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2015

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Articles 211 - 240 of 409

Full-Text Articles in Geology

Sequence Stratigraphy, Depositional Environments And Geochemistry Of The Middle Cambrian Bloomington Formation In Northern Utah, Christopher Ryan Jensen May 2015

Sequence Stratigraphy, Depositional Environments And Geochemistry Of The Middle Cambrian Bloomington Formation In Northern Utah, Christopher Ryan Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Bloomington Formation (~425 m thick) is a latest Middle Cambrian (~506.5-505 Ma.), mixed warm water, carbonate and shale unit on the Cordilleran passive margin in northern Utah and southern Idaho. The Hodges Shale and Calls Fort Shale Members are shale dominated and the Middle Limestone Member is a thick carbonate. Fossil diversity and abundance is surprisingly low for a Middle Cambrian carbonate/shale formation. Present, however, are 10-50 cm thrombolite mud mounds, associated with Girvanella oncoliths. These mud mounds represent shallow water carbonates that experienced a small flooding event that gives the mud mounds time and proper conditions to build …


Going With The Flow Or Against The Grain? The Promise Of Vegetation For Protecting Beaches, Dunes, And Barrier Islands From Erosion, Rusty A. Feagin, Jens Figlus, Julie C. Zinnert, Jake Sigren, Marisa L. Martínez, Rodolfo Silva, William K. Smith, Ashley Cox, Daniel Cox, Donald R. Young, Gregory A. Carter May 2015

Going With The Flow Or Against The Grain? The Promise Of Vegetation For Protecting Beaches, Dunes, And Barrier Islands From Erosion, Rusty A. Feagin, Jens Figlus, Julie C. Zinnert, Jake Sigren, Marisa L. Martínez, Rodolfo Silva, William K. Smith, Ashley Cox, Daniel Cox, Donald R. Young, Gregory A. Carter

Faculty Publications

Coastlines have traditionally been engineered to maintain structural stability and to protect property from storm‐related damage, but their ability to endure will be challenged over the next century. The use of vegetation to reduce erosion on ocean‐facing mainland and barrier island shorelines – including the sand dunes and beaches on these islands – could be part of a more flexible strategy. Although there is growing enthusiasm for using vegetation for this purpose, empirical data supporting this approach are lacking. Here, we identify the potential roles of vegetation in coastal protection, including the capture of sediment, ecological succession, and the building …


Comparing Slug Test Methods For Unconfined Aquifers, Hussain Jaber Alfaifi May 2015

Comparing Slug Test Methods For Unconfined Aquifers, Hussain Jaber Alfaifi

Dissertations

Slug test methods are used to determine in situ aquifer hydraulic conductivity (K) more quickly and economically than a pump test can. This study compares slug test methods for unconfined aquifers, looking at how to conduct a test using a physical slug, and at different analysis methods including Bouwer and Rice (1976), Kansas Geological Survey (KGS 1994), Hvorslev (1951) and Dagan (1978). Questions that motivated this study include: How well does the Bouwer and Rice method work? What is the most effective way to conduct a slug test? Does using a large physical slug relative to the well diameter and …


Trace Element Variations In A Stalagmite From Southwest Mexico: Implications For Paleoclimate, Chad Michael Crotty May 2015

Trace Element Variations In A Stalagmite From Southwest Mexico: Implications For Paleoclimate, Chad Michael Crotty

UNLV Theses, Dissertations, Professional Papers, and Capstones

The combination of stable isotope and trace element concentrations in speleothems has been shown to be a valuable indicator for interpreting paleoclimatic conditions. Anomalous spikes in trace element concentrations have also been shown to indicate anthropogenic environmental changes to the surface, such as deforestation events. In this study, trace element concentrations (24Mg, 25Mg, 84Sr, 88Sr, 137Ba, and 238U) of a stalagmite (JX-6) from Juxtlahuaca Cave, in southwestern Mexico, were measured using an inductively coupled plasma mass spectrometer (ICP-MS). These trace element concentrations were compared to previously analyzed δ18O and δ13C values from JX-6, and to the results of previous studies …


Modeling Background Radiation Using Geochemical Data, Kara Marsac May 2015

Modeling Background Radiation Using Geochemical Data, Kara Marsac

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma ray surveys have many applications in geology and science in general, such as locating mining prospects, defining radioactive plumes, and detecting nuclear weapons. Unfortunately there is currently no simple way to separate the natural gamma radiation of soil and rocks from that of contaminants such as radioactive plumes. This project used geochemical data (uranium, potassium and thorium concentrations) collected from national databases, private companies, and the NURE (National Uranium Resource Evaluation) Survey, to create forward models of exposure rates measured by aerial gamma ray surveys. We developed these techniques using an area in north central Arizona known as …


Carbon Isotope Variations Associated With A Middle Ordovician Karstic Unconformity, Patricia Suzanne Williams May 2015

Carbon Isotope Variations Associated With A Middle Ordovician Karstic Unconformity, Patricia Suzanne Williams

UNLV Theses, Dissertations, Professional Papers, and Capstones

Large negative carbon isotope (δ13C) excursions have been documented from late Neoproterozoic-Paleozoic successions. These δ13C excursions have been widely used for regional and global stratigraphic correlation, particularly in strata with limited paleontological and radiometric age controls. Recent studies, however, argued that some negative δ13C excursions from stratigraphic record may have been resulted from meteoric/burial diagenesis, which commonly shifts both carbon and oxygen isotopes toward lower values. Testing the diagenetic origin of δ13C excursions in stratigraphic successions without independent stratigraphic framework has been difficult because it evolves into circular arguments about stratigraphic completeness …


Org Or Inorg? Atmospheric Carbon Controls That Initiated The Late Paleozoic Ice Age 326mya, Paco Defrancis Apr 2015

Org Or Inorg? Atmospheric Carbon Controls That Initiated The Late Paleozoic Ice Age 326mya, Paco Defrancis

CLAS: Colby Liberal Arts Symposium

The Late Paleozoic Ice Age (LPIA) was a major global icehouse that initiated in the Mississippian (326 million years ago; ma) and lasted through the Early Permian (267ma). An ice sheet nucleated in southern Gondwana near the South Pole, which either paleogeography (positioning of paleocontinents) or atmospheric concentration of the greenhouse gas CO2 controlled. In this paper I accept recent findings that prove atmospheric pCO2 and not paleogeography forced global cooling that resulted in the nucleation of Gondwanan ice sheets that defined the LPIA. There remains no broad consensus of what caused pCO2 lowering in the Mississippian. Organic carbon found …


Utilizing Remote Sensing Imagery To Monitor Vegetation Change Within World Heritage Sites, Mimi Eve Hatzis Apr 2015

Utilizing Remote Sensing Imagery To Monitor Vegetation Change Within World Heritage Sites, Mimi Eve Hatzis

Theses and Dissertations

ABSTRACT

World Heritage sites provide a glimpse into the stories and civilizations of the past. There are currently 1007 unique World Heritage properties with 779 being classified as cultural sites, 197 as natural sites, and 31 falling into the categories of both cultural and natural sites (UNESCO & World Heritage Centre, 1992-2015). However, of these 1007 World Heritage sites, at least 46 are categorized as in danger and this number continues to grow. These unique and irreplaceable sites are exceptional because of their universality. Consequently, since World Heritage sites belong to all the people of the world and provide inspiration …


Identification Of Potential Vertical Gas Migration Pathways Above Gas Storage Reservoirs, Eric W. Peterson, Lauren I. Martin, David H. Malone Apr 2015

Identification Of Potential Vertical Gas Migration Pathways Above Gas Storage Reservoirs, Eric W. Peterson, Lauren I. Martin, David H. Malone

Faculty Publications - Geography, Geology, and the Environment

Natural gas is stored underground in geologic structures throughout the United States. However, complexities associated with these geologic structures may provide vertical pathways for gas migration, and thus gas loss. Possible upward migration (loss) of natural gas in an underground gas storage field in Illinois stimulated this investigation that aims to identify potential migration pathways. Spatial analysis of volume of shale (Vsh) and formation porosity (n) values were conducted in conjunction with high-resolution shallow seismic surveys to identify potential vertical pathways. Surficial gas accumulations within glacial deposits were confirmed by the seismic surveys. These gas pockets accumulated by migration along …


Fault Zone Hydrogeology In Crystalline And Sedimentary Aquifers In Arid Regions: Remote Sensing, Hydrological And Geoloectrical Methods, Lamees M. Mohamed Apr 2015

Fault Zone Hydrogeology In Crystalline And Sedimentary Aquifers In Arid Regions: Remote Sensing, Hydrological And Geoloectrical Methods, Lamees M. Mohamed

Research and Creative Activities Poster Day

An integrated study was conducted using remote sensing, hydrological and geophysical methods to investigate the role of structural elements in controlling the groundwater accumulation and flow in fractured basement complex. This research shows that the structural elements as fault and shear zones could act as a conduit or a barrier for the groundwater depending on the direction of these elements with the groundwater flow. Similar findings are observed in Central Sinai as it was found in Southern Sinai. These findings will help in more understanding of the fractured basement aquifers.


Geochemical Investigation Of The Origin Of The Back Forty Volcanogenic Massive Sulfide Deposit In Menominee County, Michigan, Joyashish Thakurta, Anthony Boxleiter Apr 2015

Geochemical Investigation Of The Origin Of The Back Forty Volcanogenic Massive Sulfide Deposit In Menominee County, Michigan, Joyashish Thakurta, Anthony Boxleiter

Faculty Research and Creative Activities Award (FRACAA)

Volcanogenic Massive Sulfide (VMS) deposits constitute one of the world’s greatest sources of copper, zinc, lead, silver, gold, and a wide range of by-products including tin, cadmium, antimony, and bismuth (Kearney, 2003). The metals we mine on earth from ore-bearing deposits, such as VMS deposits, are vital to everyday life from the vehicles we drive to the homes we build. The first step involved in unlocking the value of metal on earth begins with geologic exploration to locate these deposits within the earth. This begins with field work conducted by geologists involving mapping, rock sampling and analysis.


Revisiting Tired Old Fields With New Technologies: Three Dimensional Modeling And Structural Analysis Of The Dudley Pool Oil Reservoir, Edgar County, Il, Jordan M. Martin Apr 2015

Revisiting Tired Old Fields With New Technologies: Three Dimensional Modeling And Structural Analysis Of The Dudley Pool Oil Reservoir, Edgar County, Il, Jordan M. Martin

Theses and Dissertations

The purpose of this thesis is to better understand the Dudley Pool oil reservoir, a small, mature oil field, using geologic and geophysical data. The research focused on three-dimensional subsurface modeling of stratigraphy, structure, and porosity, to establish a more thorough understanding of oil occurrence at the Dudley Pool. An emphasis was placed on calculations of potential recoverable oil in order to determine implications on future production possibilities. This thesis also discusses the efficacy of three-dimensional modeling as an effective tool for evaluating, and potentially modifying, production efforts in mature petroleum fields with limited and/or poor-quality data. The modeling and …


Model Of Residence Time And Analysis Of Nitrogen Removal For Two Constructed Wetlands At The Franklin Demonstration Farm In Lexington, Illinois, Emma Singh Baghel Apr 2015

Model Of Residence Time And Analysis Of Nitrogen Removal For Two Constructed Wetlands At The Franklin Demonstration Farm In Lexington, Illinois, Emma Singh Baghel

Theses and Dissertations

Pollution from nonpoint agricultural runoff has become a major problem facing our streams and rivers today. Not only are fish and aquatic life affected, but so is the quality of our drinking and recreational water resources. Studies have shown that wetlands have proven to be the most cost-effective and low maintenance method of removing nonpoint or diffused contaminate inputs. The biological processes and removal of nutrients in wetlands depend on the total surface area available for microbial activity in the soil and a certain period of water retention time. Since chemical processes take time, the measure of residence time is …


Linking Hematite (Uth)/He Dating With The Microtextural Record Of Seismicity In The Wasatch Fault Damagezone, Utah, Usa, Alexis K. Ault, Peter W. Reiners, James P. Evans, Stuart N. Thomson Apr 2015

Linking Hematite (Uth)/He Dating With The Microtextural Record Of Seismicity In The Wasatch Fault Damagezone, Utah, Usa, Alexis K. Ault, Peter W. Reiners, James P. Evans, Stuart N. Thomson

Geosciences Faculty Publications

Techniques directly dating fault slip are few, limiting the ability to interpret the rock record of seismicity. Hematite is commonly found in fault zones, amenable to (U-Th)/He dating, and slip surface hematite may be reset by shear heating events and/or recrystallization. Glossy hematite-coated fault surfaces in the Wasatch fault footwall damage zone, Utah (USA), exhibit evidence of hematite cataclasis and preserve Pliocene hematite (U-Th)/He dates. Apatite (U-Th)/He and fission track data from the host gneiss indicate footwall unroofing through ∼2 km by ca. 4.5 Ma. Internally reproducible but disparate hematite (U-Th)/He dates 4.5 Ma and younger from isolated locations on …


On The Influence Of Ionic Strength On Radium And Strontium Sorption To Sandy Loam Soils, Brian A. Powell, Todd Miller, Daniel I. Kaplan Apr 2015

On The Influence Of Ionic Strength On Radium And Strontium Sorption To Sandy Loam Soils, Brian A. Powell, Todd Miller, Daniel I. Kaplan

Journal of the South Carolina Academy of Science

Models which can estimate environmental transport of radioactive contaminants in natural and engineered systems are required to 1) deploy effective remediation strategies for contaminated sites, 2) design waste repositories for future waste streams, and 3) ensure protection of human and environmental health in all cases. These models require accurate transport parameters in order to correctly predict how these contaminants will move in the subsurface. This work aimed to determine more accurately the distribution coefficients for radium and strontium sorption to Savannah River Site (SRS) soils. Radium and strontium sorption to the soils was found to be highly dependent upon ionic …


Landforms Along The Lower Columbia River And The Influence Of Humans, Charles Matthew Cannon Apr 2015

Landforms Along The Lower Columbia River And The Influence Of Humans, Charles Matthew Cannon

Dissertations and Theses

River systems, such as the Columbia River in the Pacific Northwest, USA have been influenced by human activities, resulting in changes to the physical processes that drive landform evolution. This work describes an inventory of landforms along the Columbia River estuary between the Pacific Ocean and Bonneville Dam in Oregon and Washington. Groupings of landforms are assigned to formative process regimes that are used to assess historical changes to floodplain features. The estuary was historically a complex system of channels with a floodplain dominated by extensive tidal wetlands in the lower reaches and backswamp lakes and wetlands in upper reaches. …


Mid-Holocene Speleothem Climate Proxy Records From Florida And Belize, Anna L. Pollock Apr 2015

Mid-Holocene Speleothem Climate Proxy Records From Florida And Belize, Anna L. Pollock

USF Tampa Graduate Theses and Dissertations

As global temperatures rise due to anthropogenic climate change, water resources, thus economies, are threatened. A geologically recent period of increased temperatures is the mid-Holocene and an investigation of its climate may allow for a better understanding of future precipitation and changes to regional water resources. The regions of interest are tropical Northern Central America and subtropical North America with Belize and Florida representing each climate zone. By reconstructing mid-Holocene climate in Florida and Belize, I hope to provide a better understanding of how increased temperatures and a reduced latitudinal temperature gradient impacts both precipitation patterns and variability. Today, drivers …


The Impact Of Stegastes Planifrons On The Resurgence Of Acropora Cervicornis, Zebulon Martin Apr 2015

The Impact Of Stegastes Planifrons On The Resurgence Of Acropora Cervicornis, Zebulon Martin

Undergraduate Distinction Papers

This study examines resurgent patches of Acropora cervicornis in the “Coral Gardens” back-reef area of Ambergris Caye, Belize. The goal of this study was to understand the carbonate budget and ecosystem dynamics of this successful reef, with an emphasis on the role of Stegastes planifrons (the herbivorous threespot damselfish), on the health of the coral. Benthic survey data from photo-quadrats along six transects were supplemented with counts of S. planifrons, their chimney scars, and sea urchin (Echinometra viridis) to assess their impact on the reef. The data indicate a positive correlation between the density of Stegastes …


Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier Apr 2015

Early Miocene Antarctic Glacial History: New Insights From Heavy Mineral Analysis From Andrill And–2a Drill Core Sediments, Francesco Iacoviello, Giovanna Giorgetti, Isabella Turbanti Memmi, Sandra Passchier

ANDRILL Research and Publications

The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL— SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6–20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected …


An Investigation To Remotely Sense Mineral Leeching Through Soils, Paul C. Shaffer Apr 2015

An Investigation To Remotely Sense Mineral Leeching Through Soils, Paul C. Shaffer

Thinking Matters Symposium Archive

Satellite data on Earth's surface provide a wealth of information on landscape conditions. I use Landsat data to determine an important geologic process that influences the composition of the soils. My project focusses on the experimental hypothesis that we can use plant vigor as a proxy to document mineral washing downslopes through soils. I constructed a Normalized Difference Vegetation Index (NDVI) composite image from Landsat data to help assess vegetation heath in my target location - a national park south of Mount St. Helens. This location was selected because of its steep inclines, dense undisturbed vegetation, and fertile soils. It …


Habitat Fragmenta-On In The Sebago Lake Watershed, Jared Lank Apr 2015

Habitat Fragmenta-On In The Sebago Lake Watershed, Jared Lank

Thinking Matters Symposium Archive

The goal of this research was to evaluate the extent of land use change occurring in the Sebago lake watershed of southern Maine. The primary data set used was Landsat 7 Near Infrared satellite imagery of the region which was analyzed with ESRI’s ArcGIS soQware. Data was clipped to the Portland Water District’s sub watershed shape file and analyzed with the soQware’s image analysis ‘difference’ tool which calculates the differences in pixel values between to raster datasets. The 2013 Landsat reclassifica-on was compared to 1987, 1995 and 2009 reclassifica-ons. NOAA’s Habitat Priority Planner plugin tool was also u-lized in order …


Glowing Seashells: Diversity Of Fossilized Coloration Patterns On Coral Reef-Associated Cone Snail (Gastropoda: Conidae) Shells From The Neogene Of The Dominican Republic, Jonathan R. Hendricks Apr 2015

Glowing Seashells: Diversity Of Fossilized Coloration Patterns On Coral Reef-Associated Cone Snail (Gastropoda: Conidae) Shells From The Neogene Of The Dominican Republic, Jonathan R. Hendricks

Faculty Publications

The biology of modern Conidae (cone snails)—which includes the hyperdiverse genus Conus—has been intensively studied, but the fossil record of the clade remains poorly understood, particularly within an evolutionary framework. Here, ultraviolet light is used to reveal and characterize the original shell coloration patterns of 28 species of cone snails from three Neogene coral reef-associated deposits from the Cibao Valley, northern Dominican Republic. These fossils come from the upper Miocene Cercado Fm. and lower Pliocene Gurabo Fm., and range in age from about 6.6-4.8 Ma. Comparison of the revealed coloration patterns with those of extant species allow the taxa to …


Shallow Groundwater Quality And Geochemistry In The Shields River Basin, South-Central Montana, Daniel D. Blythe Apr 2015

Shallow Groundwater Quality And Geochemistry In The Shields River Basin, South-Central Montana, Daniel D. Blythe

Graduate Theses & Non-Theses

Water samples were collected from 33 domestic wells, 2 springs, and 3 streams in the Shields River Basin (Basin) in southwest Montana. Samples were collected in 2013 to describe the chemical quality of groundwater in the Basin. Sampling was done to assess potential impacts to water quality from recent exploratory oil and gas drilling and to establish baseline water quality conditions. Wells were selected in areas near and away from oil and gas drilling and in areas susceptible to contamination. Water samples from surface water sites were collected in October to characterize base flow conditions. Physical characteristics of the land …


3d Block Modeling And Reserve Estimation Of A Garnet Deposit, Maurice Ayisi Apr 2015

3d Block Modeling And Reserve Estimation Of A Garnet Deposit, Maurice Ayisi

Graduate Theses & Non-Theses

The purpose of this project is to develop a three-dimensional block model for a garnet deposit in the Alder Gulch, Madison County, Montana. Garnets occur in pre-Cambrian metamorphic Red Wash gneiss and similar rocks in the vicinity. This project seeks to model the percentage of garnet in a deposit called the Section 25 deposit using the Surpac software. Data available for this work are drillhole, trench and grab sample data obtained from previous exploration of the deposit. The creation of the block model involves validating the data, creating composites of assayed garnet percentages and conducting basic statistics on composites using …


Geochemical Assessment And Separation Of Source Waters In The Upper Boulder River Watershed Near Boulder, Mt, John Anderson Apr 2015

Geochemical Assessment And Separation Of Source Waters In The Upper Boulder River Watershed Near Boulder, Mt, John Anderson

Graduate Theses & Non-Theses

Environmental samples were collected at three surface water sites between 5/21/2011 and 11/21/2014 along the Upper Boulder River near Boulder Montana. The sites were located at Bernice (within the mountain block), near the High Ore drainage (near the mountain block/basin transition), and at the USGS Gauging Station near Boulder, Montana (within the basin). The parameters measured in the field were SC, temperature, and alkalinity with occasional pH measurements. We collected samples for anions, cations, and stable isotopes in the catchment. We identified endmembers by sampling snow and groundwater and determined from available data an approximate endmember for rain, snow, and …


Rapid Analysis Of Secondary Manganese Oxides Using Portable Xrf: Applications To Environmental Geochemistry And Mineral Exploration, Dustin Jensen Apr 2015

Rapid Analysis Of Secondary Manganese Oxides Using Portable Xrf: Applications To Environmental Geochemistry And Mineral Exploration, Dustin Jensen

Graduate Theses & Non-Theses

Secondary manganese oxides (MnOx) are common weathering products of polymetallic vein deposits, and are also locally abundant in streams draining abandoned mine lands. MnOx are scavengers of trace metals, and the trace metal composition of MnOx could potentially be used as a vector to locate mineral anomalies or point sources of pollution in mining-impacted streams. This study is examining the chemistry of MnOx in weathered rock samples and partially flooded underground mine tunnels in the Butte Cu-Ag-Pb-Zn deposit, as well as MnOx crusts on boulders in small streams draining the nearby Basin-Boulder Superfund Site, Montana. Data obtained using a portable …


Temperature And Pressure Sensing In Three Flooded Underground Mine Workings In Butte, Montana, Usa, Tyler Hagan Apr 2015

Temperature And Pressure Sensing In Three Flooded Underground Mine Workings In Butte, Montana, Usa, Tyler Hagan

Graduate Theses & Non-Theses

Temperature and pressure were measured in several flooded underground mine shafts in order to assess the potential for the development of additional mine-based geothermal heating in Butte, Montana, USA. Temperature was sensed using both optical fibers, functioning as a distributed sensor, and thermistors, functioning as point sensors; while pressure was sensed using a piezoresistive strain gauge. Upon observing good agreement between the continuous and discrete temperature sensors, we found no significant change in temperature with increasing depth within the water column. This suggests the thorough transfer of heat throughout the mine shaft via convection. Moreover, we found water temperature (T) …


Development And Application Of A Method For Unwrapping Single Images Of Cylindrical Objects, Aaron Zosel Apr 2015

Development And Application Of A Method For Unwrapping Single Images Of Cylindrical Objects, Aaron Zosel

Graduate Theses & Non-Theses

The goal of this project was to create a software tool to unwrap digital images of cylindrical rock cores and also to create a tool to measure the accuracy of the unwrapping transform.

Measurements of an object can be taken directly from an image if the object is planar and the image plane of the camera is perpendicular to the object. If these conditions are met then picture scale allows a user to relate measurements in the image to a real world coordinate system after correcting for radial distortion. But if the object in the image is not planar or …


Azimuthal Anisotropy Beneath North Central Africa From Shear Wave Splitting Analyses, Awad A. Lemnifi, Kelly H. Liu, Stephen S. Gao, Cory A. Reed, Ahmed A. Elsheikh, Youqiang Yu, Abdala A. Elmelade Apr 2015

Azimuthal Anisotropy Beneath North Central Africa From Shear Wave Splitting Analyses, Awad A. Lemnifi, Kelly H. Liu, Stephen S. Gao, Cory A. Reed, Ahmed A. Elsheikh, Youqiang Yu, Abdala A. Elmelade

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This study represents the first multistation investigation of azimuthal anisotropy beneath the interior of north central Africa, including Libya and adjacent regions, using shear wave splitting (SWS) analysis. Data used in the study include recently available broadband seismic data obtained from 15 stations managed by the Libyan Center for Remote Sensing and Space Science, and those from five other stations at which data are publicly accessible. A total of 583 pairs of high-quality SWS measurements utilizing the PKS, SKKS, and SKS phases demonstrate primarily N-S fast orientations with an average splitting delay time of approximately 1.2 s. An absence of …


Origin Of Enigmatic Rocks Located North Of The Stillwater Complex, Montana, M. Christopher Jenkins, Jennifer A. Thomson, Michael L. Zientek Apr 2015

Origin Of Enigmatic Rocks Located North Of The Stillwater Complex, Montana, M. Christopher Jenkins, Jennifer A. Thomson, Michael L. Zientek

Geology Student Works

The Stillwater Complex is an Archean layered mafic-ultramafic intrusion located in southwestern

Montana. The complex hosts a platinum-group element ore deposit — the J-M Reef. Recent geophysical data collected by the USGS from an area to the north of the Stillwater complex suggests that the complex continues at depth under cover. The northern exposure of Precambrian rock is not the complex but some enigmatic amphibolites. During the 2013 and 2014 field seasons, eight samples were collected from this Precambrian (?) lower-amphibolite to greenschist-facies metamorphic rock unit located approximately 2 kilometers north of the complex. Vail (1955) described the unit as …