SCIENCE AT THE SHINE DOME canberra 6 - 8 may 2009

Early-career researchers

Thursday, 7 May 2009

DOROTHY HILL AWARD

Dr Daniela Rubatto
Australian National University

Daniela Rubatto is a QEII Fellow at the Australian National University (ANU) in Canberra. She moved ‘down under’ more than a decade ago after a degree in Earth science at the University of Torino in Italy, and a PhD at the ETH in Zurich, Switzerland. Overseas she gained her passion for mountains and for obtaining high quality scientific data. In her research at ANU, she combines her expertise in metamorphic petrology and geochronology in the study of the geological processes that shape the Earth’s crust. She investigates the behaviour and composition of accessory minerals during metamorphism, particularly at high pressure and temperature, to reach a rigorous interpretation of U-Pb ages. Her main interest is determining the timing of mountain building, such as the Alps and the Himalayas, of melting in the crust, and of subduction and exhumation of plates.

How fast do rocks move, rise and melt in the Earth’s crust?

Crucial information for the understanding of our Earth is the rate at which geological processes occur. To retrieve this information we need precise time constraints linked to the evolution of key geological samples. This contribution illustrates a method that uses small-scale chemical and isotopic measurements of small minerals commonly found in crustal rocks, and that relates their age to the pressure and temperature evolution of the hosting rock. The dating is achieved by measuring products of the radioactive decay of thorium and uranium incorporated in small domains of tiny minerals such as zircon and monazite, using the sensitive high resolution ion microprobe (SHRIMP), an instrument developed at the ANU. This approach can be used to monitor the travel of rocks at the roots of mountains and continents and thus constrain how plate tectonics works. For example, rock units can be exhumed from 100 kilometre depth at rates of up to 4 centimetre per year, which is the speed that fingernails grow; magma can reside at depth for few million of years before being erupted to the surface; regions of the Earth’s crust can melt intermittently for tens of millions of years.