Understanding Surface Water--Groundwater Connectivity And Discharge In Arctic Deltas, Lindsey N. Aman

Graduate Theses, Dissertations, and Problem Reports

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Increased warming is driving unprecedented hydrologic changes within arctic deltas with implications for water storage, solute processing, and terrestrial and marine ecology. Thermokarst lakes within Arctic deltas store flood waters and filter solutes and sediments, thus moderating the impact of flood water discharge to arctic seas. However, this moderating influence is diminishing as lakes shrink on annual and seasonal time scales, especially close to active channels where lakes are shrinking most rapidly. This study investigates surface water-groundwater connectivity in arctic delta plains with coupled flow and heat transport models to provide a mechanistic understanding of how lake-channel proximity will impact …

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A Periglacial Landsystem Analysis In The Canadian High Arctic: A Tool For Planetary Geomorphology, Chimira Nicole Andres

Electronic Thesis and Dissertation Repository

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Permafrost underlies 50% of Canada’s terrain and underlies 24% of the Earth’s total land area. It is a major driving force in the generation and evolution of patterned ground landforms such as polygons, stone circles, mud boils, and stripes, etc. that are seen on both the surface of the Earth and Mars, specifically in periglacial domains. The distribution of subsurface ice in these landforms (i.e. polygonal terrain) on Earth is a key constraint on past climate and process-form relationships in high arctic and periglacial regions. These landforms also have the potential of storing ice in the subsurface meaning that the …

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Impact-Generated Dykes And Shocked Carbonates From The Tunnunik And Haughton Impact Structures, Canadian High Arctic, Jennifer D. Newman

Electronic Thesis and Dissertation Repository

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The Canadian High Arctic contains two impact structures created by hypervelocity impact events in carbonate-rich target rocks. The remote locations of the Tunnunik and Haughton impact structures means that there are aspects of these impact structures which have yet to be fully investigated. This study characterizes the range of impact-generated dykes exposed from both impact structures which include lithic breccias, impact melt-bearing breccias, and impact melt rocks. Breccias may include silicate impact glass fragments and evidence for carbonate melt. Impact melt rocks from the Haughton impact structure contain the rare terrestrial mineral moissanite. This is only the third reported occurrence …

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Arctic And North Atlantic Paleo-Environmental Reconstructions From Lake Sediments, Gregory A. De Wet

Doctoral Dissertations

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ABSTRACT

ARCTIC AND NORTH ATLANTIC PALEO-ENVIRONMENTAL RECONSTRUCTIONS FROM LAKE SEDIMENTS MAY 2017 GREGORY A. DE WET, B.Sc., BATES COLLEGE M.Sc., UNIVERSITY OF MASSSCHUSETTS, AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS, AMHERST Directed by: Drs. Raymond S. Bradley and Isla S. Castañeda There are few fields in the discipline of Earth Science that hold more relevancy in 2017 than studies of earth’s climate. Called the “perfect problem” considering its complexity and magnitude, climate change will continue to be one of the greatest challenges humanity will face in the 21^st century. And while numerical models provide valuable information on conditions in the future, …

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Modern Foraminiferal Assemblages Of The Denmark Strait, Laura Larocca

Dissertations and Theses

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Foraminifera occupy a geological range from the early Cambrian to the present day. Their well preserved shells, high relative abundance, and short response time to changing environmental conditions make foraminifera ideal proxies for environmental change. Benthic foraminifera are a valuable but poorly understood paleobiological proxy for the reconstruction of environmental conditions on continental shelves occupied by arctic and subarctic waters. This study identifies, examines, and quantifies calcareous benthic foraminiferal faunas from a sediment core taken from the Denmark Strait. Our analysis of three-thousand individuals from ten discrete samples aim to provide a better understanding of the modern patterns of foraminiferal …

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Preservation And Sediment Cycling Beneath "Ghost Glaciers": How Cold-Based Ice Dictates Arctic Landscape Evolution, Lee Corbett

Graduate College Dissertations and Theses

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Constraining past episodes of climate change and glacial response is critical for understanding future impacts of climate change, especially in the high latitudes where warming is expected to be rapid and most of Earth's glaciers exist. Many studies of past glacier size utilize rare isotopes called cosmogenic nuclides to perform surface exposure dating. Since most areas of Earth's surface that were previously glaciated were covered by erosive ice, which stripped away pre-existing cosmogenic nuclides, surface exposure dating yields the timing of the most recent deglaciation. However, in some high latitude areas where glacial ice is cold-based and non-erosive (so-called 'ghost …

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Normal And Extreme Sedimentation And Physical Processes In Lake Tuborg, Ellesmere Island, Nunavut, Edward Lewis

Open Access Dissertations

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Lake Tuborg is a large lake on west-central Ellesmere Island, Nunavut. Part of the lake is meromictic, and contains trapped saltwater below about 55 m depth. The lake receives meltwater and sediments from multiple sources, including snowmelt and glacier melt. A lake process study was undertaken from 2001-2003 at Lake Tuborg that involved obtaining profiles of water temperature, salinity, transmissivity, and dissolved oxygen. Networks of short and long sediment cores were also obtained throughout the lake. During the last year of monitoring the lake and its sediments, a large catastrophic drainage of an ice-dammed lake occurred (a jökulhlaup). This was …

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Investigation Of A Possible Lead-Lag Relationship Between The Innuitian And Laurentide Ice Sheets, Arctic Canada, Paula Zimmerman

OES Theses and Dissertations

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Peaks of iron-rich grains in Arctic Ocean sediment cores matched to the Laurentide and Innuitian Ice Sheets appear to show a lead-lag relationship during the Late Pleistocene when grain abundances are plotted against time and depth below sea floor. Cores from across the Arctic have been analyzed to determine if this is the case. Of the six IRD events identified, the Innuitian leads 68% of the time with 26% of events in all cores occurring simultaneously. The Innuitian seems to lead 33.3% of the time when peaks from the Innuitian and Laurentide occur within close proximity (less than 1 cm), …

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