15 April 1997

Antarctic geology explored by UQ researchers

Rock samples collected on Heard Island in the Antarctic by a University of Queensland academic will confirm whether Australia has a second active volcano.

Earth Sciences Department head Professor Ken Collerson and PhD student Robyn Frankland have just returned from a three-month Antarctic field trip.

Professor Collerson's party travelled to Antarctica on the RSV Aurora Australis in January this year.

During this time, research was carried out at three locations Gaussberg, an isolated volcano on the Antarctic coast, Mt Brown at an elevation of 2000 metres 150km inland from Gaussberg, and Big Ben on Heard Island, until recently believed to be Australia's only active volcano.

Since 1936, Australia has claimed 42 percent of Antarctica and controlled the sub-Antarctic territories of Heard Island and the McDonald islands.

The samples collected during the field season are currently being analysed in the Department's state-of-the-art Radiogenic Isotope Laboratory. These analyses will lead to a better understanding of the geological history of the southern icy continent and sub-Antarctic islands.

On the voyage back to Australia from the Antarctic, the expedition ice-breaker Aurora Australis sailed within 8km of McDonald Island some 28km from Heard Island.

Professor Collerson said that from the ship it appeared that the side of McDonald Island, well above sea level, was smoking.

"At least three point sources and one fissure system appeared to be liberating large amounts of steam on a large pile of rubble that extended down to sea level on the northern face of the island," he said.

"This is evidence of volcanic activity and pumice which forms as a result of submarine volcanism was collected from the shores of Heard Island.

"Comparison of isotopic analysis of the pumice with rocks from McDonald Island that I have analysed previously should confirm the pumice source as being McDonald Island volcano."

During the expedition, Professor Collerson also gathered valuable geological data on Gaussberg - a 400-metre-high volcano located on the edge of the continent between the Antarctic stations of Mirny and Davis at 67 degrees south, 89 degrees east.

Even though the volcano was discovered by a German expedition 95 years ago, Professor Collerson's $351,700 study represented the first integrated field, geochemical, isotopic and geochronological study of Gaussberg.

"My research shows that the Gaussberg cone is only a remnant of an almost entirely eroded larger volcano," he said.

"This volcano is relatively young and erupted under the polar ice cap around 50,000 years ago. Subsequent massive glacial action is what caused the volcano's erosion."

He said the fact that the Gaussberg had a similar composition to rocks containing diamond in the Kimberley region of Western Australia was of particular academic interest.

"As the volcano's lavas contain small fragments of the mantle and crust that were incorporated during eruption, the study provides valuable information regarding mantle composition and the geological history of the continental crust beneath the ice cap in this part of Antarctica," Professor Collerson said.

To study and sample the Gaussberg, Professor Collerson spent three weeks camping in the isolated area with Ms Frankland and two Antarctic Division field assistants.

To reach the area, the research group travelled by ice-breaker to Davis Station 450km to the west and was then flown to the volcano in two long-range helicopters packed with 2000kgs of equipment.

In addition to employing the latest communications technology such as the satellite telephone he used to record and transmit information during the trip, Professor Collerson was also able to determine precise latitudes, longitudes and altitudes from piles of stones or cairns placed on Gaussberg by the German expedition, led by Count Drygalski, at the beginning of the century.

A few wooden planks, metal, and seal skins and skeletons under rock piles were the only traces of the early expedition. The German party discovered the Gaussberg volcano after observing it from a hot air balloon launched from their ship The Gauss which was stuck in pack ice of the Western Ice Shelf for more than a year.

Professor Collerson also added another letter to a cylinder under one of the cairns containing letters from six previous expeditions dating back to 1912 when the mountain was explored by a team from Sir Douglas Mawson's expedition.

"The Drygalski party surveyed the mountain and made an excellent topographic map. We used it as a base map. However, our new Global Positioning Systems (GPS) locations and aerial photographs obtained during the summer will allow a very accurate new map of the volcano to be made," he said.

For more information, contact Professor Collerson (telephone 3365 1180).