Mineral Physics Commons^™

High P-T Single Crystal Elasticity Of Zircon And Its Implications For Determining Metamorphic P-T Conditions In Nature, Arlacee Luu

Earth and Planetary Sciences ETDs

Understanding the natural petrologic and tectonic processes, such as slab subduction, requires accurate determination of the pressure (P) and temperature (T) conditions of these processes. Recent development of elastic thermobarometry based on the difference between the elastic evolution of mineral inclusions and their host minerals allows constraining the formation P-T conditions of the inclusion/host system without assuming thermodynamic equilibrium, which is typically needed for the widely used chemistry-based thermobarometry in metamorphic petrology. However, the reliability of elastic thermobarometry heavily depends on the accurate determination of the high P-T single-crystal elastic properties of relevant minerals. In this study, we performed the …

Single-Crystal Elasticity Of Earth’S Mantle Transition Zone Minerals And High Pressure-Temperature Phase Equilibrium Experiments On Martian Basalts, Wenyi Zhou

Earth and Planetary Sciences ETDs

Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe …

Single-Crystal Elasticity Of Clinopyroxenes And The Viscosity Of Kimberlite Magma Under High Pressure-Temperature Conditions, Ming Hao

Earth and Planetary Sciences ETDs

Clinopyroxene is not only an important mineral phase in the pyrolitic upper mantle, but also one of the dominated mineral phases in the subducted or delaminated eclogitic materials in the deep Earth. Identifying and locating these eclogitic materials requires the knowledge of the thermoelastic properties of clinopyroxene under high pressure-temperature conditions. In this dissertation, we have measured the single-crystal elastic properties of jadeite and omphacite, which are major clinopyroxene phases in the eclogitic materials, up to 18 GPa 700 K by Brillouin spectroscopy and utilized these data to identify the eclogitic heterogeneities in the mantle.

We also measured the viscosity …

Deformation Of Antigorite + Olivine Aggregates: Implications For Mantle Wedge Dynamics, Roselyn K. Hurlow

Earth and Planetary Sciences ETDs

Aggregates with varying volume proportions of antigorite and olivine were deformed at mantle wedge conditions of high-pressure (P) (2.5-7.6 GPa), -temperature (T) (675 K), and strain rates from ~1.0*10^-5 to ~1.0*10^-4 s^-1 using the deformation-DIA (D-DIA) to investigate deformation mechanisms and stress/strain partitioning. Macroscopic strain, lattice strain, and texture were measured in situ using synchrotron x-ray diffraction and radiography and were modeled for olivine using Elasto-Viscoplastic Self-Consistent (EVPSC) simulations. These modeled results are coupled with microstructure images and electron backscatter diffraction (EBSD) measurements results to determine stress and deformation mechanisms. Previous to this study, investigations have been …

Single-Crystal Elasticity Of Tremolite At High-Pressure Conditions And Its Implication For The Mid-Lithospheric Discontinuity, Soisiri Charin

Earth and Planetary Sciences ETDs

Tremolite is the calcium magnesium amphibole that widely occurs in igneous and metamorphic rocks of the crustal and upper mantle lithosphere, especially in the greenschist facies to amphibolite facies of ultramafic assemblages. The stability field of amphibole reaches 3-4 GPa and 1100-1200°C depending on water content and cation substitutions giving rise to amphibole to occur in highly variable compositions. This P-T condition, corresponding to the depth about 80-120 km, coincides with the depth range that a negative velocity gradient usually found within most stable cratonic lithospheres. This depth range is seismically called Mid-lithosphere discontinuity (MLD). The geologic processes that might …

Microstructural And Microchemical Studies Of Fluid–Chondrule Interactions In A Pristine Cr Carbonaceous Chondrite And Apatite In Martian Nakhlites, Marina Martínez

Earth and Planetary Sciences ETDs

PROJECT 1: Chondrites are the most primitive objects in the solar system, aggregates of the material that formed in the solar protoplanetary disk during the first 1-5 million years of its formation. However, petrographic observations indicate that most chondrites have been modified by secondary processes, including aqueous alteration, thermal metamorphism, and shock. Fortunately, a few chondrites largely escaped these processes and are considered pristine, such as the CR carbonaceous chondrite Queen Alexandra Range (QUE) 99177. QUE 99177 is an excellent sample for deciphering information about the reactions that took place between unaltered anhydrous solar nebular components and water under highly …

Crustal Seismic Anisotropy Of The Ruby Mountains Core Complex And Surrounding Northern Basin And Range, Justin T. Wilgus

Earth and Planetary Sciences ETDs

Metamorphic core complexes (MCC) are distinctive uplifts that expose deeply exhumed and deformed crustal rocks due to localized extensional deformation. Consequently, their detailed structure provide a window into deep crustal mechanics. The North American Cordillera contains numerous MCC, one of which is the Ruby Mountains core complex (RMCC) located in the highly extended northern Basin and Range. To constrain the extent to which anisotropy below the RMCC deviates from the regional Basin and Range average and test the depth dependence of crustal anisotropy we conduct a radial anisotropy investigation below the RMCC and surrounding northern Basin and Range. Data from …

Petrology Of The Precambrian Rocks Of Part Of The Monte Largo Area, Nm, Paul Wayne Lambert

Earth and Planetary Sciences ETDs

Approximately 7 to 8 square miles of Precambrian rocks are exposed in the vicinity of the Monte Largo Hills in north-central New Mexico. The Precambrian rocks are bounded mainly by Pennsylvanian sedimentary rocks in both fault and noncomformable contact.

The area is made up largely of quartz-feldspar gneiss, hornblende gneiss, and quartzite. Quartz-feldspar gneiss is the most abundant rock type. Mica schist and sillimanite hornfels occur in minor amounts. Other Precambrian rocks include medium-grained granite, splite and pegmatite dikes, and quartz veins. A minor amount of migmatite is present as a result of the intimate association of quartz-feldspar gneiss and …

Anisotropism In Garnets, Arthur B. Merkle

Earth and Planetary Sciences ETDs

Six anisotropic garnets are studied by optical, thermal, and X-ray diffraction methods in an attempt to determine the cause of anisotropism. The garnets are all ungrandites with compositions ranging from chromian grossularite to nearly pure andradite, the composition having been estimated from indices of refraction and unit cell dimensions. In all cases the birefringence is 0.004 or less. Both positive and negative uniaxial and biaxial figures are sometimes observed. Heating of the garnets at 900°C for periods of 96 to 264 hours reduced the anisotropism in five of the six garnets studied; this observation is in agreement with previously reported …

Geology And Ore Deposits Of The Dunmore Mine, Ouray County, Colorado, Caswell Silver

Earth and Planetary Sciences ETDs

The Dunmore lode is located near Ouray, Colorado in the northwest part of the San Juan Mountains. In structure as well as mineral assemblage it shows a connection between the chimneys and veins of the region. The lode averages about 100 feet wide for 1,200 feet along the Dunmore claim. The fissure zone is over two miles long and displacement along it has offset a folded pre-Cambrian complex 4,500 feet prior to the deposition of 2,400 feet of volcanic tuff. Fissures in the pre-Cambrian rocks controlled in part the intrusion of dikes and the formation of veins. Late Tertiary faulting …

The Minerals Of New Mexico, Lee Mcguinness

Earth and Planetary Sciences ETDs

Inorganic bodies known as minerals make up, either in whole rock-masses or in isolated form, the material of the upper crust of the earth. Through the evidence furnished by this study of meteorites, we also infer that other bodies in the universe are made up of minerals, or at least those portions of them which are represented by meteorites.

Since minerals are, then, important in making up the observable part of the earth, a study of them is importance in any study of the earth. Because the variety of minerals occurring in New Mexico is large, it will be of …