arktos: Sylfjellet: a new outcrop of the Paleogene Van Mijenfjorden Group in Svalbard

Malte Michel Jochmann1 and co-authors Lars Eivind Augland2, Olaf Lenz3, Gerd Bieg4, Turid Haugen5, Sten Andreas Grundvåg6, Mads E. Jelby7, Ivar Midtkandal8, Martina Dolezych3, and Hanna Rósa Hjálmarsdóttir1,9 have recently published an article in the journal arktos, titled “Sylfjellet: a new outcrop of the Paleogene Van Mijenfjorden Group in Svalbard”.

1 Department of Arctic Geology, The University Centre in Svalbard (UNIS), Norway
2 Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway
3 Senckenberg Naturhistorische Sammlungen Dresden, Germany
4 Gisela Bieg Mikroskopische Untersuchungen, Germany
5 Norges vassdrags-og energidirektorat (NVE), Region Nord, Norway
6 Department of Geosciences, UiT-The Arctic University of Norway
7 Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
8 Department of Geosciences, University of Oslo, Norway
9 Natural History Museum, University of Oslo, Norway

Abstract:

A hitherto unrecognized Paleogene outcrop has been discovered at Sylfjellet, a mountain located at the northern side of Isfjorden, Svalbard. The strata, which cover an area of 0.8 km2, have until now been assigned to the Lower Cretaceous succession of the Adventdalen Group. In this study, the Sylfjellet site was studied in detail to provide an updated structural and sedimentological description of strata and lithostratigraphy. The age and burial history of the investigated succession were constrained by absolute (U/PB) and relative dating methods in addition to vitrinite reflectance analyses of coal seams. The results show a Paleogene age of the deposits, which is supported by the occurrence of an angiosperm pollen grain, plant macrofossils, and a tephra layer of early Selandian age (61.53 Ma). The 250 m-thick succession of Sylfjellet is assigned to the Firkanten, Basilika and Grumantbyen formations. This succession unconformably overlies the Lower Cretaceous Helvetiafjellet Formation. Sylfjellet is incorporated into the West Spitsbergen Fold-and-Thrust Belt and interpreted to be a fourth structural outlier of the Van Mijenfjorden Group. Vitrinite reflectance data indicate that at least 2000 m overburden has been eroded above the Sylfjellet coal seams, and that maximum burial of the strata predates folding and thrusting in the area.

Keywords: Stratigraphy West Spitsbergen Fold-and-Thrust Belt Absolute dating Central Tertiary Basin Eurekan orogeny Vitrinite reflectance 

Reference:

Jochmann, M.; Augland, L.E.; Lenz, O.; Bieg, G.; Haugen, T.; Grundvåg, S.A.; Jelby, M.E.; Midtkandal, I.; Dolezych, M.; Hjálmarsdóttir, H.R. (2019): Sylfjellet: a new outcrop of the Paleogene Van Mijenfjorden Group in Svalbard. Arktos. First Online 05 Dec. 2019. DOI: 10.1007/s41063-019-00072-w. [intranet]