Journey to the heart of the earth
A journey into the interior of the earth and to the beginnings of our planet almost four billion years ago enabled the geo- and cosmochemist Thomas Meisel from the University of Leoben to develop new methods for examining the rocks in the mantle. The analysis of concentrations and isotopic ratios of precious metals in minerals from the earth's mantle allows us to look back 50 kilometers and billions of years. Like the top layer of the planet, the earth's crust, the mantle is made of solid material and extends from around 50 to 2,900 kilometers deep. There is no direct access to the earth's mantle, so far drilling has reached a maximum depth of ten kilometers. Nevertheless, geological phenomena such as volcanic eruptions or mountain-building processes bring material from the uppermost layers of the earth's mantle to the surface, where it, for example in Styria orin the Alps.
During the investigation, Meisel focuses primarily on the concentration of precious metals in the rocks. Actually, the earth's mantle material should be very poor in precious metals, since these "migrated" to a large extent into the liquid earth's core in the course of the earth's formation. "However, the composition of the Earth's mantle has changed due to heavy meteorite bombardment in the early phase of the Earth," explained the chemist from the Institute for General and Analytical Chemistry at Montanuni. For example, certain precious metals were enriched there again.
Meisel has developed a method with the help of a so-called inductively coupled plasma mass spectrometer, with which, for example, the extremely rare precious metals rhenium and osmium in the earth's mantle material can be precisely determined. This not only gives the experts an insight into the development of the earth's mantle, but also into the growth of the continents from the beginning of plate tectonics to modern times. Complementary research is being conducted at the University of Maryland, where Meisel was completing his post-doctoral year.
