MIDDLE PALEOZOIC TEAR FAULTING, BASIN DEVELOPMENT, AND BASEMENT UPLIFT, CENTRAL CANADIAN ARCTIC

The Boothia Uplift of the central Canadian Arctic Islands, located som e 1200 km west of the Caledonian collision zone, is a ''Laramide-type' ' basement-cored uplift that affected Precambrian crystalline basement and lower Paleozoic carbonate platform sequence. The two major segmen ts of the Boothia Uplift, separated by the east-trending Barrow Strait , had different deformational histories. In the southern segment, upli ft of the basement began in Late Silurian time, while in the northern segment, there was subsidence and platform drowning. In the northern s egment, a thick sedimentary succession, containing numerous potential detachment surfaces, was involved in Early Devonian deformation.Foldin g of the cover along northerly trends resulted in the longitudinal inf illing of two small, synclinal basins in the hanging wall of the uplif t. The type of basin fill was dependent on source proximity and was in fluenced by contemporaneous flexure of the sedimentary cover. The west ern basin, the Grove Lake basin, received predominantly terrestrial se diments, and the eastern one, the Sutherland River basin, received mos tly marine sediments, including a thick, possibly submarine, synsedime ntary breccia that accumulated in response to tilting of partly lithif ied, carbonate strata. Southward-transported clastic sediments of the basin-fill sequence and contours showing the amount of pre-Emsian eros ion suggest that a high-angle tear fault influenced sedimentation in t he Grove Lake basin. The areally restricted and variably transported s yntectonic clastics of the northern segment are different from coeval clastics of the southern segment. This is attributed to different defo rmational histories along the uplift and, in particular, to the deform ation of a thick, locally anisotropic sedimentary cover sequence in th e northern segment. A thick Emsian to early Eifelian carbonate platfor m sequence onlapped the eroded Boothia Uplift which had acted as a pal eohigh for some 10 - 15 Ma. Early Devonian basement faults appear to h ave been reactivated as dextral wrench faults during Tertiary time.