WORLD OF DISCOVERY: NATIONAL SCIENCE FOUNDATION GRANT FOR RECONSTRUCTING PAST ATMOSTPHERE AND OCEAN DYNAMICS USING GEOCHEMICAL TRACING OF DUST AND SEDIMENT
Determination of dust and sediment origins through geochemical approaches has allowed addressing far-reaching questions about past Earth system dynamics. For instance, provenance data have proven crucial to learning about the role of atmospheric dust in soil formation and as a nutrient source to marine and terrestrial ecosystems. These data have also illuminated the sources and transport histories of ice-rafted detritus in the North Atlantic and around Antarctica and have offered new insights on past changes in oceanic and atmostpheric circulation.
“I study past changes in Earth’s climate system using a combination of field and laboratory approaches. I am interested primarily in understanding how and why the atmospheric circulation has changed through time and the impacts these changes have had on terrestrial and marine environments.”
— Bess Koffman, Professor of Geology
Earth’s atmospheric circulation influences large-scale climate variability in several important ways: it affects the transport and delivery of oceanic heat; it exerts a strong influence on the exchange of carbon dioxide (CO2) between the ocean and atmosphere; and it plays a large role in determining global rainfall distribution. Further, because the atmosphere can respond rapidly to climate perturbations, it is central to understanding the mechanisms driving changes in Earth’s climate on a range of timescales.
While some regions have unique geochemical signatures, allowing discrimination of sources and tracing of particle transport using traditional isotopic approaches, the circum-Antarctic region presents a challenge. Despite recent refinements of potential source area fingerprints in South America and New Zealand, standard strontium-neodymium-lead (Sr-Nd-Pb) isotopic approaches do not give unique results for Antarctic ice core dust because key potential source areas share similar crustal histories. Among Southern Hemisphere dust sources, potassium/argon (K/Ar) geochronology provides a distinct and complementary perspective to that obtained by Sr-Nd-Pb radiogenic isotopes. A combined K/Ar and Sr-Nd-Pb radiogenic isotope approach will open the door to address research questions that have remained unresolved using traditional dust provenance techniques.