Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Andesite -- Analysis (1)
- Cryoconite -- Antarctica -- McMurdo Dry Valleys (1)
- Debris avalanches (1)
- Erosion -- Oregon -- Bull Run River Watershed (1)
- Geological mapping -- Eastern Oregon (1)
-
- Geomorphology -- Oregon -- Bull Run River Watershed (1)
- Glaciers -- Climatic factors -- Montana -- Glacier National Park (1)
- Glaciers -- Montana -- Glacier National Park -- Measurement -- 20th century (1)
- Glaciers -- Montana -- Glacier National Park -- Measurement -- 21st century (1)
- Igneous differentiation (1)
- Igneous rocks -- Inclusions (1)
- Impact processes (1)
- Landslide hazard analysis (1)
- Landslides -- Oregon -- Linn County (1)
- Magmas -- Oregon -- Mount Hood -- Case studies (1)
- Mars (1)
- Mass-wasting (1)
- Petrology -- Eastern Oregon (1)
- Rhyolite (1)
- Rhyolite -- Analysis (1)
- Volcanic ash tuff etc -- Eastern Oregon -- Analysis (1)
- Volcanic ash tuff etc. -- Eastern Oregon -- Analysis (1)
Articles 1 - 8 of 8
Full-Text Articles in Geology
Measuring And Modeling Evolution Of Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Felix Jacob Zamora
Measuring And Modeling Evolution Of Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Felix Jacob Zamora
Dissertations and Theses
Cryoconite holes are vertical columns of meltwater within the shallow subsurface of glaciers. In the McMurdo Dry Valleys (MDV) of Antarctica cryoconite holes are a source of meltwater and harbor microbial communities in an otherwise arid environment with low biologic activity. The holes form as sediments on the ice surface, which are darker than the surrounding ice, are preferentially heated by solar radiation. The warm sediments melt the underlying ice and migrate downwards. An ice lid forms, isolating them from the below-freezing atmosphere enabling them to remain thawed. In this study, field observations, laboratory experiments, and numerical modeling are used …
Dynamics Of Magma Recharge And Mixing At Mount Hood Volcano, Oregon -- Insights From Enclave-Bearing Lavas, Molly Kathryn Ellowitz
Dynamics Of Magma Recharge And Mixing At Mount Hood Volcano, Oregon -- Insights From Enclave-Bearing Lavas, Molly Kathryn Ellowitz
Dissertations and Theses
Magma recharge events and subsequent mixing processes are understood to precede volcanic eruptions. Textural evidence of intrusion of hot, mafic magma into a cooler, rheologically locked silicic magma is commonplace. Solidified "blobs" of injected magma, called enclaves, are evidence of magma mixing, but the petrological and mechanical conditions during their formation are debated. Mount Hood, Oregon consistently erupts andesite bearing compositionally similar enclaves. These enclaves are evidence of mingling and mixing of two magmas. However, due to the compositional similarity between enclave and host lava (e.g. ~1-5 wt.% difference in SiO2), it is unclear whether the preserved enclaves …
Using Repeat Terrestrial Laser Scanning And Photogrammetry To Monitor Reactivation Of The Silt Creek Landslide In The Western Cascade Mountains, Linn County, Oregon, Justin Craig Mccarley
Using Repeat Terrestrial Laser Scanning And Photogrammetry To Monitor Reactivation Of The Silt Creek Landslide In The Western Cascade Mountains, Linn County, Oregon, Justin Craig Mccarley
Dissertations and Theses
Landslides represent a serious hazard to people and property in the Pacific Northwest. Currently, the factors leading to sudden catastrophic failure vs. gradual slow creeping are not well understood. Utilizing high-resolution monitoring techniques at a sub-annual temporal scale can help researchers better understand the mechanics of mass wasting processes and possibly lead to better mitigation of their danger. This research used historical imagery analysis, precipitation data, aerial lidar analysis, Structure from Motion (SfM) photogrammetry, terrestrial laser scanning (TLS), and hydrologic measurements to monitor displacement of the Silt Creek Landslide in the western Cascade Mountain Range in Linn County, Oregon. This …
Quantifying Knickpoint Behavior And Erosion Mechanisms In An Urbanized Watershed, Bull Mountain, Washington County, Oregon, Max Gregory Bordal
Quantifying Knickpoint Behavior And Erosion Mechanisms In An Urbanized Watershed, Bull Mountain, Washington County, Oregon, Max Gregory Bordal
Dissertations and Theses
Quantifying spatial and temporal patterns of rapid channelized erosion, on human time scales, is critical to understanding its processes and their consequences. This investigation utilized field observations, repeat terrestrial laser scanning (TLS), and Structure-from-Motion photogrammetry (SfM) to document the size and retreat rates of a knickpoint, defined as a localized near-vertical reach of a fluvial channel, and its contribution to erosion, in an urbanizing landscape with a loess substrate. The Bull Mountain area, in Washington County, southwest of Portland, Oregon, is an ideal study area, offering a measurable knickpoint that translates the response of the rapid erosion throughout this transient …
Areal Extent And Volumes Of The Dinner Creek Tuff Units, Eastern Oregon Based On Lithology, Bulk Rock Composition And Feldspar Mineralogy, Teresa Rae Hanna
Areal Extent And Volumes Of The Dinner Creek Tuff Units, Eastern Oregon Based On Lithology, Bulk Rock Composition And Feldspar Mineralogy, Teresa Rae Hanna
Dissertations and Theses
The Dinner Creek Tuff erupted during a period of rhyolitic volcanism coeval to the flood volcanism associated with the Columbia River Basalt Group. The High Rock Caldera Complex, Lake Owyhee and McDermitt volcanic fields account for ~90% of the rhyolites erupted between 16.7-15.0 Ma. Situated at the northern end of the Lake Owyhee volcanic field, the Dinner Creek Tuff was originally mapped as a ~2,000 km2 single ignimbrite confined to the Malheur Gorge. Streck et al. (2015) correlated tuff outcrops previously mapped as generic Miocene welded tuff as well as local units such as the "Mascall" or "Pleasant Valley" …
The Wildcat Creek Tuff, Eastern Oregon: Co-Eruption Of Crystal-Poor Rhyolite And Fe-Rich Andesite With Implication For Mafic Underpinnings To Voluminous A-Type Rhyolites, Hillarie Jaye Sales
The Wildcat Creek Tuff, Eastern Oregon: Co-Eruption Of Crystal-Poor Rhyolite And Fe-Rich Andesite With Implication For Mafic Underpinnings To Voluminous A-Type Rhyolites, Hillarie Jaye Sales
Dissertations and Theses
The Wildcat Creek Tuff is a thin (~3-12 m), rhyolite to andesitic ash-flow tuff with a minimal extent of 1500 km2 in Malheur county, eastern Oregon. The previously undated tuff yielded a single crystal, anorthoclase 40Ar/39Ar age of 15.49±0.02 Ma and thus is closely related to mafic and silicic volcanism of the Columbia River Province. The tuff texturally stands out by its high proportion of co-mingled mafic inclusions appearing as dark, scoriaceous, and phenocryst-poor fragments, and their proportion dictate bulk tuff compositions ranging from rhyolite (74% SiO2) to andesite (59% SiO2). Glass analyses confirm …
Glacier Inventories And Change In Glacier National Park, Melissa Carrie Brett
Glacier Inventories And Change In Glacier National Park, Melissa Carrie Brett
Dissertations and Theses
Glacier National Park, in northwestern Montana, is a unique and awe-inspiring national treasure that is often used by the media and public-at-large as a window into the effects of climate change. An updated inventory of glaciers and perennial snowfields (G&PS) in the Park, along with an assessment of their change over time, is essential to understanding the role that glaciers are playing in the environment of this Park. Nine inventories between 1966 and 2015 were compiled to assess area changes of G&PS. Over that 49-year period, total area changed by nearly -34 ± 11% between 1966 and 2015. Volume change, …
Differentiation In Impact Melt Sheets As A Mechanism To Produce Evolved Magmas On Mars, Ari Koeppel
Differentiation In Impact Melt Sheets As A Mechanism To Produce Evolved Magmas On Mars, Ari Koeppel
Dissertations and Theses
Asteroid bombardment contributed to extensive melting and resurfacing of ancient (> 3 Ga) Mars, thereby influencing the early evolution of the Martian crust. However, information about how impact melting has altered Mars’ crustal petrology is limited. Evidence from some of the largest impact structures on Earth, such as Sudbury and Manicouagan, suggests that some impact melt sheets experience chemical differentiation. If these processes occur on Mars, we expect to observe differentiated igneous materials in some exhumed rock samples. Some rocks observed in Gale crater are enriched in alkalis (up to 14 wt% Na2O + K2O) and …