Planetary Science Institute | 21 July 2010
53Mn–53Cr and 26Al–26Mg ages of a feldspathic lithology in polymict ureilitesResearchers have aged dated a very important group of meteorites with far greater precision than previously possible by using a different type of radioactive dating on a particularly difficult type of specimen to study.
The project found that the asteroid from which ureilite meteorites are derived differentiated – or separated into parts of different composition – within 5 million years of the formation of the Solar System, said Cyrena Anne Goodrich, senior scientist at the Planetary Science Institute. “That is a really short time period,” she said.
Goodrich’s research offered dating with approximately 10 times greater precision than previously available.
Most meteorite dating research has looked at two types of meteorite – angrites and eucrites – which contain ample amounts of minerals necessary for the study. Goodrich and her team opted to investigate ureilites.
The project’s radioactive isotope dating methods looked at short-lived radionuclides rather than the long-lived radionuclides that researchers have studied for years.
“Ureilites are the second most abundant group of differentiated meteorites, but they are particularly enigmatic and are very difficult to date because they don’t contain many different minerals,” she said.
Radiometric dating is based on the principle that radioactive elements decay and change into other elements at a constant rate that can be measured in a laboratory. The basic idea behind radioactive dating is that if you can measure the ratio of parent to daughter isotopes in a rock or mineral using a mass spectrometer, which separates isotopes from one another according to their weight, you can calculate its age.
- Earth and Planetary Science Letters 295 (July 2010) doi: 10.1016/j.epsl.2010.04.036