Mineral Physics Commons^™

Effect Of Light Elements On The Melting Behavior Of Liquid Iron Alloys Under Earth’S Inner Core Boundary Conditions, Olaniyi Anisere

LSU Master's Theses

The temperature at Earth’s inner core boundary (ICB) is set by the melting temperature of the iron-rich outer core at core pressures, yet this remains uncertain because melting depends strongly on composition and pressure. Light elements are required to explain the core’s density deficit, but the identity, abundance, and combined influence of these elements on melting under ICB conditions are still debated. This thesis quantifies how candidate light elements modify the melting behavior of iron alloys at ICB-relevant pressures and uses these composition-dependent melting relations to constrain ICB temperature.

Melting relations were determined using molecular dynamics simulations in VASP accelerated …

Interconnectivity Of Melt During Partial Melting And Deformation Of A Peridotite, Jordan Collins

Williams Honors College, Honors Research Projects

The mechanisms that allow basaltic magma to be transported to the surface are well understood, but not much is known about how the transport channels form as the basalt melt forms at the source. I performed experiments to determine these mechanisms during general shear deformation of a natural olivine aggregate (dunite) from Anita Bay, New Zealand as it partially melts using a high pressure/temperature rock deformation apparatus. Samples were analyzed using the scanning electron microscope and I observed that melt pockets started to form at the grain scale (1-2 vol% melt) prior to becoming interconnected at the sample scale (3 …

Viscous Anisotropy Of Wet Olivine Aggregates, Megan Ryan

Williams Honors College, Honors Research Projects

I will deform natural olivine aggregates (Anita Bay dunite) cores in various orientations relative to a natural mineral alignment in the rock under both dry and wet conditions. Different orientations in regards to this mineral alignment will produce deformation on different slip systems. Stress measurements will be taken during the deformation of the samples in order to characterize any changes in viscous anisotropy observed due to the changes in slip system. Anita Bay dunite is a proxy for the main mineral found in the mantle wedge of subduction zones. Therefore, understanding the transformation of viscosity and slip systems in this …

Microstructural Characteristics Of Deformed Quartz Under Non-Steady-State Conditions, Hamidreza Soleymani

Dissertations, Theses, and Capstone Projects

Because of the long timescale of many geological processes (millions of years), it has been traditionally assumed that the existing forces acting on the rocks at deep crustal levels are in equilibrium (i.e., steady-state). An alternative assumption, however, suggests that rocks in the lower crust and upper mantle are continuously evolving and exchanging energy at various time scales. Under the latter assumption (i.e., non-steady-state), certain geologic systems may never attain equilibrium regardless of the length and the time scale of operating geologic events. These two “endpoint” assumptions suggest there is a wide range of geologically reasonable conditions under which rocks …

The Effects Of Heterogeneities And Syn-Deformational Partial Melting On Rock Strength Evolution And Melt Migration, Nicole Wagner

Williams Honors College, Honors Research Projects

In nature, the segregation of granitic melts at the source may be controlled by fabric and compositional heterogeneities in the source rock, such as foliation and lineation. To investigate the influence of foliation/lineation orientation and composition on rock strength and melt interconnectivity, I performed a series of experiments on cores of a fine-grained gneiss (Gneiss Minuti) and a fine-grained muscovite-bearing quartzite (Moine Thrust quartzite). These rocks were cored at six primary orientations parallel, 45 degrees, and perpendicular to the foliation and lineation and were deformed at a constant temperature of 900°C, pressure of ~2 GPa, and strain rate of ~10-6/s …

Analysis Of Water Concentration Formed Within Deformed Synthetic Quartz Crystals, Andrew Steward

Williams Honors College, Honors Research Projects

Analyzing the strength of synthetic quartz is essential to understanding the strength of natural milky quartz, which likely controls the strength of Earth’s continental crust. Synthetic quartz is sometimes used for deformation experiments because it has a homogenous water distribution unlike natural milky quartz. The purpose of this study is to determine if annealing synthetic quartz at T = 600°C will convert the water in synthetic quartz to free water, like milky quartz, but with little water loss. Following two annealing experiments at Texas A&M University, I performed four annealing experiments to measure the water content of five synthetic quartz …

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 …

Further Study Of Garnet Xenocrysts In New York City Migmatites, Stanley Schleifer, Nazrul I. Khandaker

Publications and Research

The authors have previously published an article at the 2004 Geological Society of America Annual Meeting, Petrogenetic Significance of Garnets in the Bedrock of New York City, in which they suggested that the garnet xenocrysts observed in the quartzofeldspathic zones of the migmatites, so frequently seen both at the surface, and below the surface pursuant to the construction of the Manhattan portion of New york City Water Tunnel #3, were a refractory residue of the anatectic melting of the immediately surrounding schistose bedrock. Although the relatively high melting point temperature of garnet compared to other minerals in the surrounding …

A Geophysical Analysis Of The Great Falls Tectonic Zone And The Surrounding Area, Montana Usa, Travis Lane Fultz

Graduate Theses/Dissertations

The Great Falls Tectonic Zone (GFTZ) is a northeast trending zone of high angle faults and lineaments extending from northeastern Idaho into Saskatchewan, Canada. The GFTZ is believed to have facilitated the collision between the Archean Wyoming and Hearne cratons. Previous geophysical studies have analyzed seismic refraction data across the boundary between the Paleoproterozoic GFTZ and Archean Wyoming Craton (WC), this indicated the lower crustal layer thickens as it dips beneath the boundary towards the WC. In this study, three 2 dimensional (2D) gravity models that crossed the central region of the GFTZ were produced using constraints from existing geologic …

Quartz Crystal Preferred Orientation And Recrystallization Patterns From Naturally Deformed Rocks Under Constriction, Riley Quine

Materials Engineering

This study analyzes crystal preferred orientation (CPO) patterns within constrictional quartz-rich gneisses. Quartz deformation and CPO patterns are an area of interest because quartz is one of the most prevalent minerals in earth's crust. Understanding the typical way that quartz crystals reorient under different states of strain can provide geologists with an additional tool for understanding paleo-strain. Temperature and strain geometry are two dominant factors that control the orientation of quartz crystals within a rock. Temperature determines which slip planes are active and slip planes typically reorient so that they are perpendicular to maximum stress. Previous workers have suggested that …

Precipitation And Growth Of Barite Within Hydrothermal Vent Deposits From The Endeavour Segment, Juan De Fuca Ridge, John William Jamieson, Mark D. Hannington, Margaret K. Tivey, Thor Hansteen, Nicole M.-B. Williamson, Margaret Stewart, Jan Fietzke, David Butterfield, Matthias Frische, Leigh Allen, Brian Cousens, Julia Langer

United States Department of Commerce: Staff Publications

Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, barite (BaSO₄) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, …

Microstructures And Quartz Lattice-Preferred Orientations In The Eclogite-Bearing Migmatitic Gneisses Of The D’Entrecasteaux Islands, Papua New Guinea, T. A. Little, B. R. Hacker, S. J. Brownlee, G. Seward

Environmental Science and Geology Faculty Research Publications

Lattice preferred orientations (LPO) of quartz in gneiss domes of the D’Entrecasteaux Islands, Woodlark Rift shed insight into exhumation of the world’s youngest (~5–7Ma) eclogite-bearing terrane at cm/yr rates. We focus on deformation that affected the terrane as it transited between lower crustal depths and the surface, including: (1) grain-scale deformation mechanisms; and (2) style of flow and mode of emplacement of the domes. Electron-backscatter diffraction was used to analyze microstructure and LPOs of 37 quartzofeldspathic gneiss samples that enclose meter-scale mafic blocks preserving original eclogite-facies assemblages. During exhumation of the ultrahigh-pressure (UHP) terrane, gneisses were retrogressed in the amphibolite …

Detrital Zircon Geochronology For Neoproterozoic To Cambrian Sediment Sources Of The Deep Creek Range And The Pilot Range In The Southwestern United States, Kaysea Perry

Earth and Soil Sciences

Detrital zircon studies of miogeoclinal sediments can help provide a deeper look into the mechanisms leading to continental breakup by studying the evolution of the continental margin of North America. Few detrital zircon studies have been conducted to support previous research and theories about the sedimentation of the Miogeocline from the Neoproterozoic to the Cambrian. Studies targeted at the Basin and Range province of the western United States show a trend of increasing local sediment sources. We analyzed detrital zircons from the Pilot and Deep Creek Ranges in Nevada and Utah via LA-MC-ICP-MS at the University of Arizona LaserChron Center …

Microanalytical Investigations Of Gold-Bearing Rocks From The An Najadi Region In Saudi Arabia, Nazrul I. Khandaker, M. Ahmed, M. M. Hariri, M. A. Garwan, K. R. Khan, M. M. Al-Ohali

Publications and Research

The Proton Induced X-ray Emission technique with a scanning microbeam (micro-PIXE) and Scanning Electron Microscopy (SEM) were employed to study gold-bearing rocks from the An Najadi and adjacent regions situated within the exposed northeastern part of the Arabian Shield. These microanalytical investigations, together with routine petrological and ore microscopic studies, demonstrated the presence of important partitioning of major minerals and trace elements in several samples. These measurements also revealed microstructural features including brecciation within quartz grains and metal concentrations within these fracture-controlled micro-conduits. Results showed promise in terms of using distinctive geochemical signatures for ore body recognition. Of particular interest …

Study Of Volcanic Sediments By Microbeam-Pixe Technique, Nazrul I. Khandaker, M. Ahmed, M. A. Garwan

Publications and Research

Single mineral grains in a suite of Cretaceous (85–90 Ma) volcanic sedimentary rocks were analyzed using the microbeam-PIXE technique to understand fundamental geological processes responsible for micro-scale variation in elemental composition across mineral zones, twinning, cleavage planes, fractures and grain boundaries. Distributions of major and trace elements show distinct geochemical features indicative of a specific geological setting and a subsequent diagenetic process in these volcanic sediments. Examples of mineral zoning, microstructures of variable chemistry and post-depositional fluid flow are discussed using the data on feldspar group of minerals.

Contributions To The Quaternary Geology Of Northern Maine And Adjacent Canada, J. Steven Kite (Ed.), Thomas V. Lowell (Ed.), Woodrow B. Thompson (Ed.)

Maine Collection

Contributions to the Quaternary Geology of Northern Maine and Adjacent Canada

Bulletin 37 - Maine Geological Survey, Department of Conservation,

Augusta, Maine 04333 (1988).

Contents: Introduction / A GEOMORPHIC METHOD FOR RECONSTRUCTING PALEO ICE SHEETS, Part I: GLACIAL GEOLOGY. - T. Hughes and J. Fastook / A GEOMORPHIC METHOD FOR RECONSTRUCTING PALEO ICE SHEETS, Part II: GLACIOLOGY. - J. Fastook and T. Hughes / TILL STRATIGRAPHY AT THE BALD MOUNTAIN MINE SITE, NORTHERN MAINE - W. R. Holland and F. F. Bragdon / GLACIAL DISPERSAL FROM THE PRIESTLY LAKE AND DEBOULLIE PLUTONS, NORTHERN MAINE - E. F. Halter / GLACIATION …

Tourmaline - A Prospecting Guide For Massive Base-Metal Sulfide Deposits In The Penobscot Bay Area, Maine, John F. Slack

Maine Collection

Tourmaline - A Prospecting Guide for Massive Base-Metal Sulfide Deposits in the Penobscot Bay Area, Maine

by John F. Slack, U.S. Geological Survey

Special Economic Studies Series No.8

Maine Geological Survey, Department of Conservation, Augusta, Maine (June, 1980).

Contents: Abstract / Introduction / Geologic Setting / Massive Sulfide Deposits / Tourmaline Occurrences / Tourmaline: A Guide to Ore / Acknowledgements / References Cited

A Detailed Economic Investigation Of Geochemical And Aeromagnetic Anomalies North Central Maine, W. F. Stickney, R. S. Young, L. A. Wing

Maine Collection

A Detailed Economic Investigation of Geochemical and Aeromagnetic Anomalies North Central Maine

W.F.Stickney, R.S.Young and L.A.Wing

Special Economic Series No.4, Maine Geological Survey, Department of Economic Development, Augusta, Maine (March 1965).

Contents: Foreword / Part I - Geology (W.F. Stickney) / Part II - Geophysics (R.S. Young) / Part III - Geochemistry (L.A. Wing) / References

First Annual Report On The Geology Of The State Of Maine, Lucius H. Merrill, Edward H. Perkins

Maine Collection

First Annual Report on the Geology of the State of Maine by Lucius H. Merrill, State Geologist and Edward H. Perkins, Assistant Geologist, Augusta, 1930.

Articles: Maine Granites / Report on Feldspar Quarries Visited Aug. 21-24, 1929 / Coal / Petroleum and Natural Gas in Maine / The Minerals of Maine / Minerals of Maine Index, By Mineral Names / Minerals of Maine, Index by Towns / Minerals Found at Bennett's Quarry Buckfield, Maine / List of Minerals Found at Newry, Maine / List of Minerals Found in Rumford, Maine / The Natural History of Maine Minerals (Perkins) / …