Vardebukta Formation

The Vardebukta Formation is a geologic formation in Norway. It preserves fossils dating back to the Induan stage. Outcrops are known from the Hornsund area but also from Bellsund and Isfjorden areas.

Subunits

The Vardebukta Formation is divided into the Urnetoppen Member and the overlying Wibebreen Member. Both members are of marine origin. They were deposited in a sublittoral to shallow-neritic environment. The Vardebukta Formation represents the oldest Mesozoic formation in Svalbard.

Urnetoppen Member

The Urnetoppen Member, which is approximately 30 meter thick in the Hornsund area, consists of greenish shales, siltstone and fine-grained sandstone, occasionally with clay-ironstone nodules. In the Hornsund area, it rests paraconformably on the Permian Kapp Starostin Formation. The Urnetoppen Member is correlated with the Deltadalen Member of the Vikinghøgda Formation, which is of Dienerian age.
The top of the Urnetoppen Member contains the so-called Brevassfjellet Myalina beds, a 5–6 meter thick, fossiliferous conglomerate.

Wibebreen Member

The Wibebreen Member is ca. 90–100 meter thick in the Hornsund area. It consists of black to light-grey coloured shales, marly shales, arenaceous marls and siltstone. The lower part of this member contains mainly siltsone layers. The locally developed Skilisen Retzia Limestone belongs to the uppermost part of the Wibebreen Member. The Wibebreen Member is overlain by the Smithian aged Lusitaniadalen Member of the Vikinghøgda Formation.

Paleobiota

Fossiliferous layers of the Vardebukta Formation are concentrated to the uppermost part of the Urnetoppen Member. These Dienerian aged beds have yielded the bivalves Myalina and Anodontophora, crinoids, conodonts, numerous isolated fish remains, and trace fossils.

Fish

The isolated fish teeth of bony and cartilaginous fishes have been described from the Brevassfjellet Myalina Bed of Hyrnefjellet, Hornsund. The bony fish teeth are mostly tentatively referred to Saurichthys sp.