Dr. Randy Van Schmus

My overall research interests are the application of U-Pb, Sm-Nd, and Rb-Sr geochronology and radiogenic isotope geochemistry to the evolution of Proterozoic continental crust, its tectonic history, and its role in Proterozoic supercontinent cycles.   Specific regions of interest have included the Great Lakes area (Minnesota-Wisconsin-Upper Michigan-Ontario), northern Saskatchewan, the Northwest Territories of Canada, basement rocks of the U.S. midcontinent, Proterozoic terranes in northeastern Brazil and pre-drift extensions into West Africa, southwestern parts of the Amazon craton, and portions of the Ross orogen in Antarctica.   The major orogenic cycles span the interval from 2200 Ma to 500 Ma, and one of my goals is to relate coeval cycles in diverse continents to each other on a global scale (where justified) and sequential cycles in specific areas to modes of continental growth.

Projects on Precambrian crustal evolution of northeastern Brazil and its relationship to the assembly of western Gondwana.  This project has been supported by NSF for our part of the work (primarily geochronology and isotopic studies) and involves collaboration with several colleagues and students in Brazil. I also have an on-going collaboration with a colleague in Cameroon to examine aspects of the same problem in western Africa.  I have had a long interest in the Proterozoic crustal evolution of North America, and I am continuing that interest through a collaborative project on late Paleoproterozoic granites in Minnesota and Wisconsin with Dan Holm (Kent State) and Terry Boerboom (Minn. Geol. Survey), and I maintain a continuing interest in analysis of the buried basement of the midcontinent (as new samples are discovered).  Finally, I am doing U-Pb analyses of zircons from the Ross orogen in Antarctica as part of a collaborative effort with Ed Stump (Arizona State).  Active student projects involve studies in the midcontinent region, Brazil, and Wisconsin, and several other opportunities exist.