The Wilhelmøya Formation (Upper Triassic-Lower Jurassic) at Bohemanflya, Spitsbergen

Abstract

1985: The Wilhelmeya Formation (Upper Triassic-Lower Jurassic) at Bohemanflya, Spitsbergen. Polar Research 3 n.s., 155-165. An 18.5 m thick shale sequence of Norian-Rhaetian age is described from the Bohemanflya-Syltoppen area (north of Isfjorden. central Spitsbergen). Lithological, petrographical and palynological analyses show that the sequence represents a marginal development of the lower part of the Wilhelmeya Formation. The depositional history at the Triassic-Jurassic transition is discussed in the light of this new evidence. The Wilhelmeya Formation was probably deposited during a weak marine transgression over an area of low relief. Low sediment supply and current and wave reworking of the sediments characterized the depositional conditions.

New Ginkgophytes from the Upper Triassic–Lower Cretaceous of Spitsbergen and Edgeøya (Svalbard, Arctic Norway): The History of Ginkgoales on Svalbard

“…The deposits on Edgeøya and Barentsøya have been interpreted as belonging to the De Geerdalen and Tschermakfjellet Formations (Mørk et al 1982). The De Geerdalen Formation is dated as Carnian but also extends into the Norian (e.g., Tozer and Parker 1968;Dypvik et al 1985;Dobruskina 1994;Dallmann et al 2001;Hounslow et al 2007;Vigran et al 2014). In some parts of Svalbard, the Kapp Toscana Group is not differentiated into constituent formations (Mørk et al 1982;Dallmann et al 2001;Hounslow et al 2007), as is the case on Edgeøya, where geological mapping and prospecting are not yet complete (NPI 2015a).…”

Preservation of phosphatic wood remains in marine deposits of the Brentskardhaugen Bed (Middle Jurassic) from Svalbard (Boreal Realm)

“…The lower part (the De Geerdalen Formation) is made up of grey shales grading upwards into immature sandstones (Dypvik et al 1985;Johnsen et al 2001). This interval has a number of coarsening-upward units showing increasing proportions of sandstone towards the southwest, northeast, and east.…”

“…This interval has a number of coarsening-upward units showing increasing proportions of sandstone towards the southwest, northeast, and east. The uppermost part (the Wilhelmøya Subgroup) forms a condensed clastic sedimentary succession containing some thin phosphatic nodule layers (Dypvik et al 1985;Johnsen et al 2001). The Kapp Toscana Group was deposited on Svalbard in a generally nearshore, deltaic environment; it is characterized by shallow-marine and coastal reworking of deltaic sediments.…”

“…In view of fossil assemblages obtained from the cores of the phosphatic nodules, Bäck-ström and Nagy (1985) proposed the depositional history of the Toarcian-Early Bathonian gap. During the Toarcian, a transgression reworked the deltaic sediments of the top of the underlying Wilhelmøya Subgroup (Kapp Toscana Group) over an area of low relief (Dypvik et al 1985). This resulted in a period of extremely low sedimentation rate and reworking of sediments by currents and wave activity (Knarud 1980;Mørk et al 1982).…”

“…The record in the Wilhelmøya Subgroup of phosphatic nodules (Dypvik et al 1985) and wood remains (Bäck-ström and Nagy 1985;Dypvik et al 1985;Krajewski 1989) suggests a potential source of such remains. The phosphatic nodules were most likely reworked in successive episodes as a consequence of sea-level changes, but their resistance favored the concentration and deposit in a gravel lag, the Brentskardhaugen Bed in which probably a new phosphatization episode occurred.…”