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Victoria University Antarctic Research Expedition Science and Logistics Reports 1984-85: VUWAE 29

Geophysical Surveys on Browning Pass

Geophysical Surveys on Browning Pass

Introduction

A geophysical survey was made along part of Browning Pass (Figure 15) to determine the basement structure beneath the ice. The survey, not originally planned in the geophysics programme, was made following a decision to do work near Gondwana Station during periods of bad weather or when helicopters were not available to support planned surveys. Browning Pass was chosen for study because of the suggestion of a fault that extends along the pass, on the basis of differential folding of Priestley schist on each side of the pass (Skinner, 1983). The objective of the survey was to determine whether a fault could be detected using geophysical methods. The survey consisted of gravity magnetic, and radio echo-sounding measurements, but only the gravity survey is described below.

Method

Measurements were made along a 1 km by 3 km grid oriented orthogonal to the trend of the pass, at points separated by approximately 250 m in each direction of the grid. Positions and relative elevations were surveyed with an EDM instrument. Gravity measurements were made with a Worden gravity meter. Gravity measurements were corrected for drift by linear interpolation of base-station measurement made approximately every 2 hours. Average drift was about 0.25 mgals per 2 hours. Gravity was also corrected for relative elevation, but terrain corrections have not yet been applied.

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Results

Figure 16 is a map showing the relative positions of the stations and the partially reduced relative gravity observations. Interpretations will be made after the data are fully reduced and modelled in conjunction with the radio echo-sounding and magnetic observations.

Acknowledgement

Other workers involved in this survey were R. Saltus (magnetics and geodesy), G. Druivenga (radio echo-sounding and geodesy), and G. Merkel (geodesy).

References

Skinner, D.N.B., 1983. The Geology of Terra Nova Bay. In: Antarctic Earth Science (Oliver, R.L.; James, P.R.; and Jago, J.B.; eds.) Australian Academy of Science, Canberra, A.C.T.

Figure 16. Relative Gravity observed on Browing Pass in the area indicated on Fig. 15.

Figure 16. Relative Gravity observed on Browing Pass in the area indicated on Fig. 15.