Abstract: This paper deals with a synthesis of the geophysics of the Quebec Appalachians. An emphasis is given to the regional geophysical surveys for the final geological interpretation. Regional, residual and downward continued aeromagnetic (AM) data yield information on the tectonic history of the region. The main features are pattern recognition of folded and particularly faulted structures and the boundaries of the tectonic domains. Three main fault systems have been identified and classified using AM information. In addition, depths to the crystallise basement and to the Cambro-Ordovician magnetic layers were obtained for sectors of the Gulf of St. Lawrence-Gaspé region. Nine main geological features are extracted from the processed AM data. Detailed geological modelling of some of the identified structures (e.g. nappes) are presented.Five main geological features are recognized from the gravity data. These features are correlated with the ones obtained from AM data whenever possible. Geological models based on information from surface geology, rock density contrasts and occasional contraints from regional seismic reflection data are presented. The boomerang shape of the Sutton-Bennett anticlinorium and the planar or curved slab-like shape of the obducted ophiolite bodies (upper mantle proto-oceanic floor) may be considered as the significant features.Regional reflection seismic data give a clear geological picture of three (out of four) distinguishable zones of the Quebec Appalachians, that is: autochthonous, parautochthonous, and transition zone: parautochthonous-allochthonous(corresponding approximately to the external domain). The pattern recognition of the allochthonous (approximate internal domain) is somewhat more difficult to decipher from the reflection seismic data. Intraplate seismicity and seismotectonics indicate the presence of four zones of high seismicity in southern Quebec. In almost all zones, the seismotectonic history goes back to Late Precambrian (Hadrynian) times.The scarce and scattered paleomagnetic data of geological formations located on the platform and the external domain of the Quebec Appalachians and in the internal domain are compared with those belonging to the stable North American plate. The paleomagnetic results indicate that the angular difference between the poles from the platform and external domain is large at Cambrian times (40°) and small at Devonian times (5°-10°). This suggests a fast rate of motion and accretion of the internal domain relative to the North American Plate in the Cambrian—Lower Devonian time span (∻550→-385 Ma).

EXPLOR_STEP=$WICRI_ROOT/Wicri/Lorraine/explor/InforLorV4/Data/Istex/Corpus

HfdSelect -h $EXPLOR_STEP/biblio.hfd -nk 003C42 | SxmlIndent | more

HfdSelect -h $EXPLOR_AREA/Data/Istex/Corpus/biblio.hfd -nk 003C42 | SxmlIndent | more

{{Explor lien
   |wiki=    Wicri/Lorraine
   |area=    InforLorV4
   |flux=    Istex
   |étape=   Corpus
   |type=    RBID
   |clé=     ISTEX:FBDAC260C6EF8AAB092D637B9066814337C39AA4
   |texte=   Geophysics of the Quebec Appalachians
}}