Malone finds Wisconsin’s oldest known rock

Dr. Shawn Malone (Geology) and two student coauthors, Kristal VandenElzen-Benson (Geoscience major) and Bruce Bilgreen (Geoscience ’23 graduate), presented at the 2024 Geological Society of America Conference on April 23, 2024. Their poster entitled “THE OLDEST ROCK IN WISCONSIN? SINGLE GRAIN ZIRCON U/Pb AND Lu/Hf DATA FROM WISCONSIN RIVER VALLEY GNEISSES HELP CHARACTERIZE THE ANCIENT MARSHFIELD TERRANE, PENOKEAN OROGENY” was about finding and age dating the oldest rock in Wisconsin. They used Uranium-Lead (U-Pb) Laser Ablation ICP-MS methods on tiny zircon grains found within a rock called a granitic gneiss. The rock is 3.268 billion years old and is from the Archean Marshfield Terrane near Wisconsin Rapids, WI.

You can find the presentation abstract here.