THE LOWER PERMIAN RAANES, GREAT BEAR CAPE AND TRAPPERS COVE FORMATIONS, SVERDRUP BASIN, CANADIAN ARCTIC - STRATIGRAPHY AND CONODONT ZONATION

The current late Paleozoic stratigraphic system of the Sverdrup Basin fails to acknowledge the presence of a major unconformity-bounded sequ ence, one that is mostly Artinskian (Early Permian) in age and consist s of three distinctive mappable lithostratigraphic units. These strata have previously been assigned to different sequences and to various l ithostratigraphic units. This problem is solved with the erection of t hree new formations: the Raanes, Great Bear Cape and Trappers Cove for mations. The Raanes Formation consists of generally recessive shale, s iltstone, moderately fossiliferous, argillaceous and silty limestone, mixed elastic-carbonate, and fossiliferous limestone (mixed ramp, grab en fill and horst blanket) that overlies the Nansen and correlative fo rmations. The Great Bear Cape Formation comprises resistant, pure to l ocally sandy, variably cherty, highly fossiliferous limestone (shelf, shelf-edge and upper slope) that overlies either the Raanes or the Tra ppers Cove formations. The Trappers Cove Formation is composed of dark -grey to black siliceous shale and spiculitic chert and minor yellowis h-weathering fossiliferous limestone (middle to lower slope, basin) co rrelative with the Great Bear Cape and the Raanes formations. These th ree formations are of Artinskian (Lower Permian) age; strata contained in the upper part of the Great Bear Cape and Trappers Cove formations are latest Artinskian to early Kungurian age. Five conodont zones are here formally defined and documented for the first time in the Canadi an Arctic based on material recovered from various sections, including the type-sections of the new formations. The five zones, which are co rrelated with stratotype sequences in Russia, include: 1) Zone P6a: Ne ogondolella bisseli-Adetognathus paralautus Partial Range Zone (lower Aktastinian); 2) Zone P6b: Sweetognathus inornatus-Adetognathus parala utus Concurrent Range Zone (upper Aktastinian); 3) Zone P7: Neogondole lla bisselli-Sweetognathus whitei Partial Range Zone (lower Baigendzhi nian); 4) Zone P8: Neostreptognathodus pequopensis-N. clarki Concurren t Range Zone (lower Baigendzhinian); and 5) Zone P9: Neostreptognathod us prayi-N. ruzhencevi Concurrent Range Zone (upper Baigendzhinian to Kungurian). The Raanes, Great Bear Cape and Trappers Cove formations f orm the bulk of a low-order unconformity-bounded transgressive-regress ive (T-R) sequence of the Sverdrup Basin. This sequence of latest Sakm arian-Late Artinskian age is represented by the uppermost Nansen and c orrelative formations, by the entire Raanes Formation, and by the grea ter part of the Great Bear Cape and Trappers Cove formations. The latt er two formations also contain strata belonging to an overlying latest Artinskian-Kungurian sequence. The transgressive part of the latest S akmarian-Late Artinskian sequence is recorded in the uppermost Nansen and correlative formations, in the Raanes Formation, and locally in th e basal part of the Great Bear Cape Formation. The regressive part of the sequence is contained in the Great Bear Cape and correlative Trapp ers Cove formations. The Raanes-Great Bear Cape contact closely corres ponds with the maximum flooding surface, which coincides with a major tectono-climatic event in the Sverdrup Basin. Rocks below that surface were deposited in a semiarid tropical setting during a phase of activ e tectonism; rocks above that surface accumulated in a much cooler tem perate setting at a time of passive regional subsidence.