The Silurian Upper Burgsvik and Lower Hamra-Sundre Beds, Gotland
Stel & de Coo, Silurian U. Burgsvik and L. Hamra-Sundre Beds, Gotland, Scripta Geol. 44 (1977) 1 The Silurian Upper Burgsvik and Lower Hamra-Sundre Beds, Gotland Jan H. Stel and Jan C. M. de Coo Stel, J. H. & J. C. M. de Coo. The Silurian Upper Burgsvik and Lower Hamra- Sundre Beds, Gotland. — Scripta Geol., 44: 1-43, 29 figs., Leiden, December 1977. Five facies are recognized in the Upper Burgsvik and Lower Hamra-Sundre Beds on account of a lithological and paleobiological analysis: I) siliciclastic, II) bio- clastic, III) oolitic/pisolitic, IV) oncolitic/biostromal, and V) crinoidal facies. The facies represent five depositional environments: a beach, a fore-shore, a surf, a shallow marine current, and an off-shore environment. The diversity and colony shape of tabulates in facies IV is related to discrete physical and biological fac- tors. The succession of facies reflects a transgressive sequence. Land was situated in the north-west. Jan H. Stel, Geologisch Instituut der Rijksuniversiteit Groningen, Melkweg 1, Groningen, The Netherlands; Jan C. M. de Coo, Geologisch en Mineralogisch Instituut der Rijksuniversiteit Leiden, Garenmarkt 1B, Leiden, The Netherlands; present address: Shell Tunirex, 24/26 Place de l'Afrique, Tunis, Tunisia. Introduction 2 Lithology (J. C. M. de Coo) 4 Rock types 4 Grain types 5 Facies 10 Sections 11 Interpretation 17 Paleobiology (J. H. Stel) 19 Life assemblages 19 Algal environment 26 Trophic analysis of the fauna 27 Interaction of algae and tabulates 32 Sponge biostromes in the Lower Hamra-Sundre Beds 36 Conclusions 37 Appendix 40 References 41 2 Stel & de Coo, Silurian U.
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