Upgrade of the Gravity Database

Abstract

The principal fact gravity database in Minnesota is comprised of over 59,000 measurements collected since 1950. It contains point location data, elevations, free-air and Bouguer anomaly values, field information and base U.S.G.S. quadrangle locations. Over the years gravity data in Minnesota has proven to be a useful resource for the Minnesota Geological Survey (MGS) in its mission of bedrock mapping, and it has provided mineral exploration companies with a significant supplement to exploration programs in Minnesota. Because much of the Precambrian bedrock in Minnesota lies beneath thick glacial deposits, gravity measurements, which are sensitive to density variations, are particularly helpful at inferring structures and rock types deep in the subsurface. The state-wide gravity data is most commonly used in conjunction with the high- resolution aeromagnetic data from Minnesota, which is highly sensitive to magnetic variations in the underlying Precambrian rocks.In 2003, the MGS released a state-wide gravity database with 57890 stations (gravity meter readings). This is an update to that database.