CONTENTS & ABSTRACTS
In English. Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Volume 50 No. 2 June 2001
Trace fossils Didymaulichnus cf. tirasensis and Monomorphichnus isp. from the Estonian Lower Cambrian with a discussion on the early Cambrian ichnocoenoses of Baltica; 75–85(full article in PDF format)
Sören JENSEN and Kaisa MENS
Abstract. The bilobed trace fossil Didymaulichnus cf. tirasensis Palij in the Lower Cambrian Voosi Formation of western Estonia adds to the small number of pre-trilobite Cambrian trace fossils identified from Estonia. A possible earliest Cambrian Baltica trace fossil province, including trace fossils with an undulating bilobed and three-lobed lower surface, of which D. tirasensis is an example, is proposed. In Baltica traces of this type occur also in the Ukraine and northern Scandinavia. In each occurrence they are associated with vertical spiral traces and precede the local first appearance of arthropod-type trace fossils. The earliest Estonian arthropod-type trace fossil, Monomorphichnus isp., described here from the Sõru Formation, belongs to the trilobite-bearing Lower Cambrian.
Key words: ichnofossil, Didymaulichnus tirasensis, Monomorphichnus isp., Voosi Formation, Sõru Formation, Lower Cambrian, Estonia.
A new subspecies of the clitambonitidine brachiopod Estlandia catellatus from the middle Ordovician of Osmussaar Island, Estonia; 86–94(full article in PDF format)
Abstract. A new subspecies Estlandia catellatus odini is described from the Uhaku Stage of Osmussaar Island in Estonia. The unusual co-occurrence of three representatives of the genus Estlandia (E. marginata (Pahlen), E. pyron pyron (Eichwald), and E. catellatus odini subsp. nov.) in one bed in Osmussaar Island may have resulted from their partial post-mortem concentration from different habitats.
Key words: Brachiopoda, Gonambonitidae, Estlandia catellatus odini subsp. nov., Ordovician, Llanvirn, Estonia.
Middle Artinskian (early Permian) ecological event: case study of the Urals and northern Timan; 95–113(full article in PDF format)
Olga L. KOSSEVAYA, Ekaterina A. Guseva , Alexander E. LUKIN, and Andrei V. ZHURAVLEV
Abstract. Biotic and abiotic changes established in the middle Artinskian of several sections of the northern Timan and the western slope of the Central Urals are discussed. Data on the distribution of corals, composition of the biota as a whole, palaeotemperature and microfacies changes are presented for the first time. The determination of the stratigraphic levels is based on the new and revised biostratigraphic data. The palaeotemperature decline coincides with the maximal flooding surface and is considered as a possible cause of the ecological event triggering the turnover or extinction of many faunal groups. The event level was recognized in the coeval deposits along the Pangea shelves.
Key words: middle Artinskian event, biota turnover, sequence stratigraphy, oxygen and carbon isotopes.
Waterlain glacial diamicton along the Palivere ice-marginal zone on the West Estonian Archipelago, Eastern Baltic Sea; 114–127(full article in PDF format)
Volli KALM and Ene KADASTIK
Abstract. On both the distal and proximal sides of the Palivere end-moraine zone on the West Estonian Archipelago, a sporadic distribution of up to 25 m thick subaqueous waterlain glacial diamicton (WGD) was observed. The WGD lies at an altitude between – 15 and + 10 m relative to contemporary sea level. During the Palivere stadial the distribution area of the WGD was at least 50–60 m below the water table of the Baltic Ice Lake. The WGD was deposited at the grounding zone of the glacier by continuous subaqueous basal meltout from floating ice with minor involvement of sediment flows, dumping, and grounding. In texture, the WGD resembles glaciolacustrine clay with increased amounts of gravel and clay fractions. Compared to the basal tills of the area, the WGD contains less gravel (21.5% and 6.8%, respectively) but is rich in silt and clay fractions. Petrographic, mineralogical, and chemical analyses show a similar source for the Palivere basal till and the WGD.
Key words: Late Weichselian, glacial diamicton, sedimentology, Estonia.
Lepistiku buried peat, Tallinn, Estonia; 128–134(full article in PDF format)
Leili SAARSE, Siim VESKI, and Avo MIIDEL
Abstract. The Lepistiku buried peat section, part of Mustamäe Bog, was studied in Tallinn, North Estonia. It has been a spring-mire, which started to form behind the beach formations about 4700 BP due to land uplift and was situated near the maximum limit of the Litorina Sea (21–22 m a.s.l.), at an elevation of about 16–17 m a.s.l. From the beginning of the 19th century, the construction of marine forts and other military objects destroyed the forest cover of the area around the bog and provoked aeolian processes, due to which the southern part of Mustamäe Bog was covered by sand. The aeolian processes lasted up to the 1960s, when Mustamäe housing district was built.
Key words: buried organic sediments, radiocarbon dating, Holocene, Tallinn, Estonia.