Macrofossils of the Wenlockian Slite Siltstone of Gotland

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Abstract
The Slite Siltstone, the uppermost unit in the Wenlockian Slite Beds of Gotland, Sweden, is fairly unfossiliferous as a whole, but the silty beds are intercalated with a few calcareous beds which contain a diverse and abundant fauna. The brachiopods Strophochonetes cingulatus and Plagiorhyncha cordata are the characteristic fossils of the siltstone. The preferred orientation of high-spired gastropods (Holopella sp.) and orthoconic nautiloids, recorded at two localities, was probably caused by sediment-sliding. Disarticulated Cypricardinia specimens occur in convex-up position and thus indicate a turbulent environment. An assemblage of Strophochonetes cingulatus has been found in life position, which shows that a rapid burial and a less turbulent environment are probable. The oriented fossils and the faunal composition show that the siltstone was deposited in a shallow marine environment, below the normal wave-base in the central area. In the north-cast and south-west of the siltstone extension, a shallower water depth seems probable. Large-scale transport of sediment was frequent. The presence of ‘Atrypa’ dormitzeri from the locality Svarvare 1 suggests a relation with assemblages from Scania and Bohemia. The siltstone fauna does not correlate with any depth-related assemblage from Wales or the Welsh borderland.