Location of the Precambrian Plate Boundary in the NW USA from Gravity and Magnetic Data

P028 LOCATION OF THE PRCAMBRIAN PLATE BOUNDARY IN THE NW USA FROM GRAVITY AND MAGNETIC DATA KEVIN MICKUS SW Missouri State University Department of Geosciences 65807 Springfield USA 1 SUMMARY Gravity and aeromagnetic data are used to map the location of the Precambrian continental margin in the northwestern United States plus determine tectonic features beneath the Columbia River Plateau basalts (CRPB). The Precambrian boundary may follow a sharp northwest-trending magnetic gradient that also marks the boundary of several residual gravity maxima. The Proterozoic Belt Basin is distinguished by a regional gravity minimum that extends to 118 o W beneath the