The Hunneberg Stage (Ordovician) in the area east of S. Petersburg, north-western Russia

• The bio- and lithostratigraphy of the poorly knownearly Ordovician (Arenig) Hunneberg Stage is described fromthe area east of St. Petersburg (Putilovo Quarry and Lava river),where the Lakity Beds (Leetse Fm.) consist of glauconiticsands and silty clays. The described fauna includes graptolites,conodonts, brachiopods, acritarchs, foraminifers, and severalproblematic groups. The Lakity Beds are unique within thelower Ordovician sequence of the East Baltic in the abundanceof graptolites, co-occurring with conodonts. The conodontsfrom the lower part of the Lakity Beds belong to the uppermostsubzone (Oelandodus elongatus - Acodus deltatus deltatus) ofthe Paroistodus proteus Zone, coinciding with the lower partof the Tetragraptus phyllograptoides Zone. This suggests thatthere is a hiatus between the Lakity Beds and the underlyingNazya Formation. The lower Lakity Beds also contain thebrachiopods Leptembolon lingulaeformis and Eosiphonotretacf. acrotretomorpha, which suggest that they may be correlatedwith the Joa Member of the Leetse Formation in NorthEstonia. In the upper part of the Lakity Beds, conodonts of thePrioniodus elegans Zone co-occur with graptolites indicatingthe upper subzone of the Tetragraptus phyllograptoides Zonein the Scandinavian sections. There are still problems of definingand correlating the base of the Billingen Regional Stage,which are outside the scope of this paper.

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NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

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