Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989. / Includes bibliographical references (leaves 156-158). / by Stephen Hoyt Hickman. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 109-112). / by Marja Helena Bister. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1992. / Maps folded in pocket following text. / Includes bibliographical references (leaves 41-44). / by Eric J. Buchovecky. / M.S.

Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 31-35). / The Dakota Formation was deposited during the Cenomanian, a time when the Western Interior Seaway spanned much of North America. The Dakota Formation contains a rich record of plant and animal fossils. Key to understanding their importance, it is imperative to precisely place the Dakota Formation within the geological time scale. Volcanic ash samples interlayed with fossil bearing sandstones of the Dakota were collected from two localities in Westwater, and Henrieville, Utah. Samples were dated using isotope dilution thermal ionization mass spectrometry (ID-TIMS). The samples collected from the Westwater, Utah localities have a weighted mean 206Pb/238U date of 97.656±0.082 Ma, while the samples taken from Henrieville, Utah have weighted mean 206Pb/238U dates of 95.170 0.056 Ma and 94.941±0.032 Ma. Based on an analysis of stratigraphic, paleontological, and geochronological data, the Dakota Formation was then correlated across much of the Western Interior. These dates provide a base of the initiation of the transgression across Utah, and set a context for the CT boundary and OAE2 that follow. / by Laura Meyer. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991. / Includes bibliographical references (leaves 39-41). / by William Burrell Jones. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997. / Includes bibliographical references (leaves 106-110). / by Elliot Ede Ibie. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 18-24). / The Beni Bousera ultramafic massif is a tectonically emplaced body of upper mantle material that is exposed over 72 km2 in the Betic-Rif-Tell orogenic belt of northern Morocco. The massif is composed primarily of spinel lherzolite, although meter-scale domains of harzburgite, dunite, and veins and layers of pyroxenite are relatively common. A combined field and laboratory-based investigation of Beni Bousera has yielded a new dataset comprised of whole rock and mineral chemistry data that is used to suggest the massif is more heterogeneous than previously interpreted, and that "secondary" peridotites and dunites were formed by different petrogenic processes than the remainder of the massif. Trends in the CaO-MgO-Al 203-SiO 2 system and trace element patterns suggest partial melting of the peridotite played a significant role in the evolution of the massif, as has been previously suggested for other orogenic peridotites. Heterogeneous zones - regions throughout the massif with diverse groups of peridotites and pyroxenites - are believed to be relict melt transport channels. Peridotites and pyroxenites found in these zones show evidence of interaction with a relatively depleted melt (high Cr, low Al and Ti in mineral phases), and textures that suggest the secondary precipitation of neoblastic pyroxenes along matrix olivine grain boundaries. Rare earth element concentrations of clinopyroxene from two peridotite groups suggest equilibration in the garnet stability field, and temperatures calculated from dysprosium concentrations are usually higher than those determined from two-pyroxene thermometry. Linear major element patterns versus MgO and whole rock REE compositions of Beni Bousera dunites suggest that they cannot have formed via partial melting alone. The data collected here also suggest that the massif has experienced several mantle P/T conditions, and continuously equilibrated during exhumation and emplacement into the crust. A comparison with the geometry of the melt transport domain at Ronda, another Mediterranean peridotite body, suggests that although Beni Bousera and Ronda may be related in age of exhumation, melt may have been transported via different pathways in the two massifs. / by Christian D. Manthei. / S.M.

Thesis: S.M. in Atmospheric Sciences, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 42-48). / Ice clouds scatter and absorb solar radiation, affecting atmospheric and surface temperatures (Gettelman et al., 2012). On Mars, where ice contained in clouds makes up a large portion of total atmospheric water vapor, ice clouds also alter the planetary water budget (Maltagliati et al., 2011; Rafkin et al., 2013). Thus, it is important for climate models to be able to accurately predict the conditions under which ice clouds can form. Typical Martian temperatures at cloud-formation height range from -150-200 K (Trainer, Toon, & Tolbert, 2009). Heterogeneous deposition nucleation is thought to be the dominant freezing mechanism on Mars due to the abundance of mineral dust to serve as ice nuclei (IN) (Mdittanen et al., 2005). The parameters for such nucleation are not well characterized at such low temperatures (Trainer et al., 2009). Previous experimental studies have investigated the relative humidity required for deposition nucleation within the Martian temperature range. However, most studies took place on bulk aerosol samples, did not use mineral dusts analogous to Martian dust, or were constrained by particle lifetime and temperature limits. In this project, we re-purpose a single-particle instrument and set it up to perform experiments for more precise ice nucleation data under Martian atmospheric conditions. We use an electrodynamic balance (EDB) to levitate individual particles with diameters around 10 pm. We calculate the size of the particle and changes in size based on the holding voltages. The system can be cooled to 200 K in its current configuration, and the relative humidity and atmospheric constituents can be controlled by adding gas. To test the EDB, we perform validation experiments. We investigate deliquescence and efflorescence on salts at room temperature and 0 'C. We modify the cooling system, thermocouples, and relative humidity sensors and begin freezing experiments with Arizona Test Dust (ATD) and with Mojave Mars Simulant (MMS) dust. We investigate water uptake on MMS particles and find it to be non-hygroscopic but wettable, uptaking monolayers of water between 65-95% relative humidity. From 200 K to 220 K, MMS does not nucleate up to 115% RHice, suggesting that higher supersaturations are needed for ice clouds to form; some Martian cloud modelers should revisit the critical supersaturation parameterization. Future work will improve the EDB and use it to examine phase functions and light scattering. / by Shaena R. Berlin. / S.M. in Atmospheric Sciences

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016. / Cataloged from PDF version of thesis. "June 2016." / Includes bibliographical references. / This thesis focuses on quantifying the role of H₂O in the generation and modification of mantle melts at shallow pressures in subduction zones. In the first and second chapters, two experimental studies are presented that investigate direct mantle melting and then subsequent reaction of deeper mantle melts with overlying, cooler depleted mantle. In Chapter 1, the melting behavior of an olivine + orthopyroxene +/- spinel - bearing fertile mantle composition is investigated as a function of variable pressure and water content. The experimental results are used to calibrate a model that can predict the pressure and temperature or the temperature and H₂O content of last equilibration for mantle melts that were in equilibrium with olivine orthopyroxene +/- spinel. In Chapter 2, reaction experiments were conducted to explore the role of melt - rock reaction in the shallow part of the mantle wedge. Results demonstrate the importance of both the temperature of the overlying mantle and the amount of infiltrating melt on the mantle lithology that remains after reaction. Reaction coefficients are calculated to quantify the experimental results. In Chapter 3, H₂O solubility was experimentally determined at upper mantle pressures. The 1.0 GPa result is the first H₂O solubility determination in basalt at any pressure above 0.6 GPa. The final chapter is a modeling study that shows how and when to correct for low pressure fractional crystallization to get lavas back to equilibrium with the mantle. Terms are calibrated (in part, on experiments presented in Chapter 1) that add H₂O to spinel lherzolite multiple saturation point models as well as to thermometers and barometers. The H₂O correction provides the quantitative and qualitative basis for making low pressure fractional crystallization corrections to near-primitive hydrous lavas. All chapters contribute to the understanding of subduction zone magmatism, with a particular emphasis on processes in the shallowest region of the mantle wedge. / by Alexandra Lai Ching Kao Andrews Mitchell. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references. / The 13C content of microbial products are controlled by many factors, including the 13C content of the growth substrate, growth rate, the flux of carbon through various parts of the biochemical network, and the isotopic fractionation imposed by the enzymes of that network. We analyzed the 13C content of products of the methanogen Methanosarcina barkeri and found that fractionation varied strongly with substrate availability.These results inform our analysis of methanogen lipids from carbonates of the Lost City Hydrothermal Field. This ultramafic ecosystem produces methane highly enriched in 13C relative to most biotic methane. We find that the 13C enrichment in methanogen lipids is even stronger -- demonstrating that the Methanosarcinales in active vents are methane producers, and that they are likely carbon-limited. Archaea in other parts of the vent field at Lost City are methanotrophs. The application of lipid biomarkers helps unravel the multiple biological and abiotic sources of methane at Lost City.Closer examination of lipids from Lost City shows that most are ether-type glycolipids. The dominance of glycolipids over phospholipids may be a phosphorus-conservation strategy in waters that are likely phosphorus-poor. Ether core lipids are similar to those produced by sulfate-reducing bacteria in environments where methane is oxidized anaerobically. Insoluble residues in Lost City carbonates contain proteinaceous organic material and have end-member d15N values near 0 0/00, suggesting active nitrogen fixation is occurring.Biomass and lipids from Yellowstone hot springs also showed surprising enrichments in 13C. The common factor is high pH; unusual 13C enrichment may be common in alkaline hydrothermal systems.Organisms in terrestrial and marine alkaline hydrothermal systems produced organic carbon with d13C outside of the usual biological range. / (cont) This informs our application of carbon isotopes as biosignatures, and suggests that biological and abiotic organic carbon may sometimes have 13C contents that are indistinguishable. / by Alexander Smith Bradley. / Ph.D.