Download Future Aerogeophysical Surveys are Needed over the West

Frontiers and Opportunities in Antarctic Geosciences * Certosa di Pontignano * 29-31 July 2004
Future Aerogeophysical Surveys are Needed over the West Antarctic Rift
System in the Area Covered
by the West Antarctic Ice Sheet (WAIS) and the Ross Ice Shelf
J.C. BEHRENDT
INSTAAR, University of Colorado, Boulder CO 80309-0450 – USA ([email protected])
During the 1990s a 5-km spaced orthogonal aerogeophysical survey comprising radar ice sounding, and aeromagnetic
and aerogravity observations was completed. These data combined with aeromagnetic surveys along widely spaced
flight lines made in the 1960s and combined radar ice sounding aeromagnetic profiles over the WAIS in 1978-79
provided a wealth of tectonic, volcanologic and glaciologic information over the area covered. However, much needs to
be done to complete the coverage comparable to aeromagnetic surveys along the rift shoulder from northern Victoria
Land to the Scott Glacier area. The late Cenozoic volcanism is >30 Ma; the Wais >10 Ma, but the oldest ice presently
comprising the WAIS and the Ross Ice Shelf is 100,000-200,000 Ka at most.
Therefore it is not surprising that few samples of the volcanic debris erupted into the ice, but removed by glacial action
have been recovered in the sparse core holes to the base of the ice.
Specific questions that can be addressed by these surveys are:
1)
How extensive are the late Cenozoic volcanic centers (which older data indicate are >10 6 km3) beyond the
area covered. What are the ages of the volcanic structures that produce the very high amplitude magnetic
anomalies observed over the ice?
2)
What is the relation to the dynamics of the WAIS and Ross Ice Shelf to tectonic activity (including
volcanism) in the West Antarctic rift system.