Geomorphology Commons^™

Catastrophic Landscape Modification From Massive Landslide Tsunamis: An Example From Taan Fiord, Alaska, Colin Bloom

All Master's Theses

The October 17^th 2015 Taan landslide and tsunami generated a high runup of 192 m, nearly an order of magnitude greater than most previously surveyed tsunamis. Extensive modifications observed and documented on several low gradient fan deltas within the fiord make Taan Fiord an excellent laboratory for characterizing geomorphic signatures of a high runup tsunami event. Although interest in this topic is high, most prior post-tsunami surveys are from earthquake-generated tsunamis with relatively low runup, thus the geomorphic signatures of high runup tsunamis or their potential for preservation are uncharacterized. Additionally, clear modifications described during post-tsunami surveys are typically …

Surface Offset And Slip Rates For The Winter Rim Fault System In The Summer Lake Basin, Oregon, Jennifer Hall

All Master's Theses

The 66-km-long Winter Rim Fault (WRF) system, located in the northwestern Basin and Range Province, encompasses several Holocene fault scarps within the Summer Lake basin that include the WRF system, a normal fault divided into three segments: Slide Mountain (SMF), Winter Ridge, and Ana River (ARF), and the newly-mapped Thousand Springs fault (TSF). The current least-compressive stress field is oriented ~264° (Crider, 2001). The USGS estimates a slip rate of 0.43 mm/yr, earthquake magnitudes of 6.5-7.19, and recurrence interval of 3.1 ka (Crone et al., 2009). However, these estimates are only based upon ARF and the unfavorably slip-oriented SMF. With …

Investigating Taphonomic Changes Of Deposits And Modeling Of The 2010 Earthquake And Tsunami In South-Central Chile, Alexandra Carranco Ruiz

All Master's Theses

South-central Chile has an extensive written catalog of historic earthquakes and tsunamis, but such records can be subject to inconsistencies. Dated tsunami deposits are more objective data that provide hard evidence of past tsunamis. The inland extent of deposits from past tsunamis (paleodeposits) can be used in tsunami modeling to reveal characteristics of the source earthquake, but these deposits may have undergone taphonomic processes since initial deposition. Therefore, to determine how tsunami deposits change during burial and preservation and the potential limitations of using paleodeposits in modeling, I investigated the modern 2010 M_w 8.8 Maule earthquake and tsunami as …

Spatiotemporal Slip Rate Variations Along Surprise Valley Fault In Relation To Pleistocene Pluvial Lakes, Brian N. Marion

All Master's Theses

Using mapped paleoshoreline features with high-resolution topographic data and obtained radiocarbon dates on paleoshoreline tufas, I documented precise fault offsets of dated features over the last 25 ka along the Surprise Valley Fault (SVF). Fault offset measured in three lake sections within Surprise Valley ranged from 3.6 m in the southern section to 14.4 m in the central section. The offset paleoshorelines are dated to the late Pleistocene (<22 >ka) and were formed during the latest impoundment of pluvial Lake Surprise since the last glacial maximum. Slip rates vary along strike, assuming a fault dip of 68° with 0.25 ± …

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 …

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 …

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 …

Geomorphology Of Deposits From The 2004 Indian Ocean Tsunami, Tamil Nadu, Southeastern India, Patrick Alan Johnston

All Master's Theses

In low latitudes, geologically suitable repositories for tsunami deposits are not well defined. This project characterizes the geomorphic environments on the southeastern coast of India that preserved depositional evidence of the catastrophic tsunami created by the M_w9.0-9.3 Sumatra-Andaman earthquake on December 26, 2004. The Indian coast is particularly interesting because it is approximately 1300 km from the subduction-zone source of tsunamis across the Indian Ocean, and therefore only the largest events are capable of reaching it. The main objective of this study was to identify the settings where recognizable tsunami deposits from the 2004 event have been preferentially …

Holocene Arroyo Cut And Fills Cycles, South-Central Washington, Matthew Ian Durkee

All Master's Theses

Ephemeral streams have cut deeply incised arroyos into alluvial and eolian sediments in many of the watersheds within the Yakima Training Center (YTC) military reservation, south-central Washington. The most recent channel incision episode along Selah Creek is primarily attributed to multiple failures of an irrigation reservoir dam during the winters of 1909 and 1910. The modern arroyo exposed evidence of at least one previous episode of arroyo incision to a depth of ~4 m that occurred just prior to 1530- 1340 cal yr BP. Filling of this paleo-arroyo with fine to coarse grained sand ceased between 650-103 cal yr BP. …

Documenting Magma Evolution Of The Fossa Delle Felci (Salina Island, South Tyrrhenian Sea) By Integrating In Situ Plagioclase Data With Quantitative Modeling, Aaron Mayfield

All Master's Theses

Compositional diversity occurs via processes dominated by recharge, assimilation and fractional crystallization (RAFC), quantification of which can provide insights into eruption catalysts, and therefore assist in hazard mitigation. This study evaluates the relative roles of RAFC processes in Fossa delle Felci (Salina Island, Italy) magmas, which span the basalt to dacite range (52-65 wt% SiO2). Integration of petrographic, whole rock, and in situ plagioclase data with quantitative magma chamber models suggests differentiation dominated by fractional crystallization and magma recharge/mixing in reservoirs located at different crustal levels. At ~12 km depth, magma evolved through crystallization of a pyroxene dominated assemblage; plagioclase …

Petrogenetic Relationship Of The Postcaldera Eruptions Of Mount Mazama, Crater Lake, Oregon; Evolution Of A Sub-Volcanic Magma Chamber Following A Large Silicic Eruption, Michelle Leanna Tebbe

All Master's Theses

Mount Mazama is the volcanic edifice that cataclysmically erupted ~503 km of relatively homogeneous rhyodacite lava ~ 7,700 years ago, forming the caldera known as Crater Lake. Within a few hundred years, andesitic eruptions built three distinct volcanic edifices on the floor of Crater Lake; ~ 3000 years later, rhyodacite eruptions formed a dome (Bacon et al., 2002). How magmatic systems evolve following a shallow, relatively large silicic eruption is the focus of this study. In situ geochemical analysis coupled with high-resolution textural images of plagioclase crystals in the four postcaldera volcanic edifices were used to identify distinct crystal populations …

Documenting Magnatic Processes At Filicudi Island, Aeolian Arc, Italy: Integrating Quantitative Modeling And Plagioclase Textural And In Situ Compositional Data, Michelle Harris

All Master's Theses

Documenting the physiochemical processes that influence magma composition is critical for forecasting eruption styles and managing volcanic hazards. Compositional diversity of magmas develops through recharge, assimilation, and fractional crystallization (RAFC) within subvolcanic magma reservoirs. Integration of MELTS modeling, whole rock, plagioclase textural and in situ elemental and isotopic data from Filicudi Island, Italy allow documentation of the roles and relative chronology that RAFC played in the magmatic evolution and elucidates aspects of the magma plumbing system structure.

Results indicate a polybaric magma plumbing system with deeper (3.5-4 kilobars) and shallower (0.5-1.2 kilobars) storage regions. Within the deeper system, FC acted …

Documenting The Origin Of Compositional Diversity Of Subduction Zone Magmatism, Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy) Using In Situ Plagioclase Data, Rachel Hunt

All Master's Theses

Processes that generate magma compositional diversity are important to document because composition affects degree of explosivity, which impacts hazard mitigation. Magnesium to silicon rich magmas are produced by processes such as magma recharge, assimilation, and fractional crystallization (RAFC) that occur in subvolcanic magma chamber(s). This study evaluates how magma chamber processes contribute to compositional diversity at Alicudi Volcano, Italy. Analytical and petrographic data from ten samples that span the subaerial history include whole rock major and trace elements and strontium/neodymium isotopes, and plagioclase textural types, major and trace elements, and strontium isotopes; numerical modeling was also conducted. Integration of these …

Surface Wave Inversion Of The Upper Mantle Velocity Structure In The Ross Sea Region, Western Antarctica, James D. Rinke

All Master's Theses

The Ross Sea in Western Antarctica is the locale of several extensional basins formed during Cretaceous to Paleogene rifting. Several seismic studies along the Transantarctic Mountains and Victoria Land Basin’s Terror Rift have shown a general pattern of fast seismic velocities in East Antarctica and slow seismic velocities in West Antarctica. This study focuses on the mantle seismic velocity structure of the West Antarctic Rift System in the Ross Embayment and adjacent craton and Transantarctic Mountains to further refine details of the velocity structure.

Teleseismic events were selected to satisfy the two-station great-circle-path method between 5 Polar Earth Observing Network …

Lacustrine Sediment Record Of Multiple Quaternary Lava Dams On The Owyhee River, Southeastern Oregon, Caitlin Anne Orem

All Master's Theses

Multiple lava dams and correlating lakes impacted the Quaternary evolution of the Owyhee River. Sediment records from lava-dammed lakes were investigated to understand effects of the West Crater (WC) lava dam (~70 ka), the Saddle Butte 2 lava dam (~144 ka), and the Bogus Rim lava dam (~1.9 Ma). Evidence from the WC lava dam and related features indicates that dam duration consisted of five stages (1) dam and lake formation at ~70 ka; (2) dam overflow and lake sedimentation from ~70–46 ka; (3) removal of lava dam and lake termination from ~46 ka to at least 36 ka; (4) …

Comparison Of Landslides And Their Related Outburst Flood Deposits, Owyhee River, Southeastern Oregon, Shannon Marian Othus

All Master's Theses

Numerous landslides have entered the Owyhee River canyon north of Rome, Oregon. As the river flows through different lithologic units, the style of mass wasting changes from large slump events and small rock falls to large earthflows. The change in mechanism of mass wasting from upstream to downstream seems to depend on several factors: (1) the ratio of the basalt cap to the exposed underlying sediments, (2) the composition of underlying sediments, (3) the canyon geometry, and (4) the extent and frequency of mass wasting. All three mechanisms of mass wasting have the ability to block the river channel and …

Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille

All Master's Theses

Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …

Petrogenetic Processes Characterizing The Mount Bachelor, Oregon Magmatic System: Open- Versus Closed-System Processes, Sara Elizabeth Johnson

All Master's Theses

Mount Bachelor volcanic chain (MBVC), located in central Oregon, is one of the larger basalt and basaltic-andesite edifices in central Oregon. Preliminary studies have defined how eruptions have changed composition with time, but a detailed assessment of magma chamber processes has not been conducted. To gain a more thorough understanding of the magmatic processes that have contributed to the observed compositional evolution, this study focuses on one of four eruptive episodes, specifically episode III, the most voluminous episode of the four. Magmatic processes are assessed by focusing on both whole-rock and single crystal data.

The geochemistry and textural diversity of …

Paleoflood Record Reconstruction At An Archaeological Site On The Owyhee River, Southeastern Oregon, Stephanie Louise Vandal

All Master's Theses

The magnitude and frequency of late Holocene floods on the Owyhee River in southeastern Oregon were reconstructed from fine-grained flood deposits at three sites in the river canyon. The stratigraphy at the Birch Creek study site (BCSS) preserves a record of seven to nine large floods from the last 2800 years. Two additional study sites, the Iron Gate and Waterwheel, within a 5-km reach of the BCSS, showed 18-26 floods from the late Holocene to 1993 A.D. and 17-22 floods from 8600 B.P. to 1993 A.D., respectively. Hydrologic Engineering Center-River Analysis System modeling of the 1993 flood and several paleofloods …

Late Holocene Uplift Of The Chihshang Segment Of The Longitudinal Valley Fault At Fuli, Eastern Taiwan, Brian Thomas Gray

All Master's Theses

Uplifted Holocene strath terraces of the Bieh River drainage, eastern Taiwan, were analyzed in order to determine millennial-scale uplift and horizontal shortening rates of the Longitudinal Valley fault. Detrital charcoal fragments collected from three terraces within the Bieh River drainage yield ages between 1395 and 555 cal. yr B.P, suggesting an average uplift rate of 11.3 ± 3.6 mm yr^-1 for the last 1400 cal. yr B.P. The average horizontal shortening rate of 19.7 ± 9.5 mm yr^-1 was within error of present-day conventional geodetic measurements, but near the lower limit of the geodetic measurements. This suggests that …

Fluvial Response To Intra-Canyon Lava Flows, Owyhee River, Southeastern Oregon, Cooper Cooke Brossy

All Master's Theses

At least six lava flows have entered the Owyhee River Canyon north of Rome, Oregon, since the Pliocene and directly impacted the Owyhee River. The effects on the river of the two youngest lava flows, the West Crater (60–80 ka) and Saddle Butte (> 60–90 ka), are readily apparent. These two lava flows entered a paleo-Owyhee Canyon several kilometers wide via three different tributary drainages. The flows dammed the Owyhee River, created lakes, and effectively confined the river to the opposite side of the valley from the flows’ entrance. Lava from these flows filled a paleo-Owyhee Canyon to depths of …

Deciphering The Signature Of Magma Mixing: Examples From The Castle Creek Eruptive Period, Mount St. Helens, Washington, Seth Taylor Mattos

All Master's Theses

Mount St. Helens (MSH) volcano in southwestern Washington has intermittently erupted dacitic products for the last 40,000 years. On limited occasions, the volcano has produced andesite lava flows, and during one short-lived period, basaltic lava flows. This time interval has been termed the Castle Creek eruptive period and occurred between approximately 2500 and 1700 years B.P. The Castle Creek period erupted dacite, andesite and basalt within this short span of time. Andesite and dacite eruptions dominate the first approximately 700 years of the period, and all basaltic units were erupted in approximately the last 100 years of the period. This …

Transient Detection And Modeling Of Continuous Geodetic Data, Walter Michael Szeliga

All Master's Theses

Transient surface deformation has been observed by continuously operating Global Positioning System stations in the Puget Sound area during the past decade. This surface deformation is associated with processes occurring on or near the subducting plate boundary between the Juan de Fuca and North American plates. This thesis is composed of two studies of transient deformation along the Cascadia plate margin and a discussion of the methodologies employed in these studies. We model one 7-week episode of transient deformation that occurred during 2003 beneath the Puget Sound area. Additionally, we utilize a combination of continuous Global Positioning System and seismic …

The Role Of Geomorphic Features And Hydrologic Processes On Sediment Clusters In Gravel-Bed Rivers, Washington: A Field-Based Approach, Ross Richard Hendrick

All Master's Theses

This project investigated the movement and evolution of sediment clusters after four separate flood events at two geomorphically different sites along the Entiat River, Washington. Clusters are defined as an obstacle or anchor clast(s) that impede the progress of two or more sediment particles, and are believed to be an important characteristic of the variable bed topography of gravel-bed rivers. Detailed field descriptions and digital photographs of clusters were used to determine the characteristics of clusters at chosen locations on gravel bars regularly covered by high flow events. Data were collected during low-flow conditions, and clusters were re- examined and …

A Small Look At The Big Picture: Linking Geopotential Height Anomalies To Paleofloods On The Snake River, Idaho And Oregon, Gwendolyn Bernitha Rhodes

All Master's Theses

A combined paleoflood and flood hydroclimatology study on the Snake River in Idaho and Oregon suggests a link between floods and patters of geopotential height anomalies over the North Pacific Ocean. Examination of the paleoflood record in two 4-m (12 ft) tall terraces along the Hells Canyon reach of the Snake River in Idaho and Oregon shows evidence of at least twenty-two late-Holocene extreme floods that occurred approximately 5,000 years. The ages of paleoflood deposits at these sites fall into two time periods, from 5130 ± 40 to 1960 ± 40 yr BP and from 320 ± 40 yr BP …