Physical Sciences and Mathematics Commons^™

Mineral Chemistry Of Basalts Recovered From Hotspot Snake River Scientific Drilling Project, Idaho: Source And Crystallization Characteristics, Richard W. Bradshaw

Theses and Dissertations

Mineral chemistry and petrography of basalts from the Kimama drill core recovered by Hotspot: Snake River Scientific Drilling Project, Idaho establish crystallization conditions of these lavas. Twenty-three basalt samples, from 20 individual lava flows were sampled from the upper 1000 m (of the 1912 m drilled) core drilled on the axis of the Snake River Plain, and represent approximately 3 m.y. of volcanism (rocks at the bottom of the hole are ~6 Ma). Rock from the upper 1000 m are typically fresh, while those lower in the core are more altered and are less likely to preserve fresh phenocrysts to …

The Effects Of Fractures On The Occurrence And Distribution Of Arsenic In The Upper Floridan Aquifer During Aquifer Storage And Recovery, William Charles Hutchings

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Aquifer storage and recovery (ASR) is used world-wide to supplement available water supplies by storing surplus water in aquifers and recovering it during periods of drought and increased demand. The use of ASR as an option for increasing available municipal irrigation and fresh water supplies is threatened as a result of the mobilization of arsenic in some aquifers during ASR. Arsenic is liberated from arsenic-bearing sulfide minerals as a result of the mixing of oxidizing injected water with reducing insitu groundwater. Fracture networks can have significant influence on the migration and distribution of arsenic in the Upper Floridan Aquifer …

Architecture And Stratigraphy Of The Lower Silurian Guelph Formation, Lockport Group, Southern Ontario And Michigan, Candace Brintnell

Electronic Thesis and Dissertation Repository

The Lower Silurian Lockport Group in Ontario and Michigan comprises, in ascending order: Gasport, Goat Island, Eramosa, and Guelph formations. Guelph facies architecture reveals deposition on an underlying carbonate ramp of Eramosa and/or Goat Island carbonates that dipped towards the Appalachian Basin. Temporally, Guelph facies reflect initial open marine transgressive phases that become increasingly restricted marine and karstic upward. Spatially, the facies display the most restricted marine and karstic fabrics in the central portion of the ‘Michigan Basin’ and are most open marine to the east. Newly acquired regional data supports the re-interpretation of the classic Guelph-pinnacle reef models as …

Assessment Of Student Achievement In Introductory Physical Geology: A Three -Year Study On Delivery Method And Term Length, Marianne O'Neal Caldwell

USF Tampa Graduate Theses and Dissertations

Physical Geology is a popular general education course at Hillsborough Community College (HCC) as at many other colleges and universities. Unlike many science courses, most students taking Physical Geology are not majoring in a STEM (Science, Technology, Engineering, and Mathematics) discipline. Typically most students enrolled in Physical Geology are majoring in business, education, or pursuing a general A.A degree for transfer to a four-year university. The class is likely to be one of the few, if not the only, physical science classes that many of these students will take in their academic career. Therefore, this class takes on increased importance, …

A Geochemical Analysis Of Fulgurites: From The Inner Glass To The Outer Crust, Michael L. Joseph

USF Tampa Graduate Theses and Dissertations

Cloud-to-ground lightning strikes produce natural glasses on the surface of the Earth, called fulgurites. These natural glasses are tubular in shape with a central void surrounded by an inner glass, and the inner glass is surrounded by an outer crust or toasted region. Previous studies report different kinds of melts existing in several different types of fulgurites; however, little to no chemical data has been collected that tracks chemical variations from the inner glass to the outer crust of a fulgurite. This study uses microprobe and laser ablation inductively coupled plasma mass spectrometer analytical techniques to collect transects of chemical …

Sediment Transport And Distribution Over Continental Shelves: A Glimpse At Two Different River-Influenced Systems, The Cariaco Basin And The Amazon Shelf., Laura Lorenzoni

USF Tampa Graduate Theses and Dissertations

The aim of this dissertation was to understand lithogenic suspended sediment transport mechanisms and distribution in two river-influenced margins: The Cariaco Basin, Venezuela, and the Amazon Shelf, Brazil. Lithogenic sediment input in the Cariaco Basin is controlled by small mountainous rivers (SMR), while in the Amazon Shelf it is dominated by the Amazon River, the largest river in the world in terms of freshwater discharge (~20% of global riverine discharge). Optical transmissometer measurements were coupled with particulate organic matter (POM) observations to understand changes in the geochemical composition of suspended sediment and spatial/temporal distributions over the two regions of interest. …

Temporal Trends In West Antarctic Accumulation Rates: Evidence From Observed And Simulated Records, Landon Kelly Burgener

Theses and Dissertations

Reconstructed snow accumulation rate observations from five new firn cores show a statistically significant negative trend in accumulation rates over the past four decades across the central West Antarctic ice sheet. A negative temporal trend in accumulation is unexpected in light of rising surface temperatures and simulations run by GCMs. Both the magnitude of the mean accumulation rates and the range of interannual variability observed in the new records compares favorably to older records, suggesting that the new accumulation rate records may serve as a regional proxy for recent temporal trends in West Antarctic accumulation rates. The observed negative trend …

Soil Geomorphology Of The Eastern Sevilleta Long Term Ecological Research Site, Debra Bryan-Ricketts

Earth and Planetary Sciences ETDs

Soils in the arid to semi-arid piedmont landscapes of central New Mexico were examined in order to evaluate surficial processes and landscape evolution in the central Rio Grande Rift. These soils were found to contain key information regarding pedologic and geomorphic responses to climate change, rifting and base level drop. A rare association of sepiolite and palygorskite occurs in old soils formed in eolian fines. Pedologic and mineralogical data indicate that palygorskite formed by transformation of dust-borne, aluminum-rich minerals, and that sepiolite subsequently formed by transformation of palygorskite. The association of these two minerals, and geomorphic observations, confirm the existence …

Introducing Geoscience Students To Numerical Modeling Of Volcanic Hazards: The Example Of Tephra2 On Vhub.Org, Leah M. Courtland, Charles Connor, Laura Connor, Costanza Bonadonna

Numeracy

The Tephra2 numerical model for tephra fallout from explosive volcanic eruptions is specifically designed to enable students to probe ideas in model literacy, including code validation and verification, the role of simplifying assumptions, and the concepts of uncertainty and forecasting. This numerical model is implemented on the VHub.org website, a venture in cyberinfrastructure that brings together volcanological models and educational materials. The VHub.org resource provides students with the ability to explore and execute sophisticated numerical models like Tephra2. We present a strategy for using this model to introduce university students to key concepts in the use and evaluation of Tephra2 …

Gravity Anomalies Along The East Scotia Ridge: Constraining The Relative Importance Of Magmatic And Tectonic Controls On Crustal Accretion, Briton Lee Nicholson

OES Theses and Dissertations

Similar to regions such as the Lau Basin and the Caribbean Sea, the eastern Scotia Sea is a geologically complex area that involves multiple plate boundary types. This study uses bathymetry and gravity data to infer upper mantle geodynamics in the eastern Scotia Sea region. Beneath this region is an intermediate-rate back-arc spreading center known as the East Scotia Ridge (ESR) that forms the boundary between the Scotia and Sandwich plates. To the east of the ESR are the South Sandwich island arc and the South Sandwich Trench. The ESR is a relatively young feature, with spreading estimated to have …

Tree Ring Dating Analysis Of The Zane Trace Inn, 129 West Main Street Somerset, Oh 43783

Historic Structures

Dating historical structures in Somerset, Ohio 2012. The Historical Structures collection consists of reports that are the resoult of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Appleton, Sarah; Cary, William; Nash, Andy; Wiles, Greg

Dendrochronological Analysis Of The Ridenour House And Barn, Somerset, Ohio 43783

Historic Structures

Dating historical structures in Somerset, Ohio 2012. The Historical Structures collection consists of reports that are the resoult of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Appleton, Sarah; Cary, William; Nash, Andy; Wiles, Greg

Tree Ring Dating Analysis Of The Rouskoff Barn, Somerset, Ohio 43783

Historic Structures

Dating historical structures in Somerset, Ohio 2012. The Historical Structures collection consists of reports that are the resoult of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Appleton, Sarah; Cary, William; Nash, Andy; Wiles, Greg

Tree Ring Dating Analysis Of The Scot Barn, Somerset, Ohio 43783

Historic Structures

Dating historical structures in Somerset, Ohio 2012. The Historical Structures collection consists of reports that are the resoult of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Appleton, Sarah; Cary, William; Nash, Andy; Wiles, Greg

Tree Ring Dating Analysis Of The Eliza James House And Barn, Somerset, Ohio 43783

Historic Structures

Dating historical structures in Somerset, Ohio 2012. The Historical Structures collection consists of reports that are the resoult of dendochronological analysis of timbers from structures in Pennsylvania and Ohio. Contributors: Appleton, Sarah; Cary, William; Nash, Andy; Wiles, Greg

Chronostratigraphic Framework For The Iodp Expedition 318 Cores From The Wilkes Land Margin: Constraints For Paleoceanographic Reconstruction, Lisa Tauxe, Catherine E. Stickley, Saiko Sugisaki, Peter K. Bijl, Steven M. Bohaty, Henk Brinkhuis, Carlota Escutia, J. A. Flores, A. J. P. Houben, M. Iwai, Francisco J. Jiménez‐Espejo, Robert Mckay, Sandra Passchier, Jörg Pross, Christina Riesselman, Ursula Röhl, Francesca Sangiorgi, Kevin Welsh, Adam Klaus, Annick Fehr, James Bendle, Robert B. Dunbar, J. Gonzàlez, T. Hayden, K. Katsuki, M. P. Olney, Stephen Pekar, P. K. Shrivastava, Tina Van De Flierdt, Trevor Williams, M. Yamane

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

[1] The Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin of Antarctica recovered a sedimentary succession ranging in age from lower Eocene to the Holocene. Excellent stratigraphic control is key to understanding the timing of paleoceanographic events through critical climate intervals. Drill sites recovered the lower and middle Eocene, nearly the entire Oligocene, the Miocene from about 17 Ma, the entire Pliocene and much of the Pleistocene. The paleomagnetic properties are generally suitable for magnetostratigraphic interpretation, with well‐behaved demagnetization diagrams, uniform distribution of declinations, and a clear separation into two inclination modes. Although the sequences were discontinuously …

Two Modes Of Accelerated Glacier Sliding Related To Water, J. T. Harper, Neil Humphrey, W. T. Pfeffer, B. Lazar

Neil Humphrey

We present the first glacier-wide detailed measurement of basal effective pressure and related observations including bed separation to elucidate the role of water in sliding. The hard bedded glacier instrumented in our study exhibited two phases of accelerated sliding motion apparently driven by separate mechanisms. The first acceleration phase ( up to 5 fold increase in speed) was closely tied to an increase in bed separation. The faster second phase ( up to 9 fold increase in speed) was related to an unusually high level of connectivity of subglacial waters. We infer the first mode was related to cavity opening …

Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, B. Pratt-Sitaula, D. W. Burbank, A. M. Heimsath, Neil Humphrey, M. Oskin, J. Putkonen

Neil Humphrey

Differences in the timing of glacial advances, which are commonly attributed to climatic changes, can be due to variations in valley topography. Cosmogenic Be-10 dates from 24 glacial moraine boulders in 5 valleys define two age populations, late-glacial and early Holocene. Moraine ages correlate with paleoglacier valley hypsometries. Moraines in valleys with lower maximum altitudes date to the late-glacial, whereas those in valleys with higher maximum altitudes are early Holocene. Two valleys with similar equilibrium-line altitudes (ELAs), but contrasting ages, are aspect, such that spatial differences in climate can be excluded. A glacial mass-balance cellular automata model of these two …

Depth-Varying Constitutive Properties Observed In An Isothermal Glacier, H. P. Marshall, J. T. Harper, W. T. Pfeffer, Neil Humphrey

Neil Humphrey

[1] Detailed three-dimensional in-situ measurements of deformation at depth are used to examine the rheology of a 6 x 106 m3 block of temperate glacier ice. Assuming that the viscosity of this ice is primarily dependent on stress, the relationship between inferred stress and measurements of strain-rate above similar to 115 m depth suggest a constitutive relationship with a stress exponent n similar to 1. Deformation below 115 m is described by a non-linear flow law with a power exponent of approximately 3-4. A sharp transition between the two flow regimes is likely caused by a change in the dominant …

High Altitude Himalayan Climate Inferred From Glacial Ice Flux, J. T. Harper, Neil Humphrey

Neil Humphrey

[1] Glaciological processes are modeled to investigate precipitation patterns and the resulting mass flux of snow and ice across Himalayan topography. Our model tracks the accumulation and ablation of snow and ice and the transport of snow and ice across the topography by glacier motion. We investigate high elevation precipitation on the Annapurna Massif by comparing the existing ice cover with model-simulated glaciers produced by a suite of different precipitation scenarios. Our results suggest that precipitation reaches a maximum level well below the elevation of the highest peaks. Further, essentially no snow accumulates on the topography above an elevation of …

Thermal Tracking Of Meltwater Retention In Greenland's Accumulation Area, Neil Humphrey, J. T. Harper, W. T. Pfeffer

Neil Humphrey

Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet's mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km transect of the percolation zone of west Greenland. We installed one or two thermistor strings at 14 study sites, each string having 32 sensors spaced between 0 and 10 m depth. Data from our network of over 500 sensors were collected at 15-60 min intervals for 1-2 years, thereby recording the thermal signature of meltwater …

Cooling Rates And The Depth Of Detachment Faulting At Oceanic Core Complexes: Evidence From Zircon Pb/U And (U-Th)/He Ages, C. B. Grimes, Michael Cheadle, Barbara John, P. W. Reiners, J. L. Wooden

Barbara John

Oceanic detachment faulting represents a distinct mode of seafloor spreading at slow spreading mid-ocean ridges, but many questions persist about the thermal evolution and depth of faulting. We present new Pb/U and (U-Th)/He zircon ages and combine them with magnetic anomaly ages to define the cooling histories of gabbroic crust exposed by oceanic detachment faults at three sites along the Mid-Atlantic Ridge (Ocean Drilling Program (ODP) holes 1270D and 1275D near the 15 degrees 20'N Transform, and Atlantis Massif at 30 degrees N). Closure temperatures for the Pb/U (similar to 800 degrees C-850 degrees C) and (U-Th)/He (similar to 210 …

2.685-2.671 Ga Himalayan-Type Orogeny In The Northern Teton Range, Wyoming, Usa, B R. Frost, Susan Swapp, Carol Frost

Carol Frost

Meeting abstract for “2.685-2.671 Ga Himalayan-Type Orogeny in the Northern Teton Range, Wyoming, USA,” June 2009.

Preservation Of Fe Isotope Compositions Of Iron Formation During Contact Metamorphism, Carol Frost, F. Von Blanckenburg, R. Schoenberg, B R. Frost, Susan Swapp

Carol Frost

Meeting abstract for “Preservation of Fe Isotope Compositions of Iron Formation During Contact Metamorphism,” May 2005.

Cooling History Of Atlantis Bank Oceanic Core Complex: Evidence For Hydrothermal Activity 2.6 Ma Off Axis, J. J. Schwartz, Barbara John, Michael Cheadle, P. W. Reiners, A. G. Baines

Michael Cheadle

We report 26 (U-Th)/He zircon ages from Atlantis Bank, Southwest Indian Ridge, which constrain time scales and rates of lower crustal cooling in ultraslow spreading oceanic crust in this setting. Samples from the detachment fault surface indicate that denuded oceanic crust cooled rapidly (< 1 Ma), yielding cooling rates > 1200 degrees C/Ma, consistent with existing models for the cooling of oceanic crust. (U-Th)/He zircon ages from samples collected along N-S and E-W trending faults scarps record young ages inconsistent with standard cooling models for lower oceanic crust. These samples have a mean (U-Th)/He zircon age 2.6 Ma younger than their corresponding igneous crystallization ages and …

Evolution Of The Southwest Indian Ridge From 55 Degrees 45 ' E To 62 Degrees E: Changes In Plate-Boundary Geometry Since 26 Ma, A. G. Baines, Michael Cheadle, H.J.B. Dick, A. H. Scheirer, Barbara John, N. J. Kusznir, T. Matsumoto

Michael Cheadle

[1] From 55 degrees 45'E to 58 degrees 45'E and from 60 degrees 30'E to 62 degrees 00'E, the ultraslow-spreading Southwest Indian Ridge (SWIR) consists of magmatic spreading segments separated by oblique amagmatic spreading segments, transform faults, and nontransform discontinuities. Off-axis magnetic and multibeam bathymetric data permit investigation of the evolution of this part of the SWIR. Individual magmatic segments show varying magnitudes and directions of asymmetric spreading, which requires that the shape of the plate boundary has changed significantly over time. In particular, since 26 Ma the Atlantis II transform fault grew by 90 km to reach 199 km, …

Protracted Construction Of Gabbroic Crust At A Slow Spreading Ridge: Constraints From (206)Pb/(238)U Zircon Ages From Atlantis Massif And Iodp Hole U1309d (30 Degrees N, Mar), C. B. Grimes, Barbara John, Michael Cheadle, J. L. Wooden

Michael Cheadle

Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages of 24 samples from oceanic crust recovered in Integrated Ocean Drilling Program (IODP) Hole U1309D and from the surface of Atlantis Massif, Mid-Atlantic Ridge (MAR) (30 degrees N) document a protracted history of accretion in the footwall to an oceanic detachment fault. Ages for 18 samples of evolved Fe-Ti oxide gabbro and felsic dikes collected 40-1415 m below seafloor in U1309D yield a weighted mean of 1.20 +/- 0.03 Ma (mean square of weighted deviates = 7.1). However, the ages range from 1.08 +/- 0.07 Ma and 1.28 +/- 0.05 Ma indicating …

U-Pb Discordance In Archean Detrital Quartzites, Central Wyoming: Implications For Pb Loss Mechanisms, Carol Frost, C. M. Allen, Susan Swapp, B R. Frost

Susan Swapp

Meeting abstract for "U-Pb Discordance in Archean Detrital Quartzites, Central Wyoming: Implications for Pb Loss Mechanisms," June 2010.

2.685-2.671 Ga Himalayan-Type Orogeny In The Northern Teton Range, Wyoming, Usa, B R. Frost, Susan Swapp, Carol Frost

Susan Swapp

Meeting abstract for “2.685-2.671 Ga Himalayan-Type Orogeny in the Northern Teton Range, Wyoming, USA,” June 2009.

A Mesoarchean Rifted Continental Margin In The Wyoming Province: Evidence For Supercontinent Breakup, Susan Swapp, Carol Frost, B R. Frost

Susan Swapp

Meeting abstract for "A Mesoarchean Rifted Continental Margin in the Wyoming Province: Evidence for Supercontinent Breakup."