Bedrock Geologic Map of the Putnam Lake Area, St. Louis County, Northeastern Minnesota

Abstract

This map was created by five students of the Precambrian Research Center under the guidance of Dr. George Hudak, Senior Research Associate at the Natural Resources Research Institute and Associate Director of the PRC. The map was produced from detailed (1:5000 scale) geological field mapping between August 6 and August 11, 2012. The resulting geological map is projected using a Universal Transverse Mercator (UTM) Grid, Zone 15, using the North American Datum of 1983 (NAD83). Base map LIDAR imagery, topographic contour lines, administrative boundaries, and hydrologic features were obtained as digital files from the Minnesota Department of Natural Resources Data Deli (http://deli.dnr. state.mn.us/) and the Minnesota Geospatial Information Office (http://www.mngeo.state.mn.us/chouse/elevation/lidar.html). A series of logging roads and trails provided access to the state public lands which were mapped during this exercise. This mapping was performed to: 1) conduct detailed property-scale mapping on the southwestern side of the Tower-Soudan Anticline which, to date, has only been mapped on a regional scale; 2) evaluate the supracrustal stratigraphy on the south side of the Tower-Soudan anticline, and try to make further correlations between stratigraphic units on the north side and southwest sides of the Tower-Soudan anticline; 3) to explore for evidence of syn-volcanic and/or post-volcanic hydrothermal alteration and associated mineralization in the eld area; and 4) evaluate the utility of using LIDAR basemaps for detailed geological mapping in heavily forested regions of greenstone belt terranes. Taken together, this mapping was performed to provide additional detail to existing regional geological maps of the Vermilion District (for example Peterson and Jirsa, 1999 and Peterson, 2005).