pdf № 298, October

DOI: 10.19110/2221-1381-2019-10-5-11

The results of studies of organic matter and technological features of coal from a number of deposits of the Pechora coal basin are presented. Based on data on the composition of biomarker hydrocarbons, data on the thermal maturity of organic matter (OM) of coal are confirmed, assumptions are made about the influence of aquatic and terrigenous vegetation on the formation of the initial OM, and differences between its composition for brown coals concentrated in the southern part of the Pechora coal basin are shown, and coal of the northern areas of the basin. The work demonstrates the possibility of obtaining an ash-free concentrate — the so-called hypercoal by extraction of the initial coal with N-methylpyrrolidone at the boiling point of the solvent in high yields and the similarity of the structure of the obtained product with the structure of the organic mass of the initial coal.

Keywords: Permian coal, Pechora coal basin, hydrocarbon-biomarkers, hypercoal.

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DOI: 10.19110/2221-1381-2019-10-12-15

The rise of forests in the Mid and Late Devonian has attracted much attention as potential drivers of the Earth System. In this context it is important to understand what groups contribute to the first wetlands found at the Devonian palaeoequator. A time series of Devonian coals shows that the palaeoequatorial Mid and Late Devonian humic (vitrinite rich) coals are dominated by the lycopod microspore Cymbosporites and megaspore Verrucisporites that can be confidently associated as the spores from Protolepidodendropsis. This plant has successfully colonised and probably created the wetland coal environment by the ability to shallow root and hence anchor the trees above the anaerobic layer. The progymnosperm Archaeopteris is abundant from its spores in Devonian palaeoequatorial sediments but plays no role in these coal forming wetlands. More rigorous age dating shows that there is some evidence for a Tournaisian coal gap.  

Keywords: Mid and Late Devonian, Early Сarboniferous, coals, evolution of wetlands.

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DOI: 10.19110/2221-1381-2019-10-16-22

The representative sections outcropping shallow-water and deep-water Devonian/Carboniferous successions in the East of Pechora Plate (Kamenka River section and Vangyr River section) are considered in respect of facies, conodont, and ostracode changes. In the Kamenka River section the D/C boundary beds are composed of bioclastic limestones interbedded with dark-gray clays (lower part of the Edzhid Fm.). The deposits contain abundant and diverse benthic ostracodes of Pseudoleperditia tuberculifera — Coryellina alba — Cribroconcha primaris ostracode Zone, and diverse conodont associations of praesulcata and sulcata zones. The negative shifts in d¹³C_org in conodont organic matter accompanied by weak positive shift in d¹³C_carb in bulk carbonates suggest eutrophic conditions in the lagoon environment and disbalancing of the trophic web at the terminal Famennian. D/C boundary beds in the Vangyr River section are represented by calciturbidites, pelagic carbonates, and shales (Izyayu Fm.). Transgressive phase of Hangenberg Event is marked by the black shale layers. The Upper Famennian conodont associations are dominated by Palmatolepis gracilis group; the ostracodes compose diverse associations of Turingian and slope ecotypes. The D/C boundary is marked by appearance of conodonts Siphonodella sulcata in associations with ostracodes Armilla uralica.

Keywords: Devonian-Carboniferous boundary, conodonts, ostracodes, biostratigraphy, Hangenberg Event, Pechora Plate.

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DOI: 10.19110/2221-1381-2019-10-23-27

The relevance of detailed studying Givetian-Frasnian sedimentation is defined by a proceeding discussion about a level of the lower Frasnian Stage bound (according to border of Middle and Upper Devonian) in the Eastern European platform. New results of investigation in a boundary between Middle and Late Devonian within the Southern and Middle Timan presented. There are a correlation between even-aged palynocomplexes in adjacent territories; determination of the new palynozone, which details Lower Frasnian sedimentation; establishment of higher plants spores associations features formed in continental, coastal and sea facies.

Keywords: biostratigraphy, higher plants spores, the Southern and Middle Timan, boundary sediments of Upper and Middle Devonian.

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DOI: 10.19110/2221-1381-2019-10-28-38

Conodont and ostracode distribution in the Timan (Middle — Upper Devonian, Upper Givetian — Lower Frasnian), Ust’-Yarega (Upper Devonian, Lower Frasnian) and Yba (Middle? — Upper Devonian, Upper Givetian? — Lower Frasnian) formations of Southern Timan was analyzed. The regional and interregional correlation of the established associations was conducted. The significant changes in conodont and ostracode associations are observed almost at the base of the Ust’-Yarega Formation, and they are associated with a gradual increase in the depth of the paleobasin. The conodonts of Ancyrodella rugosa and Mesotaxis asymmetricus appearing at this level characterize the Ancyrodella rugosa conodont Zone. The ostracodes of the Ust’-Yarega Formation are represented by the assemblage of the Cavellina chvorostanensis — Entomozoe (R.) scabrosa Zone. The significant changes in the conodont associations of the Yba Formation reflect an important sequence of appearance of the index-species: Mesotaxis falsiovalis, Ancyrodella rotundiloba soluta, Ancyrodella rotundiloba rotundiloba. The Ancyrodella soluta conodont Zone provide a reliable correlation of the sections of the Timan-North Urals Region and are essential for resolving the issue of the lower boundary of the Frasnian stage of the Upper Devonian in the East European Platform.

Keywords: conodonts, ostracodes, biostratigraphy, correlation, Southern Timan, Givetian-Frasnian boundary interval.

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DOI: 10.19110/2221-1381-2019-10-39-42

We presented results of comparative physical and chemical studies of the organic matter of Devonian brown coals and rocks with carbonized plant residues from Northern Timan. We used IR Fourier spectroscopy of diffuse reflection, ESR spectroscopy, quantitative chemical analysis, pyrolytic gas chromatography-mass spectrometry.

Keywords: brown coal, carbonized plant residues, Devonian, Northern Timan, physical-chemical research methods.

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