Leading international geologist to visit Temora zircon field

31 August 2006

A leading Canadian research scientist is to join a growing list of academic luminaries from around the world to visit the internationally renowned deposit of high quality zircon contained in igneous rock near Temora.

Temora zircon is considered to be amongst the best in the world to provide a reliable benchmark for dating rocks and currently is used by about 70 laboratories around the world.

Zircon is commonly found in most rocks, and when formed, locks in traces of radioactive uranium. As time passes, the uranium decays and forms lead at a fixed rate, which can be measured to determine the age of rocks.

The visiting scientist, Sandra Kamo from the Jack Satterly Geochronology Laboratory at the University of Toronto, has been dating rocks for about 20 years and is a world leader in geochronological investigations.

She is scheduled to visit Temora on Monday 4 September 2006 with a fellow scientist and colleague, Dr. Lance Black from Geoscience Australia, the organisation behind the discovery, identification and documentation of Temora zircon as well as distribution of the Temora Zircon standard.

Ms Kamo describes her passion as carrying out uranium-lead geochronology to help develop a greater understanding of possible links between major geological events, such as the Siberian traps volcanic flood event, and mass extinctions.

While in Australia Ms Kamo will attend the international Goldschmidt conference in Melbourne from 27 August to 1 September where she will present age data which shows a very close temporal link between the most devastating mass extinctions which occurred in the geologic record at the end of the Permian, to the largest volcanic eruption in the Phanerozoic rock record.

She said that both events appear to be the same age and the effects of the volcanism on the atmosphere, oceans, and biosphere may have precipitated the extinctions.

Ms Kamo also is investigating an Archaean greenstone belt in the Yilgarn craton in Western Australia and is involved in evaluating analytical methods used by different dating laboratories in North America and Europe.

Temora zircon, along with the United States Geological Survey material, R33, is being used in the evaluation of the methodology and equipment used by different laboratories to establish why there are variations between results.

Temora zircon has been chosen for the project because of its consistency resulting from its formation, coupled with its relatively limited exposure to weathering. The zircon's parent rock has been exposed above ground for only about 20 years, resulting in a virtually uncontaminated sample with limited leaching of the material within the rock.

The limited exposure time is particularly important because prolonged weathering at the surface can leach lead from the zircon, resulting in inaccurate results.

Because of these attributes, Ms Kamo has championed the use of Temora zircon and the resulting Temora standard in the evaluation of inter-laboratory date testing.

Ms Kamo says the results from dating Temora rock are so reproducible that the Temora standard helps determine whether individual laboratories are obtaining the right ages of rocks.

"The Temora standard is being used also by the international scientific group, the Earthtime community, which is attempting to understand in greater detail the geologic and biologic evolution of the Earth by calibrating the time scale," Ms Kamo said.

Topic contact: media@ga.gov.au Last updated: October 4, 2013