Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009. / Includes bibliographical references. / The primary goal of my doctoral research is to understand the crustal and upper mantle structure and deformation in southeastern Tibet. To improve the resolution in the crust, we developed a new approach for surface-wave array tomography by combining inter-station phase velocity dispersion measurements from empirical Green's functions (EGFs) recovered from ambient noise interferometry and from traditional teleseismic surface-wave two-station (TS) analysis. The non-stationarity (e.g., seasonal changes) and non-uniform distribution of ambient noise sources may obstruct full reconstruction of the surface-wave Green's functions, which may, in turn, degrade the accuracy of the tomographic models. Under the assumption of plane-wave propagation, we developed an iterative method to estimate ambient noise energy distribution, phase velocity bias primarily due to uneven noise energy distribution, and azimuthally anisotropic phase velocity maps. With phase velocity dispersion measurements at periods 10 - 150 s from 1 year data of 75 broad band stations in SE Tibet, we performed inversion for wavespeed variations and azimuthal anisotropy. The tomographic images revealed widespread crustal low-velocity zones (LVZs) at middle/lower crustal depth beneath SE Tibet. There is substantial lateral and vertical variability of these zones and some may be truncated by large faults. / (cont.) The pattern of azimuthal anisotropy in the upper crust is consistent with clockwise rotation around the eastern Himalaya syntaxis and a predominance of simple shear and strike-slip faulting in SE Tibet. Comparison of splitting from SKS observations and from our 3D anisotropic model suggests that the contribution to splitting from the crust is at least as important as from the upper mantle in the region west of Sichuan Basin and north of 26°N. However, beneath Yunnan, splitting signal originates mainly from the upper mantle. The radial changes in deformation pattern argue against vertically coherent lithospheric deformation in Tibet. Combined with the widespread crustal LVZs, this supports models of ductile crustal flow beneath SE Tibet. However, the spatial variation in strength and depth of crustal LVZs and in pattern of azimuthal anisotropy suggests that the 3-D geometry of crustal weak layers is complex and that unhindered crustal flow over large regions may not occur. / by Huajian Yao. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985. / Microfiche copy available in Archives and Science. / Includes bibliographies. / by Benoit J. Paternoster. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997. / Includes bibliographical references (leaves 31-36). / by Dana Ruth Stuart. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (leaves 255-259). / by Huai-Jen Yang. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmosphere and Planetary Sciences, 1988. / Includes bibliographical references. / by Clark Bruce Freise. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1986. / Microfiche copy available in Archives and Science. / Bibliography: leaves 89-90. / by Paul James Hancock. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000. / Includes bibliographical references (p. 225-248). / Near-infrared spectra (~0.90 to ~1.65 microns) were obtained for 196 main-belt and near-Earth asteroids to determine plausible meteorite parent bodies. These spectra, when coupled with previously obtained visible data, allow for a better determination of asteroid mineralogies. Over half of the observed objects have estimated diameters less than 20 k-m. Many important results were obtained concerning the compositional structure of the asteroid belt. A number of small objects near asteroid 4 Vesta were found to have near-infrared spectra similar to the eucrite and howardite meteorites, which are believed to be derived from Vesta. These asteroids appear almost certainly to be fragments of Vesta. Spectral variations between these objects are consistent with being primarily due to differences in particle size. These asteroids also tend to have stronger band depths with increasing ejection velocity from Vesta. Objects with distinctive olivine bands appear to provide definitive evidence that spectral alteration is occurring in the asteroid belt. These objects have similar band depths but appear significantly reddened relative to measured olivine samples due to their significantly higher reflectance values with increasing wavelength. The only laboratory-simulated "weathering" process that reddens the spectra but does not significantly suppress the bands is alteration by laser irradiation, which is hoped to duplicate the effects of micrometeorite bombardment. A number of plausible main-belt parent bodies were identified. These include 19 Fortuna and the CM chondrites, Eos family members with the CO chondrites and 599 Luisa with the CV chondrites. A significant fraction of S asteroids have spectral properties that range from similar to ordinary chondrites to much redder with weaker absorption bands. These objects tend to have spectra consistent with a mixture of ordinary chondrite material and metallic iron. However, other alteration processes cannot be ruled out. Asteroids with distinctive olivine bands are relatively rare. The available evidence is consistent with a scenario where, with the exception of Vesta, all differentiated bodies were either disrupted or had their mantles stripped very early in the age of the solar system. Olivine-rich metal-free fragments were then continually broken down until they almost all now fall below our current astronomical measurement limits. / by Thomas H. Burbine, Jr. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2013. / "June 2013." Cataloged from PDF version of thesis. / Includes bibliographical references (pages 23-24). / This thesis was designed to make spectroscopic measurements of Ceres within the visible spectrum, specifically within the wavelength range of 6000 and 7000 Angstroms. The asteroid was observed for 6 nights, for lengths of time varying from 3 to 7.5 hours. The main goal was to support/refute the previous findings about absorption features within the wavelength range being observed. Additionally, this thesis was designed to determine the rotational variability of minerals on Ceres. In order to determine the asteroid's variablity, the rotational period of Ceres was divided into eight phases, and average spectra were determined for each phase. The results show that there is a weak rotational variability of the feature between 6200 and 6400 Angstroms. The feature varies over the surface of Ceres by 2.5% with a mean error of 1.6%. There have been previous reports of absorption features on asteroids between 6000 and 6500 Angstroms, which have been associated with ferric Fe absorptions in Fe alteration minerals. Examples of such minerals include goethite and iron oxide hematite. / by Phoebe J. Henderson. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2004. / Some pages folded. / Includes bibliographical references. / (cont.) Xianshuihe-Xiaojiang fault system during growth of the southeast plateau margin. Cosmogenic ²⁶A1 and ¹⁰Be basin-wide erosion rate and burial ages indicate a background incision rate of [approximately] 0.05 to 0.10 mm/a, lower than the long-term incision rate minimum of [approximately] 0.26 mm/a. Cosmogenically-determined incision rate approximately doubles to [approximately] 0.20 mm/a in the region of maximum dip-slip displacement on the Red River fault. This thesis also develops a new cosmogenic tool for quantitative landscape analysis: using depth dependence data for multiple cosmogenic nuclides from a single site to constrain an erosion history. This method is applied in the Dry Valleys region of Antarctica. / This thesis outlines the Cenozoic development of the Red River region, exploring regional landscape evolution and tectonic accommodation of the India-Eurasia collision, focusing on the Oligo-Miocene, left-lateral Ailao Shan shear zone and the active, right-lateral Red River fault on the northeast margin of the shear zone, along which the Red River has incised a deep valley. Oligo-Miocene fluvial and alluvial conglomerates in the valley record shear zone unroofing: pervasive, syn-depositional shortening indicates transpressional exhumation. A low-relief landscape, developed in Late Miocene time, was probably uplifted in Pliocene time, triggering the incision of the Red River and isolating the low-relief landscape from modem base level. On the basis of stratigraphic data, river incision began in Pliocene time or later. Tributary longitudinal profiles indicate two-phase incision, the result of pulsed plateau growth or trunk channel adjustments to changing climate conditions. Paleo-Red River reconstruction indicates [approximately] 1400 m river incision, 1400-1500 m surface uplift and 750 m vertical displacement across the northern part of the Red River fault. Minimum right-lateral displacement on the fault is 40 km, 15-16 km of which predates river incision, plateau growth and development of other regional fault systems. Long term average slip-rate is a minimum of [approximately] 5 mm/yr. Rotation of a crustal fragment around the eastern Himalayan syntaxis, bounded on the east by the Xianshuihe-Xiaojiang fault system, causes deflection of the Red River fault, accommodated by distributed shear along strike of the Xianshuihe-Xiaojiang fault system. The Red River fault has decreased in regional importance since the initiation of the / by Lindsay M. Schoenbohm. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1987. / Microfiche copy available in Archives and Science. / Bibliography: leaves 71-75. / by Marc H. Larrère. / M.S.