Gravity survey along a traverse from Patriot Hills to the South Pole
Location map of the traverse from Patriot Hills at 812 m altitude to the South Pole at 2825 m altitude.
Source: BGR
The Centro de estudios científicos, Valdivia (CECS), in collaboration with the Chilean Army performed a tractor traverse from Patriot Hills to the South Pole covering more than 1100 km one way and returning the same route in 2004. Gravity and GPS measurement as well as accompanying ice thickness determinations were part of the scientific program of this venture. BGR carried out the processing and interpretation of the data.
Special considerations were necessary to reasonably calculate the drift of the gravimeter used. Bouguer and ice layer corrections were accomplished by two-dimensional model calculations. The resulting complete Bouguer anomaly oscillates around zero along the northern section of the profile and starts to decrease 200 to 300 km before entering the East-Antarctic craton where it stabilizes at about -130 mGal.
Free Air and complete Bouguer anomalies and surface and sub-ice topography along the traverse from Patriot Hills to the South Pole as measured during the traverse. The gravity points are marked by small triangles
Isostatic modelling yields a positive residual anomaly of about 70 mGal over East-Antarctica which can be explained by additional masses in the crust, e.g. assuming an increased density in the lower crust. Alternative models which incorporate lighter sediments in West-Antarctica or which are isostatically unbalanced are conceivable.
Literature:
A paper on the survey was presented at the 10th International Symposium on Antarctic Earth Sciences (ISAES) in Santa Barbara, USA, and can be downloaded: