Organic-walled microfossils and organic fossils across the Ediacaran–Cambrian boundary on the Digermulen Peninsula, Arctic Norway

• The Digermulen Peninsula, Arctic Norway, contains one of the most complete Ediacaran–Cambrian sedimentary rock successions on Baltica. The boundary interval spans the Manndrapselva Mbr of the Stáhpogieddi Fm. and the Lower Mbr of the Breidvika Fm.Abundant organic-walled microfossils (OWM) and organic fossils (OF) in the second and third cycles of Manndrapselva Mbr and the lower part of the Breidvika Fm., coupled with a rich record of trace fossils reinforces the potential of the area for detailed biostratigraphic studies of the Ediacaran–Cambrian transition.The second cycle of the Mandrapselva Mbr, with simple trace fossils and the Ediacaran- confined problematicum Harlaniella podolica, contains a low diversity of OWM represented by abundant filamentous cyanobacterial sheaths, thick-walled sphaeromorphs, Pterospermopsimorpha sp. and Leiosphaeridia spp. Organic fossils include abundant tussled masses of nano-scale filament interpreted as degraded sabelliditid tubular fossils. The third cycle, which yields the first occurrence of the trace fossil Treptichnus pedum, include a similar assemblage of OWM, and the first appearance of Granomarginata prima, a cosmopolitan acritarch with a first appearance in the Cambrian. Close to the base of the third cycle there is an increased diversity of OF, including the appearance of Ceratophyton at a level approximating the first T. pedum. In the upper part of the third cycle Cochleatina is found.The Lower Mbr of the Breidvika Fm. yields productive samples in levels below the lowest occurrence of the arthropod-type trace fossil Rusophycus. The association remains one of low diversity, with the continued presence of Ceratophyton and nano-scale filaments, the latter abundant in levels with rich occurrences of Sabellidites cambriensis but absent at levels close to the appearance of Rusophycus. Basal levels of the Breidvika Fm. yield the first process-bearing acritarchs, represented by rare specimens of the small and weakly ornamented Asteridium tornatum. There are also abundant clusters of Symplassosphaeridium sp. Compared to Manndrapselva Mbr there is a decrease in thick-walled sphaeromorphs.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Annan geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Other Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Digermulen

Ediacara

Cambrian

organic walled microfossils

Cochleatina

Granomarginata prima

Historical Geology and Paleontology

Historisk geologi och paleontologi

Publikations- och innehållstyp

vet (ämneskategori)

kon (ämneskategori)