| Principal Investigator: | Menounos, Brian p (4) |
| Licence Number: | 15891 |
| Organization: | University of Northern British Columbia |
| Licensed Year(s): |
2017
2016
|
| Issued: | May 27, 2016 |
| Project Team: | Adam Hawkins, Dr. Brent Goehring, Dr. Gerald Osborn |
Objective(s): To develop a robust chronology of glacier change on the Brintnell-Bologna Icefield.
Project Description: The objective of the study is to date the formation of terminal moraines fronting Brintnell Glacier, and analyze the glacigenic signature within the sediments of Glacier Lake in order to develop a robust chronology of glacier change on the Brintnell-Bologna Icefield. This decade to century scale chronology will be compared to regional-to-hemispheric climate proxies to evaluate the climate sensitivity of Brintnell Glacier. This study will incorporate glacier mass balance observations from the Geological Survey of Canada to develop and calibrate a simple flow line model for Brintnell Glacier to estimate past precipitation and temperature changes. Once calibrated with modern records, the model will be used to predict how the Brintnell Glacier will change in the future using different CO2 emission scenarios. The research team will use a percussion core system to collect 3-5 meters of sediment, in 5 cm diameter tubes, from the frozen surface of Glacier Lake (62°04’ N, 127°32’ W). Sediment cores will be taken back to the University of Northern British Columbia, where the team will split, photograph, log, and sample the sediment cores at high resolution. Changes in bulk physical properties of the sediments, such as dry bulk density and organic content can be used to constrain glacier size over time and fill in gaps from the fragmentary terrestrial record. To examine the rates and timing of these changes, terrestrial macrofossils and tephra samples will be collected for AMS 14C dating and geochemical analysis, respectively, to develop an age-depth model for the cores. The research team will return to visit the Brintnell-Bologna Icefield and the prominent end moraines that front outlet glaciers. The ages of the moraines, as well as the bedrock exposure histories of nunataks present in the icefield, will be determined through Terrestrial Cosmogenic Nuclide (TCN) dating, a numerical dating technique that allows even young (less than 500 year-old) samples to be dated. Samples will be collected using a gas-powered rock saw, leaving a roughly 15 x 20 cm patch of cleaner-looking rock on top of the boulders, which will soon be repopulated by lichens. Master’s student Adam Hawkins will extract and purify quartz from the rock samples at Tulane University, under the supervision of Dr. Brent Goehring, and prepare sample targets for Accelerator Mass Spectrometry (AMS) measurement of TCN 10Be and 14C isotopes at Purdue University’s PRIME (Purdue Rare Isotope Measurement) Laboratory. The records generated by the terrestrial and lacustrine chronologies will be compared to regional-to-hemispheric climate proxies to evaluate the climate sensitivity of the glacier. With surface mass balance observations from the GSC, the research team will develop and calibrate a simple flow line model for Brintnell Glacier. This model will incorporate our multi-proxy record and millennial-length global climate model simulations to estimate past precipitation and temperature changes. Once calibrated with modern records, the model will be used to predict how the Brintnell Glacier will change using different CO2 emission scenarios. The findings and products related to the project will be communicated through scientific publications and can be presented in an approachable pamphlet detailing the significance of the findings, as well as public presentations. Findings will be incorporated into material presented by the Geological Survey of Canada to the public. The fieldwork for this study will be conducted from May 27, 2016 to August 31, 2016.
