The lower Wenlock Hangvar Formation – a sequence previously split between the Högklint and Slite beds (Silurian, Gotland, Sweden)

Abstract

Conodont faunas solve the long-standing problem regarding the relationships between the Högklint, Tofta, and lower Slite. The name Hangvar Formation is here formally introduced for the strata identified between the Tofta Formation and the Slite Group. The Hangvar Fm. includes marls as far SW as near Paviken (previously Slite Marl), argillaceous limestones (seen only in the most distal areas accessible) followed by reefs and associated limestones SE and NE of Visby (previously Slite Beds, mostly units a and b) and northeastwards to eastern Fårö (from the area around Kappelshamnsviken and NE-wards, previously Högklint Beds). The formation is delimited below and above by prominent discontinuities i.e. sequence boundaries. These coincide with biostratigraphical boundaries, i.e. they probably represent relatively long time intervals. The Hangvar formation includes two subzones, hence lower and upper parts can be distinguished. The upper Hangvar reef generation is the third in the Wenlock of Gotland.

Key Words:

• Gotland
• lower Wenlock
• stratigraphy
• Tofta Fm
• Hangvar Fm
• Slite Group
• conodont zonation
• Ozarkodina sagitta rhenana Zone