Reconnaissance for the new Indian Antarctic Station site at Larsemann Hills
A four member “TASK FORCE” was constituted by National Centre for Antarctic & Ocean Research (NCAOR) for carrying out reconnaissance survey in the area between 550 – 820 E longitudes in the Eastern Antarctica, with the objective of recommending a suitable site for 3rd Indian Research Station in Antarctica. The Task Force selected an unnamed promontory in Larsemann Hills, East Antarctica as the site for new station. The Institutes scientist Shri Ajay Dhar was a member of this Task Force. The construction of the Larsemann Hills station is going to commence soon. Regular expeditions were sent to Larsemann Hills from 2005 onwards and the Institute established a magnetic variation monitoring station by setting up a Digital Fluxgate Magnetometer. A GPS and an AWS were installed for crustal deformation studies and recording of meteorological parameters.
Larsemann Hill Region
The Institute has conducted magnetic survey to prepare a magnetic anomaly map of Larsemann Hills region. As seen from magnetic field contour map it is observed that the high magnetic filed anomaly regions are concentrated over some pockets which are located on high ridges seen in the elevation relief map. In the southern part of the promontory, the magnetic field values generally correspond to background values and no significant anomalies were observed. The causative source of the anomaly seems to be at very shallow depth as it is observed horizontal gradient of about 1000nT per 50 m at some locations. The most likely candidate for the magnetic anomaly can be the magnetite bearing gneisses/ amphibolitic gneisses which are present as NE-SW trending bands in the region. As seen from the Geology of the Larsemann Hills – Lithology these NE-SW ridges are characterized by garnet-magentite-biotite gneisses. There are evidences of oxidation of iron rich material as seen in the form of limonitic surface exposures. As compared to Schirmachar area around Maitri, it is different because no magnetite bearing rocks have been reported from there.
Magnetic field observed, magnetic anomaly and elevation map of Larsemann Hills
Magnetic field variations simultaneously recorded at Larsemann Hills and Maitri clearly indicates that Larsemann Hills are always under the influence of auroral currents.
Magnetic field variations recorded simultaneously at Maitri and Larsemann Hills. Sever substorm was recorded at Larsemann Hills while variations at Maitri were of typically sub-auroral station type.