MAGNITUDE OF THE PYRENEAN DEVIATORIC STRE SS IN THE NORTH PYRENEAN FORELAND

This Note is a preliminary attempt to determine the magnitude of the m ajor deviatoric stress related to the Pyrenean compression in the nort hern foreland of the Pyrenees collision belt. Our results, based on a combined analysis of fault slip and calcite twin data, suggest that th is deviatoric stress, horizontal and submeridian, decreases northwards , from 60-70 MPa near the Pyrenees to about 20-30 MPa in the Paris bas in. These values probably correspond to the maximum values of the tect onic deviators applied during the Eocene Pyrenean orogeny. They are di scussed and compared with the results obtained in the Appalachian fore land and with recent data on the distribution of present-day lithosphe ric stresses.