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Articles 181 - 210 of 368

Full-Text Articles in Earth Sciences

Quantifying Channel Responses To The Removal Of The Glines Canyon Dam In The Middle Reach Of The Elwha River, Washington, Bryon J. Free Jan 2015

Quantifying Channel Responses To The Removal Of The Glines Canyon Dam In The Middle Reach Of The Elwha River, Washington, Bryon J. Free

All Master's Theses

Four different study sites throughout the middle reach of the Elwha River were monitored before, during, and after the dam removal process over a period of two years from 2012-2014. The complexity of the river geometry was a major factor in the ability of the river to trap and accumulate the new influx of woody debris and sediment from the dam removal, which influenced the response of the river channel. The change that occurred was quantified by using repeat Terrestrial LiDAR (TLS), sediment distribution surveys, and large woody debris mapping techniques. The morphologic changes that occurred during this time were …

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Geologic Mapping In The Black Mountain Area, Northern Eastern California Shear Zone: Testing A Kinematic And Geometric Fault Slip Transfer Model, Kevin M. Delano Jan 2015

Geologic Mapping In The Black Mountain Area, Northern Eastern California Shear Zone: Testing A Kinematic And Geometric Fault Slip Transfer Model, Kevin M. Delano

All Master's Theses

New geologic mapping, structural, kinematic, and 40Ar/39Ar geochronology studies in the Black Mountain area, northern eastern California shear zone, are used to test a kinematic fault slip transfer model for the Owens Valley fault-Mina deflection transition. In the Black Mountain area, range bounding ~NNW- to ~NS-striking and lesser NW- to NE-striking normal faults cut Mesozoic, Miocene (22.42 ± 0.05 Ma), Pliocene (3.53 ± 0.06 to 3.29 ± 0.02 Ma), and early-middle Pleistocene (1936 ± 12.7 to 766 ± 3.1 ka) rocks. Palinspastically restored cross-sections show that offset Pliocene markers record 1.5 +0.7/-0.6 km of ~ENE-WSW extension since …

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Timing And Source Of Alkali Enrichment At Mt. Etna, Sicily: Constraints From Clinopyroxene Geobarometry And In Situ Sr Isotope Data, Kaitlyn Nelson Jan 2015

Timing And Source Of Alkali Enrichment At Mt. Etna, Sicily: Constraints From Clinopyroxene Geobarometry And In Situ Sr Isotope Data, Kaitlyn Nelson

All Master's Theses

Since 1971, Mt. Etna, Europe’s largest and most active volcano, has exhibited increased eruption frequency and explosivity. Associated with this increased activity, researchers have documented higher abundances of alkali elements (K, Rb, Cs) as well as elevated 87Sr/86Sr in Etnean lavas. The source of this alkali-enrichment has been hotly debated, with end-member hypotheses involving mantle vs. crustal contributions. To further characterize the evolution of the subvolcanic magma storage and transport system, as well as the timing and source of alkali-enrichment, clinopyroxene from ten samples erupted between 1329 and 2004 was targeted for in situ textural, major element …

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Using Modflow To Predict Impacts Of Groundwater Pumpage To Instream Flow: Upper Kittitas County, Washington, Zoe O. Futornick Jan 2015

Using Modflow To Predict Impacts Of Groundwater Pumpage To Instream Flow: Upper Kittitas County, Washington, Zoe O. Futornick

All Master's Theses

Surface waters in the Yakima River Basin in central Washington are considered over allocated. Since 1960, new water demands have been met through groundwater withdrawals, with most groundwater users holding a later priority date than senior and junior surface water users. As a result of the discussions surrounding this issue, the Upper Kittitas Groundwater Rule has been in effect since 2010. Pumping from new domestic (i.e., permit-exempt or “exempt”) groundwater wells in Upper Kittitas County is not allowed unless mitigation is used to offset the groundwater use. The United States Geological Survey (USGS) has already created a basin-wide model for …

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Mesoamerican Sacred Geography And Archeological Landscapes: A Case Study In The Volcanic Highlands Of Michoacan, Mexico, Jarod Scott Drozdowski Jan 2015

Mesoamerican Sacred Geography And Archeological Landscapes: A Case Study In The Volcanic Highlands Of Michoacan, Mexico, Jarod Scott Drozdowski

All Master's Theses

US and Mexican teams have investigated the La Alberca Structure Complex with the community of Parangaricutiro. Their forest reserve, located near San Juan Nuevo in Michoacan, Mexico, contains several volcanic cones, including the famous Paricutin cinder cone. Sixteen earthen-rock structures have been mapped using aerial photography, GPS, GIS, and total station surveys. The structures range from 300 to 2,400 cubic meters in volume. The larger mound-like structures are traditionally called yacatas. Early radiocarbon dates for two of the three central structures (ca. 5200-2000 BCE) bracket dates for the Late Archaic burial in the La Alberca caldera. Arrangements of the larger …

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Pressure-Temperature-Time Constraints For Exhumation Of Ultrahigh-Pressure Metamorphic Rocks, North Qaidam Terrane, Western China, Brittany Kristine Fagin Jan 2015

Pressure-Temperature-Time Constraints For Exhumation Of Ultrahigh-Pressure Metamorphic Rocks, North Qaidam Terrane, Western China, Brittany Kristine Fagin

All Master's Theses

Ultrahigh-pressure rocks of a Paleozoic continental suture zone are exposed in the southeastern North Qaidam terrane (Dulan region). Garnetite sample D119 contains minor Czo+Qtz+Chl+Ttn; rutile inclusions in titanite suggest that titanite replaced rutile during decompression. Pressure-temperature estimates of sample D119 are 16.1-18.4 kbar and 485-520 °C. Sample D130B is a mafic band in calc-silicate gneiss, with garnet porphyroblasts in a fine-grained Hbl-Cpx-Pl-Qtz symplectite that is interpreted as former omphacite. D130B symplectite pressure-temperature estimates are 7.7-9.4 kbar and 623-708 °C. Titanite U-Pb ages of 419.7±3.1 Ma and 415.9±4.2 Ma are interpreted to date retrogression of D119 and D130B, respectively. Average exhumation …

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Measuring The Cost And Performance Of Lithic Industries At The Sunrise Ridge Borrow Pit Site (45pi408), Patrick Christropher Lewis Jan 2015

Measuring The Cost And Performance Of Lithic Industries At The Sunrise Ridge Borrow Pit Site (45pi408), Patrick Christropher Lewis

All Master's Theses

This thesis applies a theoretically informed protocol that focuses on variation in stone tool manufacture and use as measured in the 45PI408 lithic assemblage. The model used is based on the variables of stone tool cost and performance. Guided by this model, technological and functional paradigmatic classifications are employed to measure intra­site variation in lithic frequencies. This method avoids difficulties encountered by previous archaeologists by using mutually exclusive analytical units that measure subtle variation in the archaeological record. Variability in technological and functional paradigmatic classificatory dimensions such as stone tool heat treatment, raw materials, use wear, and reduction class were …

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Accelerated Glacier Melt On Snow Dome, Mount Olympus, Washington, Usa, Due To Deposition Of Black Carbon And Mineral Dust From Wildfire, Susan Kaspari, S. Mckenzie Skiles, Ian Delaney, Daniel Dixon Jan 2015

Accelerated Glacier Melt On Snow Dome, Mount Olympus, Washington, Usa, Due To Deposition Of Black Carbon And Mineral Dust From Wildfire, Susan Kaspari, S. Mckenzie Skiles, Ian Delaney, Daniel Dixon

Geological Sciences Faculty Scholarship

Assessing the potential for black carbon (BC) and dust deposition to reduce albedo and accelerate glacier melt is of interest in Washington because snow and glacier melt are an important source of water resources, and glaciers are retreating. In August 2012 on Snow Dome, Mount Olympus, Washington, we measured snow surface spectral albedo and collected surface snow samples and a 7 m ice core. The snow and ice samples were analyzed for iron (Fe, used as a dust proxy) via inductively coupled plasma sector field mass spectrometry, total impurity content gravimetrically, BC using a single-particle soot photometer (SP2), and charcoal …

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Applying Wetland Rating Systems To Assess Functions Of Depressional Wetlands Created By A Mass Wasting Feature, Table Mountain, Washington, Thomas S. Wachholder Jan 2015

Applying Wetland Rating Systems To Assess Functions Of Depressional Wetlands Created By A Mass Wasting Feature, Table Mountain, Washington, Thomas S. Wachholder

All Master's Theses

The formation of wetlands in the Swauk Watershed has been primarily controlled by mass wasting events, which includes landslide activity. Landslide activity has been the primary influential process in shaping the landscape where wetland systems have formed on the surface of landslide deposits. The wetland sites used in this study, near the base of Table Mountain, were chosen because they inhabit the same ancient landslide, have the same underlying geology, and vary in aspect and elevation. The elevational gradient of the sites ranges from 1300 – 1600 m and the individual wetlands differ in terms of north- and south-facing aspects. …

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Iron Sources And Dissolved-Particulate Interactions In The Seawater Of The Western Equatorial Pacific, Iron Isotope Perspectives, M. Labatut, F. Lacan, C. Pradoux, J. Chmeleff, A. Radic, J. W. Murray, F. Poitrasson, Anne M. Johansen, F. Thil Oct 2014

Iron Sources And Dissolved-Particulate Interactions In The Seawater Of The Western Equatorial Pacific, Iron Isotope Perspectives, M. Labatut, F. Lacan, C. Pradoux, J. Chmeleff, A. Radic, J. W. Murray, F. Poitrasson, Anne M. Johansen, F. Thil

All Faculty Scholarship for the College of the Sciences

This work presents iron isotope data in the western equatorial Pacific. Marine aerosols and top core margin sediments display a slightly heavy Fe isotopic composition (δ56Fe) of 0.33 ± 0.11‰ (2SD) and 0.14 ± 0.07‰, respectively. Samples reflecting the influence of Papua New Guinea runoff (Sepik River and Rabaul volcano water) are characterized by crustal values. In seawater, Fe is mainly supplied in the particulate form and is found with a δ56Fe between −0.49 and 0.34 ± 0.07‰. The particulate Fe seems to be brought mainly by runoff and transported across continental shelves and slopes. …

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Optimized Method For Black Carbon Analysis In Ice And Snow Using The Single Particle Soot Photometer, I. A. Wendl, James A. Menking, R. Färber, M. Gysel, Susan D. Kaspari, M. J. G. Laborde, M. Schwikowski Aug 2014

Optimized Method For Black Carbon Analysis In Ice And Snow Using The Single Particle Soot Photometer, I. A. Wendl, James A. Menking, R. Färber, M. Gysel, Susan D. Kaspari, M. J. G. Laborde, M. Schwikowski

All Faculty Scholarship for the College of the Sciences

In this study we attempt to optimize the method for measuring black carbon (BC) in snow and ice using a Single Particle Soot Photometer (SP2). Beside the previously applied ultrasonic (CETAC) and Collison-type nebulizers we introduce a jet (Apex Q) nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and Apex Q require small sample volumes (a few milliliters) which makes them suitable for ice core analysis. The Apex Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100–1000 nm. The CETAC has the advantage that air and liquid flows can be monitored …

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Seasonal And Elevational Variations Of Black Carbon And Dust In Snow And Ice In The Solu-Khumbu, Nepal And Estimated Radiative Forcings, Susan Kaspari, T. H. Painter, M. Gysel, S. M. Skiles, M. Schwikowski Aug 2014

Seasonal And Elevational Variations Of Black Carbon And Dust In Snow And Ice In The Solu-Khumbu, Nepal And Estimated Radiative Forcings, Susan Kaspari, T. H. Painter, M. Gysel, S. M. Skiles, M. Schwikowski

All Faculty Scholarship for the College of the Sciences

Black carbon (BC) and dust deposited on snow and glacier surfaces can reduce the surface albedo, accelerate snow and ice melt, and trigger albedo feedback. Assessing BC and dust concentrations in snow and ice in the Himalaya is of interest because this region borders large BC and dust sources, and seasonal snow and glacier ice in this region are an important source of water resources. Snow and ice samples were collected from crevasse profiles and snow pits at elevations between 5400 and 6400 m a.s.l. from Mera glacier located in the Solu-Khumbu region of Nepal during spring and fall 2009, …

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Thermodynamic Model For Energy-Constrained Open-System Evolution Of Crustal Magma Bodies Undergoing Simultaneous Recharge, Assimilation And Crystallization: The Magma Chamber Simulator, Wendy A. Bohrson, Frank J. Spera, Mark S. Ghiorso, Guy Brown, Jeffrey Creamer, Aaron Mayfield Aug 2014

Thermodynamic Model For Energy-Constrained Open-System Evolution Of Crustal Magma Bodies Undergoing Simultaneous Recharge, Assimilation And Crystallization: The Magma Chamber Simulator, Wendy A. Bohrson, Frank J. Spera, Mark S. Ghiorso, Guy Brown, Jeffrey Creamer, Aaron Mayfield

All Faculty Scholarship for the College of the Sciences

The Magma Chamber Simulator quantifies the impact of simultaneous recharge, assimilation and crystallization through mass and enthalpy balance in a multicomponent–multiphase (melt + solids ± fluid) composite system. As a rigorous thermodynamic model, the Magma Chamber Simulator computes phase equilibria and geochemical evolution self-consistently in resident magma, recharge magma and wallrock, all of which are connected by specified thermodynamic boundaries, to model an evolving open-system magma body. In a simulation, magma cools from its liquidus temperature, and crystals ± fluid are incrementally fractionated to a separate cumulate reservoir. Enthalpy from cooling, crystallization, and possible magma recharge heats wallrock from its …

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Clockwise Rotation Of The Brahmaputra Valley Relative To India: Tectonic Convergence In The Eastern Himalaya, Naga Hills, And Shillong Plateau, ‪Philippe Vernant, R. Bilham, Walter Szeliga, D. Drupka, S. Kalita, A. K. Bhattacharyya, V. K. Gaur Aug 2014

Clockwise Rotation Of The Brahmaputra Valley Relative To India: Tectonic Convergence In The Eastern Himalaya, Naga Hills, And Shillong Plateau, ‪Philippe Vernant, R. Bilham, Walter Szeliga, D. Drupka, S. Kalita, A. K. Bhattacharyya, V. K. Gaur

All Faculty Scholarship for the College of the Sciences

GPS data reveal that the Brahmaputra Valley has broken from the Indian Plate and rotates clockwise relative to India about a point a few hundred kilometers west of the Shillong Plateau. The GPS velocity vectors define two distinct blocks separated by the Kopili fault upon which 2–3 mm/yr of dextral slip is observed: the Shillong block between longitudes 89 and 93°E rotating clockwise at 1.15°/Myr and the Assam block from 93.5°E to 97°E rotating at ≈1.13°/Myr. These two blocks are more than 120 km wide in a north‐south sense, but they extend locally a similar distance beneath the Himalaya and …

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Upper Mantle Seismic Anisotropy Beneath The West Antarctic Rift System And Surrounding Region From Shear Wave Splitting Analysis, Natalie J. Accardo, Douglas A. Wiens, Stephen Hernandez, Richard C. Aster, Andrew Nyblade, Audrey D. Huerta, Sridhar Anandakrisnan, Terry Wilson, David S. Heeszel, Ian W.D. Dalziel May 2014

Upper Mantle Seismic Anisotropy Beneath The West Antarctic Rift System And Surrounding Region From Shear Wave Splitting Analysis, Natalie J. Accardo, Douglas A. Wiens, Stephen Hernandez, Richard C. Aster, Andrew Nyblade, Audrey D. Huerta, Sridhar Anandakrisnan, Terry Wilson, David S. Heeszel, Ian W.D. Dalziel

Geological Sciences Faculty Scholarship

We constrain azimuthal anisotropy in the West Antarctic upper mantle using shear wave splitting parameters obtained from teleseismic SKS, SKKS and PKS phases recorded at 37 broad-band seismometres deployed by the POLENET/ANET project. We use an eigenvalue technique to linearize the rotated and shifted shear wave horizontal particle motions and determine the fast direction and delay time for each arrival. High-quality measurements are stacked to determine the best fitting splitting parameters for each station. Overall, fast anisotropic directions are oriented at large angles to the direction of Antarctic absolute plate motion in both hotspot and no-net-rotation frameworks, showing that the …

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Influence Of Regional Precipitation Patterns On Stable Isotopes In Ice Cores From The Central Himalayas, H. Pang, S. Hou, Susan Kaspari, P. A. Mayewski Feb 2014

Influence Of Regional Precipitation Patterns On Stable Isotopes In Ice Cores From The Central Himalayas, H. Pang, S. Hou, Susan Kaspari, P. A. Mayewski

All Faculty Scholarship for the College of the Sciences

Several ice cores have been recovered from the Dasuopu (DSP) Glacier and the East Rongbuk (ER) Glacier in the central Himalayas since the 1990s. Although the distance between the DSP and the ER ice core drilling sites is only 125 km, the stable isotopic record (18O or D) of the DSP core is interpreted in previous studies as a temperature proxy, while the ER core is interpreted as a precipitation proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, …

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Seismic And Geodetic Evidence For Grounding-Line Control Of Whillans Ice Stream Stick-Slip Events, Martin J. Pratt, J. Paul Winberry, Douglas A. Wiens, Sridhar Anandakrishnan, Richard B. Alley Feb 2014

Seismic And Geodetic Evidence For Grounding-Line Control Of Whillans Ice Stream Stick-Slip Events, Martin J. Pratt, J. Paul Winberry, Douglas A. Wiens, Sridhar Anandakrishnan, Richard B. Alley

All Faculty Scholarship for the College of the Sciences

The tidally modulated, stick‐slip events of Whillans Ice Stream in West Antarctica produce seismic energy from three locations near the grounding line. Using ice velocity records obtained by combining time series from colocated broadband seismometers and GPS receivers installed on the ice stream during the 2010–2011 and 2011–2012 austral summers, along with far‐field seismic recordings of elastic waves, we locate regions of high rupture velocity and stress drop. These regions, which are analogous to “asperities” in traditional seismic fault studies, are areas of elevated friction at the base of the ice stream. Slip events consistently initiate at one of two …

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Tidal Pacing, Skipped Slips And The Slowdown Of Whillans Ice Stream, Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Douglas A. Wiens, Martin J. Pratt Jan 2014

Tidal Pacing, Skipped Slips And The Slowdown Of Whillans Ice Stream, Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley, Douglas A. Wiens, Martin J. Pratt

All Faculty Scholarship for the College of the Sciences

We summarize new observations of the deceleration and stick–slip motion of Whillans Ice Stream (WIS), Antarctica. We refine the location of the large sticky spots that resist motion between slip events, the locations of which are controlled by the patterns of subglacial water flow. Our examination of the long-term velocity time series for the ice stream reveals that the decadal-scale deceleration is not occurring at a steady rate, but varies at the sub-decadal timescale. This unsteady deceleration modulates the temporal evolution of a broad (~50 km across) surface-elevation bulge forming at the junction between the relatively narrow upstream portion of …

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Deformation And Exhumation Across Gianbul Dome, Nw India: Insight From Deformation Kinematics And Temperatures, And 40ar/39ar Thermochronology, Meilani Bowman-Kamaha’O Jan 2014

Deformation And Exhumation Across Gianbul Dome, Nw India: Insight From Deformation Kinematics And Temperatures, And 40ar/39ar Thermochronology, Meilani Bowman-Kamaha’O

All Master's Theses

New kinematic, microtextural, and thermochronology studies test the hypothesis that high temperature-moderate pressure rocks exposed in Gianbul Dome, NW India, were exhumed south of the southern Tibetan detachment system by the southward extrusion of a mid-crustal ductile channel. Mesoscopic and microscopic kinematic indicators record normal-sense shear in the Khanjar and Zanskar shear zones, which define the southwest and northeast flanks of Gianbul Dome, respectively. Microtextural analyses indicate deformation at >400°C along dome flanks increasing to > 700°C in the core. Moderate temperature cooling is asymmetric across the dome, initiating at ~22 Ma on the southwest flank of the dome-and at ~20 …

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Constraints On Interplate Locking Within The Makran Subduction Zone Using Gps, Elyse Erin Frohling Jan 2014

Constraints On Interplate Locking Within The Makran Subduction Zone Using Gps, Elyse Erin Frohling

All Master's Theses

We use GPS measurements from 20 stations located in Iran, Pakistan, and Oman along with International Seismological Centre hypocentral locations to create a fault coupling model for the Makran subduction zone. The 3-D geometry of the megathrust fault is estimated from five profiles landward of the Makran trench. Continuous GPS on the Arabian plate show convergence of ~27 mm/year, and interseismic deformation is calculated using the back-slip method of Savage [ 1983]. We find the entire subduction zone appears to be accumulating stress uniformly from ~15-60 km depth and find no evidence of along-strike segmentation in strain accumulation, suggesting the …

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Structural Deformation Across The Southwest Mina Deflection, California-Nevada: Field Studies In The Huntoon Spring Quadrangle, Eliya R. Hogan Jan 2014

Structural Deformation Across The Southwest Mina Deflection, California-Nevada: Field Studies In The Huntoon Spring Quadrangle, Eliya R. Hogan

All Master's Theses

New geologic data provides insight into Pliocene strain rates across the southwest Mina deflection. 40 Ar/39 Ar geochronology of geologic units indicate cooling of Miocene ignimbrite at 11.86 ± 0.01 Ma, Pliocene basalt lavas at 3.7241 ± 0.0051 and 3.5262 ± 0.0172 Ma, and basaltic andesite and andesite lavas at 3.4715 ± 0.0107 Ma and 3.1078 ± 0.0088 Ma. Pliocene cinder cones and Quaternary sediments are also exposed in the Huntoon Spring quadrangle. Volcanic units are cut by a dominant set of NNE-, NE-, and ENE- striking sinistral faults and a lesser set of NNW- and NW- striking normal …

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Proxy-Based Reconstructions Of Earthquakes And Tsunamis At Quidico, South-Central Chile, Isabel J. Hong Jan 2014

Proxy-Based Reconstructions Of Earthquakes And Tsunamis At Quidico, South-Central Chile, Isabel J. Hong

All Master's Theses

We utilized geomorphic, microfossil, sedimentological, and stratigraphic methods to investigate the paleotsunami history at Quidico, Chile (38.1° S, 73.2° W). A combination of pits, cores, and riverbank exposures provide stratigraphic evidence of 8 sand layers at Quidico, including tsunami deposits from 2010 and 1960. The sands are laterally continuous but display landward thinning, disappearing completely from the stratigraphy 1.2 km inland from the coast. Intervening sediment layers consist of organicrich silts and peat. Grain size analysis shows the sand units are bimodal in distribution whereas the organic-rich silts and peat have a broader, bimodal distribution. Lithological analysis showed similarities among …

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Controls On Fault Geometry During Early Stages Of Extension In The Larkspur Hills, Northwest Basin And Range, Diana Jean Strickley Jan 2014

Controls On Fault Geometry During Early Stages Of Extension In The Larkspur Hills, Northwest Basin And Range, Diana Jean Strickley

All Master's Theses

Detailed analyses of normal faults in the Larkspur Hills, CA-NV, northwest Basin and Range, offer insight into factors controlling normal fault initiation, growth, and distribution. N-trending faults in the southern portion of the study area share trends of major range-bounding structures and Pliocene linear volcanic vents; in contrast, NNW- and NNE- trending faults dominate further north and into south-central Oregon. Stress analyses and comparison with experimental and field data suggest that preexisting structures control faults in the northern Larkspur Hills, while faults form perpendicular to σ3 in the southern hills. The change in fault orientations is abrupt, occurring across a …

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Spatial Relationship Between Gps Slip And Seismic Tremor During Cascadia Slow Slip Events, Hillary Lynn Goodner Jan 2014

Spatial Relationship Between Gps Slip And Seismic Tremor During Cascadia Slow Slip Events, Hillary Lynn Goodner

All Master's Theses

We model GPS deformation and timing of seismic tremor associated with transient deformation in Cascadia to test the hypothesis that tremor and slip occur synchronously but are spatially offset. For the period 2010–2013, we use seismic tremor data with a duration-moment relationship to predict GPS time series and compare them to observations. We find that observed GPS displacements are best predicted when tremor locations on the plate interface are shifted 15 km up-dip of their published epicenter. To test whether the spatial offset of tremor and slip is due to systematic mislocation of published epicenters, we attempt to identify individual …

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Thermobarometry And Geochronology In The Dulan Region, North Qaidam Ultrahigh-Pressure Terrane: Resolving Spatial Variation Of Ages, Temperatures, And Pressures, Megan Eileen Regel Jan 2014

Thermobarometry And Geochronology In The Dulan Region, North Qaidam Ultrahigh-Pressure Terrane: Resolving Spatial Variation Of Ages, Temperatures, And Pressures, Megan Eileen Regel

All Master's Theses

The Dulan ultrahigh-pressure (UHP) terrane exposes 449-422 Ma eclogites in the east and 449-418 Ma high-pressure granulites to the west, but the relationship between the units is poorly understood. Zirconium-in-rutile temperatures show an east-west 3- 5°C/km gradient in four UHP eclogites: 662-716±10°C; garnet-omphacite-phengite thermobarometry of peak conditions yields 659-730±82°C, 25.3-27.1±3.2 kbars. Zircon U-Pb ages of four eclogites are the same within uncertainty, averaging 434±2.9 Ma. Tiin- zircon thermometry and rare earth element patterns indicate these ages represent eclogite facies metamorphism. One high-pressure/high-temperature (HP/HT) granulite yields a minimum rutile temperature of 773±4°C. Previous thermobarometry of highpressure granulites yields ≥800°C and 14-17 …

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The Crustal Thickness Of West Antarctica, Julien A. Chaput, Richard C. Aster, Audrey D. Huerta, X. Sun, Andrew Lloyd, Douglas A. Wiens, Andrew Nyblade, Sridhar Anandakrishnan, J. Paul Winberry, Terry Wilson Dec 2013

The Crustal Thickness Of West Antarctica, Julien A. Chaput, Richard C. Aster, Audrey D. Huerta, X. Sun, Andrew Lloyd, Douglas A. Wiens, Andrew Nyblade, Sridhar Anandakrishnan, J. Paul Winberry, Terry Wilson

Geological Sciences Faculty Scholarship

P-to-S receiver functions (PRFs) from the Polar Earth Observing Network (POLENET) GPS and seismic leg of POLENET spanning West Antarctica and the Transantarctic Mountains deployment of seismographic stations provide new estimates of crustal thickness across West Antarctica, including the West Antarctic Rift System (WARS), Marie Byrd Land (MBL) dome, and the Transantarctic Mountains (TAM) margin. We show that complications arising from ice sheet multiples can be effectively managed and further information concerning low-velocity subglacial sediment thickness may be determined, via top-down utilization of synthetic receiver function models. We combine shallow structure constraints with the response of deeper layers using a …

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Glacier Slip And Seismicity Induced By Surface Melt, Peter L. Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Miriam Jackson, Mark E. Mathison, Denis Cohen Dec 2013

Glacier Slip And Seismicity Induced By Surface Melt, Peter L. Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Miriam Jackson, Mark E. Mathison, Denis Cohen

All Faculty Scholarship for the College of the Sciences

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed …

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Seismic Slip Deficit In The Kashmir Himalaya From Gps Observations, Celia Schiffman, Bikram Singh Bali, Walter Szeliga, Roger Bilham Nov 2013

Seismic Slip Deficit In The Kashmir Himalaya From Gps Observations, Celia Schiffman, Bikram Singh Bali, Walter Szeliga, Roger Bilham

Faculty Scholarship for the Cascadia Hazards Institute

GPS measurements in Kashmir Himalaya reveal rangenormal convergence of 11±1 mm/yr with dextral shear of 5±1 mm/yr. The transition from a fully locked 170 km wide décollement to the unrestrained descending Indian plate occurs at ~25 km depth over an ~23 km wide transition zone. The convergence rate is consistent with the lower bounds of geological estimates for the Main Frontal Thrust, Riasi, and Balapora fault systems, on which no surface slip has been reported in the past millennium. Of the 14 damaging Kashmir earthquakes since 1123, none may have exceeded Mw = 7.6. Therefore, either a seismic moment …

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Alluvial Sediment Or Playas: What Is The Dominant Source Of Sand And Silt In Desert Soil Vesicular A Horizons, Southwest Usa, Mark R. Sweeney, Eric V. Mcdonald, Christohper E. Markley Mar 2013

Alluvial Sediment Or Playas: What Is The Dominant Source Of Sand And Silt In Desert Soil Vesicular A Horizons, Southwest Usa, Mark R. Sweeney, Eric V. Mcdonald, Christohper E. Markley

All Faculty Scholarship for the College of the Sciences

Vesicular A (Av) soil horizons form beneath desert pavements from the accretion of aeolian sediment (dust) commonly thought to be derived primarily from desiccating pluvial lakes and playas, with contributions from ephemeral washes and alluvial fans. Particle size distributions of Av horizons are typically bimodal with primary modes of very fine silt and fine sand, suggesting that the horizon matrix is derived from multiple sources. Here we conduct detailed chemical and physical analysis of both Av horizon soil samples and potential sources of aeolian sediment to better constrain the relative contributions of dust associated with the development of Av horizons. …

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Evolution Of Dike Opening During The March 2011 Kamoamoa Fissure Eruption, Kīlauea Volcano, Hawai'i, Paul Lundgren, Michael Poland, Asta Miklius, Tim Orr, Sang-Ho Yun, Eric Fielding, Zhen Liu, Scott Hensley, Susan Owen, Akiko Tanaka, Walter Szeliga Mar 2013

Evolution Of Dike Opening During The March 2011 Kamoamoa Fissure Eruption, Kīlauea Volcano, Hawai'i, Paul Lundgren, Michael Poland, Asta Miklius, Tim Orr, Sang-Ho Yun, Eric Fielding, Zhen Liu, Scott Hensley, Susan Owen, Akiko Tanaka, Walter Szeliga

Faculty Scholarship for the Cascadia Hazards Institute

The 5–9 March 2011 Kamoamoa fissure eruption along the east rift zone of Kīlauea Volcano, Hawai`i, followed months of pronounced inflation at Kīlauea summit. We examine dike opening during and after the eruption using a comprehensive interferometric synthetic aperture radar (InSAR) data set in combination with continuous GPS data. We solve for distributed dike displacements using a whole Kīlauea model with dilating rift zones and possibly a deep décollement. Modeled surface dike opening increased from nearly 1.5 m to over 2.8 m from the first day to the end of the eruption, in agreement with field observations of surface fracturing. …

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