Grad student gets geology variety at NRRI
About 2.7 billion years ago in Minnesota, an ancient ocean wound around volcanoes that erupted both above and below water. Hot magma intruded into wet sediments, forming “peperite,” a sedimentary rock peppered with splotches of magma-derived basalt.
“Peperite deposits formed in an ancient volcano near Soudan in northern Minnesota,” says UMN Duluth graduate student Jacqueline Drazan. “Millions of years later, glaciers ground away the overlying rocks and exposed them.”
Drazan hopes to learn more about the processes that shaped those outcrops—knowledge that can be applied worldwide to similar deposits in Canada, Iceland, and Africa. To do that, she compares Minnesota’s ancient peperites to Icelandic specimens that formed a mere 43,000-12,400 years ago. Because they’re so young, the Icelandic deposits hold well-preserved clues to how these rocks form.
Drazan is mapping the Minnesota peperites because they are not extensively exposed—but their presence reveals more than ancient geological history.
“The environment where peperites form can be used as a marker where scientists can assess the economic potential of an area for certain minerals related to volcanic activity,” she says.
But Drazan doesn’t only like hard rock. A certain soft rock familiar to all Minnesotans also fascinates her: the mixtures used to fill potholes. She took a summer job with Natural Resources Research Institute scientist Larry Zanko to further develop and demonstrate a product made from waste taconite resources.
“We have a current mixture that is highly reliable during lab experiments and is promising in road-scale experiments,” Drazan says. “The repairs I worked on this past summer are currently being checked. We are looking to see specifically how they hold up over winter.”
And if you’re wondering about those hockey pucks in the accompanying picture, they are actually cylinders of pothole patch mixtures.