The positions of supercontinents are largely unknown for 95 percent of earth’s history. This means that the period which included the rise of life, an increase of oxygen, the formation of continents, and a number of dramatic climate changes, is not geologically well understood.
Professor David Evans’ research hopes to change that by expanding our understanding of earth’s history back to the Precambrian period. By studying patterns of global geodynamics, this research can help to create long term models of ancient climate change and evolution.
Through researching ancient crustal fragments called cratons, the project hopes to get a sense of what the world looked like 2.6 to 1.7 billion years ago.
Taylor Kilian, a graduate student working with Professor Evans, has the specific project of looking at the Wyoming craton (which lies underneath Wyoming and parts of Montana, Idaho, South Dakota, and Colorado) in order to determine its position during that time period. Once it is established, the position of the Wyoming craton can be compared to the position of other ancient fragments all over the world.
In Wyoming, we will be travelling to mountain ranges where the craton comes to the surface, and looking for dikes—sheets of igneous rock that were once part of volcanoes. As Taylor described it, these sheets of rock are not always easy to find or sample, so it can be “a bit of a treasure hunt.”
The reason Taylor is looking for igneous rocks has to with paleomagnetism—the magnetic direction the rock assumed when it cooled relative to the North or South Pole. Igneous rocks have a high percentage of magnetic minerals, so they provide the best measure of magnetic direction.
In next week Taylor’s group plans to travel to sites in the northeastern Bighorn Mountains, moving into the central Bighorns in the second week. In the third week, we will switch scenery and move into the Ferris and Seminoe Mountains in central Wyoming.