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Articles 361 - 390 of 405
Full-Text Articles in Geology
Rain Generated Lahars Prior To The 2018 Catastrophic Eruption Of Fuego Volcano, Guatemala, Claudia Buondonno
Rain Generated Lahars Prior To The 2018 Catastrophic Eruption Of Fuego Volcano, Guatemala, Claudia Buondonno
Dissertations, Master's Theses and Master's Reports
Fuego volcano is one of the most active and hazardous volcanoes in the world. It is located in the northern part of the Central American Volcanic Arc in Guatemala and its activity can be characterized by long term, low-level background activity, and sporadic larger explosive eruptions. Its historical observations of eruptions date back to 1531, but it has been erupting vigorously since 2002 with major activity throughout 2018, producing three main eruptions in February, June and November. Its almost persistent activity generates major ashfalls, pyroclastic flows, lava flows; when heavy rains mobilize its deposits, they can form damaging lahars. Phenomena, …
Interpretive Geologic Maps And Cross Sections For Phelps, Kearney, And Adams Counties In Nebraska, Dana Divine, Leslie M. Howard
Interpretive Geologic Maps And Cross Sections For Phelps, Kearney, And Adams Counties In Nebraska, Dana Divine, Leslie M. Howard
Conservation and Survey Division: Faculty and Staff Publications
Data from thousands of test-hole and well logs were interpreted to improve understanding and management of the High Plains aquifer in a three-county study area adjacent to the Big Bend reach of the Platte River. Five principal conclusions resulted from these interpretations: (1) the extent of Neogene Ogallala deposits beneath the study area is different than previously mapped; (2) a large paleovalley incised into Cretaceous bedrock probably cuts across Kearney and Adams counties and may be the course of the ancestral Platte River prior to formation of the Big Bend; (3) a groundwater mound created by irrigation canals artificially raises …
Acoustic Space Occupancy: Combining Ecoacoustics And Lidar To Model Biodiversity Variation And Detection Bias Across Heterogeneous Landscapes, Danielle I. Rappaport, J. Andrew Royle, Douglas C. Morton
Acoustic Space Occupancy: Combining Ecoacoustics And Lidar To Model Biodiversity Variation And Detection Bias Across Heterogeneous Landscapes, Danielle I. Rappaport, J. Andrew Royle, Douglas C. Morton
United States Geological Survey: Staff Publications
There is global interest in quantifying changing biodiversity in human-modified landscapes. Ecoacoustics may offer a promising pathway for supporting multi-taxa monitoring, but its scalability has been hampered by the sonic complexity of biodiverse ecosystems and the imperfect detectability of animal-generated sounds. The acoustic signature of a habitat, or soundscape, contains information about multiple taxa and may circumvent species identification, but robust statistical technology for characterizing community-level attributes is lacking. Here, we present the Acoustic Space Occupancy Model, a flexible hierarchical framework designed to account for detection artifacts from acoustic surveys in order to model biologically relevant variation in acoustic space …
Human-Associated Species Dominate Passerine Communities Across The United States, Helen R. Sofaer, Curtis H. Flather, Catherine S. Jarnevich, Kristin P. Davis, Liba Pejchar
Human-Associated Species Dominate Passerine Communities Across The United States, Helen R. Sofaer, Curtis H. Flather, Catherine S. Jarnevich, Kristin P. Davis, Liba Pejchar
United States Geological Survey: Staff Publications
Aim: Human development and agriculture can have transformative and homogenizing effects on natural systems, shifting the composition of ecological communities towards non-native and native species that tolerate or thrive under human-dominated conditions. These impacts cannot be fully captured by summarizing species presence, as they include dramatic changes to patterns of species abundance. However, how human land use patterns and species invasions intersect to shape patterns of abundance and dominance within ecological communities is poorly understood even in well-known taxa.
Location: Conterminous United States.
Time period: 2010–2012.
Major taxa studied: Passeriformes.
Methods: We analyse continental-scale monitoring data to study the proportional …
Ecosystem Processes, Land Cover, Climate, And Human Settlement Shape Dynamic Distributions For Golden Eagle Across The Western Us, J.D. Tack, Barry R. Noon, Zachary Bowen, Brad C. Fedy
Ecosystem Processes, Land Cover, Climate, And Human Settlement Shape Dynamic Distributions For Golden Eagle Across The Western Us, J.D. Tack, Barry R. Noon, Zachary Bowen, Brad C. Fedy
United States Geological Survey: Staff Publications
Species–environment relationships for highly mobile species outside of the breeding season are often highly dynamic in response to the collective effects of everchanging climatic conditions, food resources, and anthropogenic disturbance. Capturing dynamic space-use patterns in a model-based framework is critical as model inference often drives place-based conservation planning. We applied dynamic occupancy models to broad-scale golden eagle Aquila chrysaetos survey data collected annually from 2006 to 2012 during the late summer post-fledging period in the western US. We defined survey sites as 10 km transect segments with a 1 km buffer on either transect side (n = 3540). Derived estimates …
Human-Associated Species Dominate Passerine Communities Across The United States, Helen R. Sofaer, Curtis H. Flather, Catherine S. Jarnevich, Kristin P. Davis
Human-Associated Species Dominate Passerine Communities Across The United States, Helen R. Sofaer, Curtis H. Flather, Catherine S. Jarnevich, Kristin P. Davis
United States Geological Survey: Staff Publications
Aim: Human development and agriculture can have transformative and homogenizing effects on natural systems, shifting the composition of ecological communities towards non-native and native species that tolerate or thrive under human-dominated conditions. These impacts cannot be fully captured by summarizing species presence, as they include dramatic changes to patterns of species abundance. However, how human land use patterns and species invasions intersect to shape patterns of abundance and dominance within ecological communities is poorly understood even in well-known taxa.
Location: Conterminous United States.
Time period: 2010–2012.
Major taxa studied: Passeriformes.
Methods: We analyse continental-scale monitoring data to study the proportional …
Acoustic Space Occupancy: Combining Ecoacoustics And Lidar To Model Biodiversity Variation And Detection Bias Across Heterogeneous Landscapes, Danielle I. Rappaport, J. Andrew Royle, Douglas C. Morton
Acoustic Space Occupancy: Combining Ecoacoustics And Lidar To Model Biodiversity Variation And Detection Bias Across Heterogeneous Landscapes, Danielle I. Rappaport, J. Andrew Royle, Douglas C. Morton
United States Geological Survey: Staff Publications
There is global interest in quantifying changing biodiversity in human-modified landscapes. Ecoacoustics may offer a promising pathway for supporting multi-taxa monitoring, but its scalability has been hampered by the sonic complexity of biodiverse ecosystems and the imperfect detectability of animal-generated sounds. The acoustic signature of a habitat, or soundscape, contains information about multiple taxa and may circumvent species identification, but robust statistical technology for characterizing community-level attributes is lacking. Here, we present the Acoustic Space Occupancy Model, a flexible hierarchical framework designed to account for detection artifacts from acoustic surveys in order to model biologically relevant variation in acoustic space …
Characterization Of Pallid Sturgeon (Scaphirhynchus Albus) Spawning Habitat In The Lower Missouri River, Caroline M. Elliott, Aaron J. Delonay, Kimberly Chojnacki, Robert B. Jacobson
Characterization Of Pallid Sturgeon (Scaphirhynchus Albus) Spawning Habitat In The Lower Missouri River, Caroline M. Elliott, Aaron J. Delonay, Kimberly Chojnacki, Robert B. Jacobson
United States Geological Survey: Staff Publications
Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The …
Late Quaternary Sea-Level History Of Saipan, Commonwealth Of The Northern Mariana Islands, Usa: A Test Of Tectonic Uplift And Glacial Isostatic Adjustment Models, Daniel R. Muhs, Eugene S. Schweig, Kathleen R. Simmons
Late Quaternary Sea-Level History Of Saipan, Commonwealth Of The Northern Mariana Islands, Usa: A Test Of Tectonic Uplift And Glacial Isostatic Adjustment Models, Daniel R. Muhs, Eugene S. Schweig, Kathleen R. Simmons
United States Geological Survey: Staff Publications
In 1979, S. Uyeda and H. Kanamori proposed a tectonic model with two end members of a subduction-boundary continuum: the “Chilean” type (shallow dip of the subducting plate, great thrust events, compression, and uplift of the overriding plate) and a “Mariana” type (steep dip of the subducting plate, no great thrust events, tension, and no uplift). This concept has been used to explain variable rates of Quaternary uplift around the Pacific Rim, yet no uplift rates have been determined for the Mariana Islands themselves, one of the end members in this model. We studied the late Quaternary Tanapag Limestone, which …
Stratigraphy And Geochemistry Of Rock Salt From Maha Sarakham Formation In Changwat Chaiyaphum, Northeastern Thailand, Pranot Rattana
Stratigraphy And Geochemistry Of Rock Salt From Maha Sarakham Formation In Changwat Chaiyaphum, Northeastern Thailand, Pranot Rattana
Chulalongkorn University Theses and Dissertations (Chula ETD)
Maha Sarakham Formation is one of massive potash deposits in the Khorat Plateau extending from northeastern of Thailand to central of Lao PDR. Maha Sarakham Formation consists of three rock salt members (the lower, middle and upper members) interbedded with claystone. Potash minerals are associated with the thick bed of rock salt in the upper part of lower salt member. Previous studies are still under discussion on whether the origin of rock salt from marine or non-marine (hydrothermal origin and mixed fluids) deposit. The purpose of this study is to analyze the origin of rock salt based on elemental compositions …
Fusulinacean Biostratigraphy And Carbonate Petrography Of Khao Khwang And Khao Khad Formations, Saraburi Province, Sutharat Sirot
Fusulinacean Biostratigraphy And Carbonate Petrography Of Khao Khwang And Khao Khad Formations, Saraburi Province, Sutharat Sirot
Chulalongkorn University Theses and Dissertations (Chula ETD)
These research purposes are to study petrography, fusulinids assemblage and age and study biostratigraphy correlation of Khao Khwang and Khao Khad Formations, Saraburi province. The fusulinids from the study area belong to 5 families, 11 subfamilies, 15 genera and 15 species including Robustoschwagerina, Yangchienia, Parafusulina loeyensis, Parafusulina gigantea, Laosella edoensis, Pseudofusulina, Chusenella chihsiaensis, Chusenella (Chusenella) shengi, Verbeekina verbeeki, Misellina, Pseudodoliolina, Thailandina buravasi, Neoschwagerina megasphaerica, Colania douvillei, Lepidolina shiraiwensis, Presumatrina ciryi, Sumatrina annae and Sumatrina cf. longissima. These fusulinids indicated that Khao Khad Formation was deposited oldest in Sakmarian to Yakhtashian and youngest in Midian age and Khao Khwang Formation was …
Petrochemistry Of Intrusive Rocks In Tha Takiap District, Chachoengsao Province, Thanaz Watcharamai
Petrochemistry Of Intrusive Rocks In Tha Takiap District, Chachoengsao Province, Thanaz Watcharamai
Chulalongkorn University Theses and Dissertations (Chula ETD)
In Thailand, alkaline granitoid rocks are less widespread and crop out in less extend as small stocks or plutons. The study areas are located in 2 vicinities of Tha Takiap and Mae Yan areas which respectively are a part of the eastern and central granite belts. Petrographic study of the rocks from both areas show that alkaline feldspar is the principal mineral phase with small amount of quartz and plagioclase. Compositionally, the investigated rocks fall in the range of alkali feldspar syenite to quartz-alkali feldspar syenite. High concentration of Na2O+K2O and high ratio of FeOtot/(FeOtot+MgO) vs SiO2 indicate that most …
Tropical Cyclone Hazards In Relation To Propagation Speed, Jiehao Huang
Tropical Cyclone Hazards In Relation To Propagation Speed, Jiehao Huang
Dissertations and Theses
As the population and infrastructure along the US East Coast increase, it becomes increasingly important to study the characteristics of tropical cyclones that can impact the coast. A recent study shows that the propagation speed of tropical cyclones has slowed over the past 60 years, which can lead to greater accumulation of precipitation and greater storm surge impacts. The study presented herein is meant to examine and analyze the relationships that exist between the propagation speed of tropical cyclones, their surface wind strength, displacement angles, and cyclone averaged winds. This analysis is focused on tropical cyclones spanning from 1950-2015 in …
The Quartz Of Arkansas: Geology, History And Legend, Thomas R. Paradise
The Quartz Of Arkansas: Geology, History And Legend, Thomas R. Paradise
Geosciences Faculty Publications and Presentations
Quartz Crystals has been treasured and utilized through history, and this chapter addresses its many uses, mineralogy, history, and legend over time...
Structure, Evolution, And Mesoscopic Deformation Patterns Near The Tourmaline Hill Salt Sheet, Umberatana Station, South Australia, Lillian Ruth Lueck
Structure, Evolution, And Mesoscopic Deformation Patterns Near The Tourmaline Hill Salt Sheet, Umberatana Station, South Australia, Lillian Ruth Lueck
Graduate Research Theses & Dissertations
Halokinetic structures have been proven to serve as both structural and stratigraphic traps for petroleum and mineralizing ore fluids, making them critical to the energy and technology needs of society. Although modern exploration for these resources uses often uses 3-D seismic imagery, these data often cannot resolve the complexity of the strata within 300 meters of the salt sediment interface, an area that is critical to the trapping or migration of fluids. Because of this lack of constraint, drilling near salt risks encountering unexpected overturned strata, repeated units, overpressure, or abrupt changes in stress state, making it imperative to understand …
Body Wave Analysis For Low-Angle Thrust Quakes On Titan: Implications For Dragonfly, John William Owens
Body Wave Analysis For Low-Angle Thrust Quakes On Titan: Implications For Dragonfly, John William Owens
Graduate Research Theses & Dissertations
Little is known of the structure and seismic nature of planetary bodies that have an outer shell of ice instead of a rocky crust. These bodies are called icy satellites and one such body, Saturn’s moon Titan, is unique because of its thick atmosphere, methane cycle, and assumed salty subsurface ocean. NASA’s Dragonfly mission, set to launch in 2026, will use a robotic rotorcraft to transport various instruments, including a seismometer, to the Shangri-La dune field on Titan. Until then, Titan’s seismic regime can be estimated by simulating wave propagation through assumed subsurface layers using source models. Ridge belts with …
Physical And Chemical Properties Of Clastic Sediments From Two Caves In The Northern Karst Region Of Puerto Rico, Autum R. Downey
Physical And Chemical Properties Of Clastic Sediments From Two Caves In The Northern Karst Region Of Puerto Rico, Autum R. Downey
Graduate Theses, Dissertations, and Problem Reports (ETD)
Geochemical properties and organic characteristics are essential to understanding the general depositional dynamics of a cave. Most work on clastic cave sediments focuses on physical properties of sediments. Little work has been done on bulk organic matter and geochemical properties.
This project reports physical and geochemical characterization of cave sediments from two caves in the northern karst region of Puerto Rico: El Tallonal Cave and Cueva Clara. Core and grab samples were collected and analyzed for particle size, total organic carbon, total nitrogen, organic matter characteristics using fluorescence spectroscopy, and major and minor elements using X-ray fluorescence (XRF). The sediments …
Paleoecological Successions From Shallow-Marine Depositional Environments In Upper Silurian Carbonate Rocks Of Blair County, Pennsylvania, Shadya El-Ashkar
Paleoecological Successions From Shallow-Marine Depositional Environments In Upper Silurian Carbonate Rocks Of Blair County, Pennsylvania, Shadya El-Ashkar
Graduate Theses, Dissertations, and Problem Reports (ETD)
Studies of paleoenvironment and paleoecology are important for investigating relationships between the different environmental and biological variables that influenced biodiversification patterns during the Silurian Period. The mixed carbonate and siliciclastic rocks of the Bloomsburg and Mifflintown Formations in central Pennsylvania represent transitions between carbonate ramp and deltaic settings. The goal of this study was to assess changes in depositional environment and paleoecology of an undescribed Bloomsburg/Mifflintown locality in Bellwood, Pennsylvania. In central Pennsylvania, the interfingered relationship of mixed carbonate and siliciclastic mudstones of the Mifflintown Formation with red fine-grained sandstones and shales of the Bloomsburg Formation presented challenges for deciphering …
Alluvial Fans, Loess Plains, Lakes, And Distributive Fluvial Systems: Depositional Systems Of The Permian-Triassic Red Beds And Evaporites Of Wyoming (Usa), Jonathan Knapp
Graduate Theses, Dissertations, and Problem Reports (ETD)
The end-Permian ecological crisis was a period of warming and aridity reaching extreme levels by the end Permian and not recovering before the Middle Triassic. The Permian Goose Egg Formation and the Chugwater Group’s Early Triassic Red Peak Formation and Middle Triassic Alcova Limestone are a continuous or nearly continuous succession of rocks deposited during this warm, arid time in Wyoming. Comprised of red beds, evaporites, and rare carbonates, these rocks have not been subjected to detailed sedimentological investigations in the modern era. Previous interpretations of marine and marginal marine deposition have largely been based on the laterally extensive nature …
Mapping Surficial Geology In The New River Gorge National River And Bluestone National Scenic River, West Virginia, Using Lidar-Derived Digital Elevation Data, Marla K. Denicola
Mapping Surficial Geology In The New River Gorge National River And Bluestone National Scenic River, West Virginia, Using Lidar-Derived Digital Elevation Data, Marla K. Denicola
Graduate Theses, Dissertations, and Problem Reports (ETD)
The purpose of this thesis was to determine if the surficial geology of Bluestone National Scenic River (BLUE) and New River Gorge National River (NERI), two areas of similar geology, can be mapped using visual interpretation methods applied to digital elevation models (DEMs) derived from light detection and ranging (LiDAR) data. Surficial geology in BLUE was field mapped using GPS, following definitions and characterizations for surficial geology units established with the guidance of Dr. J. Steven Kite. A 2m x 2m LiDAR-derived DEM was used for BLUE and most of NERI using US Army Corps of Engineers (USCOE) LiDAR data, …
A Machine Learning And Data-Driven Prediction And Inversion Of Reservoir Brittleness From Geophysical Logs And Seismic Signals: A Case Study In Southwest Pennsylvania, Central Appalachian Basin, Tobi Micheal Ore
Graduate Theses, Dissertations, and Problem Reports (ETD)
In unconventional reservoir sweet-spot identification, brittleness is an important parameter that is used as an easiness measure of production from low permeability reservoirs. In shaly reservoirs, production is realized from hydraulic fracturing, which depends on how brittle the rock is–as it opens natural fractures and also creates new fractures. A measure of brittleness, brittleness index, is obtained through elastic properties of the rock. In practice, problems arise using this method to predict brittleness because of the limited availability of elastic logs.
To address this issue, machine learning techniques are adopted to predict brittleness at well locations from readily available geophysical …
Evolution Of Extreme Continental Saline Environments: A Sedimentological Investigation Of Permo-Triassic Redbeds And Evaporites In Northern Ireland And Kansas, Anna Sofia S. Andeskie
Evolution Of Extreme Continental Saline Environments: A Sedimentological Investigation Of Permo-Triassic Redbeds And Evaporites In Northern Ireland And Kansas, Anna Sofia S. Andeskie
Graduate Theses, Dissertations, and Problem Reports (ETD)
The Permo-Triassic was a time of extreme environments, unusually warm and arid climates, and biotic crises. This study investigates Pangean environments and climate leading to extreme acid saline lake systems represented by the Permian Nippewalla Group of Kansas and the Triassic Mercia Mudstone Group of Northern Ireland. Sedimentological observations of the underlying rocks, the Permian Hutchinson Salt Member of Kansas and the Permian Belfast Harbour Evaporite Formation of Northern Ireland, help to understand trends in environmental and climatic conditions leading to these extreme environments. This dissertation also refines the geographic extent of extreme acid saline lake and groundwater systems through …
Process Based Analysis Of Fluvial Stratigraphic Record: Middle Pennsylvanian Allegheny Formation, North-Central Wv, Oluwasegun O. Abatan
Process Based Analysis Of Fluvial Stratigraphic Record: Middle Pennsylvanian Allegheny Formation, North-Central Wv, Oluwasegun O. Abatan
Graduate Theses, Dissertations, and Problem Reports (ETD)
Fluvial deposits represent some of the best hydrocarbon reservoirs, but the quality of fluvial reservoirs varies depending on the reservoir architecture, which is controlled by allogenic and autogenic processes. Allogenic controls, including paleoclimate, tectonics, and glacio-eustasy, have long been debated as dominant controls in the deposition of fluvial strata. However, recent research has questioned the validity of this cyclicity and may indicate major influence from autogenic controls. To further investigate allogenic controls on stratal order, I analyzed the facies architecture, geomorphology, paleohydrology, and the stratigraphic framework of the Middle Pennsylvanian Allegheny Formation (MPAF), a fluvial depositional system in the Appalachian …
Recovering Lost Information From Avocational Projectile Point Collections, Mackenzie Hughes
Recovering Lost Information From Avocational Projectile Point Collections, Mackenzie Hughes
All Master's Theses
Human prehistory in North America has sparked the interest of private citizens for decades, sometimes leading to an accumulation of avocational artifact collections that lack site-level provenience. The Wild/Clymer artifacts (n = 1,371) are one such collection where precise site provenience was lost. The analysis aims to recover regional provenience by using morphology, raw material sourcing, and typology to create a data set. The avocational collection data set was analyzed by comparing it to the professionally recorded archaeological data sets from within 100 miles of Frenchglen, Oregon. A paradigmatic classification approach identified 606 typeable points in the avocational collection, in …
The Effect Of Spacing Of Vetiver Grass (Chrysopogon Zizanioides) Hedgerows On Hillslope Erosion In Eastern Region, Ghana, Evan R. Lanese
The Effect Of Spacing Of Vetiver Grass (Chrysopogon Zizanioides) Hedgerows On Hillslope Erosion In Eastern Region, Ghana, Evan R. Lanese
Dissertations, Master's Theses and Master's Reports
Soil erosion in Ghana negatively effects many small holder farmers due to heavy rainfall, continuous land use, and a changing climate. Inexpensive, local, and sustainable practices that can be used to reduce soil movement thus building productive soils would benefit farmers in Ghana. Vetiver grass (Chrysopogon zizanioides) has been used to this effect worldwide. Its local availability and positive reputation leaves desire to learn about its applicability in Ghana. A field study was conducted on plots of sloping farmland (10ft by 60ft) with three treatments: (1) control with no vetiver grass, (2) two vetiver grass hedgerows, (3) four …
Model-Based Estimates Of The Timing Of Brine Flux Into The Victoria Land Basin From The Mcmurdo Dry Valleys, Antarctica, Valerie Nicole Voisin
Model-Based Estimates Of The Timing Of Brine Flux Into The Victoria Land Basin From The Mcmurdo Dry Valleys, Antarctica, Valerie Nicole Voisin
Graduate Research Theses & Dissertations
Submarine groundwater discharge (SGD) at a continental scale is one of the least constrained components of the hydrologic cycle and may represent a significant flux of iron and silica waters to the global ocean. Quantifying SGD along the Antarctic margin is complicated by complex subglacial and subsurface hydrogeology and limited observational data. Airborne transient electromagnetic (AEM) surveys have identified extensive high-salinity subsurface brines in the McMurdo Dry Valleys (MDV) that are hydrologically connected to surface features in the MDV (e.g. Taylor Glacier, saline lakes) and are potentially a significant source of SGD to McMurdo Sound. A 2D numerical model was …
Copper And Gold In Vapors And Liquids As A Function Of Hcl At 700°C And 100 Mpa, Corrie A. Lucchesi
Copper And Gold In Vapors And Liquids As A Function Of Hcl At 700°C And 100 Mpa, Corrie A. Lucchesi
Graduate Research Theses & Dissertations
Porphyry ore deposits are major sources of copper (Cu) and gold (Au) and form when a magmatic volatile phase (MVP) exsolves from a porphyritic intermediate to felsic melt and transports metals to surrounding country rock where they precipitate in an ore zone. There is a consensus that the chloride concentration of the MVP has a direct relationship to the concentration of Cu and Au in the MVP, but the role of dissolved HCl on Cu and Au concentrations has not been addressed. It is hypothesized that increasing HCl concentrations in the MVP will result in higher concentrations of Cu and …
Estimating Paleotemperatures In The Amundsen Sea For The Last 620,000 Years Through Diatom Morphometrics (Iodp Expedition 379), Joseph Robert Mastro
Estimating Paleotemperatures In The Amundsen Sea For The Last 620,000 Years Through Diatom Morphometrics (Iodp Expedition 379), Joseph Robert Mastro
Graduate Research Theses & Dissertations
As global climate continues to rapidly change over the coming decades, West Antarctica will continue to be a significant area of concern due to its susceptibility to marine ice sheet collapse. Past collapses during Pleistocene interglacials have been hypothesized but uncertainty exists with respect to the precise timing of specific collapse events. Drill core samples collected from the Amundsen Sea continental rise during IODP Expedition 379 allow for analysis of a more continuous record of Pleistocene glacial-interglacial cycles. Here we report paleotemperature estimates from the Amundsen Sea spanning the last 620 kyr with the objective of identifying likely late Pleistocene …
An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas
An Integrated Wellbore Stability Study To Mitigate Expensive Wellbore Instability Problems While Drilling Into Zubair Shale/Sand Sequence, Southern Iraq, Ahmed Khudhair Abbas
Doctoral Dissertations
”The Zubair Formation is the most prolific reservoir in Iraq, which is comprised of sandstones interbedded with shale sequences. Due to the weak nature of the shale sequence, the instability of a wellbore is one of the most critical challenges that continuously appears during drilling across this formation. Historically, over 90% of wellbore problems in the Zubair Formation were due to wellbore instability. Problems associated with wellbore instability, such as tight hole, shale caving, stuck logging tools along with subsequent fishing, stuck pipe, and sidetracking result in increasing the non-productive time. This non-productive time has cost an enormous amount of …
History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez
History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez
Doctoral Dissertations
”Water is essential for human subsistence. Stable freshwater supplies are needed as a source of food, drinking water, for transportation, recreation and economic development. Despite their recognized importance, anthropogenic activities have altered freshwater ecosystems around the world. Lake Izabal is the habitat for diverse aquatic species of flora and fauna, some of which are endemic and endangered. Its importance notwithstanding, anthropogenic activities developed in Lake Izabal’s catchment in recent years have compromised its status. This study used paleolimnological techniques to link past and recent anthropogenic activities such as mining operations and recent tilapia aquaculture. Relative abundances and concentrations of Pb, …