CONTENTS & ABSTRACTS
In English. Summaries in Estonian
Proceedings of theEstonian Academy of Sciences.
Geology
Volume 50 No. 2June 2001
Trace fossilsDidymaulichnus cf. tirasensis and Monomorphichnus isp. from the Estonian LowerCambrian with a discussion on the early Cambrian ichnocoenoses of Baltica;75–85
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Sören JENSEN andKaisa MENS
Abstract. The bilobed trace fossil Didymaulichnus cf. tirasensis Palij in the Lower Cambrian Voosi Formation of westernEstonia adds to the small number of pre-trilobite Cambrian trace fossilsidentified from Estonia. A possible earliest Cambrian Baltica trace fossilprovince, including trace fossils with an undulating bilobed and three-lobedlower surface, of which D. tirasensisis an example, is proposed. In Baltica traces of this type occur also in theUkraine and northern Scandinavia. In each occurrence they are associated withvertical spiral traces and precede the local first appearance of arthropod-typetrace fossils. The earliest Estonian arthropod-type trace fossil, Monomorphichnus isp., described herefrom 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 Estlandiacatellatus from the middle Ordovician of Osmussaar Island, Estonia; 86–94
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Olev VINN
Abstract. A new subspecies Estlandia catellatus odini is described from the Uhaku Stage of OsmussaarIsland in Estonia. The unusual co-occurrence of three representatives of thegenus 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 partialpost-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 theUrals and northern Timan; 95–113
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OlgaL. KOSSEVAYA, Ekaterina A. Guseva ,Alexander E. LUKIN, and Andrei V. ZHURAVLEV
Abstract. Biotic and abioticchanges established in the middle Artinskian of several sections of thenorthern Timan and the western slope of the Central Urals are discussed. Dataon the distribution of corals, composition of the biota as a whole,palaeotemperature and microfacies changes are presented for the first time. Thedetermination of the stratigraphic levels is based on the new and revisedbiostratigraphic data. The palaeotemperature decline coincides with the maximalflooding surface and is considered as a possible cause of the ecological eventtriggering the turnover or extinction of many faunal groups. The event levelwas recognized in the coeval deposits along the Pangea shelves.
Key words: middle Artinskianevent, biota turnover, sequence stratigraphy, oxygen and carbon isotopes.
Waterlain glacial diamicton along the Palivere ice-marginal zone on theWest Estonian Archipelago, Eastern Baltic Sea; 114–127
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Volli KALM and EneKADASTIK
Abstract. On both the distal andproximal sides of the Palivere end-moraine zone on the West EstonianArchipelago, a sporadic distribution of up to 25 m thick subaqueouswaterlain glacial diamicton (WGD) was observed. The WGD lies at an altitudebetween – 15 and + 10 mrelative to contemporary sea level. During the Palivere stadial thedistribution area of the WGD was at least 50–60 m below the water table ofthe Baltic Ice Lake. The WGD was deposited at the grounding zone of the glacier by continuous subaqueous basal meltoutfrom floating ice with minor involvement of sediment flows, dumping, andgrounding. In texture, the WGD resembles glaciolacustrine clay with increasedamounts 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 siltand clay fractions. Petrographic, mineralogical, and chemical analyses show asimilar source for the Palivere basal till and the WGD.
Key words: LateWeichselian, glacial diamicton, sedimentology, Estonia.
Lepistiku buried peat, Tallinn, Estonia; 128–134
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Leili SAARSE, SiimVESKI, and Avo MIIDEL
Abstract. The Lepistiku buried peatsection, part of Mustamäe Bog, was studied in Tallinn, North Estonia. It hasbeen a spring-mire, which started to form behind the beach formations about 4700 BP due to land uplift and was situatednear the maximum limit of the Litorina Sea (21–22 m a.s.l.), at anelevation of about 16–17 m a.s.l. From the beginning of the 19th century, theconstruction of marine forts and other military objects destroyed the forestcover of the area around the bog and provoked aeolian processes, due to whichthe southern part of Mustamäe Bog was covered by sand. The aeolian processeslasted up to the 1960s, when Mustamäe housing district was built.
Key words: buriedorganic sediments, radiocarbon dating, Holocene, Tallinn, Estonia.
