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Full-Text Articles in Physical Sciences and Mathematics
Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake
Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake
LSU Master's Theses
The McMurdo Dry Valleys is the largest ice-free area in Antarctica, but seasonal snow covers the valley floors sporadically throughout the year. In this study, a model to estimate areal snow coverage from satellite imagery was created. An area-volume model was created to estimate the amount of snow water equivalent (SWE) from the snow area extracted from the imagery. Snow cover influences the total albedo, the hydrologic budget, and the soil moisture and soil temperature in Taylor Valley (TV). Quantifying snow precipitation in TV is challenging because snow redistributes with winds, sublimates, or melts within a short period. Previous estimates …
Causes And Characteristics Of Electrical Resistivity Variability In Shallow (<4 M) Soils In Taylor Valley, East Antarctica, William S. Gutterman
Causes And Characteristics Of Electrical Resistivity Variability In Shallow (<4 M) Soils In Taylor Valley, East Antarctica, William S. Gutterman
LSU Master's Theses
The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are characterized as a polar desert environment. Soils in the region are typically very dry (<1% soil water by weight) and remain frozen for most of the year. Increases in air temperature and incoming solar radiation during the austral summer generate meltwater from glaciers, ground ice, and snow patches supplying moisture to soils and altering the physical and chemical makeup of the subsurface. Previous studies have utilized airborne electromagnetic surveys (AEM) to analyze groundwater systems in the deep subsurface but have not yet examined soil moisture in the shallow (<4 m) subsurface. Here, I used electrical resistivity data from two AEM surveys (2011 and 2018) and soil geochemical data from three transects to characterize the spatial heterogeneity of soil properties in the near-subsurface of lower Taylor Valley. Soil resistivities from 2011 and 2018 range from 33.2 Ωm to 3535 Ωm with low elevations of <100 meters above sea level (masl) typically displaying the lowest resistivities and high elevations displaying greater resistivities. Liquid brine fractions were empirically estimated from electrical resistivity values using Archie’s Law and range from 0.3% to 68.2% for soils with resistivities <200 Ωm. Additionally, soil transect data show greater percentages of fine-grained sediments (<63 µm) exist at elevations <100 masl where soil resistivities begin decreasing. Resistivity variability in the subsurface is ultimately controlled by the site history, local and regional climate, soil salinity, soil moisture, soil lithology.
Groundwater And Thermal Legacy Of A Large Paleolake In Taylor Valley, East Antarctica As Evidenced By Airborne Electromagnetic And Sedimentological Techniques, Krista Falcon Myers
Groundwater And Thermal Legacy Of A Large Paleolake In Taylor Valley, East Antarctica As Evidenced By Airborne Electromagnetic And Sedimentological Techniques, Krista Falcon Myers
LSU Master's Theses
During the Last Glacial Maximum, grounded ice in the Ross Sea extended into the otherwise ice-free McMurdo Dry Valleys, creating a series of large ice dammed paleolakes. Grounded ice within the mouth of Taylor Valley allowed for lake levels to reach elevations not possible at modern day and formed what is known as Glacial Lake Washburn (GLW). GLW extended from the eastern portion of Taylor Valley roughly 20 km west to a level ~300 m higher than modern day Lake Fryxell. The formation and existence of GLW has been debated, though previous studies correlate the timing of GLW with early …
Evidence Of Subglacial Brine Inflow And Wind-Induced Mixing From High Resolution Temperature Measurements In Lake Bonney, Antarctica, Jade Lawrence
Evidence Of Subglacial Brine Inflow And Wind-Induced Mixing From High Resolution Temperature Measurements In Lake Bonney, Antarctica, Jade Lawrence
LSU Master's Theses
Hypersaline brine beneath Taylor Glacier enters proglacial West Lobe Lake Bonney (WLB) subglacially as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the water column of WLB. Because of the extremely high salinities below the chemocline in WLB, density is determined almost entirely by salinity and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude in to the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. This study …
In Search Of Antarctica's Last Vegetation Refugium Within The Mcmurdo Dry Valleys, David Rau
In Search Of Antarctica's Last Vegetation Refugium Within The Mcmurdo Dry Valleys, David Rau
LSU Master's Theses
The McMurdo Dry Valleys, a hyper-arid cold polar desert located within the Transantarctic Mountains was once covered by vegetation. An in depth study of surface samples of various Neogene age, acquired throughout the Valleys, provide insight to the location of one of Antarctica’s last vegetation refugia. Boston University’s Antarctic Research Group has collected 82 surface samples from paleo lake sediments on 14 expeditions spanning 22 years in the McMurdo Dry Valleys. The ages of the samples are still not fully constrained, but 8 regions where samples were collected have been interpreted to range between 16.95 ± 0.17 to 4 Ma …
The Influence Of Marine Topography On The Antarctic Ice Sheet, Daniel Michael Mullally Jr
The Influence Of Marine Topography On The Antarctic Ice Sheet, Daniel Michael Mullally Jr
LSU Master's Theses
The primary controls on Antarctic Ice Sheet (AIS) volume and extent include changes in water temperature, precipitation, atmospheric temperature, and sea level. Here we evaluate the influence of a 5th control, the depth of the continental shelf. Shelf depth affects ice sheet mass balance in the marine environment by controlling the flux of ice that can be exported to the marine environment. This is significant because heat exchange between ocean and ice sheet have been demonstrated to be a dominant control on marine ice volume (Pollard and DeConto, 2009). We used the Parallel Ice Sheet Model (PISM) to simulate AIS …
A Palynological Analysis Of Seymour Island And King George Island Off The Antarctic Peninsula: A Dating And Climatic Reconstruction, Caven Madison Kymes
A Palynological Analysis Of Seymour Island And King George Island Off The Antarctic Peninsula: A Dating And Climatic Reconstruction, Caven Madison Kymes
LSU Master's Theses
During the Cretaceous and early Paleocene, Antarctica was covered by lush vegetation. However, Antarctica today is covered with ice and snow leaving less than 1% of the continent inhabited by vegetation. By studying this decline in vegetation and reconstructing past environments, we can gain a better understanding of environmental changes and use this knowledge to predict future changes. In this thesis, I present my results and interpretations of palynological changes across the Antarctic Peninsula during the Late Eocene, Middle Oligocene, and Miocene. The first study discusses a paleoenvironmental reconstruction of the upper La Meseta formation (Late Eocene), Seymour Island, and …
Teaching Climate Literacy Using Geospatial Tools, Steven L. Babcock
Teaching Climate Literacy Using Geospatial Tools, Steven L. Babcock
LSU Master's Theses
Antarctica is the world’s coldest, driest and windiest continent. It is a harsh environment that few people will ever see but it is a very important part of our Earth system. Over the past 34 million years the climate in Antarctica has deteriorated from one that supported lush vegetation to the conditions observed today. By studying this trend and the associated changes to ice and vegetation we can gain critical insight into climate changes taking place today. This thesis presents three pieces of curricula that will help students and the general public understand some of the research currently underway in …
On The Long Duration Of Till Sheet Construction : A Reassessment Of How Quaternary Grounding Line Translations Relate To Near-Surface Seismic-Stratigraphy Of Eastern Ross Sea, Antarctica, Sydney Grace Bowles
On The Long Duration Of Till Sheet Construction : A Reassessment Of How Quaternary Grounding Line Translations Relate To Near-Surface Seismic-Stratigraphy Of Eastern Ross Sea, Antarctica, Sydney Grace Bowles
LSU Master's Theses
Previously acquired seismic surveys provide strong evidence that the post-Last Glacial Maximum (LGM) retreat of the West Antarctic Ice Sheet (WAIS) deposited a back-stepping succession of seismically-resolved grounding zone wedges (GZWs) in eastern Ross Sea. However, the chronology of WAIS retreat is debated. The conventional view is that three GZWs (Red, Brown, and Gray Units) were deposited since the LGM. An alternative view, based on recent radiocarbon dates, is that the youngest GZW (the Gray Unit) was deposited during the LGM. If correct, then the older GZWs (Red and Brown Units) were deposited prior to LGM. A recent study (Bart …
Evaluating The Duration Of Post-Lgm Grounding Events In The Glomar Challenger Basin Paleotrough, Eastern Basin Antarctica, Using Sediment Flux Calculations, Boluwatife Owolana
Evaluating The Duration Of Post-Lgm Grounding Events In The Glomar Challenger Basin Paleotrough, Eastern Basin Antarctica, Using Sediment Flux Calculations, Boluwatife Owolana
LSU Master's Theses
Previously acquired geological and geophysical data from the eastern Ross Sea outer shelf support the view that the West Antarctic Ice Sheet (WAIS) deposited three large-volume grounding zone wedges (GZWs) during the relatively short time since the onset of ice sheet retreat began at approximately 11 ka 14C BP. Here, GZW sediment volumes were estimated from seismic data correlations to evaluate the different possible durations of the individual grounding events. The two end-member fluxes used correspond to 1) a modern flux active at Whillans Ice Stream and 2) a larger flux accounting for the larger size of the drainage basin …
West Antarctic Ice Sheet Retreat Chronology Of Two Middle-Shelf Grounding-Zone Wedges In Eastern Basin, Ross Sea, Antarctica, Lenora Nicole Copeland
West Antarctic Ice Sheet Retreat Chronology Of Two Middle-Shelf Grounding-Zone Wedges In Eastern Basin, Ross Sea, Antarctica, Lenora Nicole Copeland
LSU Master's Theses
This study isolated a small number of large, in situ and reworked foraminifera from diamicts deposited in two grounding zone wedges on the middle continental shelf in Eastern Basin, Ross Sea, Antarctica. All samples were of sufficient weight to yield Holocene dates if the samples were indeed of Holocene age. Of the twelve small samples sent for radiocarbon analysis, the two heaviest were for reworked foraminifera which yielded dates of >22,200 14C BP and >22,500 14C BP. None of the other ten samples yielded radiocarbon dates. The lack of Holocene radiocarbon dates for the six in situ and four reworked …
Antarctic Plant And Phytoplankton Response To The First Phase Of The Mid Miocene Climatic Optimum At South Mcmurdo Sound, Lee Foersterling
Antarctic Plant And Phytoplankton Response To The First Phase Of The Mid Miocene Climatic Optimum At South Mcmurdo Sound, Lee Foersterling
LSU Master's Theses
The Antarctic Drilling Program (ANDRILL) recovered 1138.54 m of sub-seafloor marine sediments with 98% core recovery at the AND2-2A drill site in South McMurdo Sound. Biostratigraphy, magnetostratigraphy, and isotopic dating (Acton et al., 2008) indicated that an Early to Middle Miocene section (223-1138.54 mbsf) was recovered. This study focuses on an interval with high concentrations of palynomorphs, located between 460.57 and 403.48 mbsf and dated to 16.7 Ma to 16.2 Ma according to the updated Acton et al. (2008) ANDRILL SMS age model. Palynological results show a pronounced increase in organic microfossils between 434.01 and 431.91 mbsf, compared to levels …
New Age Control On A Mid-Shelf Grounding Event In Eastern Basin, Ross Sea, Amy Noelle Cone
New Age Control On A Mid-Shelf Grounding Event In Eastern Basin, Ross Sea, Amy Noelle Cone
LSU Master's Theses
It is widely accepted that the West Antarctic Ice Sheet (WAIS) was grounded at the continental shelf edge in Eastern Ross Sea during the Last Glacial Maximum (LGM), but the precise chronology is debated. Existing post-LGM ice retreat chronologies are considered suspect because nearly all have been developed using radiocarbon dating of acid-insoluble organics (AIO). Foraminifer tests yield more accurate radiocarbon dates than AIO because unlike loose sediment, foram tests are unlikely to be contaminated by allochthonous carbon, but unfortunately forams are sparse in Antarctic marine sediment cores. Here I utilized a new 3-D multibeam survey of a mid-continental-shelf grounding …
Middle Miocene Grounding Events On The Ross Sea Outer Continental Shelf, Antarctica, Juan Manuel Chow
Middle Miocene Grounding Events On The Ross Sea Outer Continental Shelf, Antarctica, Juan Manuel Chow
LSU Master's Theses
The middle Miocene δ18O enrichments from deep-sea data and eustatic sea level falls are traditionally attributed to expansion of the East Antarctic Ice Sheet. Interpretations of such data have led many to conclude that the West Antarctic Ice Sheet (WAIS) was not well-developed until the late Miocene. In such a scenario, middle Miocene glaciation on the Ross Sea shelf would have had to be minimal, perhaps in the form of ice caps, to be consistent with proxy data. New seismic-stratigraphic analysis of the Ross Sea outer continental shelf suggests that at least five grounding events (ice sheet advances …