NEW SEISMIC IMAGES OF THE CRUST IN THE CENTRAL TRANS-HUDSON OROGEN OFSASKATCHEWAN

A reprocessing program to enhance the correlation between the surface geology and the seismic data has been completed for seismic line 9 (ea stern 100 km) and line 10 in the central region of the Trans-Hudson Or ogen of Saskatchewan, Canada. The new seismic images through lateral c ontinuity of reflectivity provide sufficient detail to resolve the dis crepancy between the low-dipping, layer-parallel and dextral-reverse n ature of the Sturgeon-Weir shear zone (line 9) observed in the field a nd its steeply dipping (apparent) normal displacement character interp reted on the basis of the initial processing. Furthermore, the new int erpretation provides a strong confirmation of the role of Pelican Thru st as a major detachment zone - the main 'sole thrust' - along which j uvenile allochthons have been carried across the Archaean microcontine ntal block. The images are also refined enough to suggest: (a) a bound ary within the Pelican Thrust between its internal and external suites ; (b) a possible boundary separating a lower (older?) Archaean basemen t from its upper (younger?) counterpart: and (c) sub-Moho events (M2) which reveal possible involvement of the upper mantle in the collision al tectonic process in addition to the well defined Moho (M1) which pr obably represents the youngest of the post-collisional detachments. (C ) 1998 Elsevier Science B.V. All rights reserved.