Charakterystyka węgli w południowo-zachodniej części GZW na podstawie zdolności odbicia światła witrynitu

Elżbieta Swadowska

Abstract


Zbadano zdolność odbicia światła witrynitu w pokładach węgla osadów karbońskich (od warstw załęskich do brzeżnych) południowo-zachodniej części GZW. Wykazano, że stopień zmetamorfizowania węgli określony współczynnikiem Ro wzrasta w profilu pionowym od warstw młodszych do starszych, natomiast nie wykazuje związku z pozycją stratygraficzną w rozprzestrzenieniu regionalnym. Metamorfizm przebiegał ze zmiennym natężeniem. Wysokie zmetamorfizowanie niektórych pokładów węgla związane jest z wpływem czynników towarzyszących działalności tektonicznej. Postępujący w profilu pionowym proces uwęglenia wpływał na zróżnicowanie stopnia zmetamorfizowania węgla w obrębie pokładu.

 

THE CHARACTERISTICS OF COALS FROM SOUTH-WESTERN PART OF THE UPPER SILESIAN COAL BASIN WITH REFERENCE TO LIGHT REFLECTION CAPABILITY OF VITRINITE

 

The paper presents results of studies on light reflection capability of vitrinite from coal seams in the Warszowice–Pawłowice and Bzie–Dębina regions, south-western part of the Major Basin, Upper Silesian Coal Basin. The studies covered the section of Carboniferous deposits from the Załęże to Brzeżne Beds. Degree of coal metamorphism was found to increase in the vertical from younger to older strata in accordance with the Hilt's principle.

Coalification gradient determined by increase in value Ro per 100 m increase in depth equals 0.06 at the average for the Załęże Beds, 0.07 for the Ruda Beds, 0.08 for the Siodłowe Beds and 0.12 for the Brzeżne Beds. The increase in degree of metamorphism of coals along with depth of occurrence of a seam indicates that this process still continues when critical degree of coalification is achieved.

The degree of coal metamorphism appears unrelated to stratigraphic setting in regional distribution.

This is indicated by higher values of light reflection capability of vitrinite (Ro) from individual seams in the Warszowice-Pawłowice region than in the same layers in the Bzie-Dębina region.

The process of metamorphism has been proceeding in the studied coals with varying intensity.

This phenomenon, recorded in the two studied regions, appears especially well-marked in the Warszowice–Pawłowice one, where coalification gradient equals 0,04 at depths down to 1000 m, rising to 0.09 at larger depths.

Attention should be paid to high values of the coefficient Ro in coal seam group from the borehole WP 32 and single seams (414/1 and 505/1 from the boreholes BzD 1 and BzD 8, respectively) occurring in tectonically disturbed zones. High metamorphism of coals in these seams in undoubtedly due to some factors accompanying the tectonic ones.

Attention should be also paid to coals of the Załęże Beds, encountered in the borehole BzD 4. The coals, although rather deep-seated (900–1400 m), are characterized by relatively low degree of metamorphism, markedly lower than of those found at the same depths in other boreholes in the Bzie–Dębina region. The low metamorphism of coal seams from the borehole column BzD 4 suggests their occurrence at smaller depths at critical moment of coalification that at present. The studies made it possible to trace changes in coal metamorphism in the vertical as well as to characterize the degree of coal metamorphism within individual coal seams. The seams with light reflection coefficient of vitrinite (Ro) equal about 1% are built of coals homogenous in degree of metamorphism. Along with increase in value of that coefficient, there is found increase in differentiation in degree of metamorphism in coal seam. When the value Ro is about 2%, coal seams are built of a mixture of coals markedly differing in degree of metamorphism.

 


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