Geomagnetic anomaly maps of Central Victoria Land (East Antarctica) from ground measurements

Abstract

The results of an extensive ground geomagnetic survey over the Central Victoria Land (East Antarctica) between the Transantarctic Mountains and the Ross Sea are used to plot the residual field map of the area under consideration. The data indicate that intense positive anomalies occur along two corridors, one near Mt. Nansen and the other near Mt. Melbourne. Further elaboration of our measurements has produced three other geomagnetic maps: (1) a high-pass filter (cut-off wavelength of 20 km) map; (2) a low-pass filter (cut-off wavelength of 80 km) map; and (3) an upward continuation of the geomagnetic field up to 12000 ft (3660 m) map. The residual field map and the high-pass filter geomagnetic map indicate that all the intense anomalies (both positive and negative) are of shallow origin. The low pass filter map and the upward continuation map show that the land mass of the Central Victoria Land is characterized-by a weak, negative geomagnetic anomaly whereas the near-shore area, close to Terra Nova Bay, displays a weak positive anomaly. Our measurements indicate that all rock types characterized by high susceptibility produce geomagnetic anomalies, even if their outcrop is not extensive. These rocks belong to the Mt. Melbourne volcanics, Jurassic dolerites and Granite Harbour plutons. None of the formations of the metamorphic complex are responsible for intense magnetic signals.