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The occurrence of anthracites in an area characterized by lower rank coals in the Upper Silesian Coal Basin of Poland
International Journal of Coal Geology, 7 (1987) 209-225 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
209
T h e o c c u r r e n c e of a n t h r a c i t e s in an a r e a c h a r a c t e r i z e d by l o w e r r a n k coals in the U p p e r S i l e s i a n Coal B a s i n of P o l a n d W. GABZDYL and K. PROBIERZ
Institute of Applied Geology, Silesian Technical University, ul. Pstrowskiego 2, 44-100 Gliwice, Poland (Received August 5, 1987; revised and accepted April 10, 1986)
ABSTRACT Gabzdyl, W. and Probierz, K., 1987. The occurrence of anthracites in an area characterized by lower rank coals in the Upper Silesian Coal Basin of Poland. Int. J. Coal Geol., 7: 209-225. The resultsof petrographical-geologicaland chemical examinations on anthracites, semianthracites and medium-low volatilebituminous coals from Jastrzebie in the Upper SilesianCoal Basin of Poland are presented. The coking coals mined in this region exhibit volatilematter vd~f= 18-26%, free swellingindex FSI= 3-8 and reflectanceR m = 1.10-1.35% and are inertiniterich coals (I= 25-63%). Coal Seam 504 of the Anticlinalbeds (NamurianB) has been affectedby thermal metamorphism and contains both coking coalsand coalsof higher rank. According to the criterionof Polish Standards thiscoalseam variesfrom anthracite (V d~f < 10 % ) to semianthracite (vd~f= 10-14 % ) in rank. The carbon content is slightlylower and the hydrogen content a littlehigher than those of typical anthracitesand semianthracites.The reflectancevalues (Rm = 1.56-2.62% ) are generally lower than the Rm values proposed by the International Committee for Coal Petrology as boundary values for anthracites and bituminous coal.The magnitude of anisotropy and microhardness were also examined. Examinations of opticalpropertiesprove that the metamorphism exhibited by the coals isthe resultof elevatedtemperature and variablepressure.The analyses of the maceral composition indicatethat there is a decrease in the inertinitecontent in anthracites. Vitriniteexhibitsthe featuresof thermally alteredcoal.The micrinitecontent shows a littlevariation.In coking coals,a strongly fluorescingbituminous substance with the optical features of exsudatinite was found. The constructed geologicalsection of Coal Seam 504 shows distinctregular changes in chemical and physical properties as well as the petrographic composition which may be caused by the heat fluxof a m a g m a intrusion,not localizedso far.
INTRODUCTION A n t h r a c i t e s in t h e U p p e r S i l e s i a n C o a l B a s i n o f P o l a n d are n o r m a l l y f o u n d in b o r e h o l e s a t d e p t h s g r e a t e r t h a n 1000 m. T h e i r o c c u r r e n c e a t t h e s e d e p t h s is t h e r e s u l t o f r e g i o n a l m e t a m o r p h i s m . I n t h e a r e a studied, h o w e v e r , a n t h r a -
0166-5162/87/$03.50
© 1987 Elsevier Science Publishers B.V.
210
cites occur at relatively shallow levels, in association with coking coal ( medium-low volatile bituminous coal) that is now mined. The occurrence of both anthracite and coking coal in the Jastrzebie region has been established by underground working at a depth of 430-480 m in Coal Seam 504 (Namurian B). In the present work, investigations of changes in some chemical and physical properties as well as the petrographic composition of coals in this seam are presented. Geological mapping and studies in the Jastrzebie region have documented the presence of strong secondary alteration of minor magma intrusions in the Upper Carboniferous sediments, high mineralization of deposit waters and a high gas content (CH4). Geophysical investigations indicate an increased geothermal gradient in relation to the remaining parts of the Upper Silesian Coal Basin. The occurrence of both medium and highly metamorphosed coals may thus be the result of thermal metamorphism. As yet, the presence of a larger intrusion has not been found ( Kuhl, 1963; Gabzdyl, 1964; Gabzdyl et al., 1969; Chodyniecka and Sankiewicz, 1972; Kowalski, 1977). GEOLOGICAL FEATURE OF THE JASTRZEBIE REGION
The Jastrzebie region lies in the southwestern part of the Main Basin of the Upper Silesian Coal Basin and covers the axis zone of the Jastrzebie syncline (Fig. 1). In the western synclinal flank, that seams show a variable degree of dip of 4-20 ° and in the eastern flank that of 4-12 °. Through the western part of the region the Orlova-Boguszowice overthrust runs at a dip of 40-50 ° to the west and with vertical displacements up to 1000 m. In the eastern part of the region exists an asymmetrical Jastrzebie anticline of a dip of 40-50 ° in the western flank and that of 15-25 ° in the eastern flank. The documented coexistence of anthracite and coking coal is found in the southern part of the Jastrzebie region along the line of disappearance of Coal Seam 504 and appearance of a series of red beds that do not contain coals (Fig. 2 ). The lithostratigraphical profile of the Jastrzebie region comprises Carboniferous formations consisting of the Por~ba beds ( Namurian A), Anticlinical beds ( Namurian B) and Ruda Beds ( Namurian C ). The Carboniferous overburden with a thickness of 200-800 m consists of Tertiary and Quaternary formations. The Por~ba beds examined so far only by boreholes, consist predominantly of mudstones and claystones with thin coal seams. The Anticlinal beds are prominent sandstone series with thicknesses of 200-290 m and contain 9 workable coal seams of 2-6 m thick. The Ruda beds, lithologically similar to the Anticlinal beds, contain 17 workable coal seams. The coal mined from the seams of the Anticlinal and Ruda beds is charac-
211
~!~,
TamowskieG ~
o, o ~ .
LEGEND ---Boundary
of Upper Silesian Coal Basin
Ovlrthrust: a - Michalkowice- Rybnik b- @IowaBoguszowice ~-Zone of fold tectonics J - - - l - Study area --~--~-./mtrzglxe Anticline --.- ---- - Jastrz,ebie 5yncline i , •
_
Fig. I. Tectonic scheme of the Upper Silesian Coal Basin. ~
"
"~
vh
I#_111 ..Io/D 4
-
.-~"~- i~mvolsvelar - ,,, o - samples - mine roads ~ - - strike and dip of bed -
LEGEND ~-red beds ® - borehole JAS. t ~ ~-Jostrzgbie syrlclino axis ~-~ - seam thickness
Fig. 2. Geological m a p of the study area showing variation of the volatile matter content in Coal Seam 504. The m a p was prepared on the basis of a larger number of samples than shown.
212 m.
o
--~ >~,.
200
Miocene
~
C r~e~ Rud" bed. -
_.~ z
~.':. . .
.........
--~ ~
c.s.504/2
BI:-:-:-:-:t '
600.
LEGEND - red beds
"
-
rnudstone
Anticlinal beds
~
~::i
~-
.,o,s,o.e
. . . . . . . . .
Polo b°ds
AI: : : : :
¢.s. 603
i-:----
' c.s. 606
~
- sond,tone
I -
cool seom
BO0~
Fig. 3. Lithologic profile of borehole JAS. 1.
terized by volatile matter V~ = 18-26%, free swelling index F S I = 3-8 and mean reflectance of vitrinite Rm oil= 1.10-1.35% and belongs to a medium-low volatile bituminous coal. The petrographic composition shows an increased inertinite content ( I = 25-63% ). The higher coal-bearing rocks of the Jastrzebie region almost disappear in borehole JAS.1 in the proximity of coexisting anthracites and coking coal (medium-low volatile bituminous coal). In this borehole in the Ruda and Anticlinal beds, only Coal Seam 504 occurs (Fig. 3 ). EXPERIMENTAL
Examinations were carried out on channel samples taken from Coal Seam 504 in the area where its thickness is 1.4-2.2 m (Fig. 2). The chemical properties were characterized by volatile matter content ( V ~ ) , moisture (Ma), ash content (A a), free swelling index (FSI) and the contents of carbon ( C ~f) and hydrogen ( Hdaf). Their values were determined by standard methods obligatory in Poland (Polish Standards; see Appendix 1 ). The optical properties were examined with a MPV-2 Leitz microscope using immersion oil of refractive index no= 1.5176 at a temperature of 24+273 K and wavelength 2 = 546 nm. The mean reflectance of vitrinite (Rm oil ) was measured on the polished surfaces according to the recommendations of the International Committee for Coal Petrology (ICCP) and Polish Standards (PN) and their standard deviations (sR) were calculated. R=~ and R=i. were measured on block specimens and then the magnitude ofbireflectance ( R ~ x - Rmin) was determined. Vickers microhardness of vitrinite (HV) was determined with a PMT-3 LOMO instrument. The measurements were made under a load of 0.5 N (50 G ) applied for 15 seconds. The standard deviations (sn) were then calculated. Petrographic examinations covered the analysis of macerals performed in compliance with the ICCP recommendations and Polish Standards. Special
213 TABLE 1 Position of coals from Jastrzebie in the International Classification of Coal (ECE, Geneva, 1956) CLASS NUHBER oct. t~te~ a~cmio. EGE, b~f~mv~o 1956 ~te g
Q daf
~t
8
"
S 4
,.dnf
2 0 - -
V--: % t
COALS from JASTRZI~IE UpperSib.sian Coal Basin of Poland
3
4
-
-
2 t 0 - 1
~----6-----
~ -
LowVole~
Bituminous [coking coat)
Semianthmc/te Anthracite
0
attention was paid to the petrographic differentiation of the inertinite group and a possible presence of fluorescing bituminous substance. The results of the measurements and examinations were used to draw maps and construct a cross-section. The maps were drawn based on a uniform interpolation and the isolines were drawn by parallel method. C H E M I C A L PROPERTIES
Examination of volatile matter contents, which is essential for distinguishing between anthracites and semianthracites according to the Polish Standards, pointed to the presence of: (1) anthracites of vd~f< 10% (4.77-9.53%); (2) semianthracites of vd~f-- 10-14% (11.76-13.12%); and (3) coking coals of vd~f> 14% (18.58-20.58%). No coals of 14-18% V d~f content were found in the area. The rank of the coals according to the International Classification of Coals (Geneva) is presented in Table 1. The technological and chemical data are shown in Table 2. Coals with vd~f< 14% occurred in an area of about 250 × 350 m (Fig. 2 ). The isovols depict an elongated syncline parallel to the axis of the Jastrzebie syncline. The course of the isovols is similar to the lines of disappearance of Coal Seam 502/1 which lies 20 m higher than Coal Seam 504 (Fig. 4 ). In the area bordered by isovol vd~f< 14% the coking properties in the seam disappear. The free swelling index isolines are similar to the isovols. Coking properties ( S I - 1 - 4 ) were found in the seam outside the isovol contour vd~f>~14% (Fig. 5).
214 TABLE
2
S o m e chemical data of the coals from Jastrzebie Sample
V d~f' %
SI
M ~ %
A "~ %
C~ %
H d~f' %
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
4.77 7.30 8.02 8.62 9.13 9.53 11.76 12.68 13.12 18.58 20.18 20.58
0 0 0 0 0 0 0 1/2 0 1 4 3
1.07 0.80 0.86 0.90 0.90 0.83 0.78 0.73 0.69 0.94 0.90 0.98
4.38 5.68 3.50 4.44 1.92 9.62 2.76 5.38 9.44 4.52 4.22 5.20
92.16 91.00 89.59 88.99 91.59 89.01 90.28 88.99 89.77 88.03 89.95 88.66
3.10 3.56 3.36 3.32 3.70 4.04 3.96 3.98 4.15 4.43 4.55 4.95
ida/=dry, ash free; 2M=--moisture; 3AS= ash content calculated in the analytical state. No distinct differences in the moisture contents between anthracites, semianthracites and coking coals were found. Irrespective of the coalification degree the ash content in the coals examined is low (1.92-9.44%). The sulphur content does not exceed 0.6%. The anthracites, semianthracites and coking coals differentiated by Vd~ do not differ greatly in chemical composition, since: (1) anthracites contain Cd~f=88.99-92.16% and Hd"f=3.10-4.04%; (2) semianthracites contain Cd~f=88.99-90.28% and Hd~f=3.96-4.15%; and (3) coking coals contain Cd~f= 88.03-88.95% and Hd"f= 4.43-4.95%. However, a general increase of the Cd~ content with a decrease of the Vd~fcontent and a more significant decrease in H d~fis observable. The isolines of C d'f and H d~fconfirm this finding (Figs. 6 and 7). A lack of correlation between the boundaries determined by Vd~f and C d~f can be attributed to the different petrographic compositions. LEGEND o= zo-
503/1-2
~ -
50&12
~
cloystone - mudstone
- sandstone 4o-
60
~
- coal seam
505/t
Fig. 4. Localization of Coal Seam 504 in the lithologic profile of the Anticlinal beds (Namurian
B).
215
SI(¢~~.~}6 ""-'"k~.._...,
Fig. 5. Variation of free swellingindex in Coal Seam 504. The map was prepared on the basis of a largernumber of samples than that given here. REFLECTANCE
AND MICROHARDNESS
OF VITRINITE
Examinations of rank have indicated that there is a good correlationbetween the differentiationof coals according to R . and H V values and that based on V d'f (Table 3). Speciment VII is the only exception. The reflectance and microhardness of the distinguished groups are as folC ~f , y0
H°°f, Z
oV,O
,,,///
F -.
" ~
¢~Pfv, ," ~.~
v,,
..-~~,,~ 11 .7
--'--~. I\~~----~._~ ,,
~/I
,.o
\\,~S- )
~?
;~/
oV~o vJ
-
~,~_~- -
I
vi
~
~o,o
~
2~/I.. - /
~,
,','
-,
>,\, /
o, ,oo, ~oo.."~ . ~
Fig. 6. Variation of carbon content in Coal Seam 504. Fig. 7. Variation of hydrogen content in Coal Seam 504.
N
r
.
216 TABLE 3 Physical properties of coals from Jastrzebie Sample
Rmoil
sR
%
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
2.62 2.20 2.56 2.42 1.82 1.65 1.68 1.56 1.57 1.32 1.25 1.28
0.16 0.12 0.14 0.15 0.09 0.07 0.09 0.07 0.07 0.07 0.09 0.06
Rmax
Brain
Rm,x Rmin
HVso
%
%
%
MPa
2.80 2.39 2.65 2.51 1.92 1.84 1.77 1.77 1.84 1.45 1.32 1.40
2.03 1.88 2.25 2.09 1.51 1.39 1.31 1.35 1.33 1.17 1.14 1.19
0.77 0.51 0.40 0.42 0.41 0.45 0.46 0.42 0.51 0.28 0.18 0.21
83.6 68.9 84.2 96.7 60.0 60.7 49.1 44.1 42.8 34,7 35.5 34.3
- -
SH
6.9 4.0 5.3 8.8 2.1 4.8 3.3 2.0 1.2 1.6 1.4 1.5
lows: (1) a n t h r a c i t e s R m = l . 8 2 ( 1 . 6 5 ) - 2 . 6 2 % a n d H V ~ o - - 6 0 . 0 - 9 6 . 7 M P a for V d"f < 10%; ( 2 ) s e m i a n t h r a c i t e s Rm-- 1.56-1.68% a n d HVso = 42.8-49.1 M P a for V ~ = 10-14%; a n d (3) c o k i n g coals R m < 1.32% a n d H V ~ o < 3 5 . 5 M P a for V ~ > 14%. Rm = 1.80% would separate a n t h r a c i t e s from s e m i a n t h r a c i t e s , while Rm = 1.40-1.50% w o u l d f o r m a n u p p e r limit for low volatile b i t u m i n o u s coals. T h i s classification results f r o m V d'f a c c e p t e d in P o l a n d as t h e o n l y class index. T h e r e is, however, a c o n s i d e r a b l e d i s c r e p a n c y in t h e s e p a r a t i o n o f a n t h r a c i t e s
R
-
or,°
HVso, MPo
or,,,,
\ '-,;.Kss
' - ~ 1 ~ ; ~~ "
)
,,1 V
I',I
;
Fig. 8. Variation of reflectance in Coal Seam 504. Fig. 9. Variation of microhardness in Coal Seam 504.
-'
W(¢//
/'
217 from low volatile bituminous coals based on Rm as suggested by the ICCP. The course of isoreflectance lines comparable with that of the isovols confirms the correlation between Rm and V ~ (Fig. 8). The three groups mentioned differ significantly in microhardness that correlates the best with R~ (correlation coefficient r= 0.96). It confirms a consistent relationship between isoreflectance and microhardness lines (Fig. 9 ). It appeared that the coals hold a position in the rank series characterized by complete correlation between R~ and Rm~ values and increasing bireflectance (R~x-Rmin) with R~ increase: (1) anthracites of V~f<10% show Rmax=l.84-2.80% and Rmax-Rmin=0.40-0.77%; (2) semianthracites of V~f= 10-14% show R~ax = 1.77-1.84% and R~,~x- Rmi. = 0.42-0.51%; and ( 3 ) coking coals of Vd~f> 14% show Rma~= 1.32-1.45% and R ~ - R m i . = 0.18-0.28%. The Rm~ and R~,~x-Rmi. values indicate that metamorphism of~hese coals occurred at elevated temperatures of~<400-500 ÷ 273 K (according to Bennet's experiments, 1968) and variable pressures (according to the experiments performed by Chandra, 1963 ). PETROGRAPHIC COMPOSITION The highly metamorphosed coals differ distinctly in terms of macropetrography from the coking coals which are mainly mined in the Jastrzebie region. The colour of these coals is mostly grey-black and black-steel-grey or grey. The lustre of diamond-glassy or semimetallic with yellow-golden and sometimes silvery tinge is not uniform. The irregularity of lustre does not disturb the preserved small-layer structure of the seam. It can be observed both in the seam portions with stronger lustre and in that with weaker lustre. The degree of fissuring is 17-45/5 cm which is characteristic for coals from a borderline between low volatile bituminous coal and semianthracite (for minimum values) as well as for low volatile bituminous coal (for maximum values). The Mohs hardness varies from 3 to slightly above 4, mostly from 3.5 to 4.0: In terms of macroscopy no porosity is observed. Microscopic examinations showed that the increased inertinite content characteristic for the coals of this region is also found, in the highly metamorphosed coals, although in a lower degree. The vitrinite content is thus mainly dependent on the inertinite content (Table 4): (1) anthracites contain V = 58-77% with I-content = 16-33%; (2) semianthracites contain V = 35-51% with I-content of 38-48%; and (3) coking coals contain V--30-38% with Icontent of 40-48%. The microscopic observations of vitrinite have indicated that it shows the features of thermally altered coal. The major part of vitrinite shows microporosity indicating its devolatilization. A distinct correlation between the rank expressed by V ~f and Rm and the vitrinite content is observed. The vitrinite
218 TABLE 4 Petrographic composition of coals from Jastrzebie (in vol. % ) Sample
Vitrinite V
Exinite (bitumen inclusive) E
Inertinite (micrinite inclusive) I
Mineral M
F + Sf I
Ma I
Mi I
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
77 67 76 69 69 58 51 40 35 38 30 37
0 0 0 0 0 2 2 1 1 15 16 17
16 (4) 29 (9) 22 (8) 26 (8) 22 (6) 33 (6) 38 (9) 48 (7) 46 (7) 43 (7) 48 (8) 40 (6)
7 4 2 5 9 7 9 11 18 4 6 6
26 24 22 25 35 42 33 50 63 67 56 60
51 45 39 43 36 38 42 35 23 17 28 25
23 31 39 32 29 20 25 15 14 16 16 15
(2) (2) (1) (1) (7) (7) (8)
1Strongly fluorescing exsudates; F = fusinite, Sf= semifusinite; Ma = macrinite; Mi = micrinite. isolines show a course s i m i l a r to t h a t of the isovols a n d at the s a m e t i m e a n inverse d i r e c t i o n of the value c h a n g e s (Fig. 10). C o n t r a r y t o i n e r t i n i t e - r i c h c o k i n g coals, t h e i n e r t i n i t e c o n t e n t d e c r e a s e s sig-
Vitrinite,
"/0
.w0
Fig. 10. Variation of vitrinite content in Coal Seam 504. Fig. 11. Variation of inertinite in Coal Seam 504.
Inertinite, ~'0
oV,0 - ,
219 VNo
Micrtlite, % ~...L~
7y,/
/"
vmf- °
,
I
IH i
-i-
-- [
Fig. 12. Variation of micrinite content in Coal Seam 504. nificantly in anthracites (Fig. 11 ).The proportion of macerals in this group also varies with decreasing inertinite content. Macrinite predominates as a rule in anthracites of the inertinite group. Its proportion is 36-51%. The contents of fusinite, semifusinite and micrinite are lower. In the semianthracites and coking coals, the main macerals of the inertinite group are fusinite and semifusinite: they amount to 33-63% in semianthracites and 56-67% in coking coals. A characteristic feature of the coal from this region is the permanent presence of micrinite in a quantity of 4-9%, irrespective of the coalification degree (Figs. 12, 13A,B). The changes in content and composition of macerals indicate a relative increment of the volume of thermally altered vitrinite on the one hand, and an increase in thermal instability, probably that of semifusinite, on the other. The isolines of the percent content of fusinite plus semifusinite, macrinite and micrinite plotted against the inertinite group taken as 100% (Figs. 14, 15, 16) indicate that there is a consistency with the isolines of the parameters mentioned above. The exinite content in coking coals is generally 15-17%. Apart from sporinite and cutinite, the presence of a strongly fluorescing bituminous substance in a quantity of 7-8% was found. In semianthracites exinite is represented solely by a fluorescing bituminous substance occurring in trace quantities of 1-2%. In anthracites exinite was not found in any form (Fig. 17), except in specimen VII. The bituminous substance usually fills the cell lumens in semifusinite and fusinite (Fig. 13C, D, E, F ). It shows intensive fluorescent colours from yellow to yellow-orange. This component may bear some resemblance to exsudatinite as distinguished by Teichmiiller (1982, pp. 56, 113).
220 A
15
C
D
Fig. 13.A. Micrinite and fusinite with microspores in desmocollinite. Coking coal, R~ = 1.25%, polished surface, oil imm., 250 X. B. Micrinite in vitrinite. Anthracite, R~ = 2.56%, polished surface, oil imm., 250X. C. Cell lumens of fusinite are filled with a strongly yellow fluorescing substance (exsudatinite?). Coking coal, Rm = 1.28%, polished surface, oil imm., 250 ×. D. Same field as C, under blue-light irradation.
221 E
F
i,
g
Fig. 13.E. Cell lumens of fusinite are idled with a strongly yellow fluorescing substance. Coking coal, R~ = 0.96%, polished s~rface, oil imm., 320 X. F. Same field as E, under blue-light irradation.
The content of mineral matter in the coals varies from 4 to 18%. The presence of clay minerals, carbonate and sulphide minerals was established by microscopic methods. Pyrite and pyrrhotite were found in low volatile bituminous coal and anthracites/semianthracites, respectively. SUMMARY
The anthracites and semianthracites occurring in the Jastrzebie region of the Upper Silesian Coal Basin were probably formed under the effects of heat of a magma intrusion not yet localized. From the geological section (Fig. 18 ) it follows that the coalification anomalies found in the Jastrzebie region are of local nature and are not connected with its geological structure although there is a certain relationship between the distribution of physical and chemical parameters and the petrographic composition of the coals with the axis of the Jastrzebie syncline. However, these changes disappear along the syncline axis (to the North) and at a distance of about 500 m from the boundary of the red beds in Seam 504, coking coals occur instead of anthracites and semianthracites (Fig. 2 ). The constructed geological section of Coal Seam 504 ( Fig. 18)
222 VIIo
VIIo
I-/ 211 /3A
\
..X / I '~ . v i , ,
,
c (o:O.v
/'~,-
ov'~ /
,N
,._ tt,
~
o111
Fig. 14. Variation of fusinite and semifusinite content plotted against the inertinitegroup assumed as 100%. Fig. 15. Variation of macrinite content plotted against the inertinite group assumed as 100%.
shows a distinctregularityin the changes in chemical and physical parameters as well as petrographic composition which m a y be caused by this heat flux. Metamorphism of the coal from Coal Seam 504 occurred in the red beds zone. The seams beyond the zone of thermal metamorphism contain inertinite-
Hi
~' ~t
~°
t-.7_.,//,,'
Exinite, %
~
\ .~///~4 / N
~
ov,o
,
IoI
ii
I
IV o
Fig. 16. Variation of micrinite content plotted against the inertinite group assumed as 100%. Fig. 17. Variation of exinite content in CoN Seam 504.
223
v,U/. 80
~'S "~
I 1
3.0
92
"\........__. __..~..~'~'/"
9~-I
@9
HVI@
--d---"
/
/
\
\
~
i
SI ~
t !
S
,~vm
""..~//"'.._..~// 7
\
~
.6
/~\/f
. . . . . . . . . . . . . . . . . . . .
.
.26
MP= " 80
122
l ~.0
.Is
~
-6o -1~ 16o
o
. , o . ,
,.,o
.~.t 0
" ~'
,oo ..
borwhole
1-1
200
30C
o
~o,o
2o0
3opm ~ - -
--
LEGEND - mine rood
~
- red beds
Fig. 18. Cross-section1-1' of Coal Seam504 with changesof chemical,physicalparametersand petrographiccompositionsof these coal. Locationof cross-sectionshownin Fig. 2. rich coking coal of vd~f= 18-26% and Rm= 1.10-1.35%. According to the technological classification used in Poland, the highly metamorphosed coal from the Jastrzebie region is considered as anthracites and semianthracites. The basis for differentiating these coals is only the V d'f content. Measurements of the vitrinite reflectance indicated no correlation between the boundaries of the coals determined by V d~fand the boundaries proposed by the ICCP for distinguishing bituminous coals from anthracites by a mean reflectance Rm. Furthermore, the distinguished anthracites and semianthracites show an untypical chemical composition that can be explained by their petrographic composition.
224 E x a m i n a t i o n of optical properties shows t h a t the coal m e t a m o r p h i s m in the Jastrzebie region is effected by increased t e m p e r a t u r e (Rn~x) and variable pressure (Rm~ - Rmin ). T hes e factors depart, however, in their values from the values characteristic for regional metamorphism. Petrographic e x a m i n a t i o n indicated a decreased p r o p o r t i o n of macerals of the inertinite group in anthracites. However, this p h e n o m e n o n does not apply for micrinite t h a t is p r e s e n t in a c o n s t a n t q u a n t i t y of 4-9% irrespective of the coalification degree. Hence, it can be assumed t h a t p a r t of the macerals of the inertinite group are t he r m a l l y unstable. F r o m t he macerals of the inertinite group, micrinite, macrinite and fusinite were found in the anthracites. T h e presence of a fluorescing bituminous substance impregnating the cell lumens in the seams, particularly in fusinite, proves its genetic connection with exsudates though it might be true t h a t t h e y are t he adsorbed products of migration of a petroleum-like substance.
REFERENCES
Bennet, A.J.R., 1968. The reflectance and coking behaviour of vitrinite-semifusinite transition material. Fuel, 47: 51-62. Chandra, D., 1963. Reflectanceof thermally metamorphosed coals. Fuel, 42: 69-74. Chodyniecka, L. and Sankiewicz,J., 1972. Magmatic intrusion in Lower Namurian in the Marklowice region, Upper Silesian Coal Basin Poland. Ann. Soc. Geol. Pol., XLII (4): 309-326 (in Polish, English abstract). Gabzdyl,W., 1964.Die Erscheinungen der Kontaktmetamorphose in der KohlengrubeJastrzebie. Zesz. Nauk. Politech. Slask., 12:107-121 (in Polish). Gabzdyl,W., Dudziak, T. and Tomica, J., 1969. Volcanismphenomena in the Michalkowiceoverthrust and Ortowski fold in the NW part of the Upper Silesian Coal Basin. Przegl. Geol. 3: 139-143 (in Polish, English abstract). Kowalski, W.M., 1977. The petrography of red beds from the Upper Silesian sandstones series (Upper Namurian) of the Rybnik Coal District (Upper Silesian Coal Basin). Zesz. Nauk. Akad. Gdrn.-Hutn., Cracow, Rozpr., 3 (1): 5-61 (in Polish, English abstract). Kuhl, J., 1963.Geological (natural) coke from Jastrzebie-Moszczenicacollieryof the Upper Silesian Coalfield. Przegl. Gdrn:, 1:40-46 (in Polish, English abstract). Teichmiiller, M., 1982. Fluoreszenzmikroskopische~,nderungen von Liptiniten und Vitriniten mit zunehmendem Inkohlungsgrad und ihre Beziehungen zu Bitumenbildung und Verkokungsverhalten. Geol. Landesamt, Nordrhein-Westfalen, 119 pp. APPENDIX 1 Polish standards PN-81/G-04516. Solid fuels. Determination of the volatile matter by gravimetric method. PN-74/G-04511. Solid fuels. Determination of moisture. PN-72/G-04512. Solid fuels. Determination of ash content by the combustion method. PN-81/G-04515. Hard coal. Determination of the crucible swelling number. ISO 501-1981 Coal-Determinationof the crucibleswellingnumber. (The same as PN-81/G-04515).
225 PN-73/G-04521. Solid fuels. Determination of carbon and hydrogen content by the Sheffield method. PN-79/G-04524. Hard coal. Determination of the reflectance of vitrinite. PN-79/G-04529. Hard and brown coal. Determination of petrographic composition. Determination of contents of macerals, maceral groups, mineral groups and mineral matter in reflected light. PN-82/G-97002. Types of hard coal.
209
T h e o c c u r r e n c e of a n t h r a c i t e s in an a r e a c h a r a c t e r i z e d by l o w e r r a n k coals in the U p p e r S i l e s i a n Coal B a s i n of P o l a n d W. GABZDYL and K. PROBIERZ
Institute of Applied Geology, Silesian Technical University, ul. Pstrowskiego 2, 44-100 Gliwice, Poland (Received August 5, 1987; revised and accepted April 10, 1986)
ABSTRACT Gabzdyl, W. and Probierz, K., 1987. The occurrence of anthracites in an area characterized by lower rank coals in the Upper Silesian Coal Basin of Poland. Int. J. Coal Geol., 7: 209-225. The resultsof petrographical-geologicaland chemical examinations on anthracites, semianthracites and medium-low volatilebituminous coals from Jastrzebie in the Upper SilesianCoal Basin of Poland are presented. The coking coals mined in this region exhibit volatilematter vd~f= 18-26%, free swellingindex FSI= 3-8 and reflectanceR m = 1.10-1.35% and are inertiniterich coals (I= 25-63%). Coal Seam 504 of the Anticlinalbeds (NamurianB) has been affectedby thermal metamorphism and contains both coking coalsand coalsof higher rank. According to the criterionof Polish Standards thiscoalseam variesfrom anthracite (V d~f < 10 % ) to semianthracite (vd~f= 10-14 % ) in rank. The carbon content is slightlylower and the hydrogen content a littlehigher than those of typical anthracitesand semianthracites.The reflectancevalues (Rm = 1.56-2.62% ) are generally lower than the Rm values proposed by the International Committee for Coal Petrology as boundary values for anthracites and bituminous coal.The magnitude of anisotropy and microhardness were also examined. Examinations of opticalpropertiesprove that the metamorphism exhibited by the coals isthe resultof elevatedtemperature and variablepressure.The analyses of the maceral composition indicatethat there is a decrease in the inertinitecontent in anthracites. Vitriniteexhibitsthe featuresof thermally alteredcoal.The micrinitecontent shows a littlevariation.In coking coals,a strongly fluorescingbituminous substance with the optical features of exsudatinite was found. The constructed geologicalsection of Coal Seam 504 shows distinctregular changes in chemical and physical properties as well as the petrographic composition which may be caused by the heat fluxof a m a g m a intrusion,not localizedso far.
INTRODUCTION A n t h r a c i t e s in t h e U p p e r S i l e s i a n C o a l B a s i n o f P o l a n d are n o r m a l l y f o u n d in b o r e h o l e s a t d e p t h s g r e a t e r t h a n 1000 m. T h e i r o c c u r r e n c e a t t h e s e d e p t h s is t h e r e s u l t o f r e g i o n a l m e t a m o r p h i s m . I n t h e a r e a studied, h o w e v e r , a n t h r a -
0166-5162/87/$03.50
© 1987 Elsevier Science Publishers B.V.
210
cites occur at relatively shallow levels, in association with coking coal ( medium-low volatile bituminous coal) that is now mined. The occurrence of both anthracite and coking coal in the Jastrzebie region has been established by underground working at a depth of 430-480 m in Coal Seam 504 (Namurian B). In the present work, investigations of changes in some chemical and physical properties as well as the petrographic composition of coals in this seam are presented. Geological mapping and studies in the Jastrzebie region have documented the presence of strong secondary alteration of minor magma intrusions in the Upper Carboniferous sediments, high mineralization of deposit waters and a high gas content (CH4). Geophysical investigations indicate an increased geothermal gradient in relation to the remaining parts of the Upper Silesian Coal Basin. The occurrence of both medium and highly metamorphosed coals may thus be the result of thermal metamorphism. As yet, the presence of a larger intrusion has not been found ( Kuhl, 1963; Gabzdyl, 1964; Gabzdyl et al., 1969; Chodyniecka and Sankiewicz, 1972; Kowalski, 1977). GEOLOGICAL FEATURE OF THE JASTRZEBIE REGION
The Jastrzebie region lies in the southwestern part of the Main Basin of the Upper Silesian Coal Basin and covers the axis zone of the Jastrzebie syncline (Fig. 1). In the western synclinal flank, that seams show a variable degree of dip of 4-20 ° and in the eastern flank that of 4-12 °. Through the western part of the region the Orlova-Boguszowice overthrust runs at a dip of 40-50 ° to the west and with vertical displacements up to 1000 m. In the eastern part of the region exists an asymmetrical Jastrzebie anticline of a dip of 40-50 ° in the western flank and that of 15-25 ° in the eastern flank. The documented coexistence of anthracite and coking coal is found in the southern part of the Jastrzebie region along the line of disappearance of Coal Seam 504 and appearance of a series of red beds that do not contain coals (Fig. 2 ). The lithostratigraphical profile of the Jastrzebie region comprises Carboniferous formations consisting of the Por~ba beds ( Namurian A), Anticlinical beds ( Namurian B) and Ruda Beds ( Namurian C ). The Carboniferous overburden with a thickness of 200-800 m consists of Tertiary and Quaternary formations. The Por~ba beds examined so far only by boreholes, consist predominantly of mudstones and claystones with thin coal seams. The Anticlinal beds are prominent sandstone series with thicknesses of 200-290 m and contain 9 workable coal seams of 2-6 m thick. The Ruda beds, lithologically similar to the Anticlinal beds, contain 17 workable coal seams. The coal mined from the seams of the Anticlinal and Ruda beds is charac-
211
~!~,
TamowskieG ~
o, o ~ .
LEGEND ---Boundary
of Upper Silesian Coal Basin
Ovlrthrust: a - Michalkowice- Rybnik b- @IowaBoguszowice ~-Zone of fold tectonics J - - - l - Study area --~--~-./mtrzglxe Anticline --.- ---- - Jastrz,ebie 5yncline i , •
_
Fig. I. Tectonic scheme of the Upper Silesian Coal Basin. ~
"
"~
vh
I#_111 ..Io/D 4
-
.-~"~- i~mvolsvelar - ,,, o - samples - mine roads ~ - - strike and dip of bed -
LEGEND ~-red beds ® - borehole JAS. t ~ ~-Jostrzgbie syrlclino axis ~-~ - seam thickness
Fig. 2. Geological m a p of the study area showing variation of the volatile matter content in Coal Seam 504. The m a p was prepared on the basis of a larger number of samples than shown.
212 m.
o
--~ >~,.
200
Miocene
~
C r~e~ Rud" bed. -
_.~ z
~.':. . .
.........
--~ ~
c.s.504/2
BI:-:-:-:-:t '
600.
LEGEND - red beds
"
-
rnudstone
Anticlinal beds
~
~::i
~-
.,o,s,o.e
. . . . . . . . .
Polo b°ds
AI: : : : :
¢.s. 603
i-:----
' c.s. 606
~
- sond,tone
I -
cool seom
BO0~
Fig. 3. Lithologic profile of borehole JAS. 1.
terized by volatile matter V~ = 18-26%, free swelling index F S I = 3-8 and mean reflectance of vitrinite Rm oil= 1.10-1.35% and belongs to a medium-low volatile bituminous coal. The petrographic composition shows an increased inertinite content ( I = 25-63% ). The higher coal-bearing rocks of the Jastrzebie region almost disappear in borehole JAS.1 in the proximity of coexisting anthracites and coking coal (medium-low volatile bituminous coal). In this borehole in the Ruda and Anticlinal beds, only Coal Seam 504 occurs (Fig. 3 ). EXPERIMENTAL
Examinations were carried out on channel samples taken from Coal Seam 504 in the area where its thickness is 1.4-2.2 m (Fig. 2). The chemical properties were characterized by volatile matter content ( V ~ ) , moisture (Ma), ash content (A a), free swelling index (FSI) and the contents of carbon ( C ~f) and hydrogen ( Hdaf). Their values were determined by standard methods obligatory in Poland (Polish Standards; see Appendix 1 ). The optical properties were examined with a MPV-2 Leitz microscope using immersion oil of refractive index no= 1.5176 at a temperature of 24+273 K and wavelength 2 = 546 nm. The mean reflectance of vitrinite (Rm oil ) was measured on the polished surfaces according to the recommendations of the International Committee for Coal Petrology (ICCP) and Polish Standards (PN) and their standard deviations (sR) were calculated. R=~ and R=i. were measured on block specimens and then the magnitude ofbireflectance ( R ~ x - Rmin) was determined. Vickers microhardness of vitrinite (HV) was determined with a PMT-3 LOMO instrument. The measurements were made under a load of 0.5 N (50 G ) applied for 15 seconds. The standard deviations (sn) were then calculated. Petrographic examinations covered the analysis of macerals performed in compliance with the ICCP recommendations and Polish Standards. Special
213 TABLE 1 Position of coals from Jastrzebie in the International Classification of Coal (ECE, Geneva, 1956) CLASS NUHBER oct. t~te~ a~cmio. EGE, b~f~mv~o 1956 ~te g
Q daf
~t
8
"
S 4
,.dnf
2 0 - -
V--: % t
COALS from JASTRZI~IE UpperSib.sian Coal Basin of Poland
3
4
-
-
2 t 0 - 1
~----6-----
~ -
LowVole~
Bituminous [coking coat)
Semianthmc/te Anthracite
0
attention was paid to the petrographic differentiation of the inertinite group and a possible presence of fluorescing bituminous substance. The results of the measurements and examinations were used to draw maps and construct a cross-section. The maps were drawn based on a uniform interpolation and the isolines were drawn by parallel method. C H E M I C A L PROPERTIES
Examination of volatile matter contents, which is essential for distinguishing between anthracites and semianthracites according to the Polish Standards, pointed to the presence of: (1) anthracites of vd~f< 10% (4.77-9.53%); (2) semianthracites of vd~f-- 10-14% (11.76-13.12%); and (3) coking coals of vd~f> 14% (18.58-20.58%). No coals of 14-18% V d~f content were found in the area. The rank of the coals according to the International Classification of Coals (Geneva) is presented in Table 1. The technological and chemical data are shown in Table 2. Coals with vd~f< 14% occurred in an area of about 250 × 350 m (Fig. 2 ). The isovols depict an elongated syncline parallel to the axis of the Jastrzebie syncline. The course of the isovols is similar to the lines of disappearance of Coal Seam 502/1 which lies 20 m higher than Coal Seam 504 (Fig. 4 ). In the area bordered by isovol vd~f< 14% the coking properties in the seam disappear. The free swelling index isolines are similar to the isovols. Coking properties ( S I - 1 - 4 ) were found in the seam outside the isovol contour vd~f>~14% (Fig. 5).
214 TABLE
2
S o m e chemical data of the coals from Jastrzebie Sample
V d~f' %
SI
M ~ %
A "~ %
C~ %
H d~f' %
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
4.77 7.30 8.02 8.62 9.13 9.53 11.76 12.68 13.12 18.58 20.18 20.58
0 0 0 0 0 0 0 1/2 0 1 4 3
1.07 0.80 0.86 0.90 0.90 0.83 0.78 0.73 0.69 0.94 0.90 0.98
4.38 5.68 3.50 4.44 1.92 9.62 2.76 5.38 9.44 4.52 4.22 5.20
92.16 91.00 89.59 88.99 91.59 89.01 90.28 88.99 89.77 88.03 89.95 88.66
3.10 3.56 3.36 3.32 3.70 4.04 3.96 3.98 4.15 4.43 4.55 4.95
ida/=dry, ash free; 2M=--moisture; 3AS= ash content calculated in the analytical state. No distinct differences in the moisture contents between anthracites, semianthracites and coking coals were found. Irrespective of the coalification degree the ash content in the coals examined is low (1.92-9.44%). The sulphur content does not exceed 0.6%. The anthracites, semianthracites and coking coals differentiated by Vd~ do not differ greatly in chemical composition, since: (1) anthracites contain Cd~f=88.99-92.16% and Hd"f=3.10-4.04%; (2) semianthracites contain Cd~f=88.99-90.28% and Hd~f=3.96-4.15%; and (3) coking coals contain Cd~f= 88.03-88.95% and Hd"f= 4.43-4.95%. However, a general increase of the Cd~ content with a decrease of the Vd~fcontent and a more significant decrease in H d~fis observable. The isolines of C d'f and H d~fconfirm this finding (Figs. 6 and 7). A lack of correlation between the boundaries determined by Vd~f and C d~f can be attributed to the different petrographic compositions. LEGEND o= zo-
503/1-2
~ -
50&12
~
cloystone - mudstone
- sandstone 4o-
60
~
- coal seam
505/t
Fig. 4. Localization of Coal Seam 504 in the lithologic profile of the Anticlinal beds (Namurian
B).
215
SI(¢~~.~}6 ""-'"k~.._...,
Fig. 5. Variation of free swellingindex in Coal Seam 504. The map was prepared on the basis of a largernumber of samples than that given here. REFLECTANCE
AND MICROHARDNESS
OF VITRINITE
Examinations of rank have indicated that there is a good correlationbetween the differentiationof coals according to R . and H V values and that based on V d'f (Table 3). Speciment VII is the only exception. The reflectance and microhardness of the distinguished groups are as folC ~f , y0
H°°f, Z
oV,O
,,,///
F -.
" ~
¢~Pfv, ," ~.~
v,,
..-~~,,~ 11 .7
--'--~. I\~~----~._~ ,,
~/I
,.o
\\,~S- )
~?
;~/
oV~o vJ
-
~,~_~- -
I
vi
~
~o,o
~
2~/I.. - /
~,
,','
-,
>,\, /
o, ,oo, ~oo.."~ . ~
Fig. 6. Variation of carbon content in Coal Seam 504. Fig. 7. Variation of hydrogen content in Coal Seam 504.
N
r
.
216 TABLE 3 Physical properties of coals from Jastrzebie Sample
Rmoil
sR
%
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
2.62 2.20 2.56 2.42 1.82 1.65 1.68 1.56 1.57 1.32 1.25 1.28
0.16 0.12 0.14 0.15 0.09 0.07 0.09 0.07 0.07 0.07 0.09 0.06
Rmax
Brain
Rm,x Rmin
HVso
%
%
%
MPa
2.80 2.39 2.65 2.51 1.92 1.84 1.77 1.77 1.84 1.45 1.32 1.40
2.03 1.88 2.25 2.09 1.51 1.39 1.31 1.35 1.33 1.17 1.14 1.19
0.77 0.51 0.40 0.42 0.41 0.45 0.46 0.42 0.51 0.28 0.18 0.21
83.6 68.9 84.2 96.7 60.0 60.7 49.1 44.1 42.8 34,7 35.5 34.3
- -
SH
6.9 4.0 5.3 8.8 2.1 4.8 3.3 2.0 1.2 1.6 1.4 1.5
lows: (1) a n t h r a c i t e s R m = l . 8 2 ( 1 . 6 5 ) - 2 . 6 2 % a n d H V ~ o - - 6 0 . 0 - 9 6 . 7 M P a for V d"f < 10%; ( 2 ) s e m i a n t h r a c i t e s Rm-- 1.56-1.68% a n d HVso = 42.8-49.1 M P a for V ~ = 10-14%; a n d (3) c o k i n g coals R m < 1.32% a n d H V ~ o < 3 5 . 5 M P a for V ~ > 14%. Rm = 1.80% would separate a n t h r a c i t e s from s e m i a n t h r a c i t e s , while Rm = 1.40-1.50% w o u l d f o r m a n u p p e r limit for low volatile b i t u m i n o u s coals. T h i s classification results f r o m V d'f a c c e p t e d in P o l a n d as t h e o n l y class index. T h e r e is, however, a c o n s i d e r a b l e d i s c r e p a n c y in t h e s e p a r a t i o n o f a n t h r a c i t e s
R
-
or,°
HVso, MPo
or,,,,
\ '-,;.Kss
' - ~ 1 ~ ; ~~ "
)
,,1 V
I',I
;
Fig. 8. Variation of reflectance in Coal Seam 504. Fig. 9. Variation of microhardness in Coal Seam 504.
-'
W(¢//
/'
217 from low volatile bituminous coals based on Rm as suggested by the ICCP. The course of isoreflectance lines comparable with that of the isovols confirms the correlation between Rm and V ~ (Fig. 8). The three groups mentioned differ significantly in microhardness that correlates the best with R~ (correlation coefficient r= 0.96). It confirms a consistent relationship between isoreflectance and microhardness lines (Fig. 9 ). It appeared that the coals hold a position in the rank series characterized by complete correlation between R~ and Rm~ values and increasing bireflectance (R~x-Rmin) with R~ increase: (1) anthracites of V~f<10% show Rmax=l.84-2.80% and Rmax-Rmin=0.40-0.77%; (2) semianthracites of V~f= 10-14% show R~ax = 1.77-1.84% and R~,~x- Rmi. = 0.42-0.51%; and ( 3 ) coking coals of Vd~f> 14% show Rma~= 1.32-1.45% and R ~ - R m i . = 0.18-0.28%. The Rm~ and R~,~x-Rmi. values indicate that metamorphism of~hese coals occurred at elevated temperatures of~<400-500 ÷ 273 K (according to Bennet's experiments, 1968) and variable pressures (according to the experiments performed by Chandra, 1963 ). PETROGRAPHIC COMPOSITION The highly metamorphosed coals differ distinctly in terms of macropetrography from the coking coals which are mainly mined in the Jastrzebie region. The colour of these coals is mostly grey-black and black-steel-grey or grey. The lustre of diamond-glassy or semimetallic with yellow-golden and sometimes silvery tinge is not uniform. The irregularity of lustre does not disturb the preserved small-layer structure of the seam. It can be observed both in the seam portions with stronger lustre and in that with weaker lustre. The degree of fissuring is 17-45/5 cm which is characteristic for coals from a borderline between low volatile bituminous coal and semianthracite (for minimum values) as well as for low volatile bituminous coal (for maximum values). The Mohs hardness varies from 3 to slightly above 4, mostly from 3.5 to 4.0: In terms of macroscopy no porosity is observed. Microscopic examinations showed that the increased inertinite content characteristic for the coals of this region is also found, in the highly metamorphosed coals, although in a lower degree. The vitrinite content is thus mainly dependent on the inertinite content (Table 4): (1) anthracites contain V = 58-77% with I-content = 16-33%; (2) semianthracites contain V = 35-51% with I-content of 38-48%; and (3) coking coals contain V--30-38% with Icontent of 40-48%. The microscopic observations of vitrinite have indicated that it shows the features of thermally altered coal. The major part of vitrinite shows microporosity indicating its devolatilization. A distinct correlation between the rank expressed by V ~f and Rm and the vitrinite content is observed. The vitrinite
218 TABLE 4 Petrographic composition of coals from Jastrzebie (in vol. % ) Sample
Vitrinite V
Exinite (bitumen inclusive) E
Inertinite (micrinite inclusive) I
Mineral M
F + Sf I
Ma I
Mi I
II 1A 4A 3A 2A VII V III IV VIII VI VIIa
77 67 76 69 69 58 51 40 35 38 30 37
0 0 0 0 0 2 2 1 1 15 16 17
16 (4) 29 (9) 22 (8) 26 (8) 22 (6) 33 (6) 38 (9) 48 (7) 46 (7) 43 (7) 48 (8) 40 (6)
7 4 2 5 9 7 9 11 18 4 6 6
26 24 22 25 35 42 33 50 63 67 56 60
51 45 39 43 36 38 42 35 23 17 28 25
23 31 39 32 29 20 25 15 14 16 16 15
(2) (2) (1) (1) (7) (7) (8)
1Strongly fluorescing exsudates; F = fusinite, Sf= semifusinite; Ma = macrinite; Mi = micrinite. isolines show a course s i m i l a r to t h a t of the isovols a n d at the s a m e t i m e a n inverse d i r e c t i o n of the value c h a n g e s (Fig. 10). C o n t r a r y t o i n e r t i n i t e - r i c h c o k i n g coals, t h e i n e r t i n i t e c o n t e n t d e c r e a s e s sig-
Vitrinite,
"/0
.w0
Fig. 10. Variation of vitrinite content in Coal Seam 504. Fig. 11. Variation of inertinite in Coal Seam 504.
Inertinite, ~'0
oV,0 - ,
219 VNo
Micrtlite, % ~...L~
7y,/
/"
vmf- °
,
I
IH i
-i-
-- [
Fig. 12. Variation of micrinite content in Coal Seam 504. nificantly in anthracites (Fig. 11 ).The proportion of macerals in this group also varies with decreasing inertinite content. Macrinite predominates as a rule in anthracites of the inertinite group. Its proportion is 36-51%. The contents of fusinite, semifusinite and micrinite are lower. In the semianthracites and coking coals, the main macerals of the inertinite group are fusinite and semifusinite: they amount to 33-63% in semianthracites and 56-67% in coking coals. A characteristic feature of the coal from this region is the permanent presence of micrinite in a quantity of 4-9%, irrespective of the coalification degree (Figs. 12, 13A,B). The changes in content and composition of macerals indicate a relative increment of the volume of thermally altered vitrinite on the one hand, and an increase in thermal instability, probably that of semifusinite, on the other. The isolines of the percent content of fusinite plus semifusinite, macrinite and micrinite plotted against the inertinite group taken as 100% (Figs. 14, 15, 16) indicate that there is a consistency with the isolines of the parameters mentioned above. The exinite content in coking coals is generally 15-17%. Apart from sporinite and cutinite, the presence of a strongly fluorescing bituminous substance in a quantity of 7-8% was found. In semianthracites exinite is represented solely by a fluorescing bituminous substance occurring in trace quantities of 1-2%. In anthracites exinite was not found in any form (Fig. 17), except in specimen VII. The bituminous substance usually fills the cell lumens in semifusinite and fusinite (Fig. 13C, D, E, F ). It shows intensive fluorescent colours from yellow to yellow-orange. This component may bear some resemblance to exsudatinite as distinguished by Teichmiiller (1982, pp. 56, 113).
220 A
15
C
D
Fig. 13.A. Micrinite and fusinite with microspores in desmocollinite. Coking coal, R~ = 1.25%, polished surface, oil imm., 250 X. B. Micrinite in vitrinite. Anthracite, R~ = 2.56%, polished surface, oil imm., 250X. C. Cell lumens of fusinite are filled with a strongly yellow fluorescing substance (exsudatinite?). Coking coal, Rm = 1.28%, polished surface, oil imm., 250 ×. D. Same field as C, under blue-light irradation.
221 E
F
i,
g
Fig. 13.E. Cell lumens of fusinite are idled with a strongly yellow fluorescing substance. Coking coal, R~ = 0.96%, polished s~rface, oil imm., 320 X. F. Same field as E, under blue-light irradation.
The content of mineral matter in the coals varies from 4 to 18%. The presence of clay minerals, carbonate and sulphide minerals was established by microscopic methods. Pyrite and pyrrhotite were found in low volatile bituminous coal and anthracites/semianthracites, respectively. SUMMARY
The anthracites and semianthracites occurring in the Jastrzebie region of the Upper Silesian Coal Basin were probably formed under the effects of heat of a magma intrusion not yet localized. From the geological section (Fig. 18 ) it follows that the coalification anomalies found in the Jastrzebie region are of local nature and are not connected with its geological structure although there is a certain relationship between the distribution of physical and chemical parameters and the petrographic composition of the coals with the axis of the Jastrzebie syncline. However, these changes disappear along the syncline axis (to the North) and at a distance of about 500 m from the boundary of the red beds in Seam 504, coking coals occur instead of anthracites and semianthracites (Fig. 2 ). The constructed geological section of Coal Seam 504 ( Fig. 18)
222 VIIo
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,
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Fig. 14. Variation of fusinite and semifusinite content plotted against the inertinitegroup assumed as 100%. Fig. 15. Variation of macrinite content plotted against the inertinite group assumed as 100%.
shows a distinctregularityin the changes in chemical and physical parameters as well as petrographic composition which m a y be caused by this heat flux. Metamorphism of the coal from Coal Seam 504 occurred in the red beds zone. The seams beyond the zone of thermal metamorphism contain inertinite-
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Fig. 16. Variation of micrinite content plotted against the inertinite group assumed as 100%. Fig. 17. Variation of exinite content in CoN Seam 504.
223
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92
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Fig. 18. Cross-section1-1' of Coal Seam504 with changesof chemical,physicalparametersand petrographiccompositionsof these coal. Locationof cross-sectionshownin Fig. 2. rich coking coal of vd~f= 18-26% and Rm= 1.10-1.35%. According to the technological classification used in Poland, the highly metamorphosed coal from the Jastrzebie region is considered as anthracites and semianthracites. The basis for differentiating these coals is only the V d'f content. Measurements of the vitrinite reflectance indicated no correlation between the boundaries of the coals determined by V d~fand the boundaries proposed by the ICCP for distinguishing bituminous coals from anthracites by a mean reflectance Rm. Furthermore, the distinguished anthracites and semianthracites show an untypical chemical composition that can be explained by their petrographic composition.
224 E x a m i n a t i o n of optical properties shows t h a t the coal m e t a m o r p h i s m in the Jastrzebie region is effected by increased t e m p e r a t u r e (Rn~x) and variable pressure (Rm~ - Rmin ). T hes e factors depart, however, in their values from the values characteristic for regional metamorphism. Petrographic e x a m i n a t i o n indicated a decreased p r o p o r t i o n of macerals of the inertinite group in anthracites. However, this p h e n o m e n o n does not apply for micrinite t h a t is p r e s e n t in a c o n s t a n t q u a n t i t y of 4-9% irrespective of the coalification degree. Hence, it can be assumed t h a t p a r t of the macerals of the inertinite group are t he r m a l l y unstable. F r o m t he macerals of the inertinite group, micrinite, macrinite and fusinite were found in the anthracites. T h e presence of a fluorescing bituminous substance impregnating the cell lumens in the seams, particularly in fusinite, proves its genetic connection with exsudates though it might be true t h a t t h e y are t he adsorbed products of migration of a petroleum-like substance.
REFERENCES
Bennet, A.J.R., 1968. The reflectance and coking behaviour of vitrinite-semifusinite transition material. Fuel, 47: 51-62. Chandra, D., 1963. Reflectanceof thermally metamorphosed coals. Fuel, 42: 69-74. Chodyniecka, L. and Sankiewicz,J., 1972. Magmatic intrusion in Lower Namurian in the Marklowice region, Upper Silesian Coal Basin Poland. Ann. Soc. Geol. Pol., XLII (4): 309-326 (in Polish, English abstract). Gabzdyl,W., 1964.Die Erscheinungen der Kontaktmetamorphose in der KohlengrubeJastrzebie. Zesz. Nauk. Politech. Slask., 12:107-121 (in Polish). Gabzdyl,W., Dudziak, T. and Tomica, J., 1969. Volcanismphenomena in the Michalkowiceoverthrust and Ortowski fold in the NW part of the Upper Silesian Coal Basin. Przegl. Geol. 3: 139-143 (in Polish, English abstract). Kowalski, W.M., 1977. The petrography of red beds from the Upper Silesian sandstones series (Upper Namurian) of the Rybnik Coal District (Upper Silesian Coal Basin). Zesz. Nauk. Akad. Gdrn.-Hutn., Cracow, Rozpr., 3 (1): 5-61 (in Polish, English abstract). Kuhl, J., 1963.Geological (natural) coke from Jastrzebie-Moszczenicacollieryof the Upper Silesian Coalfield. Przegl. Gdrn:, 1:40-46 (in Polish, English abstract). Teichmiiller, M., 1982. Fluoreszenzmikroskopische~,nderungen von Liptiniten und Vitriniten mit zunehmendem Inkohlungsgrad und ihre Beziehungen zu Bitumenbildung und Verkokungsverhalten. Geol. Landesamt, Nordrhein-Westfalen, 119 pp. APPENDIX 1 Polish standards PN-81/G-04516. Solid fuels. Determination of the volatile matter by gravimetric method. PN-74/G-04511. Solid fuels. Determination of moisture. PN-72/G-04512. Solid fuels. Determination of ash content by the combustion method. PN-81/G-04515. Hard coal. Determination of the crucible swelling number. ISO 501-1981 Coal-Determinationof the crucibleswellingnumber. (The same as PN-81/G-04515).
225 PN-73/G-04521. Solid fuels. Determination of carbon and hydrogen content by the Sheffield method. PN-79/G-04524. Hard coal. Determination of the reflectance of vitrinite. PN-79/G-04529. Hard and brown coal. Determination of petrographic composition. Determination of contents of macerals, maceral groups, mineral groups and mineral matter in reflected light. PN-82/G-97002. Types of hard coal.