Annette Farah

Major: Computer Science Engineering, Physics, Geology, and Mathematics
Class: Senior
University of South Florida, Tampa, Florida

Incompressibility of Nickel Oxide (NiO)

Accurately sampling the interior of the earth is not currently possible. Direct observation is limited, and structures such as uplifted mantle-derived ultramafic complexes and exposed kimberlite sections from the deep interiors of the earth provide only a glimpse of the composition of the earth’s interior. Nevertheless, to understand the earth’s interior, we must attempt to gain access to its matrix and study any information that may reveal its structure and mineralogy. Presently, our interpretation of the earth’s interior has come through indirect observations such as seismic profiles and geochemistry of recoverable samples. Interpreting the data collected through these means requires a knowledge of the physical properties of rocks and minerals under the various pressure/temperature (P/T) conditions that exist throughout the planet. Based on this methodology, the mantle of the earth has been determined to be composed primarily of an iron-bearing magnesium silicates mineral called olivine with traces of other minerals present. By attempting to simulate the P/T conditions that may be found in the mantle, such trace minerals as nickel oxide, also known as bunsenite, may be identified based on certain recognizable physical properties, such as elasticity and incompressibility.

For my project, I will be working under the supervision of Dr. Jiuhua Chen, testing the incompressibility bunsenite. Measuring the incompressibility of a mineral determines the stiffness of the mineral, that is, how much it will or will not compress at a given amount of applied external pressure. I will be using energy-dispersive x-ray diffraction data gathered from a large-volume high pressure apparatus at the National Synchrotron Light Source from Brookhaven Laboratory, and I will be analyzing the sample volume at different pressures and temperatures to derive the equation of state of bunsenite. The results will serve as a supplement to a larger project undertaken to determine more precisely the make-up of the earth’s interior.

Greg Mistler

Major: Geology & Applied Math
Class: Junior
Appalachian State University, Boone, North Carolina

I am working with Baosheng Li to measure the shear and compressional wave velocities of the peridotite KLB-1 at the pressure and temperature conditions of the Earths transition zone (400-670 km depth). This project entails hot-pressing KLB-1 samples with the USSA 2000 press. Then the shear and compressional wave velocities of the recovered samples will be measured using ultrasonic interferometry. If the recovered samples are of sufficient quality, velocity measurements will be carried out at simultaneous high pressures and temperatures. These data, along with previous data obtained from Brookhaven National Labs, will be used to analyze the effects of pressure and temperature on the acoustic velocities of KLB-1. This research should ultimately provide a better understanding of the Earths mantle, as well as a viable explanation for the velocity discontinuities in the transition zone.

Jenny Gast

Major: Geology
Class: Senior
University of Idaho, Moscow, Idaho

Crystal fractionation of a Snake River Plain olivine tholeiite at 9.3KB.

This summer I will be conducting experimental petrology research with Donald Lindsley and Hanna Neksavil. I will be using a piston cylinder apparatus to track the evolution of phases present of intracontinental basalt at high pressure and high temperature conditions. The sample ICPP123-260 which will be analyzed is from the Idaho Chemical Processing Plant, well number 123, 260 foot section of drill core located in the Snake River Plain in southern Idaho. The questions I hope to answer are as follows: Do the various anorogenic magma suites form from a common parent? Or is it that different anorogenic magma rocks form in different places or conditions in the mantle? Can fractionation produce the three trends? Is there evidence to show fractionation at different physical conditions of the Snake River Plain basalt sample following all three alkalic, subalkalic, and continental tholeiite trends? Does the sample represent the common parent?

Matthew V. Zelinskas

Major: Mechanical Engineering
Class: Junior
Delaware State University, Dover, Maryland

The Study of LiAlSiO4 at High Pressure and High Temperature

This summer, my mentor (Dr.Zhang) and I will be looking at LiAlSiO4. LiAlSiO4 is an unusual mineral in that it has a negative thermal coefficient of expansion (it shrinks when heated). LiAlSiO4 has particular value in applications where heat and material expansion are critical factors. Examples might include turbine engines and other high temperature surfaces.

Dr. Zhang and I will be concentrating our research on the behavior of LiAlSiO4 at high pressure and temperature. Dr. Zhang has already observed that crystalline LiAlSiO4 becomes amorphous at high pressures (>19Gpa) and room temperature. This Summer we’ll be investigating whether this is a reversible transformation. We will also looking to see if there are any other phases between the low pressure, low temperature crystalline material and the high pressure amorphous material. These experiments will be conducted on the USSA 2000 press in the High Pressure Lab. The results of these experiments will be examined using X-ray diffraction.

Nicholas DiFrancesco

Major: Geosciences
Class: Junior
Stony Brook University, Stony Brook, New York

Abstract

Intraplate magmatic suites exhibit a wide variety of rock types. However, they can be separated into two groups: the hyperstene-normative, quartz saturated suite and the silica under-saturated suite; my research will focus only on the former group. There are three specific compositional trends among hyperstene-normative quartz saturated rocks. The alkalic, continental tholeiitic, and ocean island tholeiitic trends all have distinct characteristics, but it seems that each may be traced back to a common parent magma, a simple olivine tholeiite. (Trace element abundances, alkali, and silica contents suggest that the parental olivine tholeiite has in turn fractionated from a more primitive mantle-derived magma.) All three compositional trends can be produced by crystal fractionation under different conditions of pressure and water content. This Summer I will be working with Dr. Donald H. Lindsley, and Dr. Hanna Nekvasil to investigate experimentally whether a continental olivine tholeiite from the Snake River Plain can produce the ocean island tholeiitic trend through fractional crystallization at lower pressures.

Nathaniel Meyer

Major: Physics & Geology
Class: Junior
St. Norbert College, De Pere, WIisconsin

My Project concerns a subducting oceanic plate entering the transition zone. This zone, which begins at approximately 410 km depth, is where olivine changes from its normal phase or a -phase to denser spinel structures, the b -phase, wadsleyite, or g -phase, ringwoodite. For this experiment, a sample of olivine, Fo90, was subjected to pressures of 17 GPa and temperatures around 750° C, within the spinel stability field. The purpose of this experiment is to determine if it is possible for metastable olivine to exist in a subducting plate, such that the olivine persists well into the transition zone. If it is found that metastable olivine does exist, this may help explain the deep-focus earthquakes observed in subducting plates. The investigation will be performed using a transmission electron microscope or TEM as well as some optical microscopy.

Scott Sojda

Major: Geology
Class: Junior
Marietta College, Marietta, Ohio

Kinetics of High Pressure Phase Transformation of Pyroxene to Garnet

I am doing experiments to study the kinetics of the phase transformation of ortho- (MgSiO3) and clinopyroxene (CaMgSi2O6) to a majoritic garnet solid solution (Mg3 (MgSi) Si3O12). This phase change takes place within the lower reign of Earth’s upper mantle and in the upper transition zone. The transformation occurs as pyroxene progressively dissolves into the garnet structure with increasing pressure, which relates to increasing depth in the mantle. This transformation is believed to be complete at about 16 Gpa, where there is a single-phase garnitite present with little to no change in chemical composition.

This experiment will be done using a 2000-ton Uniaxial-Split-Sphere Apparatus to apply pressure to a sample of KLB-1 that has been sintered and equilibrated at 6 GPa and 1300°c for 16 hours. The bulk composition of KLB-1 is similar to the pyrolite model of the Earth’s mantle composition. After the experiments, the sample will then be made into thin sections for electron microprobe and x-ray diffraction analysis