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2011

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Articles 151 - 180 of 258

Full-Text Articles in Geology

Variations In Concentrations And Compositions Of Polycyclic Aromatic Hydrocarbons (Pahs) In Coals Related To The Coal Rank And Origin, Susanne Laumann, Vesna Micic Batka, Michael A. Kruge, Christine Achten, Reinhard Sachsenhofer, Jan Schwarzbauer, Thilo Hofmann Jan 2011

Variations In Concentrations And Compositions Of Polycyclic Aromatic Hydrocarbons (Pahs) In Coals Related To The Coal Rank And Origin, Susanne Laumann, Vesna Micic Batka, Michael A. Kruge, Christine Achten, Reinhard Sachsenhofer, Jan Schwarzbauer, Thilo Hofmann

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The release of unburnt coal particles and associated polycyclic aromatic hydrocarbons (PAHs) may cause adverse impacts on the environment. This study assessed variations in the concentration and composition of PAHs in a set of fifty coal samples from eleven coal basins worldwide. The maximum PAH concentrations at high volatile bituminous rank were recorded in samples from a single basin. Considering the entire sample, the highest PAH concentrations were in fact found outside of this rank range, suggesting that the maceral composition and thus the coal's origin also influenced PAH concentrations. The examination of the PAH compositions revealed that alkylated 2-3 …


Proceedings Of The 2011 International Conference On Karst Hydrogeology And Ecosystems, Jason Samuel Polk, Leslie A. North Jan 2011

Proceedings Of The 2011 International Conference On Karst Hydrogeology And Ecosystems, Jason Samuel Polk, Leslie A. North

Environmental Sustainability Books

Jointly sponsored by the Hoffman Environmental Research Institute, the National Cave & Karst Research Institute, and the International Association of Hydrogeologists, the 2011 International Conference on Karst Hydrogeology and Ecosystems was held at Western Kentucky University in Bowling Green, Kentucy on 8-10 June 2011. Topics include karst geomorphology, engineering and modeling, isotope geochemistry, and cultural and educational aspects of karst environments.


Potential Fossil Endoliths In Vesicular Pillow Basalt, Coral Patch Seamount, Eastern North Atlantic Ocean, Barbara Cavalazzi, Frances Westall, Sherry L. Cady, Roberto Barbieri, Frédéric Foucher Jan 2011

Potential Fossil Endoliths In Vesicular Pillow Basalt, Coral Patch Seamount, Eastern North Atlantic Ocean, Barbara Cavalazzi, Frances Westall, Sherry L. Cady, Roberto Barbieri, Frédéric Foucher

Geology Faculty Publications and Presentations

The chilled rinds of pillow basalt from the Ampere-Coral Patch Seamounts in the eastern North Atlantic were studied as a potential habitat of microbial life. A variety of putative biogenic structures, which include filamentous and spherical microfossil-like structures, were detected in K-phillipsite-filled amygdules within the chilled rinds. The filamentous structures (similar to 2.5 mu m in diameter) occur as K-phillipsite tubules surrounded by an Fe-oxyhydroxide (lepidocrocite) rich membranous structure, whereas the spherical structures (from 4 to 2 mu m in diameter) are associated with Ti oxide (anatase) and carbonaceous matter. Several lines of evidence indicate that the microfossil-like structures in …


Mapped Karst Groundwater Basins In The Somerset 30 X 60 Minute Quadrangle, James C. Currens, Randall L. Paylor, Joseph A. Ray, Robert J. Blair Jan 2011

Mapped Karst Groundwater Basins In The Somerset 30 X 60 Minute Quadrangle, James C. Currens, Randall L. Paylor, Joseph A. Ray, Robert J. Blair

Map and Chart--KGS

No abstract provided.


Remaining Resources Of The Herrin Coal, Gerald A. Weisenfluh Jan 2011

Remaining Resources Of The Herrin Coal, Gerald A. Weisenfluh

Map and Chart--KGS

The Herrin coal bed (W. Ky. No. 11) is one of the most important coal resources in the Illinois Basin. To 2009, the Herrin coal had an estimated 10 million tons of production in Kentucky, and remained the second largest producer in the Western Kentucky Coal Field. The Herrin is known for its regionally extensive "blue band" rock parting, and, in Kentucky, its close association with the overlying Providence Limestone Member and Paradise coal (W. Ky. No. 11) (see, for example, Greb and others, 1992). To fact, the Herrin and Paradise coal beds were so closely spaced in some areas …


Comparing Middle Permian And Early Triassic Environments: Mud Aggregates As A Proxy For Climate Change In The Karoo Basin, South Africa, Bryce Pludow Jan 2011

Comparing Middle Permian And Early Triassic Environments: Mud Aggregates As A Proxy For Climate Change In The Karoo Basin, South Africa, Bryce Pludow

Honors Theses

The Permian-Triassic Boundary (252.6 Ma) is an interval under intense study as changes across it represent the greatest loss of life in Earth history. Although the event is well understood and constrained in the marine realm, questions remain about extinction, climate, and environmental conditions on land. The Karoo Basin of South Africa is a focus of study due to the complete nature of its terrestrial record, specifically across this boundary.


The identification of pedogenic mud aggregates document the presence of soils with abundant clays produced in a seasonally arid environment. The occurrence of these aggregates in low-sinuosity Early Triassic fluvial …


Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz Jan 2011

Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz

OES Faculty Publications

The prevailing paradigm of abrupt climate change holds that rapid shifts associated with the most extreme climate swings of the last glacial cycle were forced by changes in the strength and northward extension of Atlantic Meridional Overturning Circulation (AMOC), resulting in an abrupt reorganization of atmospheric circulation patterns with global teleconnections. To determine the timing of tropical Atlantic atmospheric circulation changes over the past 21 ka BP, we reconstruct high resolution sea surface temperature and δ18OSW (a proxy for surface salinity) records based on Mg/Ca ratios and oxygen isotope measurements in the planktonic foraminifera Globigerinoides ruber from …


Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero Jan 2011

Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero

OES Faculty Publications

Paleoproxy studies show a strong correlation between tropical climate and high-latitude temperature variability recorded in the Greenland ice cores over the last glacial cycle. In particular, abrupt cooling events in the Greenland Ice Sheet Project II δ18O ice record appear synchronous with a southward migration of the Intertropical Convergence Zone (ITCZ) in the Atlantic, a weakening of the Indian and East Asian monsoon systems, and a strengthening of the South American monsoon system. Because this high-to-low-latitude climate teleconnection significantly alters the tropical hydrologic cycle around the globe, it plays a critical role in regulating global climate on glacial-interglacial …


Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry Jan 2011

Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry

OES Faculty Publications

The waters passing through the Florida Straits today reflect both the western portion of the wind-driven subtropical gyre and the northward flow of the upper waters which cross the equator, compensating North Atlantic Deep Water export as part of the large-scale Atlantic meridional overturning circulation. It has been postulated from various lines of evidence that the overturning circulation was weaker during the Younger Dryas cold event of the last deglaciation. We show here that the contrast in the oxygen isotopic composition of benthic foraminiferal tests across the Florida Current is reduced during the Younger Dryas. This most likely reflects a …


Relationships Between Snake River Paleofloods, Occupational Patterns And Archaeological Preservation At Redbird Beach Archaeological Site In Lower Hells Canyon, Idaho, Tabitha Trosper Jan 2011

Relationships Between Snake River Paleofloods, Occupational Patterns And Archaeological Preservation At Redbird Beach Archaeological Site In Lower Hells Canyon, Idaho, Tabitha Trosper

All Master's Theses

The Snake River basin drains 282,000 km2 of the northwestern U.S. and is the largest tributary to the Columbia River. Redbird Beach, an archaeological site located in the lower Hells Canyon reach of the Snake River, contains extensive vertical exposures of archaeological materials interbedded with Snake River flood sediments. Redbird Beach formed in the lee of the Redbird Creek debris fan, is composed of interfingering deposits from large floods on the Snake River and locally-derived alluvial sediments from Redbird Creek. Through stratigraphic analyses of slackwater deposits, this study compares the temporal and spatial patterns of human occupation at Redbird …


Bedrock Geology And Tectonic Evolution Of The Western Central Maine Zone, South Central Massachusetts, Thomas Bradley Walker Jan 2011

Bedrock Geology And Tectonic Evolution Of The Western Central Maine Zone, South Central Massachusetts, Thomas Bradley Walker

Theses and Dissertations--Earth and Environmental Sciences

Bedrock geology of the East Brookfield quadrangle (EBQ), based on new 1:24000 scale mapping, consists of an interfolded sequence of Rangeley Fm. and Paxton Fm. metasediments, intruded by Early Mississippian tonalitic to granitic orthogneisses and underlain in the western half by folded orthogneisses of unknown age. Pervasive flattening strains have created planar, generally NNE-SSW striking and consistent moderately west dipping foliations. Generally strike-parallel stretching lineations and boudinage structures, with rarer dip parallel stretching lineations, reflect extrusion of CMZ metasediments and orthogneisses with a flattening component. Mapping in the EBQ demonstrates that a transition between deformational mechanisms of the southern Central …


Nummulites Biofabrics As Tool For Quality Evaluation Of The Eocene Jdeir Formation Reservoirs Nw Offshore, Libya, Abdusalam Ali Agail Jan 2011

Nummulites Biofabrics As Tool For Quality Evaluation Of The Eocene Jdeir Formation Reservoirs Nw Offshore, Libya, Abdusalam Ali Agail

Open Access Theses & Dissertations

The southern Tethys margin constitutes an important hydrocarbon reservoir. It is formed mainly of Nummulite rich facies of the Jdeir Formation deposited during the Eocene epoch (Late Ypresian age) in the giant El-Bouri oil field-Sabratah Basin-NW Libya. Deposits of the Jdeir Formation directly overlay the Jirani dolomite and Bilal Formation, and unconformably underlay the Tellil Group and Ghallil Formation.

Nummulite accumulations are good indicators for hydrocarbon studies and they have been targets for numerous studies around the world. Nummulite "Large foraminifera" tests are usually identified by two forms: A-form and B-form. Previous studies have highlighted many different aspects of foraminifers …


The East Jhomolari Fault System And The Timing Of East-West Extension In Northwest Bhutan, John Matthew Cannon Jan 2011

The East Jhomolari Fault System And The Timing Of East-West Extension In Northwest Bhutan, John Matthew Cannon

Open Access Theses & Dissertations

This investigation documents a little known, regionally significant, high angle, southeast dipping, system of normal faults in northwest Bhutan, the East Jhomolari Fault System (EJFS). The EJFS trends parallel to the Yadong Gulu rift (YG) and can be traced from Mt. Jhomolari to the northern border with Tibet. This fault zone has been demonstrably active since the last glacial maximum and there is geomorphic evidence of Holocene activity on some fault segments. The structurally lowest EJFS fault, the Lingshi fault appears on some published maps, but the full geographic extent, displacement, onset of faulting, and most recent activity have not …


Reinterpreted History Of Latest Pleistocene Lake Bonneville: Geologic Setting Of Threshold Failure, Bonneville Flood, Deltas Of The Bear River, And Outlets For Two Provo Shorelines, Southeastern Idaho, Usa, Susanne U. Janecke, P. Q. Oaks Jr. Jan 2011

Reinterpreted History Of Latest Pleistocene Lake Bonneville: Geologic Setting Of Threshold Failure, Bonneville Flood, Deltas Of The Bear River, And Outlets For Two Provo Shorelines, Southeastern Idaho, Usa, Susanne U. Janecke, P. Q. Oaks Jr.

Geosciences Faculty Publications

Geologic, geomorphic, and geophysical analyses of landforms, sediments, and geologic structures document the complex history of pluvial Lake Bonneville in northern Cache Valley, NE Great Basin, and shows that the outlet of Lake Bonneville shifted ~20 km south after the Bonneville flood. The Riverdale normal fault offsets Bonneville deposits, but not younger Provo deposits ~25 km southeast of Zenda, Idaho. Rapid changes in water level may have induced slip on the Riverdale fault shortly before, during, or after the Bonneville flood. Although other processes may have played a role, seismicity might have been the main cause of the Bonneville flood.


Seismic Interpretation And Reservoir Characterization Of The Middle Eocene Gialo Formation, Assamoud Field, Sirte Basin, Libya, Abdalla Abdelnabi Jan 2011

Seismic Interpretation And Reservoir Characterization Of The Middle Eocene Gialo Formation, Assamoud Field, Sirte Basin, Libya, Abdalla Abdelnabi

Masters Theses

"The Gialo Formation is a major gas producing reservoir in the Assamoud Field, Sirte Basin, Libya. It is called Gialo limestone because it consists of shallow marine limestone. Seismic and well data in conjunction with the results of a previous study were used to delineate the hydrocarbon reservoir of Middle Eocene Gialo Formation of Assamoud Field area located in Eastern part of concession 6, Sirte Basin, Libya. The data include three-dimensional seismic data acquired by Sirte Company in 2009. It covers approximately an area of 150 km² and with more than 10 wells penetrating the reservoir. Seismic data were used …


Adaptive Resource Management And The Value Of Information, Byron K. Williams, Mitchell J. Eaton, David R. Breininger Jan 2011

Adaptive Resource Management And The Value Of Information, Byron K. Williams, Mitchell J. Eaton, David R. Breininger

United States Geological Survey: Staff Publications

The value of information is a general and broadly applicable concept that has been used for several decades to aid in making decisions in the face of uncertainty. Yet there are relatively few examples of its use in ecology and natural resources management, and almost none that are framed in terms of the future impacts of management decisions. In this paper we discuss the value of information in a context of adaptive management, in which actions are taken sequentially over a time frame and both future resource conditions and residual uncertainties about resource responses are taken into account. Our objective …


Calcite Cementation Of Sixty-Five-Year-Old Aragonite Sand Dredge Pile, Nathan M. Snyder Jan 2011

Calcite Cementation Of Sixty-Five-Year-Old Aragonite Sand Dredge Pile, Nathan M. Snyder

Electronic Theses and Dissertations

Dredging of the harbor at Stocking Island, Bahamas (23°31'45"N, 75°49'41"W) in 1942 produced four dredge piles of cross-bedded aragonite skeletal sand. The spoils piles are on the leeward (western) shore of the island, where they are subject to minimal wave energy. Collectively they are 350 x 50 m in plan view and 2 m high. The surface is very well cemented, which requires a hammer and chisel for sampling. Samples were collected from six sites at various locations of the dredge pile. Samples were analyzed for both chemical and physical properties using thin-section examination, X-ray diffraction, X-ray fluorescence, bulk density …


A Gis Investigation Of Regional Geologic Controls On Mercury Deposits In The Southwest Region Of Arkansas, Lindsey Carol Langsdon Jan 2011

A Gis Investigation Of Regional Geologic Controls On Mercury Deposits In The Southwest Region Of Arkansas, Lindsey Carol Langsdon

Electronic Theses and Dissertations

The mercury district of southwest Arkansas, located within Clark, Pike, and Howard counties, contains 77 mapped mercury deposits, primarily in the form of cinnabar, found within the sandstones and shales of the Stanley and Jackfork Formations. The geographic locations of the majority of the deposits tend to form an east-northeast alignment in map view. Utilization of Geographic Information Systems (GIS) tools provided insight to the regional controls on the spatial distribution of the mercury deposits by examining the proposed relationships between mercury deposits and regional faults or changes in lithology, both of which have been suggested (Clardy and Bush, 1976) …


Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province, Lamuail Bashir Jan 2011

Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province, Lamuail Bashir

Doctoral Dissertations

"Stacking of about 15,500 P-to-S receiver functions recorded at 72 USArray and other broadband seismic stations placed on the Colorado Plateau and the SBRP in Arizona revealed systematic spatial variations in crustal Vp/Vs, crustal thickness and amplitude of P-to-S converted phases. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean Vp/Vs of 1.761 ± 0.014 and a mean amplitude (R) of P - to - S converted wave (relative to that of the direct P wave) of 0.181 ± 0.014 that are similar to a typical continental crust, consistent with the …


Geology Of Cumberland Gap National Historical Park, Matthew M. Crawford, Hanna Hunsberger Jan 2011

Geology Of Cumberland Gap National Historical Park, Matthew M. Crawford, Hanna Hunsberger

Map and Chart--KGS

Cumberland Gap National Historical Park is located in parts of Kentucky, Virginia, and Tennessee. The park was authorized by President Franklin Roosevelt on June 11, 1940, and is now the largest historical park in the National Park System. It contains 24,000 acres along Cumberland Mountain near Ewing, Va., proceeding southwest toward Fern Lake in Tennessee, a distance of approximately 20 miles. The average width of the park is only 1.6 miles.

The park hosts a distinctive range of geologic processes and features. Unique structural geology, caves and karst, surface and groundwater erosion, and mass wasting are just a few of …


Kentucky Landscapes Through Geologic Time, Daniel I. Carey Jan 2011

Kentucky Landscapes Through Geologic Time, Daniel I. Carey

Map and Chart--KGS

We now understand that the earth’s crust is broken up into a number of plates, some of continental size, and that these plates have been moving— centimeters a year—throughout geologic history, driven by the internal heat of the earth. This movement creates our mountain chains, earthquakes, geologic faults, and volcanoes. The theory of plate tectonics (from the Greek, tektonikos: pertaining to building) attempts to describe the process and helps explain the geology of Kentucky.

The geologic story of the rocks that form Kentucky’s landscape began a half billion years ago when the area was covered by water. Deposits of sand, …


Distribution And Properties Of Vesicular Horizons In The Western United States, Judith K. Turk, Robert C. Graham Jan 2011

Distribution And Properties Of Vesicular Horizons In The Western United States, Judith K. Turk, Robert C. Graham

Conservation and Survey Division: Faculty and Staff Publications

Vesicular horizons are thin (usuallycm) surface or near-surface horizons characterized by the predominance of vesicular porosity. Th ey are widespread in arid and semiarid lands, occurring on every continent and covering 156,000 km2 of the western United States. Vesicular horizons have critical implications for management due to their role in controlling surface hydrology and dust mobilization. Th is study evaluates the distribution and varia-tion in expression of vesicular horizons across the western United States using the soil databases available from the USDA. A vesicular horizon index (VHI) that incorporates vesicular horizon thickness and the size and quantity of vesicular pores …


Stratigraphy And Petroleum Production Potential Of The Spearfish Formation In North Central North Dakota, Nnaemeka C. Anyanwu Jan 2011

Stratigraphy And Petroleum Production Potential Of The Spearfish Formation In North Central North Dakota, Nnaemeka C. Anyanwu

Theses and Dissertations

The Spearfish oil play is unconventional requiring the use of horizontal wells that are fracture stimulated to deliver economic flow rates. However, fraccing into the underlying water has been a source of significant production problems for operators. The key to developing the area is to keep the individual fracs large enough to stimulate the tight Spearfish sands but not to let them propagate into the underlying water zone.

The Spearfish Formation of the Black Hills has been traced into the subsurface of the Williston Basin in western North Dakota from bore holes at the northern margin of the outcrop area …


Geomechanical Stability Analysis For Co2 Sequestration In Carbonate Formation, Xue J. Zhou Jan 2011

Geomechanical Stability Analysis For Co2 Sequestration In Carbonate Formation, Xue J. Zhou

Theses and Dissertations

Geomechanical analysis is one of the fundamental pillars to build up the confidence of geological sequestration of CO2. Large scale CO2 sequestration in deep carbonate formation is a complicated geological process, which will non-reversibly transform the presumed equivalent and stable status of a sedimentary basin that formed over millions of years: chemically, hydraulically, geothermally, and geomechanically. In this dissertation, thermoporoelasticity guides the theoretical establishment of a conservative baseline for the geomechanical stability analysis of CO2 sequestration.

Extensive laboratory tests, including CO2 flooding tests, permeability tests, uniaxial and triaxial tests, Brazilian tensile strength tests, poroelasticity tests, point load tests, and fracture …


Chemical Evolution And Residence Time Of Groundwater In The Wilcox Aquifer Of The Northern Gulf Coastal Plain, Estifanos Haile Jan 2011

Chemical Evolution And Residence Time Of Groundwater In The Wilcox Aquifer Of The Northern Gulf Coastal Plain, Estifanos Haile

Theses and Dissertations--Earth and Environmental Sciences

This study aims to integrate groundwater geochemistry and mathematical modeling to determine the dominant geochemical processes and groundwater residence time within the Wilcox aquifer in the northern Gulf Coastal Plain. Groundwater samples were collected and analyzed for major ion chemistry, stable isotopes (18O, 2H, and 13C), and radioisotope 36Cl content. Geochemical modeling enabled the identification of major sources and sinks of solutes in the aquifer. A two-dimensional, finite-difference, numerical model was used to determine the deep groundwater flow rate and transport of 36Cl in the aquifer. Major ion chemistry shows a chromatographic pattern along …


Arsenic Heterogeneity In Aquifer Sediments From West Bengal, India, Emily Eastridge Jan 2011

Arsenic Heterogeneity In Aquifer Sediments From West Bengal, India, Emily Eastridge

Theses and Dissertations--Earth and Environmental Sciences

Multiple studies in the Bengal basin have shown that elevated As in groundwater coincides with reduced, relatively dark sediments of Himalayan provenance. In West Bengal state (India), As concentrations > 10 μg/L tend to occur east of the River Bhagirathi-Hoogly, the main distributary of the Ganges. Associations among sediment chemistry and mineralogy for four cores from either side of the Bhagirathi-Hoogly (cores 1 and 2 to the east, 3 and 4 to the west) in Murshidabad district were investigated. Ten sediment samples were collected from each boring at various depths to a maximum of 38 to 43 m. Sediment chemistry was …


Encyclopedia Of Snow, Ice And Glaciers, Vijay P. Singh, Pratap Singh, Umesh K. Haritashya Jan 2011

Encyclopedia Of Snow, Ice And Glaciers, Vijay P. Singh, Pratap Singh, Umesh K. Haritashya

Department of Earth, Environment and Sustainability Faculty Publications

The objective of this encyclopedia is to present the current state of scientific understanding of various aspects of earth’s cryosphere – snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost – and their related interdisciplinary connections under one umbrella. Therefore, every effort has been made to provide a comprehensive coverage of cryosphere by including a broad array of topics, such as the atmospheric processes responsible for snow formation; snowfall observations; snow cover and snow surveys; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide …


Timing, Distribution, Amount, And Style Of Cenozoic Extension In The Northern Great Basin, Christopher D. Henry, Allen J. Mcgrew, Joseph P. Colgan, Arthur W. Snoke, Matthew E. Brueseke Jan 2011

Timing, Distribution, Amount, And Style Of Cenozoic Extension In The Northern Great Basin, Christopher D. Henry, Allen J. Mcgrew, Joseph P. Colgan, Arthur W. Snoke, Matthew E. Brueseke

Department of Earth, Environment and Sustainability Faculty Publications

This field trip examines contrasting lines of evidence bearing on the timing and structural style of Cenozoic (and perhaps late Mesozoic) extensional deformation in northeastern Nevada. Studies of metamorphic core complexes in this region report extension beginning in the early Cenozoic or even Late Cretaceous, peaking in the Eocene and Oligocene, and being largely over before the onset of “modern” Basin and Range extension in the middle Miocene. In contrast, studies based on low- temperature thermochronology and geologic mapping of Eocene and Miocene volcanic and sedimentary deposits report only minor, localized extension in the Eocene, no extension at all in …


'Sticky Spots' And Subglacial Lakes Under Ice Streams Of The Siple Coast, Antarctica, Olga V. Sergienko, Christina L. Hulbe Jan 2011

'Sticky Spots' And Subglacial Lakes Under Ice Streams Of The Siple Coast, Antarctica, Olga V. Sergienko, Christina L. Hulbe

Geology Faculty Publications and Presentations

Locations of subglacial lakes discovered under fast-moving West Antarctic ice streams tend to be associated with topographic features of the subglacial bed or with areas that have strong variations in basal conditions. Inversion of ice-stream surface velocity indicates that basal conditions under ice streams can be highly variable and that there can be widespread regions where basal traction is high. To seek an explanation for why lakes appear to be sited near areas with high basal traction, we use numerical models to simulate ice-stream dynamics, thermodynamics and subglacial water flow. We demonstrate that the ice flow over high basal traction …


Insights Into The 1968–1997 Dasht-E-Bayaz And Zirkuh Earthquake Sequences, Eastern Iran, From Calibrated Relocations, Insar And High-Resolution Satellite Imagery, R. T. Walker, E. A. Bergman, Walter Szeliga, E. J. Fielding Jan 2011

Insights Into The 1968–1997 Dasht-E-Bayaz And Zirkuh Earthquake Sequences, Eastern Iran, From Calibrated Relocations, Insar And High-Resolution Satellite Imagery, R. T. Walker, E. A. Bergman, Walter Szeliga, E. J. Fielding

Faculty Scholarship for the Cascadia Hazards Institute

The sequence of seismicity in the Dasht-e-Bayaz and Zirkuh region of northeastern Iran, which includes 11 destructive earthquakes within a period of only 30 years, forms one of the most outstanding examples of clustered large and intermediate-magnitude seismic activity in the world.We perform a multiple-event relocation analysis, with procedures to remove systematic location bias, of 169 earthquakes, most of which occurred in the period 1968–2008, to better image the distribution of seismicity within this highly active part of Iran. The geographic locations of the clustered earthquakes were calibrated by the inclusion of phase arrivals from seismic stations at short epicentral …