of mineral phases, and how this affects both the differentiation of magmas and the modification of the upper mantle by hydrous fluid release during subduction. Chapter 1 models the crystallization of the asteroid Vesta, which melted almost completely during the early history of the solar system. Chemical modeling of the crystallization of this water-free "magma ocean" shows that the howardite-eucrite- diogenite (HED) meteorite suite that makes up Vesta's crust was likely formed by a combination of fractional crystallization and magmatic recharge from the asteroid's deeper interior. Chapter 2 investigates the sodium-rich tuffs deposited during the ~75 kyr eruption of Newberry Volcano, Oregon. Experiments at different pressures and water contents show that the magma differentiated in the shallow crust in the presence of 1-2 wt.% water. These conditions produce characteristic magma compositions that are also observed in many other parts of the Cascade arc and further afield. Chapter 3 tests the hypothesis that the tonalities, trondhjemites, and granodiorites (TTG) that make up much of the Archean crust may have been generated by fractional crystallization. Experiments show that fractional crystallization at modest water contents (1-2 wt.%) and high pressures (>/= 12 kbar) may have played an important role in the evolution of the Archean crust. Chapter 4 provides experimental constraints on the stability and composition of the hydrous mineral amphibole in the Earth's lithosphere. The results are used to develop a new thermobarometer for metasomatized peridotites, and provide improved constraints on the water storage capacity of the Earth's upper mantle and the conditions under which amphibole breaks down. Collectively, these studies show and help to quantify the important roles of fractional crystallization and water in modifying the crust and upper mantle of rocky planets. / by Benjamin Ehrlich Mandler. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaf 53. / by Richard A. Wagner, Jr. / M.S.

Thesis: Ph. D. in Geophysics, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 267-274). / A wide range of problems in seismology have a localized nature. Examples include inversion for time-lapse change, salt boundary position and Amplitude or Phase Versus Angle (AVA/PVA). With increasing computational power, many inversion procedures have transitioned away from forward models with simplified physics and now simulate synthetic wavefields on a model representation of the Earth. These simulated wavefields form the basis for the model updates in the inversion. Usually these wavefields are simulated on the entire computational model, even though the region of interest and the associated updates of the computational model are localized. In this thesis I explore ways of making use of the localized nature of the inversion by limiting the wavefield generation to the region of interest. This shrinking of the computational domain leads to faster solutions, reducing the time between the start and finish of the local inversion. This shorter turn-around time facilitates decision making and improves the interactivity of the inversion procedure. I first introduce a frequency domain local solver which can generate exactly the same wavefields as a full domain solver. I then apply this local solver to both a time-lapse problem and to salt boundary inversion. I then take a step back and look at time-lapse inversion outside the scope of local solvers. By looking at differences in the Full Waveform Inversion (FWI) gradient obtained from baseline and monitor datasets I compute a confidence map of locations likely to contain time-lapse change. This confidence map is then used to regularize a joint inversion for both the baseline and monitor datasets. I compare this methodology to other existing time-lapse algorithms on a synthetic North Sea model. In this study I notice the importance of post-critical reflections and become aware of their potential for reservoir characterization. Motivated by this observation I introduce a local solver for simulating elastic reflections in a region of interest. These elastic reflections can then be used for AVA and PVA to for instance invert for reservoir characteristics. The wavefield is efficiently propagated through the overburden using precomputed acoustic Green's functions obtained from a cheap acoustic solver. / by Lucas Abraham (Bram) Willemsen / Ph. D. in Geophysics

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984. / Bibliography: leaves 100-102. / by John McClements Lambie. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997. / Vita. / Includes bibliographical references. / by Laura Suzan Magde. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1998. / Includes bibliographical references (leaves 117-120). / by Xiaoyun Zang. / M.S.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2012. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 60-61). / Atmospheric thermal equilibration occurs when all thermal forcings diminish. Characteristics of equilibration include low diabatic heating and calm conditions throughout the atmospheric column. Large-scale planetary waves can remain in these equilibrated states for long time periods, as identified in previous work. Relationships between thermal equilibration and large-scale atmospheric blocking episodes however have not been explored in much detail previously. In this paper we evaluate whether or not thermal equilibration becomes more evident in blocking episodes. We identify wintertime, large-scale blocking episodes over the North Atlantic and Europe using a dynamical blocking index on the ECMWF ERA40 reanalysis dataset. After identifying episodes, evidence of thermal equilibration is presented and analyzed through global composites of atmospheric variables in blocked and nonblocked situations. Relationships between potential vorticity and streamlines are also described and presented through scatter plots. Results from composites, and primarily scatter plots, provide significant evidence that thermal equilibration is more probable in blocking episodes than in non-blocked states. / by Roman S. Kowch. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994. / Includes bibliographical references (leaves 256-267). / by Renyi Zhang. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2003. / Includes bibliographical references. / Recent field work and DEM analysis show that remnant, local areas of a low-relief land scape (or "erosion surface") are geographically continuous across the southeastern Tibetan Plateau margin and can be correlated in order to define the maximum envelope of topogra phy of the margin itself. This observation contradicts earlier notions that the low-gradient plateau margin slope (i.e. the maximum elevation of the margin) is a product of landscape dissection and reduction by fluvial incision due to the presence of major rivers which drain this portion of the plateau and plateau margins. Although initial development of the erosion surface is likely diachronous, we propose that a continuous low-relief landscape existed at low elevations prior to uplift and long-wavelength tilt of the southeastern plateau margin. The modern altitude of the erosion surface provides an excellent datum for constraining the total amount of surface uplift of the southeastern plateau margin. The long-wavelength tilt of the surface across the plateau margin without major disruption mirrors the low-gradient decrease in crustal thickness across the plateau margin, which suggests that crustal thickening has occurred in a distributed manner. Because large-magnitude compressional structures of late Cenozoic age are lacking, we propose that crustal thickening beneath the southeastern plateau margin has largely been accomplished by preferential thickening the lower crust. Perched, relict landscape remnants that reflect slow erosion, low initial elevations and slow uplift rates contrast sharply with the rapidly eroding modern river gorges that incise the surface, indicating that the modern landscape is not in equilibrium. Surface remnants are preserved because incision of the fluvial system has been largely limited to major rivers and principle tributaries, and has not yet progressed throughout the entire fluvial network. / (cont.) This "transient condition" of the landscape in southeastern Tibet reflects the initiation of rapid bedrock incision into a developing plateau margin, and the altitude of the remnant erosion surface can also be used as a datum by which to measure the total amount of erosion since the beginning of plateau uplift. 2.1 Introduction The continent-continent collision between India and Eurasia is largely responsible for creating the Tibetan Plateau, the most extensive region of elevated topography on Earth [Figure 2.1]. The development of such an anomalously high landmass has been of interest to scientists in a broad range of disciplines ranging from lithospheric dynamics to the inter action between tectonics, climate and surface processes. Studies of the Tibetan Plateau have raised several first-order questions such as: 1) how is plate convergence accommodated in the continents and what are the relative contributions of continental subduction, uniform or differential shortening in the upper and lower crust, and lateral extrusion of rigid lithospheric blocks?; 2) how do spatial (or temporal) variations in crust and mantle rheology partition deformation throughout theorogen?; 3) does the convective removal of the mantle lithosphere contribute to surface uplift and high plateau elevation? ... / by Marin Kristen Clark. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, September 2000. / Includes bibliographical references. / Experimental and numerical modeling studies are used to place constraints on the kinetics of chemical exchange during partial melting within the mantles of the terrestrial planets. Chapter 1 presents experiments on the diffusion rates of La, Ce, Nd, Dy and Yb in diopside at pressures of 0 to 2.5 GPa and temperatures of 1050 to 1450 'C. The results demonstrate a large variation in diffusivity among the rare earth elements, with the diffusion coefficient for La a factor of -35 smaller than for Yb at a given temperature and pressure. Chapter 2 presents experiments on the diffusion of Sm, Dy and Yb in pyrope at 2.8 GPa and 1200-1450 "C. No significant difference in diffusivity is found among these elements, and their absolute diffusion rates are similar to those of the heavy rare earth elements in diopside at the same pressure and temperature. Chapter 3 presents a numerical model for diffusion-controlled fractionation of trace elements during adiabatic decompression melting of a polyphase solid. The model is used to simulate the fractionation of rare earth elements between solid and melt during partial melting of Earth's upper mantle. Diffusion is found to exert a strong control on the evolution of the system at conditions typical of melting beneath ocean spreading centers, leading to less efficient fractionation of the rare earth elements than under conditions of local chemical equilibrium. Chapter 4 presents experiments on the diffusion of U and Th in diopside at I atm pressure. Uranium and thorium are found to diffuse at similar rates, and diffusive fractionation between these elements is therefore unlikely to be significant during partial melting in Earth's upper mantle. Thorium and radium may be diffusively fractionated, however, enhancing the production of 22 Ra/230Th radioactive disequilibrium during partial melting while inhibiting chromatographic fractionation during melt transport. Chapter 5 presents phase equilibrium and dissolution kinetics experiments that constrain hypotheses for the origin of lunar high-Ti ultramafic glasses. The experimental results demonstrate that assimilation of ilmenite-bearing cumulates is not a viable mechanism for production of the high-Ti glasses. It is proposed that the source of the high-Ti ultramafic glasses formed by shallow level mixing and reaction of late-stage magma ocean liquids with underlying olivine-orthopyroxene cumulates, followed by sinking of these dense hybrid materials into the lunar mantle. / by James Ashton Van Orman. / Ph.D.