John Stodt and Virginia Maris install a site near the TAM-Ross Sea transition. Mountaineer Danny Uhlmann works near the helicopter.
CTAM MT Transect Science Team, L to R: Danny Uhlmann (mountaineer, Raytheon Polar Services, Inc.), Ted Bertrand (NZ GNS), Jamie Pierce (lead mountaineer, Pike’s Peak Alpine School, Inc.), John Stodt (Numeric Resources, Inc.), student Marie Green (U Utah), Graham Hill (NZ GNS), student Danny Feucht (U CA Berkeley), post-doc Virginia Maris (U Utah) and P.I. Phil Wannamaker (U Utah).
Post-doc Kate Selway (U Adelaide) and Co-Investigator Yasuo Ogawa (TITech.) left camp before the photo shoot.
(multispectral) image / map of central Transantarctic Mountains. The grey scale intensity provides information about the surface material (snow, ice, gravel, rock, etc.) Orange dots denote 33 acquired MT sites; yellow dots, part of a planned future survey. The red star marks the CTAM camp.
An international team has used Phoenix MT systems to see through the Antarctic icecap that is up two kilometres thick in the survey area. This is the first time that such a survey, investigating the deep geological structure of the Trans-Antarctic Mountains (TAM) of the Antarctic interior, has been carried out.
In December 2010 and January of this year, the team of nine scientists and two mountaineers, led by Principal Investigator Prof. Phil Wannamaker (University of Utah, USA), acquired 33 MT sites along a 230 km profile across the central TAM. The 45-million-year-old TAM is the uplifted shoulder of a very large rift system which is comparable to the well-known rifts of the southwest USA and of East Africa.
The team worked in a spectacular setting out of a sizable but temporary camp that also supported research in paleontology, glacier dynamics, and bedrock geology. Helicopters deployed the research crews to most of the profile sites 25 kilometres or more from the central TAM camp. More distant sites on the polar plateau, up to 140 kilometres from camp, were reached by Twin Otter fixed-wing aircraft.
The danger of crevasses (deep snow-covered fissures) required very careful site selection: satellite images were examined; then Twin Otters flew reconnaissance over the area; and finally, locations were pinpointed by observation from low-flying helicopters. The team’s mountaineers probed the area immediately upon landing. And as a final safety precaution, the researchers walked in pairs, roped together, to install electrodes.
The study was funded by the U.S. National Science Foundation with participation and support by New Zealand Geological and Nuclear Sciences (NZ GNS), Tokyo Institute of Technology (TITECH) and University of Adelaide, Australia. TITECH and GNS provided ten Phoenix MT systems for the project. The Phoenix technology, long proven in far northern latitudes, was well suited for the Antarctic conditions.
The high contact impedance (up to two megaohms) was mitigated by using buffer pre-amplifiers developed for the University of Utah by John Stodt. Recording times were up to one week to ensure data down to at least 3000 s period. System battery power was backed up by solar panels. Signal was steady and environmental noise (e.g., electrically charged blowing snow) was low. Data quality generally was excellent.
The recent CTAM MT project builds upon successful smaller MT surveys in central West Antarctica (1994–95) and at South Pole (1997–98). MT can now be considered a standard tool for geophysical investigation of the Antarctic interior.
Thank you to Prof. Phil Wannamaker of the University of Utah for his assistance with this article and for the accompanying photographs.