Fangzhen Teng, a geologist in the University of Arkansas, has been awarded a CAREER award worth $458,928 for a five-year period by the National Science Foundation (NSF) for his unique and novel approach to solving the mysteries of the cooling histories of rocks and minerals.
Teng is using his expertise and extensive understanding of isotopes to find solutions and reveal the secrets behind the formation and evolution of our planet.
Teng revealed that he utilizes fractionation of magnesium to a great extent and stated that it could be used as a speedometer, a tracer of crust-mantle interactions and as a thermometer. As and when the magma cools, the isotopes get separated on their atomic masses. The isotopes, which are light, would form bonds first and later crystallize into rocks. The heavier isotopes would also follow the same procedure later. Scientists could determine the temperature when the rocks crystallize on the basis of the ratios of heavy to light isotopes in a piece of rock. This process is called Geothermometry and it has been utilized for years in low temperature procedures such as carbonate formation. Till recently, scientists had believed that isotopes are mixed together uniformly at high temperatures, but the work carried out by Teng and his colleagues showed that isotopes do not mix uniformly, but fractionate at high temperatures. Technological improvements in instruments measuring isotopic ratios have reduced the errors to a great extent and thus high temperature fractionation is now measurable.
Teng stated that Magnesium isotopes could be used to determine the time taken for the crystals to grow from the magma. In the Hawaii Basalts, the time taken for them to cool could be determined as the time of eruption is already known. However this cannot be done for other rocks. But with the advent of magnesium isotope fractionation, scientists could use this for all kinds of rocks.
The isotopic signature when used as a tracer would inform scientists about the origins of rocks, give data about the cooling of the planet and also about the mechanisms that work deep below the earth’s crust. The fractionation could also be used to determine the age of rocks and asteroids from the Moon and other planets.
The NSF award would allow Teng to take under his wing, one master’s student for two years, one doctoral student for five years and undergraduate students to work in the lab. The award would also allow him to concentrate on ground-breaking research activities.
Source: http://www.uark.edu/home/