Coal seams of the Walbrzych formation, Intrasudetic Basin, Poland: inferences on changing depositional environment
The University of British Columbia, Department of Geological Sciences, 6339 Stores Rd., Vancouver, B.C. V6T 1Z4, CanadaInternational Journal of Coal Geology (Impact Factor: 3.38). 04/1992; 20(s 3–4):243–261. DOI: 10.1016/0166-5162(92)90016-P
The petrological composition of coal seams of the Walbrzych Fm. was studied, and depositional conditions were reconstructed on the basis of both coal and clastic sediment analysis. Coal of this formation is of medium- to low-volatile bituminous rank; vitrinite reflectance Ro max ranges from 0.8 to 2.0% and volatile matter content from 29 to 16%.The coal seams of the Walbrzych Formation contain mainly banded coal; bright and dull lithotypes occur sporadically. The amount of banded and banded dull coals increases towards the top of the formation at the expense of banded bright coal. Consequently, vitrinite and vitrite content tends to decrease upwards. Peat deposition in the lower part of the Walbrzych Formation occurred predominantly in a telmatic forest zone. The mires were located between interdistributary channels on a delta plain, and they were probably ombrotrophic. In the upper part of the Walbrzych Formation, swamps were the primary sites of peat deposition. Abandoned channels were favoured as peat deposition sites for seams where increases in seam thickness are associated with increases in coarse clastic content below seams. Continuous peat deposition in overbank zones is postulated for seams wherein decreases in seam thickness are associated with increases in coarse clastic content. Where no relationship between seam thickness and coarse clastic content beneath the seam exists, the swamp may have encroached into overbank and channel zones rapidly. Changes in the environment of peat deposition may be related to tectonic activity along the basin margins during the Namurian.
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ABSTRACT: Lithotype variations in the coal seams of the Westphalian żacler Formation were studied with reference to their maceral and microlithotype composition. District variability of lithotypes and petrography in particular seam sections have been observed. Generally, semibright coals predominate in the coal seams of the NW part of the Intrasudetic Basin (the Wałbrzych area), whereas in the Nowa Ruda area (E part) the seams studied consist mostly of bright lithotypes. The variation in lithotypes is directly related to petrographic variation on the microscopic scale. The seams studied predominantly contain vitrite, vitrinertite- vitrite, and trimacerites in particular parts of the Intrasudetic Basin. Megascopic lithology and petrography of coals are the result of the different coal deposition environments.Organic Geochemistry 02/1993; 20(2):295-313. DOI:10.1016/0146-6380(93)90046-E · 3.07 Impact Factor
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ABSTRACT: Extensive Westphalian D to Stephanian coal seams divide the Sydney Mines Formation of Cape Breton Island into large-scale repetitive sedimentary packages. The Backpit seam, one of the most continuous seams within this formation, was studied in detail to establish compositional trends and relate these to paleomire development within an overall transgressive setting. The seam is of high-volatile B to A bituminous rank and ranges in thickness from 0.6 to 1.5 m onshore. Agglutinated foraminifera occur in strata directly below and above the seam, indicating a coastal setting for the mire. Ash and sulphur contents average 15.3 ± 6 and 5.2 ± 2%, respectively. Sulphur, predominantly in the form of pyrite, increases near the roof of the seam, consistent with a brackish influence in the roof strata.The planar Backpit mire was subjected to widespread, periodic flooding, marked by thin dull to coaly shale lithotype intervals. Some intervals can be correlated across the onshore portion of the basin for more than 45 km and this distribution suggests regional controls on their formation. Seam lithology changes frequently in vertical section and banded lithotypes predominate. Vitrinite macerals and vitrinite-rich microlithotypes are abundant and thin discrete fusain bands, the remains of ancient fires, are also common. Coal facies patterns record a series of wetting upward pulses in the upper portion of the seam that culminated in the drowning and termination of the mire. A broad, relatively shallow embayment subsequently formed that supported a fresh- to brackish water fauna.Palaeogeography Palaeoclimatology Palaeoecology 01/1994; 106(1-4):223-239. DOI:10.1016/0031-0182(94)90012-4 · 2.34 Impact Factor
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ABSTRACT: The Carboniferous succession of the Intrasudetic Basin is an important source of medium- and low-volatile bituminous coal in Poland. Three lithostratigraphic units comprise this succession: the Walbrzych, Bialy Kamien and Zacler Formations. The Walbrzych Formation (Namurian A) is a 300 m thick (maximum) succession that is composed of fining-upward cyclothems with over twenty coal seams.The northern part of the Intrasudetic Basin was very favorable for peat deposition during Namurian A times and coal seams generally are thicker in this region. In some seams, the greates seam thickness occurs along the eastern margin of the basin. Seam thickness in seam 678 is relatively uniform, whereas coal and clastic parting thickness varies greatly in seams 672 and 664/665. In seam 672, the greatest seam thickness occurs above channel zones, which suggests that abandoned channels were sites favorable for peat deposition. Coal in such zones is typified by increased liptinite content. In contrast, the greatest thickness in seam 664/665 is associated with floodplain sediments. In such regions, bright coal/clastic parting couplets occur repetitively proximal to natural levees, whereas duller coal with few dirt bands is characteristic of the central part of backswamps. Peat deposition in the lower part of the Walbrzych Formation occurred dominantly in ombrotrophic mires, whereas swamps were primary sites of peat deposition in the upper part of this formation. Coal quality parameters vary considerably within each seam and more data are needed to determine the factors influencing them.Palaeogeography Palaeoclimatology Palaeoecology 01/1994; 106(1-4):157-169. DOI:10.1016/0031-0182(94)90008-6 · 2.34 Impact Factor
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