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1
Ramsey, Lucy Ann. "Topographic evolution of emerging mountain belts." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614292.
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2
Prince, Philip S. "Evolution of transient topography on passive margins: A study of landscape disequilibrium in the southern Appalachian Mountains." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77065.
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The mechanism through which the Appalachian Mountains have maintained moderate relief some ~300 Myr after the cessation of mountain building has long puzzled geomorphologists. As recent studies have shown that Appalachian exhumation has occurred at slow rates consistent with isostatic rebound of thickened crust, the driving forces behind localized episodes of accelerated incision and the associated rugged topography have been difficult to explain given the absence of tectonic uplift. This study uses previously undocumented relict fluvial gravels and knickpoint location to confirm the role of drainage rearrangement in producing local base level drop and subsequent basin-scale transient incision in the southern Appalachians. This process is fundamentally driven by the high potential energy of streams flowing across the elevated, slowly eroding Blue Ridge Plateau relative to the present Atlantic and landward interior base levels. Gravel deposits confirm that repeated capture of landward-draining Plateau streams by Atlantic basin streams, whose immediate base level is 250-300 m lower, forces episodic rapid incision and overall erosional retreat of the Blue Ridge Escarpment along the Plateau margin. The distribution of knickpoints, bedrock gorges, and relict surfaces in the interior of the Plateau indicate that the New River, which drains to the continental interior, is actively incising the low-relief Plateau surface due to episodic drops in landward base level. The origin of landward base level perturbation is unclear, but it may be the result of glacially-driven shortening and steepening of the lower New River during the Pleistocene. Collectively, these data indicate that rapid base level drop through drainage reorganization can energize streams in otherwise stable landscapes and accelerate fluvial incision and relief production without uplift of the land surface. This process is likely quite significant in post-orogenic settings, where inherited drainage patterns may not reflect the most direct, and thus energetically appropriate, path to present base level. Passive margins may therefore never achieve a topographic steady-state, despite uniformly slow and constant uplift due to isostatic rebound.Ph. D.
3
Brocklehurst, Simon H. (Simon Howard) 1975. "Evolution of topography in glaciated mountain ranges." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29929.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.Includes bibliographical references.
This thesis examines the response of alpine landscapes to the onset of glaciation. The basic approach is to compare fluvial and glacial landscapes, since it is the change from the former to the latter that accompanies climatic cooling. This allows a detailed evaluation of hypotheses relating climate change to tectonic processes in glaciated mountain belts. Fieldwork was carried out in the eastern Sierra Nevada, California, and the Sangre de Cristo Range, Colorado, alongside digital elevation model analyses in the western US, the Southern Alps of New Zealand, and the Himalaya of northwestern Pakistan. The evidence presented here suggests that the so-called "chicken-and-egg" hypothesis is overstated in its appeal to glacial erosion as a major source of relief production and subsequent peak uplift. Glaciers in the eastern Sierra Nevada and the western Sangre de Cristos have redistributed relief, but have produced only modest relief by enlarging drainage basins at the expense of low-relieftopography. Glaciers have lowered valley floors and ridgelines by similar amounts, limiting the amount of "missing mass" that can be generated, and causing a decrease in drainage basin relief.
(cont.) The principal response of glaciated landscapes to rapid rock uplift is the development of towering cirque headwalls. This represents considerable relief production, but is not caused by glacial erosion alone. Large valley glaciers can maintain their low gradient regardless of uplift rate, which supports the "glacial buzzsaw" hypothesis. However, the inability of glaciers to erode steep hillslopes as rapidly can cause mean elevations to rise. Cosmogenic isotope dating is used to show that (i) where plucking is active, the last major glaciation removed sufficient material to reset the cosmogenic clock; and (ii) former glacial valley floors now stranded near the crest of the Sierra Nevada are at varying stages of abandonment, suggesting a cycle of drainage reorganisation and relief inversion due to glacial erosion similar to that observed in river networks. Glaciated landscapes are quite distinct from their fluvial counterparts in both landforms and processes. Given the scarcity of purely fluvial, active mountain ranges, it is essential that glacial erosion be considered amongst the processes sculpting active orogenic belts.
by Simon H. Brocklehurst.
Ph.D.
4
Barnes, Jason B. "Variable Denudation in the Evolution of the Bolivian Andes: Controls and Uplift-Climate-Erosion Feedbacks." Thesis, The University of Arizona, 2002. http://hdl.handle.net/10150/240131.
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Controls on denudation in the eastern Bolivian Andes are evaluated by synthesis of new and existing denudation estimates from basin-morphometry, stream - powered fluvial incision, landslide mapping, sediment flux, erosion surfaces, thermochronology, foreland basin sediment volumes, and structural restorations. Centered at 17.5 °S, the northeastern Bolivian Andes exhibit high relief, a wet climate, and a narrow fold- thrust belt. In contrast, the southeastern Bolivian Andes have low relief, a semi-arid climate, and a wide fold-thrust belt. Basin -morphometry indicates a northward increase in relief and relative denudation. Stream-power along river profiles shows greater average incision rates in the north by a factor of 2 to 4. In the south, profile knickpoints with high incision rates are controlled by fold-thrust belt structures such as the surface expressions of basement megathrusts, faults, folds, and lithologic boundaries. Landslide and sediment-flux data are controlled by climate, elevation, basin morphology, and size and show a similar trend; short -term denudation-rate averages are greater in the north (1- 9 mm/yr) than the south (0.3-0.4 mm/yr). Long-term denudation-rate estimates including fission track, basin fill, erosion surfaces, and structural restorations also exhibit greater values in the north (0.2-0.8 mm/yr) compared to the south (0.04-0.3 mm/yr). Controls on long-term denudation rates include relief, orographic and global atmospheric circulation patterns of precipitation, climate change, glaciation, and fold-thrust belt geometry and kinematics. The denudation synthesis supports two conclusions: 1) denudation rates have increased towards the present 2) an along-strike disparity in denudation (greater in the north) has existed since at least the Miocene and has increased towards the present. Denudation rates and controls suggest that Bolivian mountain morphology is controlled by both its orientation at mid-latitude, and the feedbacks between uplift, kinematics, orographic effects on precipitation, glaciation, and the increased erosion that accompanies orogenesis.
5
Richardson, Paul William Ph D. Massachusetts Institute of Technology. "Topographic asymmetry and climate controls on landscape evolution." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101346.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 145-157).
Landscapes are expected to evolve differently under the influence of different climate conditions. However, the relationship between landscape evolution and climate is not well understood. I investigate the relationship between landscape evolution and climate by using natural experiments in which climate varies with slope aspect (geographic orientation) and causes differences in landscape form, such as steeper equator- or pole-facing slopes. In order to understand which mechanisms are responsible for the development of this topographic asymmetry, I adapted a numerical landscape evolution model to include different asymmetry-forming mechanisms such as aspect-induced variations in soil creep intensity, regolith strength, and runoff, and also lateral channel migration. Numerical experiments reveal topographic signatures associated with each of these mechanisms that can be compared with field sites that exhibit asymmetry. I used these numerical model results, along with estimates of field-saturated hydraulic conductivity, soil strength, evidence of stream capture and channel beheadings, and erosion rates determined from cosmogenic radionuclides to determine which asymmetry forming mechanisms are likely responsible for the topographic asymmetry at Gabilan Mesa, a landscape in the central California Coast Ranges. I find that aspect-dependent differences in runoff are most likely responsible for the bulk of the asymmetry at Gabilan Mesa, but lateral channel migration has contributed to the asymmetry in some locations. To further investigate climate's influence on landscape evolution, I compiled new and previously published estimates of slope-dependent soil transport efficiency across a range of climates. I find that soil transport efficiency increases with mean annual precipitation and the aridity index, a measure that describes water availability for plants. I also find that soil transport efficiency varies with lithology and that different measurement techniques can bias estimates of the soil transport coefficient.
by Paul William Richardson.
Ph. D.
6
Zimmer, Janek, Armin Raabe, and Gerd Tetzlaff. "Quantification of topographic effects on predicted precipitation in the Erzgebirge." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-222025.
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Orographically enhanced precipitation played a major role in the flooding event in August 2002 in the Eastern Erzgebirge mountains. Both global and mesoscale models underestimated local intensities even with the correct position of the associated large-scale front. The limited area model LM of the DWD has been used in a sensitivity study of orographic precipitation involving an idealized bell-shaped orography. The dependence of precipitation on different determining parameters is investigated, with special emphasis on layer stability and wind structure. With the operational horizontal grid spacing of about 7 km, the LM simulations reproduce common distributions of vertical velocity and precipitation for uniformly stratified flows of varying stability. Highest rates are computed for stratiform cases with decreasing stability at higher levels and for convective environments. Both situations differ from the wave-like appearance of the uniformly stratified flows. Several vertical profiles of horizontal wind velocity structure are found to significantly influence magnitude and vertical decay of upward motion. Simplified profiles of the Eastern Erzgebirge mountain range and atmospheric conditions comparable to that of the flooding event are introduced to estimate the orographically-induced precipitation in a homogeneous flow. These numerical simulations are compared with values computed by the diagnostic maximum precipitation model MAXRR. Due to the relatively coarse grid in LM, small-scale differences through enhanced orographic lift cannot be resolved. Nevertheless, the amounts observed in this flooding case are reproduced with the high-resolution diagnostic modelOrografisch verstärkter Niederschlag im Bereich des Osterzgebirges spielte eine große Rolle bei der Entstehung des Elbehochwassers im August 2002. Sowohl globale als auch mesoskalige Vorhersagemodelle unterschätzten die lokalen Niederschlagsintensitäten trotz richtiger Positionierung des synoptisch-skaligen Frontenzuges. Zur Untersuchung der Gründe wurde das Lokalmodell des DWD für eine Sensitivitätsstudie bezüglich orografisch beeinflussten Niederschlags im Bereich eines idealisierten Glockenberges verwendet. Die Abhängigkeit des Niederschlags von verschiedenen Kontrollparametern wurde untersucht, mit besonderer Beachtung von Schichtungsstabilität und Horizontalwindstruktur. Bei Verwendung der operationellen Gitterweite von 7 km reproduzieren die Simulationen mit dem LM die bekannten Verteilungen von Vertikalwind und Niederschlag für unterschiedliche Schichtungen mit höhenkonstanten Temperaturgradienten. Die höchsten Niederschlagsraten ergeben sich jedoch für stratiforme Aufgleitprozesse im Fall von abnehmender Stabilität in mittleren und hohen Bereichen der Troposphäre sowie für konvektive Umgebungen, in beiden Fällen mit signifikanter Änderung des Vertikalwindfeldes verglichen mit der zuvor erwähnten Strömung. Der Einfluss des Vertikalprofils des horizontalen Windes auf Stärke und vertikale Abschwächung der Aufwärtsbewegung muss beachtet werden. Schließlich wurden die Sensitivitätsstudien ausgedehnt auf ein vereinfachtes Höhenprofil des Osterzgebirges. Als Ausgangssituation wurden dabei die atmosphärischen Bedingungen verwendet, die mit denen des Hochwasserereignisses vergleichbar sind. Diese numerischen Simulationen wurden mit Werten des einfachen diagnostischen Maximalniederschlagsmodells MAXRR verglichen. Entsprechend der relativ groben Gitterweite des LM können kleinräumige Unterschiede durch verstärkte orografische Hebung nicht wider gegeben werden, wogegen die beobachteten Niederschlagsmengen des Hochwasserereignisses mithilfe des hoch aufgelösten diagnostischen Modells erreicht werden
7
Steele, Jason Keith. "Influence of elevation on tree species distribution and growth in the southern Appalachian Mountains." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31875.
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The southern Appalachian Mountains have long been an area of interest for the analysis of forest species growth and composition. Past forest vegetation studies focus on species composition and structure for relatively local scale research areas. Species distribution within this geographic area was compiled from studies published from 1956 to 2006. The distribution of hardwood species within the southern Appalachians decreased as the elevation of the sites increased, but this relationship could not be solely attributed to elevation gradient. In order to better understand the relationship between elevation on the radial growth of tree species within the region, an elevation microsite was selected to explore the relationship between elevation and the radial growth of upland oak. Eight study sites across an elevation gradient were selected, and 20 oak tree cores were collected, cross-dated, measured, and a master chronology was created for each site. The correlation between ring width index and Palmer drought severity index (PDSI), precipitation and temperature was calculated with each siteâ s master chronology. There was a significant positive correlation between PDSI and ring width index during the growing season for a majority of the year, and a significant positive correlation between precipitation and ring width index during the growing season. Even though the master chronologies originated from eight separate sites, there were common dendroclimatic responses across seven of the sites. Canonical correspondence analysis of site characteristics and ring width index indicate that the master chronologies can be grouped into three separate chronologies based upon similar environmental and site characteristic responses.Master of Science
8
Mitchell, Sara Gran. "Late-Cenozoic topographic evolution of the Cascade Range, Washington State, USA /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/6713.
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9
Zimmer, Janek, Armin Raabe, and Gerd Tetzlaff. "Quantification of topographic effects on predicted precipitation in the Erzgebirge." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 37 = Meteorologische Arbeiten aus Leipzig … und Jahresbericht … des Instituts für Meteorologie der Universität Leipzig ; 11 (2006), S. 125-136, 2006. https://ul.qucosa.de/id/qucosa%3A15499.
Full textAbstract:
Orographically enhanced precipitation played a major role in the flooding event in August 2002 in the Eastern Erzgebirge mountains. Both global and mesoscale models underestimated local intensities even with the correct position of the associated large-scale front. The limited area model LM of the DWD has been used in a sensitivity study of orographic precipitation involving an idealized bell-shaped orography. The dependence of precipitation on different determining parameters is investigated, with special emphasis on layer stability and wind structure. With the operational horizontal grid spacing of about 7 km, the LM simulations reproduce common distributions of vertical velocity and precipitation for uniformly stratified flows of varying stability. Highest rates are computed for stratiform cases with decreasing stability at higher levels and for convective environments. Both situations differ from the wave-like appearance of the uniformly stratified flows. Several vertical profiles of horizontal wind velocity structure are found to significantly influence magnitude and vertical decay of upward motion. Simplified profiles of the Eastern Erzgebirge mountain range and atmospheric conditions comparable to that of the flooding event are introduced to estimate the orographically-induced precipitation in a homogeneous flow. These numerical simulations are compared with values computed by the diagnostic maximum precipitation model MAXRR. Due to the relatively coarse grid in LM, small-scale differences through enhanced orographic lift cannot be resolved. Nevertheless, the amounts observed in this flooding case are reproduced with the high-resolution diagnostic model.Orografisch verstärkter Niederschlag im Bereich des Osterzgebirges spielte eine große Rolle bei der Entstehung des Elbehochwassers im August 2002. Sowohl globale als auch mesoskalige Vorhersagemodelle unterschätzten die lokalen Niederschlagsintensitäten trotz richtiger Positionierung des synoptisch-skaligen Frontenzuges. Zur Untersuchung der Gründe wurde das Lokalmodell des DWD für eine Sensitivitätsstudie bezüglich orografisch beeinflussten Niederschlags im Bereich eines idealisierten Glockenberges verwendet. Die Abhängigkeit des Niederschlags von verschiedenen Kontrollparametern wurde untersucht, mit besonderer Beachtung von Schichtungsstabilität und Horizontalwindstruktur. Bei Verwendung der operationellen Gitterweite von 7 km reproduzieren die Simulationen mit dem LM die bekannten Verteilungen von Vertikalwind und Niederschlag für unterschiedliche Schichtungen mit höhenkonstanten Temperaturgradienten. Die höchsten Niederschlagsraten ergeben sich jedoch für stratiforme Aufgleitprozesse im Fall von abnehmender Stabilität in mittleren und hohen Bereichen der Troposphäre sowie für konvektive Umgebungen, in beiden Fällen mit signifikanter Änderung des Vertikalwindfeldes verglichen mit der zuvor erwähnten Strömung. Der Einfluss des Vertikalprofils des horizontalen Windes auf Stärke und vertikale Abschwächung der Aufwärtsbewegung muss beachtet werden. Schließlich wurden die Sensitivitätsstudien ausgedehnt auf ein vereinfachtes Höhenprofil des Osterzgebirges. Als Ausgangssituation wurden dabei die atmosphärischen Bedingungen verwendet, die mit denen des Hochwasserereignisses vergleichbar sind. Diese numerischen Simulationen wurden mit Werten des einfachen diagnostischen Maximalniederschlagsmodells MAXRR verglichen. Entsprechend der relativ groben Gitterweite des LM können kleinräumige Unterschiede durch verstärkte orografische Hebung nicht wider gegeben werden, wogegen die beobachteten Niederschlagsmengen des Hochwasserereignisses mithilfe des hoch aufgelösten diagnostischen Modells erreicht werden.
10
Yuan, Chao, and 袁超. "Magmatism and tectonic evolution of the West Kunlun Mountains." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B29815162.
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Hall, L. A. F. "Ordovician tectonic evolution of the southern Long Range Mountains, Newfoundland." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ42388.pdf.
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Hall, Lindsay Anne Forsyth. "Ordovician tectonic evolution of the southern Long Range Mountains, Newfoundland /." Internet access available to MUN users only, 1998. http://collections.mun.ca/u?/theses,39263.
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13
Wong, Po-wan Kenny, and 王步雲. "Paleozoic tectonic evolution of the Chinese Altai Orogen: contraints from geochemical and geochronologic studies ofmafic rocks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44920878.
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14
Cai, Keda, and 蔡克大. "Magmatism and tectonic evolution of the Chinese Altai, NW China: insights from the paleozoic mafic andfelsic intrusions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47147192.
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15
Sanchez, Alvarez Jaime Orlando. "Structural and stratigraphic evolution of Shira Mountains, central Ucayali Basin, Peru." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2077.
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Sanchez, Alvarez Jaime Orlando. "Structural and stratigraphic evolution of Shira Mountains, central Ucayali Basin, Perú." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85841.
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The Ucayali Basin is a Peruvian sub-Andean basin that initially formed during
the extensive tectonics of the Early Paleozoic. Originally, the Ucayali Basin was part
of a larger basin that extended east of the current Andean chain along the Peruvian
territory. Subsequently, this large basin was divided into many smaller sub-Basins
during the Andean Orogeny. Today, the basin covers an area of about 140,000 km2,
and it is morphologically defined by two well-differentiated structural features: the sub-
Andean fold and thrust belt (SFTB) to the west and the Amazon plain and Brazilian
shield to the east. It is limited to the north and south by the Contaya and Fitzcarrald
Arches respectively, the Andes to the west and the Brazilian Shield to the east. These
structural features acted as favorable elements to add sediments and to contribute to the
structural development of this basin. The sedimentary section of the basin varies in
thickness from 1 to 10 km, with ages of strata ranging from the Paleozoic to
Quaternary. The strata were deposited in deep and shallow marine as well as
transitional and fluvial continental environments. The most important phase of marine
sedimentation was initiated with the transgression of the Cretaceous sea (Aptian - Albian) over the irregular paleogeography defined by morphologic highs and
peneplains.
Tectonic features of the basin show structural deformations parallel to the
Andean front, where overturned structures are observed. These are commonly cut by
thrusts and laterally displaced by strike-slip faults.
To better understand the development of the Shira Mountains in the central part
of the Ucayali Basin, the structural and stratigraphic relationships were mapped out
using a dense grid of 2D seismic reflection data and well log control. Three regional EW
cross sections were constructed and restored to the top of the Cretaceous to
determine the nature of deformation and faulting during the Paleozoic and Mesozoic.
The reconstructions show that Shira Mountains fault was initially a major
normal fault bounding a half graben. The fault was reactivated by later compression as
a thick-skinned thrust fault that detaches between 21 and 24 km depth. Reactivation
occurred during Upper Miocene between 7.2 and 5.3 Ma, corresponding to the
Quechua 3 compressive phase of Andean Orogeny. The shortening of the central
Ucayali Basin determined by the reconstructed cross sections ranges between 3 and
5.5%.
17
Reid, Leslie. "Structural evolution of the Isaac Lake Synclinorium, Cariboo Mountains, British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20850.pdf.
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Schweitzer, Janet. "Structural evolution of crystalline lower plate rocks, Central Sacramento Mountains, Southeastern California /." This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10022007-144516/.
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Booth, Adam, and Adam Booth. "The Role of Deep-Seated Landslides in Landscape Evolution: Quantitative Modeling and High-Resolution Topographic Analysis." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12534.
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In many mountainous settings, landslides are the primary geomorphic agent that sets fundamental landscape characteristics, such as topographic relief and catchment-averaged erosion rate. The coupled system of landslides and other geomorphic processes responds to changes in climatic or tectonic forcing, but few studies have addressed these responses quantitatively, especially in terrain prone to deep-seated landslides (those thicker than the upper layer of soil). This study quantifies the topographic expressions and mechanics of deep-seated landslides using a combination of high-resolution topographic data and mathematical modeling. I first demonstrate that deep-seated landslides distinguish themselves from surrounding terrain by generating meter spatial scale surface roughness associated with gradients in strain rate of the deforming material. These methods are capable of mapping landslides with more than 80% accuracy in three study sites throughout the Pacific Northwest, United States. At longer, kilometer scale spatial wavelengths analysis of slope and drainage area data shows that landslides lengthen hillslopes and reduce ridge top elevations to leave their signature on the topography. I then develop and implement a mathematical landscape evolution model including a novel treatment of deep-seated landslide flux to simulate landslides at these longer spatial scales. The model generates topographic profiles for two different bedrock types in agreement with those observed in a study area in the Eel River catchment, California, United States. The sediment fluxes required to produce these profiles are in agreement with independently estimated modern rates. Two-dimensional simulations constrain two essential geomorphic conditions at which landslides occur. First, there must be pre-existing pockets of deep weathering, which allow landslides to erode large volumes of material at rates that episodically exceed the long term average erosion rate. Second, the characteristic time scale for landslide processes must be shorter than the time scales associated with both soil creep and river incision. As the landslide time scale shortens, landslides systematically reduce hillslope relief and increase valley spacing to reduce the mean topographic gradient. This dissertation therefore improves the objectivity of analyzing landslide-prone terrain and provides a framework for rigorously interpreting landscape response to changing climatic and tectonic forcing.
This dissertation includes both previously published and co-authored material.
20
Kasselas, Grigorios D. "Stratigraphic framework, structural evolution and tectonic implications of the eastern Blue Ridge sequence in the central Appalachians near Warrenton, Virginia." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-02132009-172918/.
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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993.Six maps included in back pocket. Vita. Abstract. Includes bibliographical references (leaves 115-116). Also available via the Internet.
21
Davisson, Cole M. "Stratigraphic and structural evolution of the early Diligencia Basin, Orocopia Mountains, Southeastern California." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-04072010-020140/.
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Reis, Jonathan Hunter. "Jurassic and Cretaceous tectonic evolution of the southeast Castle Dome Mountains, southwest Arizona." [Ames, Iowa : Iowa State University], 2009.
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Yule, John Douglas Saleeby Jason B. "Geologic and tectonic evolution of jurassic marginal ocean basin lithosphere, Klamath Mountains, Oregon." Diss., Pasadena, Calif. : California Institute of Technology, 1996. http://resolver.caltech.edu/CaltechTHESIS:02262010-073813373.
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Thesis (Ph. D.)--California Institute of Technology, 1996. UM #9617430.Eleven folded maps in pocket. Advisor names found in the Acknowledgments pages of the thesis. Title from home page. Viewed 02/26/2010. Includes bibliographical references.
24
Wichura, Henry. "Topographic evolution of the East African Plateau : a combined study on lava-flow modeling and paleo-topography." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5236/.
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The East African Plateau provides a spectacular example of geodynamic plateau uplift, active continental rifting, and associated climatic forcing. It is an integral part of the East African Rift System and has an average elevation of approximately 1,000 m. Its location coincides with a negative Bouguer gravity anomaly with a semi-circular shape, closely related to a mantle plume, which influences the Cenozoic crustal development since its impingement in Eocene-Oligocene time.
The uplift of the East African Plateau, preceding volcanism, and rifting formed an important orographic barrier and tectonically controlled environment, which is profoundly influenced by climate driven processes. Its location within the equatorial realm supports recently proposed hypotheses, that topographic changes in this region must be considered as the dominant forcing factor influencing atmospheric circulation patterns and rainfall distribution. The uplift of this region has therefore often been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While the far-reaching influence of the plateau uplift is widely accepted, the timing and the magnitude of the uplift are ambiguous and are still subject to ongoing discussion. This dilemma stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift.
In order to quantify the amount of plateau uplift and to find evidence for the existence of significant relief along the East African Plateau prior to rifting, I analyzed and modeled one of the longest terrestrial lava flows; the 300-km-long Yatta phonolite flow in Kenya. This lava flow is 13.5 Ma old and originated in the region that now corresponds to the eastern rift shoulders. The phonolitic flow utilized an old riverbed that once drained the eastern flank of the plateau. Due to differential erosion this lava flow now forms a positive relief above the parallel-flowing Athi River, which is mimicking the course of the paleo-river.
My approach is a lava-flow modeling, based on an improved composition and temperature dependent method to parameterize the flow of an arbitrary lava in a rectangular-shaped channel. The essential growth pattern is described by a one-dimensional model, in which Newtonian rheological flow advance is governed by the development of viscosity and/or velocity in the internal parts of the lava-flow front. Comparing assessments of different magma compositions reveal that length-dominated, channelized lava flows are characterized by high effusion rates, rapid emplacement under approximately isothermal conditions, and laminar flow. By integrating the Yatta lava flow dimensions and the covered paleo-topography (slope angle) into the model, I was able to determine the pre-rift topography of the East African Plateau.
The modeling results yield a pre-rift slope of at least 0.2°, suggesting that the lava flow must have originated at a minimum elevation of 1,400 m. Hence, high topography in the region of the present-day Kenya Rift must have existed by at least 13.5 Ma. This inferred mid-Miocene uplift coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa.
Accordingly, the combination of my results regarding the Yatta lava flow emplacement history, its location, and its morphologic character, validates it as a suitable “paleo-tiltmeter” and has thus to be considered as an important topographic and volcanic feature for the topographic evolution in East Africa.Das Ostafrikanische Plateau ist ein eindrucksvolles Beispiel für aktive, kontinentale Grabenbildung, aber auch für geodynamische Hochebenenbildung mit weitreichendem klimatischen Einfluss auf die gesamte Region. Als integraler Bestandteil des Ostafrikanischen Grabensystems beläuft sich die mittlere Höhe des Plateaus auf durchschnittlich 1000 m ü.NN. Seine Lage korreliert gut mit der Präsenz einer halbkreisförmigen negativen Bouguer-Schwereanomalie, die an den Aufstieg eines Manteldiapirs im Untergrund gekoppelt ist. Dieser prägte die känozoische Krustenentwicklung seit seinem Aufstieg im Eozän-Oligozän. Die Hebungsgeschichte und topographische Entwicklung des Hochlandes steht seither in enger Beziehung zum einsetzenden Vulkanismus, der Bildung erster Abschiebungssysteme und führte schließlich zur Entwicklung des heutigen Vollgrabensystems. Neueste Hypothesen lassen den Schluss zu, dass topographische Veränderungen als dominierende Einflussgrößen atmosphärischer Zirkulationsmuster sowie der regionalen Niederschlagsverbreitung anzusehen sind. Zusätzlich werden diese Prozesse durch die äquatoriale Lage des Ostafrikanischen Plateaus verstärkt und die Hebung dieser Region oft mit wichtigen Klima- und Umweltveränderungen in Ostafrika und angrenzende Gebiete in Verbindung gebracht. Während der weitreichende klimatische Einfluss des Hochlandes größtenteils akzeptiert ist, sind Zeitpunkt und Ausmaß seiner Heraushebung nicht eindeutig bestimmt und daher noch immer Grundlage bestehender Diskussionen. Diese Zwangslage hat ihre Ursache im Fehlen aussagekräftiger und datierbarer Referenzhorizonte. Um den Hebungsbetrag zu quantifizieren und Beweise signifikanten Reliefs vor der Entwicklung des Grabensystems entlang des Ostafrikanischen Hochlandes zu erbringen, analysierte und modellierte ich einen der längsten terrestrischen Lavaströme. Dieser vor 13,5 Ma abgelagerte Yatta-Lavastrom hat mit 300 km Länge seinen Ursprung in der Region der heutigen östlichen Grabenschulter des zentralen Kenia-Rifts. Die phonolitische Lava ergoss sich entlang eines Flussbettes, das einst die östliche Flanke des Hochlandes entwässerte. Aufgrund unterschiedlicher Erosionspotentiale bildet der Lavastrom gegenwärtig ein positives Relief und befindet sich oberhalb des Athi Flusses, der parallel zum Paläofluß, und somit versetzt zu seinen früheren Verlauf, strömt. Mein Ansatz der Lavastrom-Modellierung basiert auf einer Methode, die das Fließverhalten einer beliebigen Lava in Abhängigkeit von Temperatur und Magmenzusammensetzung in einem rechtwinkligen Kanal berechnet. Die wesentlichen Wachstumsmuster des Lavastroms sind durch ein eindimensionales Modell beschrieben, wobei Newtonsches Fließverhalten im Innern hinter der Lavastromfront von der zeitlichen Entwicklung der Viskosität und/oder der Fließgeschwindigkeit bestimmt wird. Vergleiche meiner Resultate mit verschiedenen Magmenzusammensetzungen zeigen, dass sich lange, kanalisierte Lavaströme mit hohen Ergussraten und schneller Platznahme bilden können. Dies geschieht unter annähernd isothermalen Bedingungen und erfordert laminares Fließen. Die Integration der Yatta- Lavastrom-Dimensionen und der bedeckten Paläotopographie (Neigungswinkel) in das Modell, erlaubte es mir die Topographie des Ostafrikanischen Hochlandes vor der Grabenbildung zu modellieren. Das Ergebnis der Modellierung ergibt einen Neigungswinkel von mindestens 0,2° und impliziert, dass der Lavastrom seinen Ursprung in einer Höhe von mindestens 1400 m ü.NN gehabt haben muss. Somit existierte bereits vor 13,5 Ma hohe Topographie in der heutigen Region des zentralen Kenia-Rifts. Diese abgeleitete regionale Hebungsgeschichte im mittleren Miozän korreliert mit der zweistufigen Ausbreitung der Graslandschaften, sowie dem Aufkommen neuer Arten im tropischen Afrika. Die Kombination aus Fließverhalten, Entstehungsort und morphologischer Eigenschaften macht den Yatta-Lavastrom zu einem “Paläoneigungsmesser” und wichtigen vulkanischen Untersuchungsobjekt für die topographische Entwicklung in Ostafrika.
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Stock, Gregory Morgan. "Topographic evolution and climate change in the Sierra Nevada, California, deduced from isotopic studies of cave deposits /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.
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Sutton, Brian. "Glacial landforms and sedimentology and Late Pleistocene evolution of the Mourne Mountains, Northern Ireland." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267825.
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CHAKRABORTY, SUVANKAR. "THE GEOCHEMICAL EVOLUTION OF ALKALINE MAGMAS FROM THE CRARY MOUNTAINS, MARIE BYRD LAND, ANTARCTICA." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1174187928.
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Cook, Geoffrey William. "Volcanic evolution of the Otowi Member of the Bandelier Tuff, Jemez mountains, New Mexico." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Fall2009/G_Cook_120109.pdf.
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Thesis (Ph. D.)--Washington State University, December 2009.Title from PDF title page (viewed on Dec. 15, 2009). "School of Earth and Environmental Sciences." Includes bibliographical references (p. 232-247).
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Jiang, Yingde, and 蒋映德. "High-grade metamorphic rocks in southern Altai Range, SW Central Asia: their origings, tectonothemal [i.e.tectonothermal] evolution and tectonic implications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47752567.
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The Central Asian Orogenic Belt (CAOB), the largest accretionary collage on the Earth, has a complicated and prolonged accretionary history which remains being highly debated. High-grade terranes were previously interpreted as Precambrian micro-continents which played a very important role during the evolution of the CAOB. However, some of their presumed old ages are challenged by recent high-resolution dating results which raise questions on their Precambrian origins.
The Chinese Altai and Tseel Terrane in the SW CAOB, two typical high-grade terranes occupy vital structural positions, feature various lithological elements and exhibit complicated deformation-metamorphism patterns, making them key areas in the reconstructing of the evolution of central Asia. However, their origins are not firmly constrained. Paragneisses were considered as Precambrian basements, but yielded detrital zircon ages predominantly between 440 and 580 Ma. The associated granitic gneisses and amphibolite gave crystallization ages at 420-463 Ma. Geochemical and zircon Hf isotopic data of paragneisses support that their protoliths may represent significant erosion products of arc rocks that were developed in a subduction environment. This feature is similar with that of the associated low-grade volcanogenic schists which probably represent immature sediments in an active margin. Detrital zircons from the paragneisses and schists show similar age patterns, supporting derivation from similar provenance. Accordingly, our data reveal that these high-grade terranes do not represent Precambrian microcontinents.
Moreover, the U-Pb age pattern for the detrital zircons, and some xenocrystic zircons from the associated granitoids, is comparable with the age patterns of the micro-continents and arc terranes in western Mongolia. The predominant zircon population of 440-580 Ma matches the widely distributed granitoids within the Neoproterozoic-early Paleozoic terranes in western Mongolia, while the minor Precambrian ages (>540 Ma) resemble those old rocks preserved in the Tuva-Mongolian (TM) block and its adjacent Neoproterozoic arc terranes. These features suggest that detrital and xenocrystic zircons more likely represent the detritus recycled from western Mongolia. Accordingly, the crustal growth of the SW CAOB in the early Paleozoic could be outlined by secular amalgamation of magmatic arcs around a Precambrian micro-continent. In addition, the TM-derived Precambrian zircons are further used to trace the origin of the TM block, which favors that the TM block was possibly rifted from the Indian block in the Neoproterozoic.
Further efforts have been made to decipher the controversial tectono-metamorphic history. In the Chinese Altai, U-Pb dating on the metamorphic zircon portions yielded consistent ages of ~390 Ma. Temperature estimations using mineral-pair as well as Ti-in-zircon thermometers revealed high-temperature conditions up to ~720℃. Detailed investigations on the metamorphic rocks in the Tseel area revealed that middle-pressure metamorphic fabrics developed under progressive NNE-SSW convergent setting, possibly at 385-374 Ma. A later low-pressure/high-temperature metamorphic sequence developed during decompression, associated with high-level anatexis at 374-363 Ma. Collectively, our data support that the final amalgamation of North Mongolian Domain on its southern margin occurred at Middle-Late Devonian, and might be immediately followed by the subduction of an active oceanic ridge.published_or_final_version
Earth Sciences
Doctoral
Doctor of Philosophy
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Tsou, Ching-Ying. "Landscape Evolution by Fluvial Processes and Gravitational Slope Processes in Tectonically Active Mountains in Taiwan." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188494.
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Cooper, David James Walton. "The Hamrat Duru Group : evolution of a Mesozoic passive carbonate margin in the Oman mountains." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/12007.
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Hopkins, Chelsea Elizabeth. "Beryllium-10 derived erosion rates from the Hangay Mountains, Mongolia: landscape evolution in a periglacially-dominated continental interior." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45799.
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Terrestrial cosmogenic nuclides such as beryllium-10 have recently been used as a way to determine basin-average erosion rates around the world. These erosion rates are useful to geomorphologists investigating landscape evolution. The Hangay Mountains in Mongolia are a prime location to use beryllium-10 because of the granitic rocks that provide the quartz needed for cosmogenic analysis as well as the lack of observed evidence of recent or old mass wasting events that mobilize sediment and bedrock with much lower cosmogenic concentrations that cause underestimations of erosion rates.
Basin-average erosion rates observed in seven basins across the eastern Hangay Mountains range from 12 m/My to about 20 m/My. These are of similar magnitude to those found in tectonically inactive regions such as the southern Appalachians. Comparing basin-average erosion rates to basin parameters, whole basin relief had the highest calculated R2 value and elevation had the lowest P-value. No strong relationships were seen between erosion rate and mean slope angle, hypsometric integral, area, or mean local relief.
The basin-average erosion rates observed in the Hangay were compared to previous studies by Ahnert (1970), Portenga and Biernman (2011), and Matmon et al. (2009). We found erosion rates from the Hangay to be much lower than expected in our analyses. The differences in erosion rates from the Hangay Mountains compared to other places around the world are likely due to the fact that the streams in the Hangay are eroding into alluvium as opposed to bedrock, and are located in a landscape dominanted by diffusive hillslope sediment transport mechanisms. The erosion rate is limited to the amount of sediment that can be transported by the streams.
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Vernon, Rowan Emma. "Tectonic evolution and plateau uplift around the Changma Basin in the Qilian Mountains, NE Tibetan Plateau." Thesis, University of Leicester, 2016. http://hdl.handle.net/2381/37964.
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The Qilian Mountains are one of the most actively uplifting regions of the Tibetan Plateau and may provide a type example for the early evolution of its older regions. The mountains form a 300 km wide, NW – SE trending fold-thrust belt which extends 1000 km along the northeast margin of the Plateau and over-thrust the Hexi Corridor to the northeast and the Qaidam Basin to the southwest. An early-mid Palaeozoic orogenic suture belt, composed of faulted terranes of Late Proterozoic to early-mid Palaeozoic meta-sedimentary and meta-volcanic strata, is exposed in the Qilian Mountains and has been previously suggested to be reactivated by Late Cenozoic deformation. NE-directed crustal shortening, associated with the far-field effects of the Indo-Asian collision, has been active in the Qilian Mountains since the early-mid Miocene. It is characterised by the uplift of high mountain ranges along crustal scale thrust faults which splay south-eastwards from the sinistral-slip, north-northeast trending Altyn Tagh Fault and are postulated to connect along a shallow-dipping decollement in the midlower crust. Initiation of uplift in the Qilian Mountains was associated with a considerable decrease in the slip rate along the eastern end of the Altyn Tagh Fault and coincides with a plateau-wide reorganisation of deformation. This project presents new field mapping and remote sensing analysis and integrates this with existing geophysical data to i) understand and constrain the tectonic evolution of the northeast corner of the Qilian Mountains and the northwest corner of the Hexi Corridor, ii) examine the structural and lithological control of the Palaeozoic accretionary crust over Late Cenozoic deformation within the mountain ranges, and iii) establish the spatial and temporal extent of different styles of deformation within the northeastern Qilian Mountains.
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Roots, Charles F. (Charles Frederick) Carleton University Dissertation Geology. "Regional tectonic setting and evolution of the late proterozoic Mount Harper volcanic complex, Ogilvie Mountains, Yukon." Ottawa, 1987.
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Balgord, Elizabeth A. "Triassic to Neogene Evolution of the Andean Retroarc: Neuquén Basin, Argentina." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/595810.
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The Andes Mountains provide an ideal natural laboratory to analyze the relationship between the tectonic evolution of a subduction margin, retroarc shortening, basin morphology, and volcanic activity. Timing of initial shortening and foreland basin development in Argentina is diachronous along strike, with ages varying by 20-30 million years. The Neuquén Basin (32°S-40°S) of southern-central Argentina sits in a retroarc position and provides a geological record of sedimentation in variable tectonic settings from the Late Triassic to the early Cenozoic including: 1.) active extension and deposition in isolated rift basins in the Late Triassic-Early Jurassic; 2.) post-rift back-arc basin from Late Jurassic-Late Cretaceous; 3.) foreland basin from Late Cretaceous to Oligocene; and 4.) variable extension and contraction along-strike from Oligocene to present. The goal of this study is to determine the timing of the transition from post-rift thermal subsidence to foreland basin deposition in the northern Neuquén Basin and then assess volcanic activity and composition during various tectonic regimes. The Aconcagua and Malargüe areas (32°S and 35°S) are located in the northern segment of the Neuquén Basin and preserve Upper Jurassic to Miocene sedimentary rocks, which record the earliest phase of shortening at this latitude. This study presents new sedimentological and detrital zircon U-Pb data from the Jurassic to latest Cretaceous sedimentary strata to determine depositional environments, stratigraphic relations, provenance, and maximum depositional ages of these units and ultimately evaluate the role of tectonics on sedimentation in this segment of the Andes. The combination of provenance, basin, and subsidence analysis shows that the initiation of foreland basin deposition occurred at ~100 Ma with the deposition of the Huitrín Formation, which recorded an episode of erosion marking the passage of the flexural forebulge. This was followed by an increase in tectonic subsidence, along with the appearance of recycled sedimentary detritus, recorded in petrographic and detrital zircons analyses, as well development of an axial drainage pattern, consistent with deposition in the flexural forebulge between 95 and 80 Ma. By ca. 70 Ma the volcanic arc migrated eastward and was a primary local source for detritus. Growth structures recorded in latest Cretaceous units very near both the Aconcagua and Malargüe study areas imply 35-40 km and 80-125 km of foreland migration between 95 and 60 Ma in the Aconcagua and Malargüe areas, respectively. Strata ranging in age from Middle Jurassic to Neogene were analyzed to determine their detrital zircon U-Pb age spectra and Hf isotopic composition to determine the relationship between magmatic output rate, tectonic regime, and crustal evolution. When all detrital zircon data are combined, significant pulses in magmatic activity occur from 190-145 Ma, and at 128 Ma, 110 Ma, 69 Ma, 16 Ma, and 7 Ma. The duration of magmatic lulls increased markedly from 10-30 million years during back-arc deposition (190-100 Ma) to ~40-50 million years during foreland basin deposition (100-~30 Ma). The long duration of magmatic lulls during foreland basin deposition could be caused by flat-slab subduction events during the Late Cretaceous and Cenozoic or by long magmatic recharge events. There are three major shifts towards positive Hf isotopic values and all are associated with regional extension events whereas compression seems to lead to more evolved isotopic values.
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Argent, John David. "The geology and Tertiary structural evolution of the Northwest Sacramento Mountains footwall core complex, southeast California, USA." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337561.
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Schram, Katherine Elisabeth. "Images and Voices from the Cumberland Mountains: Surface Coal Mining and the Evolution of Appalshop's Documentary Activism." Digital Commons @ East Tennessee State University, 2005. https://dc.etsu.edu/etd/1056.
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Since the early 1970s, Appalshop, a regional film workshop in Whitesburg, Kentucky, has been examining social, economic, and environmental issues important to the people of Appalachia. Appalshop’s goal has always been to give a voice to a community that is often stereotyped and misunderstood by the media. Since its creation, Appalshop has devoted ample attention to the practice of surface mining, its potential consequences to the region, and most importantly, local opposition to the practice. While Appalshop’s early surface mining documentaries are focused on educating the general public about the issue, its later documentaries appeal to viewers’ emotions and develop an angry, passionate tone. Appalshop’s changing filmmaking techniques and increasing devotion to activism are discussed here with an incorporation of film theory and references to various environmental, literary, and historical texts. Comparisons and contrasts are drawn between Appalshop surface mining films from the 1970s, 1980s and 1990s.
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Sandström, Sonja. "Central Asian ice-marginal moraines of the global last glacial maximum : An analysis of topographic features affecting the glaciation pattern in the Tian Shan and Altai mountains." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-155171.
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Glacial runoff from the Tian Shan and Altai Mountains is an important water resource, especially for people living in the arid areas of Central Asia. Measured water volumes from glaciers have decreased, and glacier area have shrunk with 50-90% since the Little Ice Age. Lack of knowledge regarding glaciers in high mountain areas, and the impact from climate change makes this an important field to investigate. This thesis focuses on topographic features and their impact on spatial glaciation patterns; today and during the global last glacial maximum, 19-30 thousand years ago (ka). From selected marginal moraines in the Tian Shan and Altai mountains, with a deglaciation age between 19-30 ka, an analysis was created in ArcMap (GIS, Geographic Information System) with 1 arc second resolution ASTER GDEM2 (Digital Elevation Model) and in Google Earth. An elevation profile, hypsometry and mapping were created for the analysis. The interpretations made from the limited dataset resulted in topographic features affecting the glaciation extension today and percentage of decreasing glacier area since 19-30 ka, to be connected to north/south-facing direction of the drainage area and the elevation. Drainage areas experiencing the highest percentage of glacial shrinkage were southfacing and/or at elevation below 3961 m a.s.l.Central Asia Paleoglaciology Project
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Walker, James David. "The structure and metamorphic evolution of the High Himalayan Slab in SE Zanskar and NW Lahaul." Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:fc8b8fd3-e155-4f2f-9256-3667c2b31f4f.
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This thesis attempts to unravel the complex thermal and structural history of part of the High Himalayan Slab in NW India and combines reconnaissance-style field structural mapping of an area covering ~10,000 km2 with petrography, microstructural analysis, thermobarometry and geochronology techniques. The results of this work show that the oldest protoliths of the High Himalayan Slab are at least Cambrian in age and that they may have experienced a major pre-Himalayan metamorphism at c.500 Ma. The youngest protoliths are Mesozoic in age (the Tandi Group) and demonstrate that the High Himalayan Slab represents the metamorphosed equivalents of the Tibetan Sedimentary Series. Metamorphism was achieved via substantial crustal shortening and thickening following the India-Asia collision at 50-54 Ma ago. Phase relationships demonstrate that metamorphism was a regional Barrovian-type event associated with the growth of biotite-, garnet-, staurolite-, kyanite- and sillimanite-bearing assemblages in metapelites. Quantitative thermobarometry demonstrates that near-peak conditions of c.6-8 kbar and 550-650°C were attained in the deepest exposed levels. Growth of metamorphic assemblages was underway by at least 30 Ma, as indicated by U-Pb ages of metamorphic monazites. Exhumation of the High Himalayan Slab was achieved through a combination of extensional unroofing along major detachments (namely the Zanskar Shear Zone), thermal doming, thrusting along the Main Central Thrust and surface erosion. Exhumation is closely associated with the growth of sillimanite- and cordierite-bearing assemblages in pelites and the generation and emplacement of crustal melt leucogranites in the upper parts of the slab. U-Pb dating of accessory phases from one of the crustal melt leucogranites (the Gumburanjon leucogranite) constrains its crystallisation and emplacement age at c.21-22 Ma. This is only slightly older than its 40Ar/39Ar muscovite and biotite cooling ages of c.20-21 Ma, which is attributed to the emplacement of the Gumburanjon leucogranite into the immediate footwall of the ZSZ. Field and geochronological data therefore support a strong temporal and spatial relationship between upper crustal melting and extension in a convergent orogen.
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Al-Wardi, Mohammed. "Structural evolution of the Jebel Akhdar culmination and its implications for exhumation processes in the northern Oman Mountains." Thesis, University of Leeds, 2006. http://etheses.whiterose.ac.uk/21094/.
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Many orogenic belts show evidence for coeval extension and compressional tectonics. Here I present new evidence for such activity during the tectonic evolution of the Oman Mountains, a Late Cretaceous orogenic system on the NE margin of the Arabian continent. The tectonic significance and implications of this discovery are discussed within the context of convergent plate boundary processes. During the Late Cretaceous the NE margin of the Arabian continent was overthrust by "exotic" sheets of oceanic and continental margin units (the Semail ophiolite allochthon). Some parts of this margin (Saih Hatat Massif) were deeply buried through subduction, to depths suitable for eclogite facies metamorphism, while other parts are unmetamorphosed (Jebel Akhdar Massif). Consequently an almost continuous metamorphic gradient is preserved, that creates an ideal setting with which to relate both shallow and deep-seated tectonic processes to orogenic development Current mapping and structural studies reveal that the extensional deformation that followed the obduction of the allochthons and concomitant partial subduction of the continental margin is very much more extensive than previously recognized and was synchronous with the folding of the culminations of the Oman orogen. The extensional deformation appears to be partitioned into two orthogonal structural styles: NNE-directed shearing and vertical thinning, together with a local NW -SE contraction manifested by lineation-parallel folds. In the lebel Akhdar massif the NNE-shear deformation is extensively developed, forming steep faults and bedding-parallel detachments that extend stratigraphy with a top-to-the-NNE sense of shearing. No evidence of ongoing NW-SE contraction is seen, and hence deformation is apparently plane strain. In contrast, lebel Nakhal is arked with widespread deformation of both NNE-shearing and the concomitant NW -SE contraction, indicating non-plane strain. In Saih Ratat NNE-shearing is penetrative, with a component of orthogonal contractjon. Coeval orthogonal layer contraction, layer-thinning and elongation describe the bulk constrictional 3D strain. While this might be indicative of regional transtension, large-scale strike-slip faults active during the extension, as predicted by general transtensional models, are not evident. Consequently it is inferred that the constriction was the result of laterally-varying crustal extension, where the top NNE extension was locally combined with left-lateral shearing. For the Nakhal anticline, where the direction of the finite elongation axis is N030E, the orientation of sinistral transtension deformation is NNE-SSW. Exhumation of the metamorphic series ccurred beneath a carapace of extending allochthons which defined an elongate pip of material that returned to shallow crustal levels. There is an imbalance however, between the net extension and the possible contraction within the Arabian continent which requires deformation within a volume of net-divergent tectonics. Thus crustal extension continued after the end of convergent tectonics in the region.
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LaMaskin, Todd Allen. "Stratigraphy, provenance, and tectonic evolution of Mesozoic basins in the Blue Mountains Province, eastern Oregon and western Idaho /." Connect to title online (ProQuest), 2009. http://proquest.umi.com/pqdweb?did=1790314181&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Leschin, Michael F. "A Hydrogeochemical Study of the Evolution of the Headwaters of the Bear River in the Uinta Mountains, Utah." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/4422.
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The headwaters of the Bear River in the Uinta Mountains of Utah provide a good setting in which to examine the influence of geological materials on stream chemistry. Ionic contributions to the stream-water from soils, vegetation, and the atmosphere generally are sparse enough that they do not mask the geologic contributions. Samples from 37 sites on the four major headwater streams and several minor tributaries were examined geochemically. Data derived from the samples allowed the construction of a hydrogeochemical weathering model specific to the study area. A significant feature of this model is that carbonic acid is the dominant chemical agent involved in geochemical weathering.
The aim of this study was to examine the geologic influences on river chemistry. However, atmospheric contributions dominate the hydrochemistry through at least the first 10 kilometers of stream length for the easternmost three of the four major headwater streams.
Except for the atmospheric contribution, surface-water chemistry is dominated by the groundwater chemistry, which is indelibly marked by the lithology the groundwater passes through. Other geologic factors in the study area that appear to influence groundwater chemistry, and hence stream chemistry, are the glacial till and outwash deposits and a major zone of east-west trending high-angle thrust faults. A technique for estimating the hydrochemistry of the groundwater based on surface-water chemistry and flow measurements was developed in this study.
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Crowley, James L. Carleton University Dissertation Geology. "Tectonic evolution of the Standfast Creek fault and Clachnacudainn terrane, southern Omineca Belt, Canadian Cordillera." Ottawa, 1992.
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Mackey, Benjamin Hunter. "The contribution of large, slow-moving landslides to landscape evolution." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10555.
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xvi, 136 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.This dissertation discusses the contribution of deep-seated landslides and earthflows to the morphology, erosion, and evolution of mountainous landscapes, focusing on the northern California Coast Ranges. In active landscapes, channel incision is necessary to create relief but also increases stresses in adjacent hillslopes, ultimately leading to slope failure. While conceptually simple, the spatial relationships between channel incision and landsliding have not been well quantified. Along the South Fork Eel River, I mapped the distribution of deep-seated landslides using light detection and ranging (LiDAR) derived maps. Landslide density increases in regions subject to late Pleistocene-Holocene channel incision and particularly in response to lateral incision at the apex of meander bends. Wavelet analysis of channel sinuosity reveals hillslopes are most sensitive to meander wavelengths of 1.5 km. Argillaceous lithology generates abundant earthflow activity along the main stem Eel River, yet spatial and temporal patterns of earthflow movement are poorly understood. I undertook a detailed study of the Kekawaka Earthflow using LiDAR, meteoric 10 Be in soil, orthorectified historical aerial photographs, and field surveys. Inventories of 10 Be in soil pits increase systematically downslope, indicate an average movement rate of 2.1 ± 1.3 m/a over the past 150 years, and establish a minimum earthflow age of 1700 years. The Kekawaka earthflow has a systematic history of movement, both spatially, with greatest movement in the narrow transport zone, and temporally, as velocities peaked in the 1960's and have slowed since 1981. I used LiDAR and aerial photographs to map earthflow movement and calculate sediment flux across 226 km 2 of the main stem Eel River. From 1944-2006, 7.3% of the study area was active, and earthflows account for an erosion rate of 0.53 ± 0.04 mm/a, over half the regional average sediment yield. Velocity time series on 17 earthflows suggest temporal earthflow behavior is influenced by decadal-scale changes in precipitation, temperature, and river discharge, although local topographic factors can overwhelm this climatic signal. When active, earthflows erode an order of magnitude faster than surrounding terrain; however, source supply limitations appear to govern long- term earthflow evolution. This dissertation includes previously published coauthored material.
Committee in charge: Joshua Roering, Chairperson, Geological Sciences; Ilya Bindeman, Member, Geological Sciences; Dean Livelybrooks, Member, Physics; Ray Weldon, Member, Geological Sciences; W. Andrew Marcus, Outside Member, Geography
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Moertle, Jasmine A. "Stable isotope evidence for a complex fluid evolution of the Northwestern British Columbia Coast Mountains related to terrane accretion." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10147322.
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Stable isotope analysis of thirty-five samples from the Northwestern Coast Mountains indicates a complex fluid history related to terrane accretion, metamorphism, and magmatism. The greenschist to amphibolite facies metasedimentary rocks from the Western Metamorphic Belt have variable δD and δ 18O values that appear to be in isotopic equilibrium with metamorphic fluids at low water-rock ratio conditions. Carbon isotope values indicate organic rich protoliths. Stable isotope values from the Coast Shear Zone indicate the involvement of both magmatic and meteoric-hydrothermal fluids during deformation, in contrast to meteoric-free fluid systems related to Au-mineralization along strike to the north (Goldfarb et al., 1988). The Coast Mountain Batholith and Central Gneiss Complex have homogeneous δD and δ 18O values that indicate magmatic fluids at low water-rock ratio (Magaritz and Taylor, 1976). Further to the east, large amounts of meteoric-hydrothermal fluids circulated through a network of ductile-to-brittle normal faults (Andronicos et al., 2003; Heah, 1990).
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Scherer, Hannah Howell. "Field, geochronologic, and geochemical constraints on the early mesozoic paleogeographic and tectonic evolution of the central Klamath Mountains, California /." May be available electronically:, 2006. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Mansour, Sherif Elshahat Elsayed [Verfasser], and Ulrich A. [Akademischer Betreuer] Glasmacher. "Long-term topographic evolution of the African plate, causes and consequences for surrounding lithospheric plates / Sherif Elshahat Elsayed Mansour ; Betreuer: Ulrich A. Glasmacher." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180609689/34.
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Anderson, H. Elizabeth (Hattie Elizabeth) Carleton University Dissertation Geology. "A chemical and isotopic study of the age, petrogenesis and magmatic evolution of the Mount Pleasant Caldera complex, New Brunswick." Ottawa, 1992.
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Stepner, Daniel. "Source and Magma Evolution of the Tuff of Elevenmile Canyon, Stillwater Range, Clan Alpine and Northern Desatoya Mountains, Western Nevada." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36893.
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The tuff of Elevenmile Canyon (TEC) is a 25.1 Ma trachydacite to rhyolite intracaldera tuff produced by the largest of 6 Oligocene overlapping calderas that, along with related plutons, constitute the Stillwater Caldera Complex, one of the largest eruptions of the Western Nevada Volcanic Field during the mid-Tertiary ignimbrite flare-up. Typically crystal-rich with a mineral assemblage of plagioclase > quartz sanidine > biotite ± hornblende and clinopyroxene, there are two discernable pumice types throughout the tuff: a lighter crystal-rich pumice and a darker, commonly aphyric pumice type. Rb-Sr and Sm-Nd isotopic compositions of pumice fragments and whole rock samples indicate an enriched mantle component (87Sr/86Srin = 0.70495 – 0.70535, Nd[t=25.1Ma] = -1.13 to -0.39) similar to that of coeval Cenozoic mafic lavas. Pb isotopes (206Pb/204Pbin = 19.042 – 19.168, 207Pb/204Pbin = 15.557 – 15.664) fall along a tight trend between the Northern Hemisphere Reference Line (Hart 1984) and an endmember similar to local granitic units. Major and trace element modelling support a source for the TEC derived from the mixing of anatectic melts of crustal rocks with intruded mantle-derived magmas similar to a local basaltic-andesite.
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Scharf, Taryn E. "Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/4220.
Full textAbstract:
Includes abstract.Includes bibliographical references.
Southern Africa is host to a unique mountain system, the Cape Mountains, which includes the coastal Cape Fold Belt (CFB) and an inland Escarpment. Apatite fission track analysis has shown that this mountain system is an erosion feature, exhumed from beneath 2-7 km of overburden by large-scale denudation processes affecting the subcontinent during Gondwana break-up (ca. 140 – 65 Ma). Despite its antiquity and location on a passive continental margin, the ruggedness of the present-day topography of the Cape Mountains compares to that of the world’s active orogens. The coastal Cape Mountains are traversed by deeply-incised, meandering rivers that cut canyons through the most resistant quartzite ridges of these mountains, perpendicular to their structural grain inherited from the CFB. The evolution of this landscape is poorly understood, because little quantitative data exists on the denudation history of the Cape Mountains. This study presents the first in situ-produced cosmogenic 10Be inventories determined for quartz from catchment sediments and bedrock surfaces within the coastal Cape Mountains, with which to quantify denudation rates, exposure ages and the recent geomorphic evolution of these Cape Mountains. River sediments sampled from catchments within the Langeberg and Swartberg Ranges of the Western Cape, as well as bedrock from the Tradouw River traversing the Langeberg Range, were analysed. In addition, charcoal from alluvial material was collected for radiocarbon dating. Catchment-averaged denudation rates reported from these mountains range between 2.1 ± 0.3 and 6.9 ± 1.9 m·Myr-1. These are amongst the lowest reported rates globally, despite the rugged terrain of the mountain system. The spatial consistency between the low denudation rates suggests a landscape approaching geomorphic steady-state. This finding is best attributed to lithological control on denudation rates in a tectonically quiescent environment, and a relatively dry climate.