Density and magnetic susceptibility measurements on Precambrian rocks in the central Upper Peninsula, Michigan, 2021-2022

The U.S. Geological Survey (USGS) collected rock physical property measurements to help understand causative sources of gravity and magnetic survey anomalies in the central Upper Peninsula of Michigan. A total of 1,460 measurements of magnetic susceptibility and density from 61 outcrops and 37 boreholes have been conducted on Precambrian rocks. The measurements aid in interpretation of gravity and airborne magnetic data that are helping to understand Precambrian geology and potential mineral resources. For outcrop measurements, lithologic info is provided. Sample locations were determined using handheld Global Position System units. Measurements from drill core samples at the State of Michigan public core facility in KI Sawyer and the Cleveland Cliffs Inc. drill core facility in Ishpeming are also presented. For these measurements, the drill hole name, depth, and lithologic unit are provided. We thank Cleveland Cliffs Inc. for allowing access to their drill core facility and outcrops on their lands.