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Victoria University Antarctic Research Expedition Science and Logistics Reports 2001-02: VUWAE 46

Gravity and Magnetics

Gravity and Magnetics

Gravity and magnetic data were acquired along each seismic profile, as well as over a selected detailed grid in New Harbour and McMurdo Ice shelf sites. Additionally, a reconnaissance trip led by Gary Wilson acquired gravity and magnetic records over a grid in Southern McMurdo Sound on the ice shelf between Minna Bluff-Black Island-Brown Peninsula. Gravity measurements were acquired with a Lacoste-Romberg geodetic meter. Magnetic measurements were acquired with a Barringer Research GM122 proton magnetometer. Gravity measurements were "tied-in" to temporary base stations in the survey region which themselves were tied to the gravity base station located as Scott Base. The seismic, gravity and magnetic data were positioned using differential GPS. Some sites were re-occupied and their position measured over several weeks (by GPS to dcm accuracy) to establish ice movement rate and direction. The gravity and magnetic data were reduced in the field Smoothed data were gridded using minimum curvature techniques. The data were then modelled using both indirect (e.g. line integral) and direct (e.g. matrix inversion) techniques. Particular emphasis was placed on the determination of the geometry of the gravity and magnetic basement and, hence, the distribution of the sedimentary depocentres and the rim thicknesses of volcanic islands of the Ross archipelago.