Ages and Differentiation Series of the Batholiths Near the Minnesota-Ontario Boundary
Introduction During the last ten years the great batholiths of northeastern Minnesota have been visited many times and studied in considerable detail by parties of the Minnesota Geological Survey. The work has now reached a stage where a summary of the broader relations of these masses can be presented with some confidence. The succession of events disclosed by the study is somewhat more complex than that supposed by earlier workers. The essential facts can perhaps be best indicated by descriptions and sketches of two areas and by brief notes on the others. It is a pleasure to acknowledge the help received in this work from geologists of the Minnesota Geological Survey and from the Graduate School of the University of Minnesota, which provided funds that made the chemical studies possible. Basis of the Age Determination The ages of the batholiths along the boundary have been determined largely by their relations . . .