Gravity and Magnetic Expression of Terranes in France and Their Correlation Beneath Overstep Sequences

Abstract

The geological basement of France appears to be composed of different terranes having various corn-positions. The presence of these bodies, even if concealed beneath the cover, is reflected by the pattern of gravity or magnetic data. These geophysical techniques are excellent criteria, that allow a real discrimination of granite-rich zones from mafic-rich areas in plan view. Sutures and plate boundaries are also easily characterized by studies of potential field character; their dip is best defined by gravity and magnetics, since mafic rocks incorporated in the major scars are never imaged on seismic reflection records.