B. Beauchamp et Cm. Henderson, THE LOWER PERMIAN RAANES, GREAT BEAR CAPE AND TRAPPERS COVE FORMATIONS, SVERDRUP BASIN, CANADIAN ARCTIC - STRATIGRAPHY AND CONODONT ZONATION, Bulletin of Canadian petroleum geology, 42(4), 1994, pp. 562-597
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.