The Frænkelryggen Formation is a geologic formation in Svalbard, Norway. The fluvial sandstones and green shales preserve flora and early fish fossils dating back to the Lochkovian stage of the Early Devonian period.
Description
Defined at the Frænkelryggen mountain () by Kiaer in 1918, the formation was originally described as Silurian, later dating of the formation provided likely ages between 413.5 and 411 Ma, dating the formation to the Lochkovian stage of the Early Devonian. The formation belongs to the Red Bay Group, conformably overlying the Andréebreen Formation and overlain conformably by the Ben Nevis Formation.
The formation comprises sandstone and green shales deposited in a fluvial environment.
Fossil content
The Frænkelryggen Formation has provided fossils of:
Vertebrates
Anglaspis insignis
Dinaspidella robusta
Poraspis brevis
P. polaris
Machairaspis sp. Waengsjoeaspis sp.
Flora
Calamospora nigrata
Cyclogranisporites plicatus
Emphanisporites minutus
Granulatisporites muninensis
Leiotriletes parvus
Pachytheca cf. fasciculata
Punctatisporites glabar
?Taeniocrada spitsbergensis
Prototaxites sp. ?Zosterophyllum sp. Hostinella indet.