Physical Sciences and Mathematics Commons^™

Investigating The Petrogenesis Of The Naifeh And Plumeria Seamounts: Insights Into The Geochemical Diversity Of Seamounts Adjacent To The Hawaiian Seamount Chain, Geoffrey Montour

Boise State University Theses and Dissertations

The Naifeh and Plumeria seamount clusters, which consist of 10 submarine volcanoes located ~220km north of the Northwest Hawaiian Ridge, were mapped and sampled by the E/V Nautilus expedition NA101 in 2018. The origin of these seamounts is unknown, but their unique orientation and location imply several possible mechanisms of formation. Four possible mechanisms of formation include: 1) off-axis upwelling of the Hawaiian mantle plume, 2) ancient arch volcanism, 3) intraplate extension and deformation, 4) hotspot volcanism. Investigating the origin of these seamount clusters will better constrain the composition of the underlying mantle, as well as the depth and extent …

Petrochronology And Statistical Analysis To Integrate Different Types Of Data To Solve Complex Earth Systems Problems, Claire Ostwald Harrigan

Boise State University Theses and Dissertations

Complex Earth systems problems, like reconstructing orogens and calibrating the geologic time scale, require investigations that link time to geologic processes. To use time as a means of organizing geologic evidence, geochronometric dates must be contextualized by integrating with different data types. This is the work of petrochronology—linking mineral ages to geochemical, textural, or other geologic information. The U-Pb isotopic system as preserved in the minerals zircon (ZrSiO₄) and titanite (CaTiSiO₅) can be used in a petrochronological context to date geologic events including the age of granitoid pluton emplacement, the age of rock fabric formation in …

Re-Evaluation Of The First Metamorphic P-T Path Using Quig Barometry And Equilibrium Thermodynamics, Sam Couch

Boise State University Theses and Dissertations

Quartz in garnet (“QuiG”) barometry is a relatively new technique that uses physical properties of minerals to estimate the pressure of garnet nucleation and growth history independent of chemical equilibrium. QuiG barometry was used to determine pressures of garnet growth and compared to thermodynamically calculated P-T conditions for two samples (FH-1M and Z3H) from the Lower Shieferhülle (Formation), Tauern Window, Austria. FH-1M was the first sample for which a P-T path was calculated through inversion of chemical zoning in garnet (Selverstone et al., 1984). Mineral Assemblage Diagrams (MADs) and geothermobarometric techniques were used to determine P-T conditions for garnet nucleation …

A Record Of Vapour Pressure Deficit Preserved In Wood And Soil Across Biomes, Adrian Broz, Gregory J. Retallack, Toby M. Maxwell, Lucas C.R. Silva

Biology Faculty Publications and Presentations

The drying power of air, or vapour pressure deficit (VPD), is an important measurement of potential plant stress and productivity. Estimates of VPD values of the past are integral for understanding the link between rising modern atmospheric carbon dioxide (pCO₂) and global water balance. A geological record of VPD is needed for paleoclimate studies of past greenhouse spikes which attempt to constrain future climate, but at present there are few quantitative atmospheric moisture proxies that can be applied to fossil material. Here we show that VPD leaves a permanent record in the slope (S) of least-squares …

Geochemical Variability & Implications For Magma Transport At 14°N On The Mid-Atlantic Ridge, Emma Elizabeth Mccully

Boise State University Theses and Dissertations

Observations of seafloor bathymetry and gravity surveys indicate that magma focuses in the center of slow spreading Mid-Ocean Ridge (MOR) segments, however; it is not well constrained how magma is generated, stored, and transported to the segment ends. There are two end-member models for magma transport: 1) a focused magma model wherein the magma upwells beneath the entire ridge axis, is focused and pools beneath the center of the segment, and is then transported towards the segment ends via lateral diking in the shallow crust and 2) a distributed magma model wherein magma vertically upwells and is erupted on the …

Insights Into The Evolution Of The Galápagos Archipelago And Its Mantle Source From Monogenetic Near-Island Seamounts, Darin M. Schwartz

Boise State University Theses and Dissertations

Lavas erupted at ocean island volcanoes are classically used as probes of the deep Earth, with ultimate goals of discerning the compositional heterogeneity, structure and dynamics of the Earth’s mantle. However, sampling restricted to volcanic islands and large, submarine volcanic constructs alone likely results in limited spatial resolution of the mantle’s composition and structure, owing to homogenization in sub-island magma reservoirs. Further, islands provide poor temporal resolution given that their multigenetic construction can overprint any time progressive chemical variations and they subside with age making detailed sampling difficult. For my dissertation I investigate whether seamounts surrounding islands in the Galápagos …

Petrogenesis Of Off-Axis Lavas Erupted Along The 8˚20’ N Seamount Chain, East Pacific Rise, Molly Kassandra Anderson

Boise State University Theses and Dissertations

Lavas erupted at off-axis seamounts provide a window into mantle heterogeneity and melting systematics that are not easily observed on-axis at fast spreading mid-ocean ridges (MORs). This is because axial melts are efficiently mixed and homogenized within shallow axial magma chambers prior to eruption. To understand the deeper magmatic processes contributing to oceanic crustal formation, we examine the compositions of lavas erupted along a chain of off-axis seamounts, adjacent to the East Pacific Rise (EPR). Essential questions include: (1) What is the range of compositional variability erupted off-axis and how does that compare to lavas erupted on-axis? (2) Is there …

Stable Isotope Geochemistry Of Bioapatite, Amanda E. Drewicz

Boise State University Theses and Dissertations

The Cenozoic Era was a time period where dynamic shifts in climate created for both warm-wet greenhouse environments of the mid-Miocene Climatic Optimum (MMCO), and cool-dry, glacial periods of the late Pleistocene. The Cenozoic is close to our own time period, and although past climate reconstructions cannot be used as direct analogs for future climate change, understanding previous environmental responses can help inform policy surrounding future climate change. Presented here are climate reconstructions of the interior western United States, from two different geologic time periods. Each had a different climate, that differed greatly from modern day environments. The use of …

Evaluating Stable Isotope And Geochronologic Techniques For Paleoclimate Reconstruction: Case Study Of The Santa Cruz Formation, Argentina, Robin B. Trayler

Boise State University Theses and Dissertations

Stable isotope analysis has become the method of choice for many studies investigating the paleoecology and paleoclimate of fossil mammal faunas. While organic tissues (collagen, keratins, proteins) persist for < 10⁵ years highly mineralized tooth enamel is resistant to alteration and degradation and faithfully preserves its isotopic composition for millions (> 10⁶) years. Reconstructing past climates from these records relies on both understanding both micro-scale mechanisms of isotope incorporation into individual teeth, and macro-scale changes in isotope compositions over hundreds of thousands or millions of years. In this dissertation I address three questions.

First, how does the geometry and …

Geochemical Dynamics And Nitrous Oxide Release From The Hyporheic Zone Of Streams, Annika Marie Quick

Boise State University Theses and Dissertations

The hyporheic zones of streams and rivers, consisting of the sediments beneath and immediately adjacent to the stream channel, are an important site of geochemical processing. Due to the difficulty of measuring these geochemical processes in the hyporheic zone in situ with meaningful spatial and temporal resolution, we conducted multiple column and large-scale flume experiments to model 1D and 2D hyporheic flow paths and observed important geochemical reactions, including the production and consumption of nitrous oxide (N₂O). N₂O is a significant greenhouse gas, but the controls on its emissions from streams are poorly constrained. We describe …

Trace Chemical Evaluation Of Cloud Seeding In The Payette Basin, James Mitchell Fisher

Boise State University Theses and Dissertations

Glaciogenic cloud seeding increases the fraction of super cooled liquid water precipitating from a given storm. Orographic clouds tend to be inefficient at higher cloud temperatures due to the lack of active natural ice nuclei. Adding artificial ice nuclei active at temperatures greater than -12^oC (where most natural ice nuclei are inactive) may result in an increase in snow precipitation, especially in orographic clouds. Silver iodide (AgI) is typically the artificial nucleating agent for winter orographic cloud seeding. Recent estimates suggest the addition of AgI to orographic storm clouds enhance precipitation by 3 - 15%. However, the National …

Geochronology Of The Tectonic, Stratigraphic, And Magmatic Evolution Of Neoproterozoic To Early Paleozoic, North American Cordillera And Cryogenian Glaciation, Vincent H. Isakson

Boise State University Theses and Dissertations

Neoproterozoic sedimentary successions contain evidence for some of the most extreme climate fluctuations, breakup of the paleo-supercontinent Rodina, multiple low-latitude global glaciations, and the resultant evolution and radiation of complex life. The stratigraphic record of these events are found on all major continents and have been associated with, in part, global ‘Snowball Earth’ events. However, the understanding and integration of these, and related phenomenon, are limited by disparate and imprecise age constraints that prohibit clear correlation between locations.

This research focused on high-precision geochronology within an integrated framework of sedimentology, stratigraphy, and geochemistry to resolve the timing and duration of …

Protracted Thrusting Followed By Late Rapid Cooling Of The Greater Himalayan Sequence, Annapurna Himalaya, Central Nepal: Insights From Titanite Petrochronology, Jesse Bennett Walters

Boise State University Theses and Dissertations

Temperature-time (T-t) paths derived from coupled Zr-in-titanite thermometry and U-Pb geochronology are useful for examining middle-crustal tectonic processes. T-t data collected from the titanite-bearing calcsilicates of the upper Greater Himalayan Sequence (GHS) along the Marsyandi River, Annapurna Himalaya, illustrate a significantly different metamorphic history than previously recorded in central Nepal. Combined with traditional thermobarometry, textural relationships, and field mapping, titanite T-t data reveal a protracted history of mid-crustal tectonics. Peak Zr-in-titanite temperatures are 750-850 °C at 10-14 kbar. T-t paths are divided into two groups, which are separated by the Chame Shear Zone (CSZ). Group I (upper) rocks show cooling …

Geologic, Geochemical, And Geophysical Characterization Of The Gold Deposits Of The Horseshoe Bend Mining District, Idaho: Building A Four Dimensional Model For Ore Exploration, Joshua Ekhoff

Boise State University Theses and Dissertations

The Eocene aged Trans-Challis Fault System of central Idaho provides the tectonic and magmatic framework for a series of Au-Ag and Cu-Mo ore deposits. From its northernmost extension near Butte, Montana to its southwestern terminus in the Boise Basin of south-central Idaho the Trans-Challis Fault System is associated with some of the richest precious metal deposits found in Idaho. However, the southernmost tip of the Trans-Challis Fault System, composed of the Horseshoe Bend and Pearl mining districts, remains understudied, receiving little economic or academic attention. As a result, how the Pearl to Horseshoe Bend mining districts fit within the established …

Pre-Eruptive Timescales And Processes Of Large Shallow Magma Systems Revealed By Compositional Variability In Silicic Ignimbrites, Amanda C. Laib

Boise State University Theses and Dissertations

Intracontinental magmas are stored at shallow crustal depths and commonly produce compositionally variable deposits when erupted. A core objective of igneous petrology is to understand the processes and pathways by which these magmas are generated and differentiated. Despite decades of research, debate persists regarding the comparative effects of processes like assimilation, fractional crystallization, and magma mixing in the production of compositional zonation. There are two end member hypotheses of how compositional variability develops in pre-eruptive magma bodies; one proposes long-term storage and crystal fractionation of a mafic or intermediate parent magma, while the other proposes a more transient system resulting …

A Precambrian History Of Cratonic North American Crust Beneath The Snake River Plain, Idaho, Emerald Kirke Shirley

Boise State University Theses and Dissertations

Granulite xenoliths erupted in Neogene basalts, and a rare outcrop of Precambrian basement along the northern margin of the Snake River Plain (SRP), can be used as windows into the origin and stabilization of the lower crust of southern Idaho. Previous work to determine the nature of the lower crust beneath the Snake River Plain was conducted on a suite of xenoliths exposed in Southern Idaho at Square Mountain (SM), Craters of the Moon National Monument and Preserve (CRMO), and the Spencer-Kilgore (SK) area (Leeman, 1979; Leeman et al., 1985; Matty, 1984; Wolf et al., 2005), as well as on …

Assessing The Reliability Of Stable Isotopes In Fossil Bone: A Unique Case Study Of Prehistoric Lung Pathology., Kathleen Bundy, Samuel D. Matson

Student Research Initiative

Mammals at Ashfall Fossil Beds State Historical Park (NE Nebraska) offer a unique opportunity to test for the preservation of primary isotopic signatures in fossilized materials. At this site, large herbivores such as rhinoceroses, horses and camels are buried in volcanic ash sourced from an eruption of the Bruneau-Jarbridge caldera (Idaho/Nevada) ca. 11.8 million years ago. Most fossils from Ashfall display pathologic bone symptomatic of a lung disease (hypertrophic osteopathy or HPOA) likely related to inhalation of volcanic ash. In this study, we compare the stable oxygen isotopic composition (δ¹⁸O) of pathologic bone with that of normal cortical …

Cyclic Distributional Model Of The Late Moscovian Fusulinids In The Donets Basin (Ukraine) In Response To Eustatic Sea Level Fluctuations And Its Application In Biostratigraphy And Correlation, Rimma Khodjanyazova

Boise State University Theses and Dissertations

The continuous Pennsylvanian shallow-marine, paralic, siliciclastic succession in the Donets Basin is pivotal for correlation of marine and continental strata in northern Pangaea with coeval shallow-marine mainly carbonate strata in the Moscow Basin, a historical type area of Moscovian Horizons. The details of the history of establishment, lithostratigraphy and current biostratigraphy of Podolskian and Myachkovian Horizons in the Moscow Basin that are not readily available in Western literature are reviewed.

A model of cyclic recurrence (~0.6 —1myr) of three main fusulinid assemblages in the Pennsylvanian siliciclastic-carbonate succession in the Donets Basin is proposed. A Hemifusulina-association (A) indicates the onset …

Assessing Eolian Dust Inputs To Soils In Dry Creek Experimental Watershed, Sw Idaho, Brian Jameson Stark

Boise State University Theses and Dissertations

A geochemical investigation of upland soils in the Dry Creek Experimental Watershed (DCEW) near Boise, Idaho was conducted to assess the potential contributions of eolian dust. Major and trace element compositions of soils within the watershed, loess deposits in the adjacent Western Snake River Plain (WSRP), and underlying granodiorite bedrock were evaluated. Multiple lines of evidence suggest a significant contribution of dust in the soils. Plots of Co/Ti, V/Ti and Cr/Ti indicate that the loess and bedrock occupy distinctly different compositional spaces and that the soils are of intermediate composition, suggesting that the soils are a mixture of the loess …

Measuring The Rate Of Garnet Growth: Implications For Rb-Sr Garnet Chronology, Jessica Sousa

Boise State University Theses and Dissertations

Garnet growth rates have provided valuable information for understanding the rates of tectonometamorphic processes. In theory, during its growth, garnet records the decay of 87Rb within a rock matrix as steadily increasing ⁸⁷Sr/⁸⁶Sr from core to rim. By measuring the Sr isotopic zoning within garnet and matrix Rb/Sr and ⁸⁷Sr/⁸⁶Sr, the rate of garnet growth can be determined. To test this, we used ID-TIMS to measure Rb-Sr data for five samples from three major orogenic belts: central New England, southernmost Chile, and western Italian Alps. These new data introduce two major difficulties encountered using …

Geochemical And Geochronological Constraints On The Tectonothermal History Of The Central And Eastern Nepal Himalaya: Implications For Thermal-Mechanical Models, Stacey Lynn Corrie

Boise State University Theses and Dissertations

Syntheses of Himalayan tectonics imply an average shortening rate of ~2 cm/yr across the Himalaya over the last 20-25 Myr. However, despite decades of research, basic questions still remain about how strain was partitioned. Fluctuations in the timing and rate of thrusting could have significant implications for strain partitioning across the Himalaya, and for partitioning during collisional orogenesis as a whole.

Due to the observed chronology and thermobarometry of Greater Himalayan Sequence (GHS) rock units in the Annapurna region of central Nepal, we revise the original interpretation of the Bhanuwa Fault from a normal fault to a thrust, and identify …