Geochemist and director of Terrestrial Magnetism, Richard Carlson, looks at the diversity of the chemistry of the early solar nebula and the incorporation of that chemistry into the terrestrial planets. He is also interested in questions related to the origin and evolution of Earth’s continental crust.
Most all of the chemical diversity in the universe comes from the nuclear reactions inside stars, in a process called nucleosynthesis. To answer his questions, Carlson developes novel procedures using instruments called mass spectrometers to make precise measurements of isotopes--atoms of an element with different numbers of neutrons--of Chromium (Cr), strontium (Sr), barium ( Ba), neodymium (Nd), samarium (Sm) and hafnium (Hf) to detect the isotopic anomalies, correlate them with the responsible nucleosynthetic processes, and then map their distribution in different types of meteorites and the terrestrial planets. The work contributes to our understanding of the stellar nucleosynthetic processes that created the elements in the first place.
Carlson also looks at how well mixed the solar nebula was before the start of planet formation, and how compositional differences in the nebula may have influenced the composition of the terrestrial planets.
Another effort is directed at determining the time of Moon formation, the growth of its first crust, and whether Moon formation is recorded in Earth history as would be expected if the Moon formed by ejection of materials into Earth orbit by a giant impact into Earth.
Carlson is also examining sections of the oldest crust on Earth. One of these is the Nuvvuagittuq terrane of northern Quebec where work is providing a strong argument that this crustal section formed via convergent margin related volcanic processes at roughly 4.3 billion years. He is also looking at isotope variation in ancient rocks from both Quebec and Greenland to determine formation processes.
Other projects include a multidisciplinary examination of the cause of modern volcanism in the Pacific Northwest using a combination of geochemistry and geochronology. A similar effort is underway in Mongolia.
Carlson received his B.A. in chemistry from UC-San Diego and his Ph. D. in Earth sciences from Scripps Institution of Oceanography. Before joining the Carnegie staff in 1981, he was a research and teaching assistant at Scripps and a postdoctoral fellow at Carnegie. For more see http://www.dtm.ciw.edu/people/richard-w-carlson