Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Climate Change (3)
- Antarctic Glaciology (2)
- Alaska (1)
- Canada (1)
- Climate integration (1)
-
- Climatology (1)
- Coastal zone management (1)
- Continental-oceanic terrane (1)
- Cosmic impact event (1)
- Geohazards (1)
- Greenland (1)
- Groundwater Studies (1)
- Gulf of Maine (1)
- Ice Streams (1)
- Ice sheets (1)
- Mathematical models (1)
- Natural gas (1)
- Orogen (1)
- Rheology (1)
- Sea floor (1)
- St. Elias Mountains (1)
- Subduction (1)
- Tectonic plates (1)
- Publication
- Publication Type
Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
Spatial And Temporal Melt Variability At Helheim Glacier, East Greenland, And Its Effect On Ice Dynamics, M. L. Andersen, T. B. Larsen, M. Nettles, P. Elosegui, D. Van As, Gordon S. Hamilton, Leigh A. Stearns, J. L. Davis, A. P. Ahlstrøm, J. De Juan, G. Ekström, L. Stenseng, S. A. Khan, R. Forsberg, D. Dahl-Jensen
Spatial And Temporal Melt Variability At Helheim Glacier, East Greenland, And Its Effect On Ice Dynamics, M. L. Andersen, T. B. Larsen, M. Nettles, P. Elosegui, D. Van As, Gordon S. Hamilton, Leigh A. Stearns, J. L. Davis, A. P. Ahlstrøm, J. De Juan, G. Ekström, L. Stenseng, S. A. Khan, R. Forsberg, D. Dahl-Jensen
Earth Science Faculty Scholarship
Understanding the behavior of large outlet glaciers draining the Greenland Ice Sheet is critical for assessing the impact of climate change on sea level rise. The flow of marine-terminating outlet glaciers is partly governed by calving-related processes taking place at the terminus but is also influenced by the drainage of surface runoff to the bed through moulins, cracks, and other pathways. To investigate the extent of the latter effect, we develop a distributed surface-energy-balance model for Helheim Glacier, East Greenland, to calculate surface melt and thereby estimate runoff. The model is driven by data from an automatic weather station operated …
Late 20th Century Hydrologic Change In Western North America: Regional Impacts And The Role Of Climate, Shaleen Jain
Late 20th Century Hydrologic Change In Western North America: Regional Impacts And The Role Of Climate, Shaleen Jain
University of Maine Office of Research Administration: Grant Reports
Hydroclimatic variations and change directly impact the freshwater supplies in western North America. Streamflow in this region has shown increased variability of annual flow volumes and increasing synchroneity in the largest basins in the west towards the end of last century. As land-use change seems to play a lesser role, the PI will study the sensitivity of the western North American winter precipitation and related streamflow to El Nino-Southern Oscillation variations. The PI will use observations and multi-model ensemble integrations to study the decadal variations. The broader impact of this project will be an increase of the scientific knowledge required …
Discovery Of A Nanodiamond-Rich Layer In The Greenland Ice Sheet, Andrei V. Kurbatov, Paul Andrew Mayewski, Jorgen P. Steffensen, Allen West, Douglas J. Kennett, James P. Kennett, Ted E. Bunch, Mike Handley, Douglas S. Introne, Shane S. Que Hee, Christopher Mercer, Marilee Sellers, Feng Shen, Sharon B. Sneed, James C. Weaver, James H. Wittke, Thomas W. Stafford, John J. Donovan, Sujing Xie, Joshua J. Razink, Adrienne Stich, Charles R. Kinzie, Wendy S. Wolbach
Discovery Of A Nanodiamond-Rich Layer In The Greenland Ice Sheet, Andrei V. Kurbatov, Paul Andrew Mayewski, Jorgen P. Steffensen, Allen West, Douglas J. Kennett, James P. Kennett, Ted E. Bunch, Mike Handley, Douglas S. Introne, Shane S. Que Hee, Christopher Mercer, Marilee Sellers, Feng Shen, Sharon B. Sneed, James C. Weaver, James H. Wittke, Thomas W. Stafford, John J. Donovan, Sujing Xie, Joshua J. Razink, Adrienne Stich, Charles R. Kinzie, Wendy S. Wolbach
Earth Science Faculty Scholarship
We report the discovery in the Greenland ice sheet of a discrete layer of free nanodiamonds (NDs) in very high abundances, implying most likely either an unprecedented influx of extraterrestrial (ET) material or a cosmic impact event that occurred after the last glacial episode. From that layer, we extracted n-diamonds and hexagonal diamonds (lonsdaleite), an accepted ET impact indicator, at abundances of up to about 5!106 times background levels in adjacent younger and older ice. The NDs in the concentrated layer are rounded, suggesting they most likely formed during a cosmic impact through some process similar to carbon-vapor deposition or …
Softening The Lower Crust: Modes Of Syn-Transport Transposition Around And Adjacent To A Deep Crustal Granulite Nappe, Parry Sound Domain, Grenville Province, Ontario, Canada, Nicholas Culshaw, Christopher Gerbi, Jeff Marsh
Softening The Lower Crust: Modes Of Syn-Transport Transposition Around And Adjacent To A Deep Crustal Granulite Nappe, Parry Sound Domain, Grenville Province, Ontario, Canada, Nicholas Culshaw, Christopher Gerbi, Jeff Marsh
Earth Science Faculty Scholarship
The Parry Sound domain is a granulite nappe-stack transported cratonward during reactivation of the ductile lower and middle crust in the late convergence of the Mesoproterozoic Grenville orogeny. Field observations suggest the following with respect to the ductile sheath: (1) Formation of a carapace of transposed amphibolite facies gneiss derived from and enveloping the western extremity of the Parry Sound domain and separating it from high-strain gneiss of adjacent allochthons. This ductile sheath formed dynamically around the moving granulite nappe through the development of systems of progressively linked shear zones. (2) Transposition initiated by hydration (amphibolization) of granulite facies gneiss …
Collaborative Research: St. Elias Erosion/Tectonics Project (Steep), Peter O. Koons
Collaborative Research: St. Elias Erosion/Tectonics Project (Steep), Peter O. Koons
University of Maine Office of Research Administration: Grant Reports
This is a multi-disciplinary study to address the evolution of the highest coastal mountain range on Earth - the St. Elias Mountains of southern Alaska and northwestern Canada. This orogen has developed over the past few million years as the Yakutat block, a continental-oceanic terrane, has attempted subduction beneath the eastern end of the Aleutian arc-trench system. The ~500 km-long, 150 km-wide St. Elias mountain range is the product of the dynamic balance between rapid uplift induced by crustal convergence and rapid exhumation by a regional system of large, fast-moving temperate glaciers. Most sediments are deposited either on a broad …
Three-Dimensional Mechanics Of Yakutat Convergence In The Southern Alaskan Plate Corner, Peter O. Koons, B. P. Hooks, T. Pavlis, P. Upton, A. D. Barker
Three-Dimensional Mechanics Of Yakutat Convergence In The Southern Alaskan Plate Corner, Peter O. Koons, B. P. Hooks, T. Pavlis, P. Upton, A. D. Barker
Earth Science Faculty Scholarship
Three-dimensional numerical models are used to investigate the mechanical evolution of the southern Alaskan plate corner where the Yakutat and the Pacific plates converge on the North American plate. The evolving model plate boundary consists of Convergent, Lateral, and Subduction subboundaries with flow separation of incoming material into upward or downward trajectories forming dual, nonlinear advective thermal/mechanical anomalies that fix the position of major subaerial mountain belts. The model convergent subboundary evolves into two teleconnected orogens: Inlet and Outlet orogens form at locations that correspond with the St. Elias and the Central Alaska Range, respectively, linked to the East by …
Collaborative Research: Grounding-Line Retreat In The Southern Ross Sea - Constraints From Scott Glacier, Brenda L. Hall
Collaborative Research: Grounding-Line Retreat In The Southern Ross Sea - Constraints From Scott Glacier, Brenda L. Hall
University of Maine Office of Research Administration: Grant Reports
This award supports a project to investigate late Pleistocene and Holocene changes in Scott Glacier, a key outlet glacier that flows directly into the Ross Sea just west of the present-day West Antarctic Ice Sheet (WAIS) grounding line. The overarching goals are to understand changes in WAIS configuration in the Ross Sea sector at and since the last glacial maximum (LGM) and to determine whether Holocene retreat observed in the Ross Embayment has ended or if it is still ongoing. To address these goals, moraine and drift sequences associated with Scott Glacier will be mapped and dated and ice thickness, …
Sudden Increase In Tidal Response Linked To Calving And Acceleration At A Large Greenland Outlet Glacier, Julia De Juan, Pedro Elósegui, Meredith Nettles, Tine B. Larsen, James L. Davis, Gordon S. Hamilton, Leigh A. Stearns, Morten L. Andersen, Göran Ekström, Andreas P. Ahlstrøm, Lars Stenseng, S. Abbas Khan, Rene Forsberg
Sudden Increase In Tidal Response Linked To Calving And Acceleration At A Large Greenland Outlet Glacier, Julia De Juan, Pedro Elósegui, Meredith Nettles, Tine B. Larsen, James L. Davis, Gordon S. Hamilton, Leigh A. Stearns, Morten L. Andersen, Göran Ekström, Andreas P. Ahlstrøm, Lars Stenseng, S. Abbas Khan, Rene Forsberg
Earth Science Faculty Scholarship
Large calving events at Greenland's largest outlet glaciers are associated with glacial earthquakes and near instantaneous increases in glacier flow speed. At some glaciers and ice streams, flow is also modulated in a regular way by ocean tidal forcing at the terminus. At Helheim Glacier, analysis of geodetic data shows decimeter-level periodic position variations in response to tidal forcing. However, we also observe transient increases of more than 100% in the glacier's responsiveness to such tidal forcing following glacial-earthquake calving events. The timing and amplitude of the changes correlate strongly with the step-like increases in glacier speed and longitudinal strain …
Collaborative Proposal: 2000+ Year Detailed, Calibrated Climate Reconstruction From A South Pole Ice Core Set In An Antarctic - Global Scale Context, Paul Andrew Mayewski Dr., Karl J. Kreutz, Andrei V. Kurbatov
Collaborative Proposal: 2000+ Year Detailed, Calibrated Climate Reconstruction From A South Pole Ice Core Set In An Antarctic - Global Scale Context, Paul Andrew Mayewski Dr., Karl J. Kreutz, Andrei V. Kurbatov
University of Maine Office of Research Administration: Grant Reports
This award supports a project to examine an existing ice core of opportunity from South Pole (SPRESO core) to develop a 2000+ year long climate record. SPRESO ice core will be an annually dated, sub-annually-resolved reconstruction of past climate (atmospheric circulation, temperature, precipitation rate, and atmospheric chemistry) utilizing continuous, co-registered measurements (n=45) of: major ions, trace elements, and stable isotope series, plus selected sections for microparticle size and composition. The intellectual merit of this project relates to the fact that few 2000+ year records of this quality exist in Antarctica despite increasing scientific interest in this critical time period as …
Coupled Deformation And Metamorphism, Fabric Development, Rheological Evolution And Strain Localization, Scott E. Johnson
Coupled Deformation And Metamorphism, Fabric Development, Rheological Evolution And Strain Localization, Scott E. Johnson
University of Maine Office of Research Administration: Grant Reports
When Earth's tectonic plates interact with one another the rocks that comprise them are deformed, commonly forming great mountain chains. During this deformation, the minerals that make up the rocks can become spatially or crystallographically aligned to form a fabric. The development of rock fabric is a primary factor affecting the strength, or rheological evolution of deforming rocks. Fabric development commonly involves coupling of both physical and chemical processes. For example, crenulation cleavage is the most common type of fabric in multiply deformed rocks, and its formation leads to extreme mineral segregation and rheological anisotropy. It is also commonly associated …
A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, N. E. Spaulding, D. A. Meese, I. Baker, Paul Andrew Mayewski Dr., Gordon S. Hamilton
A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, N. E. Spaulding, D. A. Meese, I. Baker, Paul Andrew Mayewski Dr., Gordon S. Hamilton
Earth Science Faculty Scholarship
Firn microstructure is accurately characterized using images obtained from scanning electron microscopy (SEM). Visibly etched grain boundaries within images are used to create a skeleton outline of the microstructure. A pixel-counting utility is applied to the outline to determine grain area. Firn grain sizes calculated using the technique described here are compared to those calculated using the techniques of Cow (1969) and Gay and Weiss (1999) on samples of the same material, and are found to be substantially smaller. The differences in grain size between the techniques are attributed to sampling deficiencies (e.g. the inclusion of pore filler in the …
Ice Layers As An Indicator Of Summer Warmth And Atmospheric Blocking In Alaska, Eric P. Kelsey, Cameron P. Wake, Karl J. Kreutz, Erich Osterberg
Ice Layers As An Indicator Of Summer Warmth And Atmospheric Blocking In Alaska, Eric P. Kelsey, Cameron P. Wake, Karl J. Kreutz, Erich Osterberg
Earth Science Faculty Scholarship
Samples were collected from a snow pit and shallow urn core near Kahiltna Pass (2970 m a.s.l.), Denali National Park, Alaska, USA, in May 2008. The record spans autumn 2003 to spring 2008 and reveals clusters of ice layers interpreted as summertime intervals of above-freezing temperatures. High correlation coefficients (0.75-1.00) between annual ice-layer thickness and regional summertime station temperatures for 4 years (n=4) indicate ice-layer thickness is a good proxy for mean and extreme summertime temperatures across Alaska, at least over the short period of record. A Rex-block (aka high-over-low) pattern, a downstream trough over Hudson Bay, Canada, and an …
Subcritical Propagation And Coalescence Of Oil-Filled Cracks: Getting The Oil Out Of Low-Permeability Source Rocks, Z.-H. Jin, Scott E. Johnson, Z. Q. Fan
Subcritical Propagation And Coalescence Of Oil-Filled Cracks: Getting The Oil Out Of Low-Permeability Source Rocks, Z.-H. Jin, Scott E. Johnson, Z. Q. Fan
Earth Science Faculty Scholarship
We use a fracture mechanics model to study subcritical propagation and coalescence of single and collinear oil-filled cracks during conversion of kerogen to oil. The subcritical propagation distance, propagation duration, crack coalescence and excess oil pressure in the crack are determined using the fracture mechanics model together with the kinetics of kerogen-oil transformation. The propagation duration for the single crack is governed by the transformation kinetics whereas the propagation duration for the multiple collinear cracks may vary by two orders of magnitude depending on initial crack spacing. A large amount of kerogen (>90%) remains unconverted when the collinear cracks …
Climate Investigations Using Ice Sheet And Mass Balance Models With Emphasis On North American Glaciation, Sean David Birkel
Climate Investigations Using Ice Sheet And Mass Balance Models With Emphasis On North American Glaciation, Sean David Birkel
Electronic Theses and Dissertations
This dissertation describes the application of the University of Maine Ice Sheet Model (UM-ISM) and Environmental Change Model (UM-ECM) to understanding mechanisms of ice-sheet/climate integration during ice ages. The UM-ECM, written by the author for this research, calculates equilibrium biome and snow/ice mass balance solutions for the globe based on modern input climatology and user-defined parameter values. The program was produced in conjunction with a National Science Foundation ITEST grant meant to seed inquiry-based classroom study of Earth systems using computer models. To that end, the UM-ECM serves as both a research and teaching tool. The model has a web-based …
Higher-Order Physic For Modeling Ice Streams In Ice Sheets, Debra A. Kenneway
Higher-Order Physic For Modeling Ice Streams In Ice Sheets, Debra A. Kenneway
Electronic Theses and Dissertations
Ice streams are transitional between inland glaciers and ice shelves. Hence no stresses can be neglected. Ice streams are important dynamic features of a glacier; it is well known that ice streams drain up to 90% of the ice from an ice sheet. Herein I model ice streams as a multiphysics system of coupled components. This includes treating ice as a non-Newtonian fluid since empirical measurements show a power law relation between stress and strain rate. Sliding is a physical feature that must be included. This is done with a novel approach to sliding by way of a slippery layer. …
Development In The Gulf Of Maine: Avoiding Geohazards And Embracing Opportunities, Laura L. Brothers, Joseph T. Kelley, Melissa Landon Maynard, Daniel F. Belknap, Stephen M. Dickson
Development In The Gulf Of Maine: Avoiding Geohazards And Embracing Opportunities, Laura L. Brothers, Joseph T. Kelley, Melissa Landon Maynard, Daniel F. Belknap, Stephen M. Dickson
Maine Policy Review
Mapping for marine-spatial planning is crucial if Maine is to safely develop its offshore resources, especially wind and tidal energy. The authors focus on shallow natural gas (methane) deposits, an important and widespread geohazard in Maine’s seafloor. They describe the origin, occurrence, and identification of natural gas in Maine’s seafloor; explain the hazards associated with these deposits and how to map them; and discuss what Maine can learn from European nations that have already developed their offshore wind resources. Because the U.S. gives states a central role in coastal management, Maine has the chance to be proactive in delineating coastal …