Estonian Journal of Earth Sciences 

About: Estonian Journal of Earth Sciences is an academic journal published by Estonian Academy Publishers. The journal publishes majorly in the area(s): Ordovician & Geology. It has an ISSN identifier of 1406-0132. It is also open access. Over the lifetime, 397 publications have been published receiving 3640 citations. The journal is also known as: Izvestiâ Akademii Nauk èestonii. & Eesti Teaduste Akadeemia toimetised..

Calcareous tubeworms of the Phanerozoic

Abstract: Morphological similarities indicate that Palaeozoic problematic tubeworms, e.g. tentaculitids, cornulitids, microconchids, trypanoporids, Anticalyptraea, and Tymbochoos, form a monophyletic group. This group may also include hederelloids. Members of this group share affinities with lophophorates and their evolution could have partly been driven by predation. The extinction of Palaeozoic tubeworms in the Middle Jurassic was possibly at least partly caused by the ecological pressure by serpulid and sabellid polychaetes. The input of Palaeozoic tubeworms to the general ocean biocalcification system may have been smaller in the Ordovician to Jurassic than that of calcareous polychaetes in the Late Triassic to Recent. There seems to have been some correlation between the aragonite-calcite seas and the skeletal mineralogy of Triassic-Recent polychaete tubeworms.

The succession of Hirnantian events based on data from Baltica: brachiopods, chitinozoans, conodonts, and carbon isotopes

Abstract: The Hirnantian (late Ordovician) environment was complex and dynamic. Understanding the correct order of events and their precise correlation with a time scale are extremely important for the development of different kinds of environmental interpretations. The lower boundary of the Hirnantian Stage is officially defined by "the lowest occurrence of Normalograptus extraordinarius, the base of major positive carbon-13 isotope excursion, and the beginning of a pronounced sea-level fall associated with onset of a major glaciation" (ICS website). Our aim is to check if these events are synchronous, particularly how the situation is with respect to the Baltic. Thus several sections were analysed using mainly East Baltic data (drill cores), but also data from elsewhere, including brachiopod, chitinozoan, and conodont biostratigraphy combined with graptolite and carbon isotope data. Brachiopod faunas of the Pirgu and Porkuni stages are rather similar to those of the Ellis Bay Formation of Anticosti Island, Quebec, but the Pirgu assemblage, as well as that of the lower Ellis Bay Fm. lack key elements of the Hirnantian faunas. The primary criterion quoted above is stable, but auxiliary data like the isotope curve are less convincing. When the latter is used, it should be specified, e.g. that the carbon isotope excursion begins usually slightly earlier (in the Diceratograptus mirus Biozone), but it might be conventionally placed into the N. extraordinarius Biozone when a biostratigraphical proxy is available. The peak of the excursion is in the lower N. persculptus Biozone, but the main increase in values takes place in the N. extraordinarius Biozone. The Spinachitina taugourdeaui Biozone marks at many localities the bottom of the Hirnantian, and only the recent chitinozoan-graptolite data from the topmost Lousy Cove Member (on Anticosti Island) suggest a mid-Hirnantian age, which is at variance with common correlation schemes.

Ordovician conodont diversity in the northern Baltic

Abstract: The diversity data presented in this paper are based on recently revised collections of conodonts from outcrops (northern Estonia) and core sections of Estonia and western and northern Latvia. Based on variations in the abundance of taxa, four intervals with different general trends in diversity changes can be recognized in the Ordovician part of the succession: (1) the proavus-crassus zones and (2) crassus-anserinus zones, both intervals forming quite distinct diversity cycles; (3) the variabilis- ventilatus zones, characterized in general by stable diversity values, and (4) the ventilatus Zone-the topmost Ordovician, with a steady increase in diversity up to the ordovicicus Zone, followed by a decline during the End-Ordovician Extinction Event. Diversity was lowest in the earliest and latest Ordovician but reached maximum values at the end of the Early Ordovician radiation of conodonts, in the middle and upper Darriwilian, and just before the start of the End-Ordovician Extinction Event. Four supersequences (transgressive-regressive cycles) are proposed here for the northern Baltic Ordovician succession. The diversity changes recognized in the conodont succession demonstrate general correlation with these supersequences: boundaries between supersequences are characterized by low diversity values; diversity increases more or less rapidly in the lower, transgressive parts of the supersequences and decreases in their upper parts.

Three global carbon isotope shifts in the Silurian of Podolia (Ukraine): stratigraphical implications

Abstract: Podolia is a classical Silurian area in the southwestern part of the Ukraine. Shallow to open shelf rocks cropping out there are usually, except for a few dolomitic horizons, highly fossiliferous and therefore the biostratigraphy of the region has a long successful history. The Ukrainian meeting of the Subcommission on Silurian Stratigraphy of the International Union of Geological Sciences, held in 1983, became an important milestone. Tsegelnyuk et al. summarized different results and views in a field guide published for the meeting (The Silurian of Podolia. The Guide to Excursion. Naukova Dumka, Kiev, 1983) and introduced a practically new stratigraphical terminology, and in some parts of the section, also new age interpretation of the beds. For our paper carbon isotopes were studied in eight sections on the banks of the Dniester River and its tributaries, covering ca 80% of the Silurian succession (Pridoli excluded). Three positive δ 13 C excursions were identified. The first excursion in the Kitaigorod 30 section reaches its peak value of 4.0‰ in the very bottom of the Demshin Subformation. The second shift reaches the peak value of 4.3‰ in the middle of the Muksha Subformation. The third shift is the most prominent one identified in the Silurian of Podolia - δ 13 C values increase steadily through the Isakovtsy Subformation, reaching 6.9‰ in the top, and a slightly lower value of 6.6‰ occurs in the bottom of the Prigorodok Formation. In the "middle" Silurian of the World three major positive excursions have been identified: in the early and latest Wenlock and in the late Ludlow. The general character of the carbon isotope trend and stratigraphical positions of the excursions established in this paper demonstrate that in Podolia there occurs the same set of global shifts, which can be used for the improvement of regional and global correlation of Wenlock and Ludlow sections of that area. Some refinements are suggested, but some details need additional study.

The wave climate and its seasonal variability in the northeastern Baltic Sea

Abstract: The basic features of wave properties in the Baltic Sea and their seasonal variations are estimated by the use of a highresolution version (3 miles) of the wave model, WAM, driven by adjusted geostrophic winds for 1970–2007 under ice-free conditions. The model qualitatively reproduces the time series of the sea state and adequately replicates the seasonal patterns of wave intensity and the probability distribution functions for different wave heights in both offshore and coastal regions of the northern Baltic Proper and the Gulf of Finland. The areas of the largest overall wave activity are located in the eastern parts of the Bothnian Sea and northern Baltic Proper, south of Gotland, and in the Arkona Basin. The windiest season (September–February) and the time with the largest measured or modelled wave activity (October–March) occur with a time lag of 0.5–2 months.