Physical Sciences and Mathematics Commons^™

Petrology Of An Oxidized Blueschist Cobble From The San Onofre Breccia, California, Usa, Alaina A. Helm

Honors Papers

The mid-Miocene San Onofre Breccia (SOB) found along the southern California borderlands contains clasts of several lithologies including high-pressure metamorphic rocks commonly thought to be shed from the Catalina Schist. Sorensen concluded the San Onofre Schist was part of the Franciscan Complex, although at that time the Catalina subduction was considered to be part of the Franciscan Complex. In this study, a ~10 cm cobble collected from the San Onofre type locality was studied to describe its mineralogy and estimate its conditions of metamorphism. The cobble is composed of glaucophane (35%) + epidote (15%) + garnet (13%) + phengite (12%) …

The Molluscan Taphofacies Of And Influence Of Callianassid Shrimp On A Carbonate Lagoon (St. Croix, Us Virgin Islands), Rowan Lee

Honors Papers

Sediments collect in reef lagoons, and the shells within these can record changes in the environment as they accumulate. Smuggler’s Cove (St. Croix, USVI) has been accumulating a sediment package for at least 5,000 years based on radiocarbon ages. Callianassid shrimp severely bioturbate this lagoon’s sediment package by moving shell material into shelly, subsurface lags that have a high chance of becoming fossilized. Shell condition (taphonomy) was compared between surface and lag to see whether the lag is an accurate representation of the living surface fauna. Guild membership, taxon, and mollusk size between surface and lag assemblages were analyzed. It …

Glaciovolcanic Megapillows Of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland, Rachel Heineman

Honors Papers

At Undirhliðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring throughout this area demonstrate their role in the multi-stage construction of the ridge modeled by Pollock et al. (2014). The outcrops exhibit radial jointing, bands of vesicles and glassy rims, they occur in high relief surrounded by basalt breccia resembling pillow rubble, and are composed of plagioclase-phyric olivine basalt with plagioclase-rich groundmass. They occur in multiple pillow lava units …

Experimental Biomechanics Of Trinucleid Fringe Pits (Trilobita), Kirk Pearson

Honors Papers

The morphometric uniqueness of the trinucleid family of fossil arthropods, known as the trilobites, has led to a considerable amount of attention in paleontology literature. In particular, the distinctive hourglass-shaped pits that dot their anterior have been the subject of debate for over a century. Though anatomically well understood, their function remains unknown. Many proposals have been suggested, including its use as a sieve for filter-feeding, a strong shield for defense, and a sensory mechanism to compensate for their blindness. Despite the wide range of speculations, no study has attempted to model these hypotheses experimentally. Flume experiments and mechanical strength …

An Investigation Of Ams In Oman Ophiolite Gabbros, Sarah D. Trutner

Honors Papers

Crustal accretion processes at mid-ocean ridges are still poorly understood, and several competing models exist that try to explain exactly how magma from the mantle is incorporated into oceanic crust at a crustal spreading center. Ophiolites, or fragments of oceanic crust exposed on land, are useful sites at which to conduct rock fabric studies to understand oceanic crust formation processes. This study focuses on samples of upper foliated gabbros taken from the Oman ophiolite in order to characterize their fabric orientations and contribute to a better model of crustal formation. Much of the focus of this study is on using …

Paleoenvironmental Analysis Of Cretaceous Mudstones At Slope Mountain, Alaska Using Carbon Stable Isotopes, Ashley Ratigan

Honors Papers

This project uses field samples, microfacies analysis, and carbon stable isotopes of mudstones to determine past environmental conditions of North Slope, Alaska during the Albian-Cenomanian (Cretaceous). Samples were taken at Slope Mountain, Alaska located north of the Brooks Range. Slope Mountain includes the Torok Formation and the upper and lower Nanushuk Formations that consist of alluvial, deltaic, and shallow marine facies that were deposited into the North Slope foreland basin on the Arctic Alaska micro plate. An exhaustive search for identifiable microfossils, such as pollen, diatoms, and foraminifera in the samples yielded nothing but charcoal and carbon residue. No other …

Pillars And Buttes: A Petrologic Comparison Of Modern And Ancient Hydrocarbon Seep Rock, Erica C. Morelli

Honors Papers

Purpose: Literature on the formation of authigenic rock at cold seeps focuses on the role of microbes in creating geochemically favorable environment for the precipitation of carbonate and barite minerals. Less understood is the pathway that lithified microbial patches of seafloor sediment follow to become rock formations that are identified in strata dating back to the Silurian. In this study I will compare Holocene seep rock from the Gulf of Mexico to Cretaceous carbonates that have been identified as seep rock. Through the study of rock in its early stages of formation to rock that has likely undergone multiple phases …

How Unusual Is Tropical Storm Irene? A Case Study Of Storm Deposition In Littleville Lake, Huntington, Ma, Catherine Dunn

Honors Papers

Tropical Storm Irene hit the northeastern United States in August 2011 with impressive rates of precipitation and river discharge. However, it was the combination of this heavy rain with high antecedent soil moisture that made Irene so unusual. The Connecticut River had a particularly high sediment yield after the storm, with a sediment concentration over 1,000 mg/L at the mouth of the river. Littleville Lake on the Westfield River was selected as a study site because of its flood control feature, which allows for the calculation of trapping efficiency in dammed rivers. Coring in the lake showed that there was …

Low-Temperature Deformation Of Mixed Siliciclastic & Carbonate Fault Rocks Of The Copper Creek, Hunter Valley, And Mcconnell Thrusts, Jack R. Hoehn

Honors Papers

This study analyzes the low-temperature deformation of fault rocks associated thrust faults. Each fault has dominantly carbonate rocks in one wall and dominantly siliciclastic rocks in the other. The rocks from the Hunter Valley and Copper Creek thrusts of the Southern Appalachians, and McConnell thrust of the Canadian Rockies, were analyzed using data extracted at the thin section and SEM scale. The rocks, all of which featured a fine-grained carbonate matrix surrounding larger carbonate and siliciclastic carbonates, all experienced general shearing, but deformed by different deformation mechanisms. The Hunter Valley and McConnell samples showed evidence of cataclasis, diffusive mass transfer, …

The Effect Of Rainfall And Post-Revolutionary Land-Use Changes On Sediment Yield In Weixi Basin, Yunnan, China : New Insights From Multi-Temporal Land-Use Classification And Radionuclide Analyses, Yue Qiu

Honors Papers

This paper looks at the dynamic interphase connecting post-revolutionary politics, modern land use practices, precipitation patterns, basin slope, and sediment yield records in Weixi basin, a small mountainous watershed in Southwestern China with a total upstream area of 198 m2. The goal is to identify what processes, climatic or not, account for the changes in local sediment yield and erosion budget. Weixi basin has an average annual sediment yield of 175 ton/km2 with two anomalously large peaks in 1979 and 1984. Precipitation is moderately correlated with sediment yield at interannual scale. It also affects seasonal fluctuations in sediment yield as …

Eclogites And Eclogites: Oxygen Isotope Evidence Of A Shared Subduction Origin For Franciscan Eclogites And Moses Rock Eclogite Xenoliths, William F. Hoover

Honors Papers

Eclogites can be found in two distinct tectonic settings in the western USA: in the Franciscan Complex as tectonic blocks in a fossil accretionary wedge, and in the Navajo Volcanic Field as xenoliths in diatremes. Intra-crystal oxygen isotope analyses of garnets from these two settings provide important information on the source, composition and timing of fluid interactions in both eclogite settings. Because of the well-documented relationship between Franciscan subduction and the volcanism in the Navajo Volcanic Field, the samples in this study can be directly compared to determine if they share a common origin. The Navajo eclogites in this study …

Full Of Hot Air: Heat Flow At The Medicine Lake Volcano Hot Spot, Modoc County, California, Katrina D. Gelwick

Honors Papers

Changes in volcanic hydrothermal systems can shed light on the physical processes associated with volcanic unrest such as changes in an underlying magma body. The U.S. Geological Survey recently implemented an experimental hydrothermal monitoring network throughout the Cascade volcanic arc. Despite being ranked as the 12th highest threat among all Cascade volcanoes, Medicine Lake Volcano in northeastern California is considered under-monitored. The primary hydrothermal-monitoring site at Medicine Lake Volcano is a weak fumarole contained within a small area of heated ground, called the Hot Spot, located near the caldera rim. This study uses data from a survey conducted in August …

Controlling Factors On Bedrock River Sinuosity In The Eastern Tibetan Plateau, Lydia Curliss

Honors Papers

Average sinuosity of bedrock rivers across the eastern Tibetan Plateau (including the Yangtze, Mekong, Salween, Irrawaddy, and Tsang Po) ranges from 1.20-1.41. From 25°-30°N, sinuosity marginally increases east to west; over the entire distance of each river, sinuosity increases north to south. Increases in sinuosity parallel a regional tectonic gradient in an area with a marginal climate gradient. Several past studies correlate sinuous bedrock rivers in mountainous regions with gradients in climate, arguing that landslides are the main mechanism by which bedrock rivers increase sinuosity. Other studies find correlations between tectonics and increasing landslide frequency. To investigate the role of …

Thermobarometric Modeling Of The Catalina Amphibolite Unit: Implications For Tectonic And Metasomatic Models, Henry W. Towbin

Honors Papers

On Santa Catalina Island, Ca high-grade amphibolite units overlie progressively lower- grade blueschist units in an inverted stack structure. This juxtaposition of high grade and low-grade metamorphic units has long been the subject of much debate as to the tectonic origins of the formation and how it relates to California's tectonic evolution. Previous petrography and thermobaromety of blocks in the amphibolite unit estimate pressures and temperatures of ~8-11 kbar and ~640-750 °C (Platt, 1975; Sorensen and Barton 1987). These estimates were calculated before many of the computational advances in modern thermobarometry. Using Equilibrium Assemblage Diagrams (EAD) calculated with Theriak Domino, …

Magnetic Properties Of The Bishop Ash In The San Andreas Fault Borderlands, Becky Strauss

Honors Papers

The San Andreas Fault marks one of the most tectonically active regions of the United States, producing frequent earthquakes that have decimated major population centers throughout central and southern California. Its northern regions have been thoroughly studied, but the complex behavior of the southeast portion of the fault is often neglected, in spite of its potential to nucleate a major earthquake within the next few centuries. In this study, I examined the magnetic traits of the Bishop Ash, a well-dated marker horizon of volcanic ash, to assess deformation adjacent to this part of the fault at hand-sample scale. To this …

Taphonomic And Sedimentologic Study Of The Cretaceous Tepee Buttes Limestone, Hilary G. Close

Honors Papers

The Tepee Buttes methane seep deposits exist today as topographically defined limestone features in the surrounding Pierre Shale of the Campanian Western Interior Seaway. The present sloping surface has previously been assumed to be indicative of original seep structure, and biofacies were interpreted as roughly ringing a central vent core. Contradictory field observations in this study have prompted a more detailed taphonomic approach to the Tepee Buttes limestone, and certain depositional features such as reworked horizontal shell beds were noted and examined in detail for the first time. The results of a taphonomic and sedimentologic analysis reveal a complex history …

Microstructures And Deformation In Some Fault Rocks From The Mcconnell Thrust At Mount Yamnuska (Alberta): Implications For Fluid Flow And Faulting And Cycles Of Strain-Hardening And Softening, Lowell Miyagi

Honors Papers

Fault rocks from the McConnell thrust consist of limestone mylonite, carbonate and shale cataclasites, and deformed sandstones. The limestone mylonite in the hanging wall mayor may not show different levels of cataclastic overprint. Just below these hanging wall rocks is a zone of comminuted material. This zone contains cataclasites that are produced by the mixing of hanging wall and footwall materials. Underneath this unit are the shale cataclasites of the footwall and beneath this are deformed sandstones that become progressively less deformed further from the fault zone. Based on microstructural evidence these rocks show cycles of mesoscopically brittle and ductile …

Epibiont Guilds As Paleoecological Tools In Environmental Analysis: An Example From Modern And Ordovician Shell Substrates, Stacy M. Boore

Honors Papers

Paleocommunities of encrusting organisms exhibit characteristics that allow comparisons of modern and fossil systems and subsequent environmental analyses. Encrusting organisms attach to a substrate that is generally limited in area. Interactions between bionts and the host organism, and bionts and the environment, are preserved on epibiont encrusted fossils. Modern biont communities from known environments can be compared to fossil biont communities in order to determine the ancient environment experienced by that fossil. Using epibionts as a tool in paleo-environmental analyses employs the somewhat problematic idea that the present can be used as a key to the past. I suggest that …

Impact Spherules From Western Australia: A Textural Analysis Of Really Old Tiny Rocks, Dawn C.S. Ruth

Honors Papers

The fourth shale macroband of the Dales Gorge Member of the Brockman Iron Formation in the Hamersley Basin in Western Australia contains a 2.49 billion years-old impact ejecta layer (Hassler and Simonson,2001). The S4 layer is the least studied Paleoproterozoic impact layer in the Hamersley Basin. It displays textures and replacement minerals not seen in other layers. Analysis of this layer will help our understanding of the processes that form impact ejecta, especially in the Paleoproterozoic.

It is believed that these ejecta settled in a deep basin environment; laterally extensive beds and mud-sized grains are evidence of the deep basin …

Disarticulation And Dissolution Of Crab Remains Across A Depth Gradient In The Bahamas: A Taphonomic Study, Rebecca A. Lincoln

Honors Papers

The fields of Paleontology and Paleoecology would not be complete without taphonomy, the study of the processes affecting organisms between death and fossilization. Taphonomy is important because it allows us to make more complete conjectures about prehistoric organisms and environments, and makes us aware of possible holes and biases in the fossil record due to highly destructive processes or the loss of delicate, non-resistant organisms. Studies on the processes affecting modern organisms have contributed greatly to the understanding of ancient processes; however, most of these studies are nearshore and short-term. What is lacking is information on the effects of these …

Bad-Boy Bryozoan Biomarkers: Cheilostome Distribution Patterns Along A Bahamian Depth Gradient, Christopher J. Nytch

Honors Papers

In 1993 and 1994, the Shelf and Slope Experimental Taphonomy Initiative (SSETI) deployed thirty-five samples of sea urchins along the continental shelf/slope of the Bahamas in an effort to explore the paleoecology and taphonomic potentials of shallow water carbonate environments. Samples were retrieved at 1-, 2-, and 6-year intervals for examination and comparison of epibiont accumulation. Tests and spines of the sea urchin Eucidaris were examined for encrusting cheilostome Bryozoa. Specimens were identified to the genus level. Assessment of abundance and distribution patterns with water depth shows that cheilostomes are prevalent in photic waters, and lacking at depth. Burial of …

Bridger Formation Sandstones Used As An Indication Of Tectonics In The Green River Basin And Western Wyoming, Lisa S. Novins

Honors Papers

Sandstone from the Eocene Bridger Formation of southwestern Wyoming can be used as a tool to constrain the timing and order of controversial tectonic events in the region. The key tectonic element in this region is the Wind River Range. Sandstones in the Bridger were derived from two source areas to the north, one being the basement rocks from the Wind River Range and the other volcanic rocks from the Absaroka Volcanic field (AVF). The abundance of volcanic grains increases upsection in the Bridger indicating that more volcanic material was carried through the Wind River Range. This evidence supports the …

Olivine Petrofabric Analysis From The Leka Ophiolite Complex, Sarah J. Titus

Honors Papers

Peridotites, gabbros and basaltic volcanic rocks on the island of Leka, Norway in the western Scandinavian Caledonides compose a nearly complete ophiolite sequence. I examined samples from the harzburgite to dunite transition within the ultramafic tectonites of the Leka Ophiolite Complex. This rock sequence probably corresponds to the petrologic Moho, which is the true base of the oceanic crust and lies below the seismic Moho. I used universal stage techniques to determine the crystallographic preferred orientations (CPO) of olivine grains in both dunites from the base of the oceanic crust and residual harzburgites in the uppermost upper mantle. Olivine CPOs …

The Petrography Of The Buck Creek Dunite Body, Clay County, Nc: Implications About Its Origin And Emplacement, Trista L. Thornberry

Honors Papers

The Buck Creek dunite body, which is part of the Chunky Gal mafic and ultramafic complex, is well exposed on Corundum Knob in Clay County, North Carolina. These ultramafic rocks are surrounded here by mafic schists and gneisses. Gradational geochemical / mineralogical contacts between the mafic and ultramafic rocks of the this complex imply the same protolith for both rock types. They may have originated as distinct parts of an ophiolitic suite beneath a mid-ocean spreading ridge. The metamorphic history of these ophiolitic rocks suggest further that they were subdued to depths of -18km before being emplaced along fault zones …

Modern Marine Sediments Of Bahia Concepcion: Patterns, Processes, And Potential Analogues To Neogene Rift Basin Deposits Of Baja California, Timothy William Reardon

Honors Papers

Neogene strata in Baja California preserve a record of extensional basins produced during early phases of rifting in the Gulf of California. This actualistic study addresses the feasibility of using Holocene sediments of Bahia Concepcion - a rift basin forming a shallow marine bay In southern Baja California - as analogues for the interpretation of Neogene strata in the Pliocene Loreto Basin. Three major lithofacies occur in Bahia Concepcion: Mud sediments dominate most of the central portion of the bay. Moderately sorted sands occur adjacent to shorelines formed by coalesced alluvial fans and a broad alluvial plain, while carbonate sands …

Using Fourier Transform Analysis To Extract Information From The Shapes Of Folded Layers, Thomas Billiard

Honors Papers

Objective methods of fold shape analysis are nessesary to better understand the behavior of folds and the folding process. I examined two methods of analysis, and used a method based on the Fourier Transform to show that the method based on the Fourier Series was insufficient for identifying shape characteristics of aperiodic natural fold trains. I also showed that the Fourier Transform method accessed information that was inaccessable using the Fourier Series method.

Strain And Volume Loss In A Second Order Buckle Fold, Central Appalachian Valley And Ridge, U.S.A., Michelle J. Markley

Honors Papers

Large scale thrusts and imbricates overlain by folded sedimentary strata characterize structure in the Valley and Ridge Province of the Central Appalachians. The Cambrian Waynesboro Formation is a decollement zone that detached an imbricated Cambro-Ordovician sequence from an unfaulted Pre-Cambrian basement. The Ordovician Martinsburg Shale is a second zone of major detachment that de-coupled the blind thrust system in the Cambro-Ordovician carbonates from the overlying orogenic wedge. Thus, the Central Valley and Ridge deformed during the late Paleozoic Alleghenian orogeny as a three tiered system consisting of the undeformed basement, the imbricated stiff layer, and the primarily folded cover layer. …

Paleoenvironmental History Of The Middle Ordovician Rugosa Of Eastern North America, Gretchen Hampt Andreasen

Honors Papers

Our understanding of the structure and function of biological systems can be increased when viewed in the context of their evolutionary history on a geological time scale. Generally, both paleoecology and ecology have focused on the interrelationships of organisms and their environments in short time frames. For instance, a paleoecologist might study the fossil communities of the Columbus Limestone reefal environment at Marblehead, Ohio, or an ecologist might attempt to characterize the interrelationship of glacier lilies and their pollinators. Both workers may realize that the organisms they study evolved in response to ecological pressures, yet neither, most likely, considers that …

Petrographic Criteria For The Recognition Of 'Magadi-Type' Cherts, Kathryn A. Schubel

Honors Papers

The Magadi cherts, inorganic lacustrine deposits from the Lake Magadi area, Kenya, are widely used as a modern analog to explain the origin of ancient inorganic cherts. Formed in a highly alkaline lake, as the result of a transformation from the sodium silicates minerals, magadiite and/or kenyaite, to quartz, the Magadi cherts possess a distinctive set of textural characteristics that allow them to be distinguished from cherts of different origin with only a limited number of samples. Textural characteristics that are diagnostic of the Magadi cherts and that can be used as a test for the occurrence of ancient 'Magadi-type' …

Two Upper Cretaceous Flysch Sequences In The Caribbean Mountains Of Venezuela And Their Relationship To Caribbean Tectonics, Stephen A. Meyer

Honors Papers

The Caribbean Mountains of Venezuela reach from the Venezuelan Andes to the Northern Ranges of Trinidad. Upper Cretaceous and Paleocene flysch units deposited in a marine euxinic basin are crucial in unraveling the evolution of the mountains. Two formations in the Acarigua region (near the termination in the Venezuelan Andes), the Rio Guache and Nuezalito formations, are the most complete sections of these flysch sequences. A sedimentary petrologic study was undertaken to determine the source areas for these formations, to put age brackets on the timing of uplift and rotation of portions of the Caribbean Mountains.

The mountains are divided …