Distribution of Sabellidites (Annelida?) in the Basal Cambrian of the Digermulen Peninsula, Arctic Norway

University essay from Uppsala universitet/Institutionen för geovetenskaper

Abstract: The Digermulen Peninsula, Arctic Norway, offers a unique section of late Ediacaran to Cambrian sediments in an almost complete succession within the Vestertana Group. The proposed annelidan fossil Sabellidites cambriensis is found here, within the Lower Breidvika Member and is believed to exist also in the underlying Manndrapselva Member of the Stáhpogieddi Formation. Three cycles are recognized from the Manndrapselva Member, the uppermost being the third cycle, and the sediment interval of interest for this study ranges from the third cycle of the Manndrapselva Member to the Lower Breidvika Member where the Ediacaran–Cambrian boundary is situated. The distribution of Sabellidites has been investigated in three different localities on the Digermulen Peninsula, and from two of these stratigraphical logs were made and the sections were documented with photographs. The logs were created over sediments from Locality 1: Bárdeluovttjohka and Locality 3: Manndrapselva in the interval of the top of the Manndrapselva Member and Lower Breidvika Member. Previous studies have shown that the stratigraphical distribution of Sabellidites is within the Lower Breidvika Member. New results presented in this study extended the temporal distribution downwards in the third cycle of the Manndrapselva Member and closer to the Ediacaran–Cambrian boundary. The boundary is indicated by the trace fossil Treptichnus pedum. A few samples, collected from the logged sections, were found below the T. pedum level, indicating late Ediacaran origin. Three samples were collected even further down, close to the base of the Manndrapselva log, but these could only loosely be identified as Sabellidites and further analysis is required on these specimens. The Sabellidites distribution range from the Digermulen Peninsula was briefly compared to other locations and a global correlation is possible. The results here indicate that Sabellidites is an excellent reference taxon for the terminal Ediacaran and early Cambrian and that the succession on the Digermulen Peninsula may be one of the most important for global correlation across the Ediacaran-Cambrian boundary.

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