Directory

G 298 M: Resistivity mapping of subsurface microbial habitats in the McMurdo region

Start date:
Mid November
End date:
Late December
Locations:
Taylor Glacier, Marble Point, Hut Point
Principle Investigator:
Dr Jill Mikucki
Organisation:
Dartmouth College
Field season overview:
The McM SkyTEM project will map subsurface resistivity using the Time Domain Electromagnetic (TEM) method to determine subsurface distribution of water salinity, hydrogeologic connectivity, buried geomorphic surfaces, including buried ice and permafrost extent. The instrument is sling mounted on a helicopter, with monitoring instruments located inside the aircraft. The project will deploy seven participants to McMurdo during the 2011-2012 summer season. One participant will be a SkyTEM experienced pilot who will assist in the training of helicopter personnel. The instrument and framework will be constructed on the sea ice in front of McMurdo Station and later staged at the survey sites by helicopter. The three survey sites are Taylor Glacier/Bonney Basin, Marble Point/Fryxell Basin and Hut Point/Cape Barne. The participants will move with the instrument and stay in established camps at Lake Bonney and Lake Fryxell. Biological samples-of-opportunity will be taken to ground truth the TEM findings and address questions of geomicrobiology in relation to parameters elucidated by the SkyTEM, including water distribution and salinty. Two members of the field team will be involved in geomicrobiological sampling and remain beyond the survey portion of the field campaign to collect and process samples.
The McMurdo-SkyTEM project aims to map subsurface resistivity using the Time Domain Electromagnetic (TEM) method, which offers a non-invasive and efficient way to determine the subsurface distribution of water salinity, hydrogeologic connectivity, buried geomorphic surfaces, including buried ice and permafrost extent. A newly developed transient electromagnetic system is ideal for use in Antarctica for distinguishing between high resistivity (glacier ice and bedrock, permafrost) and low resistivity materials (geologic materials that are clay-rich and/or saturated by salty water) to a depth of 300 meters or more. The SkyTEM system can be mounted under a helicopter for an extensive geophysical survey of the McMurdo region to generate three-dimensional maps of subsurface resistivity structure over inaccessible terrain. Despite the high potential for TEM to address important science questions in geobiology and the earth sciences, Heli-borne TEM to date has not been deployed in the polar regions. Thus, researchers propose this effort as a proof-of-concept for the applicability of the TEM method for mapping the conductivity and depth of water and permafrost in Antarctic subglacial and subsurface environments. Prioritized targets include: 1. Taylor Glacier and the Bonney Basin, 2. Hut Point and Peninsula (in the vicinity of McMurdo Station)/Cape Barne marine intrusions, and 3. Marble Point/Fryxell Basin - into the Wright Valley. These three targets represent a range of Antarctic environments and provide data on the validity of this method to the broader scientific community. Researchers selected these targets because there are significant existing background data on each system, and they believe these targets can serve as models for the application of TEM to high-priority science questions in the Antarctic community and beyond. The survey will consist of a sequence of profiles each offset from the other by a spacing of 150-200 meters dependent on the spatial variability of the subsurface. Dense measurements (50-meter line spacing) can be achieved for higher resolution of near surface features; researchers intend to exercise this configuration for mapping the Taylor Glacier terminus.