Sammendrag
The transition from the Upper Permian chert dominated successions to the soft, fine-grained clastics of the early Triassic Sassendalen Group has, in combination with sedimentological work, been studied for palynology in order to establish a stratigraphic framework applicable for relative dating. The new basal Triassic Hindeodus parvus conodont Zone as defined in China is clearly overlying beds with Otoceras boreale implying that the basal beds of the Sassendalen Group are of late Permian age.
Samples from 21 sections in transitional beds from Tempelfjorden and the lower part of the Sassendalen Group in Svalbard were analyzed for palynology. Not all sections yielded productive samples and preservation varies considerably. Several shallow stratigraphic cores and exploration wells are studied in addition, adding important knowledge about the palynofloras.
The upper Permian palynological assemblages of the Tempelfjorden Group are dominated by gymnosperm pollen. A marked change to a total dominance of spores in the earliest Triassic is characteristic.
In the lowermost part of the Sassendalen Group consistently occurring “typical Permian” species represent characteristic elements of the ammonite dated Griesbachian succession. Based on relatively consistent occurrence through the Griesbachian and their gradual fading-out we consider them as in situ. However, the recent definition of the Permian/Triassic boundary also renders that the lowermost Sassendalen Group belong to the latest Permian. Traditionally the lithological boundary was considered as the P-T boundary.
Changes in spore-pollen assemblages representing a subtle succession of recovery following the globally recognised end Permian extinction, has resulted in a high resolution palynostratigraphic framework of seven composite assemblage zones spanning the five million years of the Early Triassic. Five of these zones are calibrated to the boreal ammonoid zonation.
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