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Articles 1 - 25 of 25
Full-Text Articles in Entire DC Network
Step-Wise Changes In Glacier Flow Speed Coincide With Calving And Glacial Earthquakes At Helheim Glacier, Greenland, M. Nettles, T. B. Larsen, P. Elósegui, Gordon S. Hamilton, Leigh A. Stearns, A. P. Ahlstrom, J. L. Davis, M. L. Andersen, J. De Juan, S. A. Khan, L. Stensing, G. Ekstrom, R. Forsberg
Step-Wise Changes In Glacier Flow Speed Coincide With Calving And Glacial Earthquakes At Helheim Glacier, Greenland, M. Nettles, T. B. Larsen, P. Elósegui, Gordon S. Hamilton, Leigh A. Stearns, A. P. Ahlstrom, J. L. Davis, M. L. Andersen, J. De Juan, S. A. Khan, L. Stensing, G. Ekstrom, R. Forsberg
Earth Science Faculty Scholarship
Geodetic observations show several large, sudden increases in flow speed at Helheim Glacier, one of Greenland's largest outlet glaciers, during summer, 2007. These step-like accelerations, detected along the length of the glacier, coincide with teleseismically detected glacial earthquakes and major iceberg calving events. No coseismic offset in the position of the glacier surface is observed; instead, modest tsunamis associated with the glacial earthquakes implicate glacier calving in the seismogenic process. Our results link changes in glacier velocity directly to calving-front behavior at Greenland's largest outlet glaciers, on timescales as short as minutes to hours, and clarify the mechanism by which …
Itase Synthesis Workshop, Paul Mayewski
Itase Synthesis Workshop, Paul Mayewski
University of Maine Office of Research Administration: Grant Reports
This award supports a workshop to bring together scientists involved in the International Trans-Antarctic Scientific Expedition (ITASE). Since 1999 the US has supported a program of traverses across both East and West Antarctica (US ITASE). US ITASE is part of the ITASE multi-national effort to understand the past 200-1000+ years of climate change over Antarctica and the Southern Ocean. ITASE is organized under the auspices of Scientific Committee for Antarctic Research (SCAR) and now comprises twenty-one countries. The international representatives from ITASE have met several times in the past to discuss national traverse plans; coordinate efforts; synthesize results; and develop …
Collaborative Research: Geophysical Evaluation Of Biogenic Gasses In Peatlands, Andrew S. Reeve
Collaborative Research: Geophysical Evaluation Of Biogenic Gasses In Peatlands, Andrew S. Reeve
University of Maine Office of Research Administration: Grant Reports
Biogenic gas emission from northern peatlands, by wicking from vascular plants and by episodic ebullition events, accounts for approximately 7% of the global annual emission of methane to the atmosphere. This proposal involves experiments to apply ground penetrating radar (GPR) for (1) estimating the amount of biogenic gas stored in peatlands, (2) determining the spatial distribution of biogenic gas within the peat, and (3) monitoring biogenic gas release to the atmosphere. Data from a large northern peatland in Maine (EAR-0242353) show that (1) higher CH4 and CO2 concentrations correlate with high velocity/high attenuation zones in cross-borehole GPR data as well …
Tb200: Carbon And Nutrients In Maine Forest Soils, Ivan J. Fernandez
Tb200: Carbon And Nutrients In Maine Forest Soils, Ivan J. Fernandez
Technical Bulletins
Recent public concerns surrounding climate change and greenhouse gas emissions have resulted in a lively debate about approaches to fossil fuel offsets and carbon (C) sequestration in forests. The forest community sees opportunities for the intensification of the use of forests for markets ranging from forest products, such as fuel or fuel feedstock, to a range of new bioproducts. This report provides initial insights from an ongoing effort to synthesize forest soils data for Maine. The specific objectives presented here were (1) to develop descriptive statistics for C and measures of available forms of the essential nutrients N, P, and …
Dry Valleys Late Holocene Climate Variability, Karl J. Kreutz, Paul Andrew Mayewski
Dry Valleys Late Holocene Climate Variability, Karl J. Kreutz, Paul Andrew Mayewski
University of Maine Office of Research Administration: Grant Reports
This award supports a project to collect and develop high-resolution ice core records from the Dry Valleys region of Antarctica, and provide interpretations of interannual to decadal-scale climate variability during the last 2000 years (late Holocene). The project will test hypotheses related to ocean/atmosphere teleconnections (e.g., El Nino Southern Oscillation, Antarctic Oscillation) that may be responsible for major late Holocene climate events such as the Little Ice Age in the Southern Hemisphere. Conceptual and quantitative models of these processes in the Dry Valleys during the late Holocene are critical for understanding recent climate changes, and represent the main scientific merit …
The Most Extensive Holocene Advance In The Stauning Alper, East Greenland, Occurred In The Little Ice Age, Brenda L. Hall, Carlo Baroni, George H. Denton
The Most Extensive Holocene Advance In The Stauning Alper, East Greenland, Occurred In The Little Ice Age, Brenda L. Hall, Carlo Baroni, George H. Denton
Earth Science Faculty Scholarship
We present glacial geologic and chronologic data concerning the Holocene ice extent in the Stauning Alper of East Greenland. The retreat of ice from the late-glacial position back into the mountains was accomplished by at least 11 000 cal years B.P. The only recorded advance after this time occurred during the past few centuries (the Little Ice Age). Therefore, we postulate that the Little Ice Age event represents the maximum Holocene ice extent in this part of East Greenland.
Foreword To The Special Issue: Arctic Palaeoclimate And Its Extremes (Apex), Martin Jakobsson, Robert F. Spielhagen, Jörn Thiede, Claus Andreasen, Brenda L. Hall, Ólafur Ingólfsson, Kurt H. Kjær, Thijs Van Kolfschoten, Gerhard Krinner, Antony Long, Juha-Pekka Lunkka, Dmitry Subetto, John Inge Svendsen
Foreword To The Special Issue: Arctic Palaeoclimate And Its Extremes (Apex), Martin Jakobsson, Robert F. Spielhagen, Jörn Thiede, Claus Andreasen, Brenda L. Hall, Ólafur Ingólfsson, Kurt H. Kjær, Thijs Van Kolfschoten, Gerhard Krinner, Antony Long, Juha-Pekka Lunkka, Dmitry Subetto, John Inge Svendsen
Earth Science Faculty Scholarship
No abstract provided.
Recommended Nomenclature For The Sapphirine And Surinamite Groups (Sapphirine Supergroup), Edward S. Grew, U. Hålenius, M. Pasero, J. Barbier
Recommended Nomenclature For The Sapphirine And Surinamite Groups (Sapphirine Supergroup), Edward S. Grew, U. Hålenius, M. Pasero, J. Barbier
Earth Science Faculty Scholarship
Minerals isostructural with sapphirine-1A, sapphirine-2M, and surinamite are closely related chain silicates that pose nomenclature problems because of the large number of sites and potential constituents, including several (Be, B, As, Sb) that are rare or absent in other chain silicates. Our recommended nomenclature for the sapphirine group (formerly-aenigmatite group) makes extensive use of precedent, but applies the rules to all known natural compositions, with flexibility to allow for yet undiscovered compositions such as those reported in synthetic materials. These minerals are part of a polysomatic series composed of pyroxene or pyroxene-like and spinel modules, and thus we recommend that …
The Use Of Ships' Protests For Reconstruction Of Synoptic-Scale Weather And Tropical Storm Identification In The Late Eighteenth Century, Louis K. Mcnally, Kirk A. Maasch, Kimberly A. Zuill
The Use Of Ships' Protests For Reconstruction Of Synoptic-Scale Weather And Tropical Storm Identification In The Late Eighteenth Century, Louis K. Mcnally, Kirk A. Maasch, Kimberly A. Zuill
Earth Science Faculty Scholarship
Ships’ protests have been used for centuries as legal documents to record and detail damages and indemnify Captains from fault. We use them in this article, along with data extracted through forensic synoptic analysis (McNally, 1994, 2004) to identify a tropical or subtropical system in the North Atlantic Ocean in 1785. They are shown to be viable sources of meteorological information. By comparing a damaging storm in New England in 1996, which included an offshore tropical system, with one reconstructed in 1785, we demonstrate that the tropical system identified in a ship’s protest played a significant role in the 1785 …
Chopinite-Sarcopside Solid Solution, (Mg, Fe)(3) (Po(4))(2), In Lodranite Gra 95209, Edward S. Grew, Martin G. Yates, R. J. Beane, C. Floss, Christopher Gerbi
Chopinite-Sarcopside Solid Solution, (Mg, Fe)(3) (Po(4))(2), In Lodranite Gra 95209, Edward S. Grew, Martin G. Yates, R. J. Beane, C. Floss, Christopher Gerbi
Earth Science Faculty Scholarship
No abstract provided.
Interpretation Of The High Resolution, Multivariate Mt. Logan (Yukon Territory) Ice Core - A Record Of North Pacific Climate And Atmospheric Chemistry, Paul Andrew Mayewski
Interpretation Of The High Resolution, Multivariate Mt. Logan (Yukon Territory) Ice Core - A Record Of North Pacific Climate And Atmospheric Chemistry, Paul Andrew Mayewski
University of Maine Office of Research Administration: Grant Reports
The recently developed Mt. Logan ice core glaciochemical dataset provides an unprecedented opportunity to understand Holocene climate change and the sources and fluxes of natural and anthropogenic chemicals in the North Pacific atmosphere. The 185 m-long ice core has been sampled at very high resolution using a refined and updated continuous ice core melter system, and analyzed for over 40 chemical species, including major ions, trace elements, rare earth elements, and stable isotopes. Subseasonal samples spanning the top ~500 years allow for annual layer counting, followed by ice flow modeling for the remainder of the timescale spanning the Holocene and …
Primary Oil Migration Through Buoyancy-Driven Multiple Fracture Propagation: Oil Velocity And Flux, Z.-H. Jin, Scott E. Johnson
Primary Oil Migration Through Buoyancy-Driven Multiple Fracture Propagation: Oil Velocity And Flux, Z.-H. Jin, Scott E. Johnson
Earth Science Faculty Scholarship
We present a fracture-mechanics-based formulation to investigate primary oil migration through the propagation of an array of periodic, parallel fractures in a sedimentary rock with elevated pore fluid pressure. The rock is assumed to be a linearly elastic medium. The fracture propagation and hence oil migration velocity are determined using a fracture mechanics criterion together with the lubrication theory of fluid mechanics. We find that fracture interactions have profound effects on the primary oil migration behavior. For a given fracture length, the mass flux of oil migration decreases dramatically with an increase in fracture density. The reduced oil flux is …
A Paleolimnological Assessment Of Three Oligotrophic Watersheds In Maine, Tiffany Ann Wilson
A Paleolimnological Assessment Of Three Oligotrophic Watersheds In Maine, Tiffany Ann Wilson
Electronic Theses and Dissertations
Phosphorus (P) is a limiting nutrient in aquatic ecosystems. Its bioavailability determines the trophic status of lakes. The biogeochemistry of P in surface waters can be controlled by a combination of abiotic and biotic factors. Dissolved inorganic aluminum (Al) and iron (Fe) hydrolyze in streams and lakes to produce Al(OH)3 and Fe(OH)3 in the water column. These hydroxides may also form through photo-oxidation of complexes with DOC, liberation of inorganic metal species, and precipitation, followed by sedimentation. These solid phases readily adsorb P from the water column, reducing the amount that is available for biological nutrition (Kopácek et …
Three-Dimensional Modeling Of Continental Subduction And The Evolution Of Ultra High Pressure Metamorphism, Peter O. Koons
Three-Dimensional Modeling Of Continental Subduction And The Evolution Of Ultra High Pressure Metamorphism, Peter O. Koons
University of Maine Office of Research Administration: Grant Reports
This project investigates driving forces and material behavior associated with continental subduction and ultra high-pressure metamorphism through an integration of numerical modeling of continental subduction and structural/petrological evolution of the material caught in the collision. The natural ultra high-pressure and high-pressure assemblages of the Western Gneiss of Norway provide rheological, geometric and geochronological information for the modeling, while the active obliquely convergent plate boundary of central New Zealand serves as a modern analog of a collision-subduction transition. Continental subduction zones represent regions where the crust-mantle interaction changes from nearly horizontal to dominantly vertical, accentuating the competing influences of body and …
Ice Core Record Of Rising Lead Pollution In The North Pacific Atmosphere, E. Osterberg, Paul Andrew Mayewski, Karl J. Kreutz, D. Fisher, M. Handley, Sharon B. Sneed, C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, J. Bourgeois
Ice Core Record Of Rising Lead Pollution In The North Pacific Atmosphere, E. Osterberg, Paul Andrew Mayewski, Karl J. Kreutz, D. Fisher, M. Handley, Sharon B. Sneed, C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, J. Bourgeois
Earth Science Faculty Scholarship
A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a > 10-fold increase in Pb concentration (1981-1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970-1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific …
Magma-Driven Multiple Dike Propagation And Fracture Toughness Of Crustal Rocks, Z.-H. Jin, Scott E. Johnson
Magma-Driven Multiple Dike Propagation And Fracture Toughness Of Crustal Rocks, Z.-H. Jin, Scott E. Johnson
Earth Science Faculty Scholarship
Dike swarms consisting of tens to thousands of subparallel dikes are commonly observed at Earth's surface, raising the possibility of simultaneous propagation of two or more dikes at various stages of a swarm's development. The behavior of multiple propagating dikes differs from that of a single dike owing to the interacting stress fields associated with each dike. We analyze an array of parallel, periodically spaced dikes that grow simultaneously from an overpressured source into a semi-infinite, linear elastic host rock. To simplify the analysis, we assume steady state (constant velocity) magma flow and dike propagation. We use a perturbation method …
Seasonal Geophysical Monitoring Of Biogenic Gases In A Northern Peatland: Implications For Temporal And Spatial Variability In Free Phase Gas Production Rates, Xavier Comas, Lee Slater, Andrew S. Reeve
Seasonal Geophysical Monitoring Of Biogenic Gases In A Northern Peatland: Implications For Temporal And Spatial Variability In Free Phase Gas Production Rates, Xavier Comas, Lee Slater, Andrew S. Reeve
Earth Science Faculty Scholarship
A set of high resolution surface ground penetrating radar (GPR) surveys, combined with elevation rod ( to monitor surface deformation) and gas flux measurements, were used to investigate in situ biogenic gas dynamics within a northern peatland (Caribou Bog, Maine). Gas production rates were directly estimated from the time series of GPR measurements. Spatial variability in gas production was also investigated by comparing two sites with different geological and ecological attributes, showing differences and/or similarities depending on season. One site characterized by thick highly humified peat deposits (5-6 m), wooded heath vegetation and open pools showed large ebullition events during …
Collaborative Research: West Antarctic Ice Sheet Stability: The Glacial Geologic Record From The Ohio Range Of The Horlick Mountains In The Bottleneck, Harold W. Borns Jr.
Collaborative Research: West Antarctic Ice Sheet Stability: The Glacial Geologic Record From The Ohio Range Of The Horlick Mountains In The Bottleneck, Harold W. Borns Jr.
University of Maine Office of Research Administration: Grant Reports
This award supports a project to document former high stands and assess the stability of the West Antarctic ice sheet (WAIS) at the Ohio Range near the head of Mercer Ice Stream (formerly Ice Stream A). The field location is situated in the "Bottleneck", a unique, relatively narrow passage in the Transantarctic Mountains connecting the West and East Antarctic ice sheets. The location lies near the ice divide and is thus well situated to determine past interior ice elevation. The research will involve geologic mapping of glacial deposits and erosion features combined with cosmogenic surface exposure dating on the Ohio …
Collaborative Research: What Limits Denitrification And Bacterial Growth In Lake Bonney, Taylor Valley, Antarctica?, Mark L. Wells, Charles Trick
Collaborative Research: What Limits Denitrification And Bacterial Growth In Lake Bonney, Taylor Valley, Antarctica?, Mark L. Wells, Charles Trick
University of Maine Office of Research Administration: Grant Reports
Denitrification is the main process by which fixed nitrogen is lost from ecosystems and the regulation of this process may directly affect primary production and carbon cycling over short and long time scales. Previous investigations of the role of bioactive metals in regulating denitrification in bacteria from permanently ice-covered Lake Bonney in the Taylor Valley of East Antarctica indicated that denitrifying bacteria can be negatively affected by metals such as copper, iron, cadmium, lead, chromium, nickel, silver and zinc; and that there is a distinct difference in denitrifying activity between the east and west lobes of the lake. Low iron …
Metamorphism, Transient Mid-Crustal Rheology, Strain Localization And The Exhumation Of High-Grade Metamorphic Rocks, Wesley G. Groome, Peter O. Koons, Scott E. Johnson
Metamorphism, Transient Mid-Crustal Rheology, Strain Localization And The Exhumation Of High-Grade Metamorphic Rocks, Wesley G. Groome, Peter O. Koons, Scott E. Johnson
Earth Science Faculty Scholarship
We present a series of three-dimensional numerical models investigating the effects of metamorphic strengthening and weakening on the geodynamic evolution of convergent orogens that are constrained by observations from an exposed mid-crustal section in the New England Appalachians. The natural mid-crustal section records evidence for spatially and temporally variable mid-crustal strength as a function of metamorphic grade during prograde polymetamorphism. Our models address changes in strain rate partitioning and topographic uplift as a function of strengthening/weakening in the middle crust, as well as the resultant changes in deformation kinematics and potential exhumation patterns of high-grade metamorphic rock. Results suggest that …
Co(2) Diffusion In Polar Ice: Observations From Naturally Formed Co(2) Spikes In The Siple Dome (Antarctica) Ice Core, Jinho Ahn, Melissa Headly, Martin Wahlen, Edward J. Brook, Paul Andrew Mayewski, Kendrick C. Taylor
Co(2) Diffusion In Polar Ice: Observations From Naturally Formed Co(2) Spikes In The Siple Dome (Antarctica) Ice Core, Jinho Ahn, Melissa Headly, Martin Wahlen, Edward J. Brook, Paul Andrew Mayewski, Kendrick C. Taylor
Earth Science Faculty Scholarship
One common assumption in interpreting ice-core CO(2) records is that diffusion in the ice does not affect the concentration profile. However, this assumption remains untested because the extremely small CO(2) diffusion coefficient in ice has not been accurately determined in the laboratory. In this study we take advantage of high levels of CO(2) associated with refrozen layers in an ice core from Siple Dome, Antarctica, to study CO(2) diffusion rates. We use noble gases (Xe/Ar and Kr/Ar), electrical conductivity and Ca(2+) ion concentrations to show that substantial CO(2) diffusion may occur in ice on timescales of thousands of years. We …
Snow Accumulation Rate On Qomolangma (Mount Everest), Himalaya: Synchroneity With Sites Across The Tibetan Plateau On 50-100 Year Timescales, Susan Kaspari, Roger Hooke, Paul Andrew Mayewski, Shichang Kang, Shugui Hou, Dahe Qin
Snow Accumulation Rate On Qomolangma (Mount Everest), Himalaya: Synchroneity With Sites Across The Tibetan Plateau On 50-100 Year Timescales, Susan Kaspari, Roger Hooke, Paul Andrew Mayewski, Shichang Kang, Shugui Hou, Dahe Qin
Earth Science Faculty Scholarship
Annual-layer thickness data, spanning AD 1534-2001, from an ice core from East Rongbuk Coll on Qomolangma (Mount Everest, Himalaya) yield an age-depth profile that deviates systematically from a constant accumulation-rate analytical model. The profile clearly shows that the mean accumulation rate has changed every 50-100 years. A numerical model was developed to determine the magnitude of these multi-decadal-scale rates. The model was used to obtain a time series of annual accumulation. The mean annual accumulation rate decreased from similar to 0.8 m ice equivalent in the 1500s to similar to 0.3 m in the mid-1800s. From similar to 1880 to …
Ice Core Record Of Rising Lead Pollution In The North Pacific Atmosphere, E. Osterberg, Paul Andrew Mayewski, Karl J. Kreutz, D. Fisher, Michael Handley, Sharon Sneed, C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, J. Bourgeois
Ice Core Record Of Rising Lead Pollution In The North Pacific Atmosphere, E. Osterberg, Paul Andrew Mayewski, Karl J. Kreutz, D. Fisher, Michael Handley, Sharon Sneed, C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, J. Bourgeois
Earth Science Faculty Scholarship
A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a >10-fold increase in Pb concentration (1981–1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970–1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific …
Methodology And Assessment Of The Susceptibility Of Potato Genotypes To Phytophthora Erythrosetpica Causal Organism Of Pink Rot, Erica Fitzpatrick-Peabody
Methodology And Assessment Of The Susceptibility Of Potato Genotypes To Phytophthora Erythrosetpica Causal Organism Of Pink Rot, Erica Fitzpatrick-Peabody
Electronic Theses and Dissertations
Phytophthora erythroseptica Pethyb., causal organism of potato (Solanum tuberosum L.) pink rot is a soil-borne ubiquitous oomycete pathogen that can cause severe losses in both the field prior to harvest and during storage. The efficacy of the most effective fungicide, mefenoxam for control of P. erythroseptica is in jeopardy due to the widespread development of resistance in the US. Cultivar resistance may provide the best option for management of P. erythroseptica in the future. Recently published reports of cultivars susceptible to P. erythroseptica are based on evaluation techniques involving detached tubers and nontuber germplasm rather than field evaluations. Screening detached …
Geoarchaeological Investigations Along The Tambo-Ilo Coast Of Southern Peru, Louis Fortin
Geoarchaeological Investigations Along The Tambo-Ilo Coast Of Southern Peru, Louis Fortin
Electronic Theses and Dissertations
The south coast of Peru has had a long history of cultural occupancy from the Preceramic through Chiribaya periods, and into Spanish Colonial / Post-Colonial periods. Procurement and modification of lithic material was an important activity throughout each of these periods but remains an under-explored dataset for late Prehispanic and Colonial populations in the region. Analysis at the Cola de Zorro archaeological site and within the Tambo-Ilo region examined the relation cultures have with their environment through a geoarchaeological analysis of the local geology and the distribution of lithics. Surveys were completed at Cola de Zorro in the quebrada drainage, …