SEDIMENTOLOGY AND DEPOSITIONAL ENVIRONMENT OF THE LOWER DEVONIAN WAPSKE FORMATION, PERTH-ANDOVER MOUNT-CARLETON REGION, NORTHWESTERN NEW-BRUNSWICK

The Lower Devonian Wapske Formation of the Tobique Group in the Perth- Andover/Mount Carleton region, northwestern New Brunswick, forms part of the tectonostratigraphic Tobique Zone. In this area, the formation, 4000 to 9000 m thick, is interpreted to comprise seven regionally rec ognizable sedimentary facies. These are: conglomerate facies (Facies 1 ), massive and parallel-laminated sandstone facies (Facies 2), thin- t o thick-bedded sandstone with minor mudstone interbeds and/or mud-capp ed facies (Facies 3), thin-bedded sandstone and mudstone facies (Facie s 4), thin-bedded, graded, fine-grained sandstone facies (Facies 5), v ery thin-bedded, fine-grained sandstone and silty mudstone facies (Fac ies 6), and thin- and medium-bedded siltstone and mudstone facies (Fac ies 7). The absence of unequivocal shallow-water sedimentary structure s, depositional cycles and in situ body fossils in these lithofacies a nd, instead, the presence of Bouma depositional sequences and deep-wat er trace-fossil associations, is supportive of a deep-marine origin (b elow storm-wave base) for the Wapske Formation in the study area. Acco rdingly, the facies are grouped into five facies associations interpre ted to reflect a deep-marine fan system comprising distributary channe ls, depositional lobes, lobe or fan fringes, and interchannel areas as sociated with a basin plain. Regional considerations suggest that the Wapske Formation records a transition from shallow-water marine, local ly terrestrial, deposition to the east and southeast of the study area , to deep-water deposits, as described herein, to the west and northwe st in the Perth-Andover/Mount Carleton region.