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Variation in the chemistry of macerals in coals of the Mist Mountain Formation, Elk Valley coalfield, British Columbia, Canada
International
Journal of Coal Geology 33 (1997) 43-59
Variation in the chemistry of macerals in coals of the Mist Mountain Formation, Elk Valley coalfield, British Columbia, Canada Maria Mastalerz a3*, R. Marc Bustin b a Indiana Geological Surrey, Indiana UnilersiQ. 611 North Walnut Grow, Bloomington, IN. 47405-2208. USA h tkpartment
qf Gedogical
Sciences, The University of British Columbia,
Received 9 May 1995; accepted 9 February
Vancouver, B.C., Canada V6TIZ4 1996
Abstract Variations in elemental and molecular chemistry of macerals, with vitrinite, semifusinite and sporinite in particular, are discussed for the coal seams of the Mist Mountain Formation in the Elk Valley coalfield, in western Canada. In the south Elk Valley coalfield, carbon content of vitrinite oscillates around 85%, and oxygen content increases gradually up section, from seam A to C. In the north Elk Valley coalfield, carbon content in vitrinite shows marked variations (from 70% to 85%) between the samples and is lower than in the south Elk Valley coalfield, which is consistent with a higher maturation level of south Elk Valley coalfield samples. Sulphur content is below 1Q, in both coalfields. Semifusinite, in general, has higher carbon and lower oxygen content than vitrinite, whereas cutinite has higher carbon content than vitrinite and slightly higher or comparable to that of semifusinite. Functional group distributions show large variations between the seams and these variations are attributed mainly to differences in a primary depositional environment and only occasionally to later weathering and oxidation processes. The results presented in this paper provide also information on the length and branching of aliphatic chains, which, for liptinite macerals is valuable from the oil generation viewpoint, whereas for semifusinite, it may help to understand reactive versus non-reactive behaviour during coking.
* Corresponding
author.
0166-5 162/97/$17.00 Copyright PII SO 166-5 162(96)00003-
0 1997 Elsevier Science B.V. All rights reserved.
1
44
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (1997) 43-59
1. Introduction Naturally occurring organic matter comprises distinct and complex mixtures of components (macerals) of various origins, distinct chemistries and, consequently, different utility with respect to hydrocarbon generation and technological applications. This heterogeneity necessitates studying macerals separately, rather than using bulk sample analysis techniques. Analyzing individual macerals can be achieved by means of: (1) mechanical isolation of macerals (density gradient separation techniques, DGC); and (2) applying techniques which permit in-situ analysis of macerals. The analysis of mechanically isolated maceral separates considerably advanced the understanding of the chemistry of macerals, especially from high-volatile bituminous rank (Dyrkacz et al., 1984, 1991). However, concentration of macerals by crushing followed by liquid separation results in such a small particle size that the components are difficult to distinguish and degree of separation difficult to evaluate. Thus, optimal liberation of macerals has to be compromised with reliable maceral identification. In addition, grinding to fine particle sizes enhances oxidation and, as a result, maceral chemistry may be altered. Even assuming ideal segregation of macerals, this technique permits determination of differences between maceral groups at best, and not within individual macerals or submacerals. Currently there are a few microtechniques in use to study macerals in situ. Laser micropyrolysis-GCMS holds promise as technique for chemical fingerprinting of macerals, allowing determination of aliphatic and aromatic compound in the pyrolysate from an area of 15-50 pm (Stout, 1992). Another technique is the electron microprobe, allowing precise and accurate determination of elemental composition (major and minor elements) of areas a few micrometres in diameter (Bustin et al., 1993). Micro-Fourier Transform Infra-red Spectroscopy (micro-FTIR) enables determination of functional groups of macerals in transmission or reflectance mode (Landais and Rochdi, 1990; Rochdi et al., 1991; Pradier et al., 1992; Mastalerz and Bustin, 1993b,1995) at a scale of N 20 km. Even though these micro-techniques, are still qualitative and semi-quantitative, rather than quantitative (with an exception of the electron microprobe), when applied collectively they provide much more information about chemical variation between macerals and within macerals than any other available technique. These methods of the first time allow petrologists for the first time to directly determine the chemistry of macerals and to evaluate what differences exist, if any, between submacerals. The purpose of this paper is to determine variation in the chemistry of vitrinite, semifusinite and cutinite in coal seams of the Mist Mountain Formation using the electron microprobe and reflectance micro-FTIR. The Mist Mountain Formation was chosen because: (1) it is the main coal-bearing formation of economic interest in western Canada; (2) it covers a considerable rank range (high-volatile bituminous to semianthracite; Bustin and Dunlop, 1992); and (3) maceral composition of the seams is well documented (Cameron, 1972; Bustin and Dunlop, 1992) thus, the chemistry of selected samples can be interpreted and discussed in the framework of already known trends in coal petrography. In addition, semifusinite is a significant constituent of the Mist Mountain Formation and its degree of reactivity during coking remains controversial.
M. Mastalerz, R.M. Bustin / International
Journal
of Coal Geology 33 (1997143-59
45
2. General geology The Mist Mountain Formation is a elastic sequence of Late Jurassic age up to 700 m thick (Donald, 1984, Gibson, 1985), located in the southeastern Canadian Cordillera (Fig. 1). This formation is a part of the Kootenay Group (Fig. 2); it conformably overlies the Moose Mountain Member of the Morrisey Formation, considered to represent backshore, beach-ridge and dune deposits of a wave-dominated delta (Gibson and Hughes, 1981; Gibson, 1985; Hughes and Cameron, 1985; Dunlop and Bustin, 1987). The Mist Mountain Formation is conformably overlain by alluvial fan braid plain deposits of the Elk Formation (Gibson, 1985). The Mist Mountain Formation is the main coal-bearing unit in the southeastern Canadian Cordillera. It is a non-marine sequence; its lower part has been interpreted as delta-interdeltaic coastal plain deposits and the upper part as upper delta plain/alluvial plain deposits (Dunlop and Bustin, 1987). Coal seams occur throughout the sequence, locally there are more than 15 seams, ranging in thickness from a few centimetres to 20 m. The coal is characterised by low sulphur ( < 1%) and low ash content and it varies in rank from high-volatile bituminous to anthracite.
1 study area Fig. 1. Location map for the area studied, showing the regional geology.
1
46
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (1997) 43-59
3. Methods Coal samples from seams of south Elk Valley Coalfield referred to here as samples A, B, C and D and from seams of the north Elk Valley Coalfield named here seams 1, 2, 3 and 4 have been collected from the Mist Mountain Formation. Three coal samples, representing the dominant lithology of the upper, middle and lower part of each seam (24 samples in total) were selected for study. Each sample was made into a polished block according to standard coal preparation techniques (Bustin et al., 1985) and photographed using a 20 X oil immersion objective. In addition, pellets for maceral analysis were also made for all samples. Random reflectance in oil (R,) was measured using a Leitz MPV II microscope. Samples chosen for electron microprobe analysis were sputter-coated with a carbon layer 0.023 km thick. A Cameca SX-50 electron microprobe with the PAP matrix correction routine (Pouchou and Pichoir, 1991) was used to analyze major and minor elements in coal; a PC2 (NiC) pseudocrystal was used for analyzing the light elements (carbon and oxygen). The physical conditions of the analyses were as follows: an accelerating voltage of 10 kV, a beam current of 10 nA and a beam size of 5 km (Bustin et al., 1993). Anthracite, magnesite and barite were used as carbon, oxygen and sulphur standards, respectively. Iron, Si and Al contents also were determined, with siderite as a standard for iron, wollastonite as a standard for silica and anorthite as a standard for aluminum. Following microprobe analysis the samples were carefully repolished to remove the carbon coat for micro-FTIR analysis.
AGE
SETTING
LITHOLOGY
FORMATION
GROUP
.
.
. . TmioNIAN
ELK
. - -3 /--q
. .
2 e g
. ._ 7
KIYMERIDGW
E : ‘2
1 .s .
. . ??
MIST MOUNTAIN
??
Marine
--
FERNIE
-
Fig. 2. Lithostratigraphic
E
A MORRISSEY
--
OXFORDLW
T
N
s
.
??
0
;
k
.
K 0
position of the Mist Mountain Formation
y
M. Mastalerz, R.M. Bustin /International Journal
of CoalGeology
33 (1997) 43-59
4:
Functional groups in macerals of all samples were determined from FIIR spectra collected using a Nicolet 710 micro-FIIR spectrometer equipped with a NICPLAN microscope. A 35 X IR objective was used. All spectra were obtained in reflectance mode at a resolution of 4 cm- ’; 128 scans were co-added (a ratio to a background of 128 scans was calculated) with the Kramers-Kronig transformation applied. Bands were assigned according to Painter et al. (1981) and Wang and Griffith (1985). A commercial program FOCAS’(Nicolet) was used to deconvolute FTIR spectra and integrate areas under selected peaks.
4. Results and discussion 4.1. Muceral composition Maceral composition of the samples from the Mist Mountain Formation is presented in Fig. 3. Samples from the seams in south Elk Valley coalfield (seams C, B, A) are characterized by high inertinite content (> 20%). Inertinite is represented mainly by semifusinite of both variable reflectance and degree of cell structure preservation.
Maceralcomposition
seam B
seam A
Fig. 3. Maceral composition of the samples analysed (each value represents an average of 3 samples). Note the high inertinite content in the seams from the south Elk Valley coalfield and in seam 1 from the north Elk Valley coalfield.
48
M. Mastalerz, R.M. Bustin/lnternational Journal of Coal Geology 33 (1997) 43-59
Inertodetrinite is also common (Fig. 4A). Other inertinite macerals are rare; fusinite can be locally abundant, especially in seam A. Seam 1 in the north Elk Valley coalfield has also high inertinite content (> 20%). In the samples from the younger seams (2-4) of this area, inertinite content decreases (to a few % in seam 4) and vitrinite and cutinite increase (Fig. 3 and Fig. 4B). The well-documented trend in maceral composition of the seams in the Mist Mountain Formation, with vitrinite increasing upward at the expense of inertinite (Cameron, 1972; Bustin and Dunlop, 1992) may reflect more herbaceous vegetation in the lower part of the section, as suggested by Cameron (1972) and Donald (1984). This is consistent with the observation from this study that inertinite in high-inertinite coals is represented mainly by semifusinite with large proportion of a low-reflectance variety and minor distinctly wood-derived fusinite. 4.2. Elemental
composition
of macerals
4.2.1. Vitrinite Carbon, oxygen and sulphur contents of vitrinite together with minor elements for all the seams are listed in Tables 1 and 2. In the south Elk Valley coalfield (seams A, B, C; Table l), carbon content of the vitrinite is uniform, with a medium of - 85%, whereas oxygen content increases gradually up section (from seam A to C). Sulphur content (determined on optically homogeneous vitrinite) is usually < 0.5%. In contrast, in the north Elk Valley coalfield (seams 1-4; Table 21, carbon content in vitrinite shows marked variations between samples, being generally lower than in the samples from the south Elk Valley coalfield, which is consistent with a higher maturation level of south Elk Valley coalfield samples (R, from 1.2% to 1.5% in the south Elk Valley coalfield versus 0.9% to 1.00% in the north Elk Valley coalfield, Table 3). In seam 1, mean carbon content is - 81%, increases to 84-85% in seams 2 and 3, and decreases to 70% in seam 4. Oxygen content shows a reverse trend, being relatively high in seam 1 (15.5%, Table 2), decreasing to 6-9% in seams 2 and 3, and increasing to 28% in seam 4. Sulphur content in the seams of the north Elk Valley coalfield is < l%, but its content is somewhat higher than in the samples from the south Elk Valley coalfield. and jiisinite 4.2.2. Semijusinite Semifusinite is characterized by a higher carbon and lower oxygen content than vitrinite in the samples from the south Elk Valley coalfield and most samples from the north Elk Valley coalfield. (Tables 1 and 2). Carbon, oxygen and sulphur contents of semifusinite vary throughout the section, concurrently with vitrinite. Samples in seams of the south Elk Valley coalfield have very uniform carbon content (- 88%; Table l), higher than those in the north Elk Valley coalfield. In the north Elk Valley coalfield, semifusinite in seam 4 has the lowest carbon content, whereas seams 2 and 3 have the highest carbon contents (Table 2). Oxygen content is, similarly to vitrinite, highest in seams 1 and 4. Sulphur content is < 1% and the seams in the north Elk Valley coalfield are somewhat richer in this element than the seams in the south Elk Valley coalfield. In all samples, fusinite has higher C content than semifusinite and vitrinite and usually higher than cutinite. Oxygen and sulphur content are usually lower than other macerals. Fusinite also has lower Al, Si and Ca contents than other macerals.
M. Mastalerz, R.M. Bustin/Intemational
FIlg. 4. Photomicrographs A High-inertinite-content in ertodetrinite). B Low-inertinite-content
Journal of Coal Geology 33 (1997) 43-59
of coal: coal, seam D, south Elk Valley
coalfield
coal, seam 3, north Elk Valley coalfield
(s = semifusinite;
L‘= vitrinite:
(t’= vitrinite; c = cutinite).
4’)
i=
50
M. Mastalerz, R.M. Bustin /International
Table 1 Elemental
composition
Seam
Maceral
C
0
C
vitrinite
fusinite
85.9 (0.45) 88.3 (1.81) 90.4
B
vitrinite semifusinite
85.0 87.9
A
vitrinite semifusinite
85.3 (0.56) 87.8
fusinite
(1.04) 91.7
semifus
of macerals
Values are in wt%. Numbers observations (n) >_5.
Journal of Coal Geology 33 (1997143-59
from south Elk Valley coaltield S
Si
Al
Fe
Ca
0.3 (0.07) 0.3 (0.14) 0.2
0.33 (0.09) 0.33 (0.12) 0.04
0.30 (0.08) 0.34 (0.11) 0.00
0.04 (0.03) (:::, 0.00
0.02 (0.01) 0.02 (0.01) 0.03
5
(1.4) 4.7 (2.81) 2.8 8.6 4.1
0.2 0.2
0.33 0.35
0.29 0.34
0.07 0.00
0.02 0.03
2 2
7.5 (1.41) 4.5 (1.02) 2.2
0.3 (0.07) 0.2 (0.09) 0.1
0.03
0.01 (0.01) 0.06 (0.05) 0.15
0.02 (0.01) 0.03 (0.02) 0.00
0.01 (0.02) 0.06 (0.03) 0.19
10
(0.04) 0.02 (0.03) 0.03
9.5
in parentheses
are standard
deviations,
computed
where
n
5 2
10 2
the number
Table 2 Elemental
composition
Seam
Maceral
C
0
S
Si
Al
Fe
Ca
n
4
vitrinite
70.2 (0.56) 78.4 (1.16) 76.4 (0.64)
21.6 (2.21) 14.8 (3.50) 17.8 (1.91)
0.3 (0.14) 0.3 (0.14) 0.2 (0.04)
0.15 (0.09) 0.40 (0.15) 0.25 (0.04)
0.05 (0.07) 0.01 (0.05) 0.00 (0.00)
0.06 (0.09) 0.06 (0.05) 0.05 (0.04)
0.03 (0.03) 0.03 (0.03) 0.01 (0.03)
10
84.8 (0.43) 86.2 (0.92) 89.1 (0.44)
6.5 (1.12) 7.1 (2.31) 3.6 (0.69)
0.5 (0.07) 0.5 (0.06) 0.4 (0.05)
0.15 (0.05) 0.10 (0.03) 0.03 (0.03)
0.03
0.04 (0.06) 0.10 (0.06) 0.03 (0.02)
0.08 (0.03) 0.00 (0.00) 0.02 (0.01)
10
(0.04) 0.04 (0.06) 0.01 (0.03)
85.2 (0.33) 86.3 (1.10) 87.7 87.2
0.6 (0.04) 0.5 (0.03) 0.5 0.5
0.08 (0.02) 0.06 (0.02) 0.10 0.10
0.02 (0.02) 0.01 (0.01) 0.04 0.08
0.02 (0.02) 0.00 (0.00) 0.10 0.02
0.01 (0.01) 0.01 (0.01) 0.00 0.00
10
KS 6.7 (0.90) 7.2 5.00
81.2 (0.78) 81.5 (1.01) 91.5 82.6
15.5 (0.82) 12.8 (1.12) 3.3 10.5
0.3 (0.04) 0.3 (0.05) 0.1 0.2
0.15 (0.05) 0.05 (0.06) 0.05 0.04
0.08 (0.03) 0.00
0.00 (0.00) 0.02 (0.00) 0.05 0.01
0.01 (0.01) 0.01 (0.01) 0.19 0.02
5
semifusinite cutinite
3
vitrinite semifusinite cutinite
2
vitrinite semifusinite fusinite cutinite
1
vitrinite semifusinite fusinite cutinite
of macerals
Values are in wt%. Numbers observations (n) 2 5.
of
from north Elk Valley coalfield
in parentheses
are standard
(0.00) 0.07 0.00
deviations,
computed
where
10 5
5 5
5 1 2
5 1 1
the number
of
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (I 997143-59
51
Table 3 FUR-derived Seam
ratios for selected macerals Maceral
CH,
(bands used for integration
/(CH, +CHJ
explained
in the text)
c=o/c=c
C=O/(CH, +CH,)
R,, (%‘c)
South Elk Valley coaljield: Seam D
vitrinite semifusinite
0.64 (0.18) 0.40 (0.47)
0.56 (0.3 1) 0.57 (0.67)
0.74 (0.46) 1.03 (0.51)
1.3 2.0
Seam C
vitrinite semifusinite
0.33 (0.18) 0.48 (0.45)
0.42 (0.22) 0.42 (0.33)
0.80 (0.32) 0.97 (0.44)
1.5 2,s
Seam B
vitrinite semifusinite
0.36 (0.2 CHZ=O
0.60 (0.32) 0.64 (0.3 1)
0.80 (0.36) 0.73 (0.34)
I .3 2.0
Seam A
vitrinite semifusinite
0.43 (0.32) 0.47 (0.41)
0.45 (0.22) 0.52 (0.63)
0.74 (0.5 I) 0.7 I (0.39)
I.2 2.0
vitrinite cutinite semifusinite
0.49 (0.22) 0.41 (0.13) 0.53 (0.41)
0.56 (0.44) 0.67 (0.13) 0.56 (0.25)
3.00 (1.31) I .24 (0.62) 2.03 (0.45)
0.9 0.2
Seam 3
vitrinite cutinite semifusinrte
0.47 (0.17) 0.37 (0.09) 0.45 (0.32)
0.30 (0.14) 0.40 (0.09) 0.34 (0.4 I)
1.16(0.21) 0.51 (0.14) 0.70 (0.38)
0.9 0.3 1.7
Seam 2
vitrinite cutinite sporinite semifurinite fusinite
0.49 0.27 0.40 0.36 0.55
0.31 0.70 0.68 0.49 0.60
1.71 1.40 0.75 I .25 I .76
0.9 0.4 0.2
vitrinite cutinite semifusinite fusinite
0.63 (0.25) 0.46 (0.08) 0.46 (0.48) 0.63
I)
North Elk Valley coalfield Seam 4
Seam
1
Each value represents brackets.
(0.26) (0.11) (0.09) (0.24)
a mean of IO analyses,
(0.19) (0. IO) (0.1 I ) (0.29)
0.34 (0.19) 0.66 (0. IO) 0.45 (0.32) 0.61 except fusinite
I .4
(0.21) (0.07) (0.1 I) (0.30)
I .-I 2.1
1.57(0.26) 0.90 (0.07) 2.52 (0.63) 0.78
(2 analyses),
standard
0.9 0.5 1.7 1.7 deviation
is given in
4.2.3. Cutinite
Liptinite is rare in seams of the south Elk Valley coalfield due, at least partly, to the higher coal rank than in the north Elk Valley coalfield. In the north Elk Valley coalfield, cutinite is abundant (Fig. 4B) and its elemental composition varies from seam to seam similarly to vitrinite and semifusinite (Table 2). Cutinite in seams 1 and 4 has higher oxygen content and lower carbon content than the cutinite in seams 2 and 3. Carbon content of cutinite is higher than that of vitrinite and slightly higher or comparable to that in semifusinite, except seam 4, where C content of cutinite is substantially lower than in semifusinite. Macerals other than already described are uncommon in the samples studied or they are of very small size and because of that no elemental data have been obtained.
52
M. Mastalerz, R.M. Bustin/International
Journal
qf Coal Geology 33 (1997143-59
CH3 KHZ + CH3
,’ 0
0.1
,’
0.2
,’
,’
0.3
0.4
,’
0.5
0.6
0.7
semifus. Wcutinite Illlvitrinite
Fig. 5. FTIR-derived ratios of vitrinite, semifusinite and cutinite in the seams of the north Elk Valley coalfield (seams l-4). Ratio values are the same as in Table 3.
The above results show that each maceral (vitrinite, semifusinite and cutinite) varies with respect to C and 0 contents even between samples of very similar rank. This is particularly apparent for samples from the north Elk Valley coalfield. At the reflectance range from 0.92% to 1.O%, C content of vitrinite ranges from 70% to 84% and 0 content from 25% to 8%. The same range of variations exists even for seams with almost identical R, (samples from seams 2-4). Variations in elemental composition of semifusinite are of the same magnitude as vitrinite; variations within cutinite are somewhat smaller but still substantial. The coals from the south Elk valley coalfield represent higher rank (R, 1.33- 1.44%) than those from the north Elk Valley coalfield and smaller variations in elemental composition between vitrinite and semifusinite, are, at least partly, a function of higher rank. 4.3. Functional
group distribution
Fig. 5 and Fig. 6 and Table 3 present parameters derived from micro-FTIR spectra of vitrinite, semifusinite and cutinite for the coals studied. The parameters calculated are: (1) a ratio of CH,/(CH, + CH,) in the 2800-3000 cm-’ region; (2) C=O/(CH, + CH,); and 3) C=O/C=C in the 1550-1750 cm-‘. The first ratio is related to the length of aliphatic chains (Pradier et al., 1992) whereas the last two reflect the degree of oxidation of organic matter.
M. Mastalerz, R.M. Bustin/International
Journal
of Coal Geology 33 (1997) 43-59
S?
CH3lCH2 + CH3
seam A
C=QICHZ + CH3
0
0.2
0.4
0.6
0.6
1
1.2
Fig. 6. FTIR-derived ratios of vitrinite and semifusinite A-D). Ratio values are the same is in Table 3.
in the seams of the south Elk Valley coalfield (seams
For the vitrinite in samples from the north Elk Valley coalfield, CH,/(CH2 + CH,) ratio is N 0.5 for seams 4, 3 and 2 and increases to 0.63 in seam 1 (Fig. 5) reflecting the vitrinite of seam 1 has shorter aliphatic chains. The C=O/C=C and C=O/(CH, + CH,) ratios of vitrinite are greatest in the topmost seam 4, indicating more advanced oxidation of the vitrinite of this seam compared to others. In cutinite, the lowest CH,/(CH, + CH,) ratio occurs in seam 2, whereas the highest occur in seam 1, again suggesting shortest aliphatic chain of cutinite in the latter. The C=O/C=C and C=O/(CH, + CH,) ratios are lowest in seam 3, indicating the lowest oxidation level. Seams 4 and 2 show the greatest oxidation of cutinite. Semifusinite shows comparable CH,/(CH, + CH,) ratio for all seams, except a lower value in seam 2. The C=O/C=C and C=O/(CH2 + CH,) ratios are lowest in seam 3, similar to cutinite. In the south Elk Valley coalfield, vitrinite has the highest CH,/(CH, + CH,) ratio in seam D (Fig. 6) suggesting the shortest aliphatic chains. The C=O/C==C ratio is higher in seams D and B than in the other two. The C=O/(CH, + CH,) ratio is comparable in all seams, which suggests a similar oxidation level. Semifusinite in all seams shows comparable CH,/(CH, + CH,) ratio except seam B, whose semifusinite shows no detectable CH, (Table 3). The C=O/C=C ratio is highest in seam B, whereas C=O/(CH, + CH,) is highest in seams D and C. In addition to the ratios discussed above, the values of CH,/CH, in 2900-3000
54
M. Mastalerz, R.M. Bustin/International
Vitfinite
Ro (36
Journal of Coal Geology 33 (1997) 43-59
:i1:/:3-
0
“Eli”““““““““““’
0.5
1
CH3 EH2
0
Semifusinite
Ro (%
05 CH3/CH2
15
2
25
3
35
0
'(2800-2biO)
1 CH3
(2900-3000)
2
0
0.5 C%
2 /CH2
1 /CH2
3
4
(2900-3000)
1.5
2
2.5
3
3.5
(2800-2900)
Fig. 7. Relationships between reflectance and CH, /CH, ratios for vitrinite and semifusinite from all the samples studied. For calculation of these ratios, the following band integration areas (in cm-‘) were used: 2850 (CH,), 2870 (CH,), 2925 (CH,) and 2955 (CH,).
cm-’ and CHJCH, in 2800-2900 cm-’ for vi&mite, semifusinite and liptinite have been plotted against reflectance in order to determine the evolution of CH, and CH, groups as well as their individual bands with maturation. Fig. 7 shows an increase in CHJCH, ratio with maturation in vitrinite. Comparisons of CHJCH, ratios in the 2800-2900 and 2900-3000 cm-’ regions suggest that it is the 2800-2900 cm-i region that contributes to the increase in CHJCH, ratio with rank. The bands in the 2900-3000 cm-’ region do not correlate with R,. Plots for semifusinite show very weak to non-existent correlation between FTIR-derived functional group ratios and reflectance (Fig. 7). Fig. 8 depicts relationships for liptinite group. Because of a limited number of analyses on individual liptinite macerals, cutinite, sporinite and resinite are grouped together. For this maceral group the only significant correlation has been obtained for R, and CH,/CH, in the 2900-3000 cm-’ region (r2 = 0.641, whereas there is no correlation between R, and CHJCH, in the 2800-2900 cm-’ region. The lack of correlation between reflectance and CH,- and CH,-related ratios implies that other factors than maturation strongly affect these ratios. One of the factors might be inhomogeneity of organic material. Because each maceral was considered separately, petrographic inhomogeneity can be ruled out. However, the fact that elemental and molecular chemistry of individual macerals vary from one seam to another, even though reflectance values are very similar implies that CH,- and CH,-related ratios should also vary from seem to seam. It should be mentioned here that for the seams studied, a
M. Mastalerz. R.M. Bustin /International Journal of Coal Geology 33 (1997) 43-59
55
Liptinite 06
0.5
04 03 0.2
t
................................................ ........ ............ ........... ..~..*.5:.......__._ .A’ r"0.64 ....
",
CH+CH2
(29’20-3000)
Ro(%) 0.6
05
t
I
?? ??? ? ? ? ? ? ? ? ?? ?? ? ? ? ? ? ??? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
~~
0.4 0.3 02 01
0
02
04
06
0.8
CH31CH2 (2800-2900)
Fig. 8. Relationships between reflectance studied. Ratios calculated as in Fig. 7.
and FTIR-derived
ratios for liptinite macerals
from all the samples
correlation between carbon content and reflectance for individual macerals is also poor. Positive, though very weak correlations were obtained for semifusinite and vitrinite (with r2 of 0.45 and 0.62, respectively). Better correlations between reflectance and carbon content were obtained for cutinite (r2 = 0.76) and inertodetrinite (r2 = 0.74). but these may not be significant because of small number of analyses (8 for each maceral). Weak correlations between reflectance and carbon content on a maceral scale were also noticed elsewhere (Mastalerz and Bustin, 1993a). The results obtained provide also information on the length and branching of aliphatic chains in individual macerals, which gives insight into maceral structure and is valuable from the oil and gas generation point of view. Assuming that higher ratio CH,/(CHz + CH,) represents shorter and more branched aliphatic chains, the results obtained (Table 3) show that of all the macerals studied cutinite has longest or least branched aliphatic chains. This is consistent with observations by Lin and Ritz (1993), who documented longer aliphatic chains for cutinite than for alginite. Sporinite in the coal studied shows shorter aliphatic chains than cutinite. Fusinite always had the shortest chains of all macerals. Vitrinite is usually characterized by longer aliphatic chains than semifusinite. there are examples, however, where semifusinite is comparable to vitrinite with respect to chain length. Such a semifusinite has usually low reflectance and, thus, is likely reactive. Perhaps the reactivity is related to the length of aliphatic chains and, if this
56
M. Mastalerz, R.M. Bustin/International
Journal of Coal Geology 33 (1997143-59
suggestion is correct, FTIR would be a very useful technique to determine semifusinite reactivity versus non-reactivity. This problem, however, requires further study. 4.4. Remarks on coal (peat) deposition The coals of the Mist Mountain Formation were deposited in an protected from marine incursion. This is inferred from sedimentological elastic sediments associated with the seams (Bustin and Dunlop, 1992) as their low sulphur content (Gibson, 1985). It has been suggested that the developed on a broad, relatively flat coastal marsh-swamp complex, remaining part of the section is related to fluvial (flood plain)-dominated
environment studies of well as from oldest seams whereas the environment,
cutinite
. 4000
. 3600
. 3200
. 2600
.
.
.
2400
2000
1600
Wavenumber
. 1200
3600
3200
2800
2400
. 400
(cm-‘)
, . . . . . . .
4000
. 600
2000
Wavenumber
1600
1200
I
600
400
(cm“)
Fig. 9. FTIR spectra of vitrinite and cutinite from seams 3 and 4. Assignment of bands: 2925 and 2856 cm- ’ - CH,; 1738 and 1711 cm-’ - C=O; 1610 cm-’ - C=C; 1448 cm-’ - CHZ; and 812 cm-’ compounds containing rings with two neighbouring C-H groups. Note large reduction of aliphatic stretching bands in the 2800-3000 cm-’ region for both vitrinite and cutinite in seam 3 due to oxidation.
M. Mastalerz, R.M. Bustin / International Journal
of Coal Geology 33 (19971 43-S9
57
with changeable influence of active alluvial channels (Bustin and Dunlop, 1992). The mentioned earlier vertical trend in maceral composition of the seams throughout the formation may reflect a change from the dominance of herbaceous vegetation (high-inertinite coals) to more arborescent vegetation (high-vitrinite coals) with time. In the south Elk Valley coalfield, all the seams studied come from the high inertinite portion of the Mist Mountain Formation. Semifusinite in these coals often occurs in extensive, regular layers, suggesting local exposure to very dry (likely wildfire) conditions. In the north Elk Valley coalfield, only seam 1 is inertinite-rich. Lower seams, not sampled for this study, have high inertinite content; from 40% to 48% (Dawson and Clow, 1992). Younger seams in the north Elk Valley coalfield are vitrinite-rich with common cutinite, whereas inertinite occurs as rare irregular fragments. This suggests lack of aerial exposure of peat surface even though most material comes from arborescent vegetation and one could expect drier swamp conditions than prevailing earlier when more herbaceous vegetation was dominant. Elemental and molecular data from the seams studied do not favour drier, and consequently, more oxidizing environment for vitrinite-rich coals. The vitrinite-rich samples from the seams of the north Elk Valley coalfield sections do not show evidence of oxidation, and vitrinite in those samples has lower C=O/C=C and C=O/(CH, + CH,) ratios than vitrinite in inertinite-rich coals in both coalfields. These two ratios are expected to be higher in more oxidized material due to formation of oxygenated groups. This suggests that there was higher oxidation during formation and preservation of the inertinite-rich coals (peats), representing the lower portion of the Mist Mountain Formation. Vitrinite-rich seam 4 in the north Elk Valley section has unique chemical characteristics. This seam has unusually low C content in vitrinite and cutinite associated with distinctly elevated 0 content. Much higher C=O/(CH, + CH,) and C=O/C=C ratios in this seam relative to other seams suggest high proportion of oxygenated groups, with high contribution of those formed due to the consumption of CH, and CH, during oxidation (Fig. 9). These observations suggest that weathering and oxidation influenced coal chemistry.
5. Conclusions (1) Inertinite-rich coal seams in the lower portion of the Mist Mountain Formation reflect the dominance of herbaceous vegetation and a climate with distinct seasonality and frequent aerial exposure, whereas vitrinite-rich coals in the upper part of the formation depict more arborescent vegetation and consistently humid conditions. (2) Individual macerals are inhomogeneous with regard to C and 0 content, and C=O/C=C and CH,/CH, ratios. In the case of the seams studied, this inhomogeneity results from the geochemical character of a depositional environment as well as post-depositional oxidation. (3) Coal macerals vary substantially with regard to the length and branching of aliphatic chaines; for these from the Mist Mountain Formation, cutinite had the longest or least branched aliphatic chains, and was followed by sporinite, vitrinite, semifusinite and fusinite.
58
M. Mastalerz, R.M. Bustin/International
Journal of Coal Geology 33 (1997) 43-59
Acknowledgements Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research and an NSERC operating grant to Bustin. Comments by Drs. A. Aihara, A. Dutcher, M. Kruge and P. Robert are greatly appreciated.
References Bustin, R.M. and Dunlop, R.L., 1992. Sedimentological factors affecting mining, quality, and geometry of coal seams of the Late Jurassic-Early Cretaceous Mist Mountain Formation, southern Canadian Rocky Mountains. Geol. Sot. Am., Spec. Pap., 267: 117-138 Bustin, R.M., Cameron, A., Grieve, D. and Kalkreuth, W., 1985. Coal Petrology, Its Principles, Methods and Applications. Geol. Assoc. Can., Short Course Notes, 2nd ed. Bustin, R.M., Mastalerz, M. and Wilks, K.R., 1993. Direct determination of carbon. oxygen and nitrogen content in coal using the electron microprobe. Fuel, 72: 181-185. Cameron, A.R., 1972. Petrography of Kootenay coals in the Upper Elk River and Crowsnest areas, British Columbia and Alberta. Proc. 1st Geol. Conf. on Western Canadian Coal, Edmonton, Alta., Res. Count. of Alberta, Info. Ser. No. 60, pp. 31-46. Dawson, F.M. and Clow, J.T., 1992. Coalbed methane research, Elk Valley Coalfield. In: B.D. Ryan and J. Cunningham (Compilers), The Canadian Coal and Coalbed Methane Geoscience Forum, Parksville, B.C., pp. 57-72. Donald, R.L., 1984. Sedimentology of the Mist Mountain Formation in the Fording River area. southeast Canadian Rocky Mountains. M.Sc. Thesis, University of British Columbia, Vancouver, B.C., 186 pp. Dunlop, R.L. and Bustin, R.M., 1987. Depositional environments of the coal-bearing Mist Mountain Formation, Eagle Mountain, southeastern Canadian Rocky Mountains, Bull. Can. Pet. Geol., 35: 389-415. Dyrkacz, G.R., Bloomquist, C.A.A. and Solomon, P.R., 1984. Fourier transform infrared study of high purity maceral types. Fuel, 63: 5366542. Dyrkacz, G.R., Bloomquist, C.A.A. and Rustic, L., 1991, An investigation of the vitrinite maceral group in microlithotypes using density gradient separation methods. Energy Fuels, 5: 155% 163. Gibson, D.W., 1985. Stratigraphy, sedimentology, and depositional environments of the coal-bearing Jurassic-Cretaceous Kootenay Group, Alberta and British Columbia. Geol. Surv. Can., Bull. 357, 108 pp. Gibson, D.W. and Hughes, J.D., 1981. Structure, stratigraphy, sedimentary environments and coal deposits of the Jura-Cretdceous Kootenay group, Crowsnest Pass area, Alberta and British Columbia. Field Guides Geol. Miner. Deposits, Calgary ‘81, Geol. Assoc. Can.-Mineral. Assoc. Can.-Can. Geophys. Union, pp. I-39. Hughes, J.D. and Cameron, A.R., 1985. Lithology, depositional setting and coal rank - Depth relationships in the JurassiccCretaceous Kootenay Group at Mount Allen, Cascade Coal Basin, Alberta. Geol. Surv. Can., Pap. 81-11, 41 pp. Landais, P. and Rochdi, A., 1990. Reliability of semiquantitative data extracted from transmission microscopy-Fourier transform infrared spectra of coal. Energy Fuels, 4: 290-295. Lin. R. and Ritz, G.P., 1993. Reflectance FT-IR microspectroscopy of fossil algae contained in organic-rich shales. Appl. Spectrosc., 47: 265527 1. MastaJerz, M. and Bustin, R.M., 1993a. Variation in elemental composition of macerals; an example of the application of electron microprobe to coal studies. Int. J. Coal Geol., 22: 83-99. Mastalerz, M. and Bustin, R.M., 1993b. Variation in maceral chemistry within and between coals of varying rank: an electron microprobe and micro-Fourier transform infra-red investigation. J. Microsc., 17lt2): 153-166. Mastalerz, M. and Bustin, R.M., 1995. Application of reflectance micro-Fourier transform infrared spectrometry in studying coal macerals: comparison with other Fourier transform infrared techniques. Fuel, 74: 5366542.
M. Mastalerz, R.M. Bustin/International
Journal
ofCoal Geology 33 (19971 43-59
59
Painter, P.C., Snyder, R.W., Starsinic, M., Coleman, M.M.. Kuehn, D.W. and Davis, A., 1981. Concerning the application of FTIR to the study of coal: a critical assessment of band assignments and the application ot spectral analysis programs. Appl. Spectrosc., 35: 475-485. Pouchou, J.L. and Pichoir, F., 1991. Quantitative analysis of homogenous or stratified microvolume applying the model “PAP”. In: K.F.J. Heimich and D.E. Newbury (Editors), Electron Probe Quantitation. Plenum. New York, NY, pp. 31-75. Pradier, B.. Landais. P., Rochdi. A. and Davis, A., 1992. Chemical basis of fluorescence alteration of crude oils and kerogens, II. Fluorescence and infrared micro-spectrometric analysis of vitrinite and liptinite. Org. Geochem., 18: 241-249. Rochdi, A., Landais, P. and Burneau, A., 1991. Analysis of coal by transmission FAIR microspectroscopy: methodological aspect. Bull. Sot. GCol. Fr., 162: 1555162. Stout, S.A., 1992 Chemical fingerprinting of individual macerals in situ using laser micropyrolysis-GCMS. 9th Annu. Meet., Sot. Org. Petrol., Abstr. Prog., University Park, PA, p.59. Wang, S.H. and Griffith, P.R., 1985. Resolution enhancement of reflectance IR spectra of coals by Fourier self-deconvolution. I CH stretching and bending modes. Fuel, 64: 229-236.
Journal of Coal Geology 33 (1997) 43-59
Variation in the chemistry of macerals in coals of the Mist Mountain Formation, Elk Valley coalfield, British Columbia, Canada Maria Mastalerz a3*, R. Marc Bustin b a Indiana Geological Surrey, Indiana UnilersiQ. 611 North Walnut Grow, Bloomington, IN. 47405-2208. USA h tkpartment
qf Gedogical
Sciences, The University of British Columbia,
Received 9 May 1995; accepted 9 February
Vancouver, B.C., Canada V6TIZ4 1996
Abstract Variations in elemental and molecular chemistry of macerals, with vitrinite, semifusinite and sporinite in particular, are discussed for the coal seams of the Mist Mountain Formation in the Elk Valley coalfield, in western Canada. In the south Elk Valley coalfield, carbon content of vitrinite oscillates around 85%, and oxygen content increases gradually up section, from seam A to C. In the north Elk Valley coalfield, carbon content in vitrinite shows marked variations (from 70% to 85%) between the samples and is lower than in the south Elk Valley coalfield, which is consistent with a higher maturation level of south Elk Valley coalfield samples. Sulphur content is below 1Q, in both coalfields. Semifusinite, in general, has higher carbon and lower oxygen content than vitrinite, whereas cutinite has higher carbon content than vitrinite and slightly higher or comparable to that of semifusinite. Functional group distributions show large variations between the seams and these variations are attributed mainly to differences in a primary depositional environment and only occasionally to later weathering and oxidation processes. The results presented in this paper provide also information on the length and branching of aliphatic chains, which, for liptinite macerals is valuable from the oil generation viewpoint, whereas for semifusinite, it may help to understand reactive versus non-reactive behaviour during coking.
* Corresponding
author.
0166-5 162/97/$17.00 Copyright PII SO 166-5 162(96)00003-
0 1997 Elsevier Science B.V. All rights reserved.
1
44
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (1997) 43-59
1. Introduction Naturally occurring organic matter comprises distinct and complex mixtures of components (macerals) of various origins, distinct chemistries and, consequently, different utility with respect to hydrocarbon generation and technological applications. This heterogeneity necessitates studying macerals separately, rather than using bulk sample analysis techniques. Analyzing individual macerals can be achieved by means of: (1) mechanical isolation of macerals (density gradient separation techniques, DGC); and (2) applying techniques which permit in-situ analysis of macerals. The analysis of mechanically isolated maceral separates considerably advanced the understanding of the chemistry of macerals, especially from high-volatile bituminous rank (Dyrkacz et al., 1984, 1991). However, concentration of macerals by crushing followed by liquid separation results in such a small particle size that the components are difficult to distinguish and degree of separation difficult to evaluate. Thus, optimal liberation of macerals has to be compromised with reliable maceral identification. In addition, grinding to fine particle sizes enhances oxidation and, as a result, maceral chemistry may be altered. Even assuming ideal segregation of macerals, this technique permits determination of differences between maceral groups at best, and not within individual macerals or submacerals. Currently there are a few microtechniques in use to study macerals in situ. Laser micropyrolysis-GCMS holds promise as technique for chemical fingerprinting of macerals, allowing determination of aliphatic and aromatic compound in the pyrolysate from an area of 15-50 pm (Stout, 1992). Another technique is the electron microprobe, allowing precise and accurate determination of elemental composition (major and minor elements) of areas a few micrometres in diameter (Bustin et al., 1993). Micro-Fourier Transform Infra-red Spectroscopy (micro-FTIR) enables determination of functional groups of macerals in transmission or reflectance mode (Landais and Rochdi, 1990; Rochdi et al., 1991; Pradier et al., 1992; Mastalerz and Bustin, 1993b,1995) at a scale of N 20 km. Even though these micro-techniques, are still qualitative and semi-quantitative, rather than quantitative (with an exception of the electron microprobe), when applied collectively they provide much more information about chemical variation between macerals and within macerals than any other available technique. These methods of the first time allow petrologists for the first time to directly determine the chemistry of macerals and to evaluate what differences exist, if any, between submacerals. The purpose of this paper is to determine variation in the chemistry of vitrinite, semifusinite and cutinite in coal seams of the Mist Mountain Formation using the electron microprobe and reflectance micro-FTIR. The Mist Mountain Formation was chosen because: (1) it is the main coal-bearing formation of economic interest in western Canada; (2) it covers a considerable rank range (high-volatile bituminous to semianthracite; Bustin and Dunlop, 1992); and (3) maceral composition of the seams is well documented (Cameron, 1972; Bustin and Dunlop, 1992) thus, the chemistry of selected samples can be interpreted and discussed in the framework of already known trends in coal petrography. In addition, semifusinite is a significant constituent of the Mist Mountain Formation and its degree of reactivity during coking remains controversial.
M. Mastalerz, R.M. Bustin / International
Journal
of Coal Geology 33 (1997143-59
45
2. General geology The Mist Mountain Formation is a elastic sequence of Late Jurassic age up to 700 m thick (Donald, 1984, Gibson, 1985), located in the southeastern Canadian Cordillera (Fig. 1). This formation is a part of the Kootenay Group (Fig. 2); it conformably overlies the Moose Mountain Member of the Morrisey Formation, considered to represent backshore, beach-ridge and dune deposits of a wave-dominated delta (Gibson and Hughes, 1981; Gibson, 1985; Hughes and Cameron, 1985; Dunlop and Bustin, 1987). The Mist Mountain Formation is conformably overlain by alluvial fan braid plain deposits of the Elk Formation (Gibson, 1985). The Mist Mountain Formation is the main coal-bearing unit in the southeastern Canadian Cordillera. It is a non-marine sequence; its lower part has been interpreted as delta-interdeltaic coastal plain deposits and the upper part as upper delta plain/alluvial plain deposits (Dunlop and Bustin, 1987). Coal seams occur throughout the sequence, locally there are more than 15 seams, ranging in thickness from a few centimetres to 20 m. The coal is characterised by low sulphur ( < 1%) and low ash content and it varies in rank from high-volatile bituminous to anthracite.
1 study area Fig. 1. Location map for the area studied, showing the regional geology.
1
46
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (1997) 43-59
3. Methods Coal samples from seams of south Elk Valley Coalfield referred to here as samples A, B, C and D and from seams of the north Elk Valley Coalfield named here seams 1, 2, 3 and 4 have been collected from the Mist Mountain Formation. Three coal samples, representing the dominant lithology of the upper, middle and lower part of each seam (24 samples in total) were selected for study. Each sample was made into a polished block according to standard coal preparation techniques (Bustin et al., 1985) and photographed using a 20 X oil immersion objective. In addition, pellets for maceral analysis were also made for all samples. Random reflectance in oil (R,) was measured using a Leitz MPV II microscope. Samples chosen for electron microprobe analysis were sputter-coated with a carbon layer 0.023 km thick. A Cameca SX-50 electron microprobe with the PAP matrix correction routine (Pouchou and Pichoir, 1991) was used to analyze major and minor elements in coal; a PC2 (NiC) pseudocrystal was used for analyzing the light elements (carbon and oxygen). The physical conditions of the analyses were as follows: an accelerating voltage of 10 kV, a beam current of 10 nA and a beam size of 5 km (Bustin et al., 1993). Anthracite, magnesite and barite were used as carbon, oxygen and sulphur standards, respectively. Iron, Si and Al contents also were determined, with siderite as a standard for iron, wollastonite as a standard for silica and anorthite as a standard for aluminum. Following microprobe analysis the samples were carefully repolished to remove the carbon coat for micro-FTIR analysis.
AGE
SETTING
LITHOLOGY
FORMATION
GROUP
.
.
. . TmioNIAN
ELK
. - -3 /--q
. .
2 e g
. ._ 7
KIYMERIDGW
E : ‘2
1 .s .
. . ??
MIST MOUNTAIN
??
Marine
--
FERNIE
-
Fig. 2. Lithostratigraphic
E
A MORRISSEY
--
OXFORDLW
T
N
s
.
??
0
;
k
.
K 0
position of the Mist Mountain Formation
y
M. Mastalerz, R.M. Bustin /International Journal
of CoalGeology
33 (1997) 43-59
4:
Functional groups in macerals of all samples were determined from FIIR spectra collected using a Nicolet 710 micro-FIIR spectrometer equipped with a NICPLAN microscope. A 35 X IR objective was used. All spectra were obtained in reflectance mode at a resolution of 4 cm- ’; 128 scans were co-added (a ratio to a background of 128 scans was calculated) with the Kramers-Kronig transformation applied. Bands were assigned according to Painter et al. (1981) and Wang and Griffith (1985). A commercial program FOCAS’(Nicolet) was used to deconvolute FTIR spectra and integrate areas under selected peaks.
4. Results and discussion 4.1. Muceral composition Maceral composition of the samples from the Mist Mountain Formation is presented in Fig. 3. Samples from the seams in south Elk Valley coalfield (seams C, B, A) are characterized by high inertinite content (> 20%). Inertinite is represented mainly by semifusinite of both variable reflectance and degree of cell structure preservation.
Maceralcomposition
seam B
seam A
Fig. 3. Maceral composition of the samples analysed (each value represents an average of 3 samples). Note the high inertinite content in the seams from the south Elk Valley coalfield and in seam 1 from the north Elk Valley coalfield.
48
M. Mastalerz, R.M. Bustin/lnternational Journal of Coal Geology 33 (1997) 43-59
Inertodetrinite is also common (Fig. 4A). Other inertinite macerals are rare; fusinite can be locally abundant, especially in seam A. Seam 1 in the north Elk Valley coalfield has also high inertinite content (> 20%). In the samples from the younger seams (2-4) of this area, inertinite content decreases (to a few % in seam 4) and vitrinite and cutinite increase (Fig. 3 and Fig. 4B). The well-documented trend in maceral composition of the seams in the Mist Mountain Formation, with vitrinite increasing upward at the expense of inertinite (Cameron, 1972; Bustin and Dunlop, 1992) may reflect more herbaceous vegetation in the lower part of the section, as suggested by Cameron (1972) and Donald (1984). This is consistent with the observation from this study that inertinite in high-inertinite coals is represented mainly by semifusinite with large proportion of a low-reflectance variety and minor distinctly wood-derived fusinite. 4.2. Elemental
composition
of macerals
4.2.1. Vitrinite Carbon, oxygen and sulphur contents of vitrinite together with minor elements for all the seams are listed in Tables 1 and 2. In the south Elk Valley coalfield (seams A, B, C; Table l), carbon content of the vitrinite is uniform, with a medium of - 85%, whereas oxygen content increases gradually up section (from seam A to C). Sulphur content (determined on optically homogeneous vitrinite) is usually < 0.5%. In contrast, in the north Elk Valley coalfield (seams 1-4; Table 21, carbon content in vitrinite shows marked variations between samples, being generally lower than in the samples from the south Elk Valley coalfield, which is consistent with a higher maturation level of south Elk Valley coalfield samples (R, from 1.2% to 1.5% in the south Elk Valley coalfield versus 0.9% to 1.00% in the north Elk Valley coalfield, Table 3). In seam 1, mean carbon content is - 81%, increases to 84-85% in seams 2 and 3, and decreases to 70% in seam 4. Oxygen content shows a reverse trend, being relatively high in seam 1 (15.5%, Table 2), decreasing to 6-9% in seams 2 and 3, and increasing to 28% in seam 4. Sulphur content in the seams of the north Elk Valley coalfield is < l%, but its content is somewhat higher than in the samples from the south Elk Valley coalfield. and jiisinite 4.2.2. Semijusinite Semifusinite is characterized by a higher carbon and lower oxygen content than vitrinite in the samples from the south Elk Valley coalfield and most samples from the north Elk Valley coalfield. (Tables 1 and 2). Carbon, oxygen and sulphur contents of semifusinite vary throughout the section, concurrently with vitrinite. Samples in seams of the south Elk Valley coalfield have very uniform carbon content (- 88%; Table l), higher than those in the north Elk Valley coalfield. In the north Elk Valley coalfield, semifusinite in seam 4 has the lowest carbon content, whereas seams 2 and 3 have the highest carbon contents (Table 2). Oxygen content is, similarly to vitrinite, highest in seams 1 and 4. Sulphur content is < 1% and the seams in the north Elk Valley coalfield are somewhat richer in this element than the seams in the south Elk Valley coalfield. In all samples, fusinite has higher C content than semifusinite and vitrinite and usually higher than cutinite. Oxygen and sulphur content are usually lower than other macerals. Fusinite also has lower Al, Si and Ca contents than other macerals.
M. Mastalerz, R.M. Bustin/Intemational
FIlg. 4. Photomicrographs A High-inertinite-content in ertodetrinite). B Low-inertinite-content
Journal of Coal Geology 33 (1997) 43-59
of coal: coal, seam D, south Elk Valley
coalfield
coal, seam 3, north Elk Valley coalfield
(s = semifusinite;
L‘= vitrinite:
(t’= vitrinite; c = cutinite).
4’)
i=
50
M. Mastalerz, R.M. Bustin /International
Table 1 Elemental
composition
Seam
Maceral
C
0
C
vitrinite
fusinite
85.9 (0.45) 88.3 (1.81) 90.4
B
vitrinite semifusinite
85.0 87.9
A
vitrinite semifusinite
85.3 (0.56) 87.8
fusinite
(1.04) 91.7
semifus
of macerals
Values are in wt%. Numbers observations (n) >_5.
Journal of Coal Geology 33 (1997143-59
from south Elk Valley coaltield S
Si
Al
Fe
Ca
0.3 (0.07) 0.3 (0.14) 0.2
0.33 (0.09) 0.33 (0.12) 0.04
0.30 (0.08) 0.34 (0.11) 0.00
0.04 (0.03) (:::, 0.00
0.02 (0.01) 0.02 (0.01) 0.03
5
(1.4) 4.7 (2.81) 2.8 8.6 4.1
0.2 0.2
0.33 0.35
0.29 0.34
0.07 0.00
0.02 0.03
2 2
7.5 (1.41) 4.5 (1.02) 2.2
0.3 (0.07) 0.2 (0.09) 0.1
0.03
0.01 (0.01) 0.06 (0.05) 0.15
0.02 (0.01) 0.03 (0.02) 0.00
0.01 (0.02) 0.06 (0.03) 0.19
10
(0.04) 0.02 (0.03) 0.03
9.5
in parentheses
are standard
deviations,
computed
where
n
5 2
10 2
the number
Table 2 Elemental
composition
Seam
Maceral
C
0
S
Si
Al
Fe
Ca
n
4
vitrinite
70.2 (0.56) 78.4 (1.16) 76.4 (0.64)
21.6 (2.21) 14.8 (3.50) 17.8 (1.91)
0.3 (0.14) 0.3 (0.14) 0.2 (0.04)
0.15 (0.09) 0.40 (0.15) 0.25 (0.04)
0.05 (0.07) 0.01 (0.05) 0.00 (0.00)
0.06 (0.09) 0.06 (0.05) 0.05 (0.04)
0.03 (0.03) 0.03 (0.03) 0.01 (0.03)
10
84.8 (0.43) 86.2 (0.92) 89.1 (0.44)
6.5 (1.12) 7.1 (2.31) 3.6 (0.69)
0.5 (0.07) 0.5 (0.06) 0.4 (0.05)
0.15 (0.05) 0.10 (0.03) 0.03 (0.03)
0.03
0.04 (0.06) 0.10 (0.06) 0.03 (0.02)
0.08 (0.03) 0.00 (0.00) 0.02 (0.01)
10
(0.04) 0.04 (0.06) 0.01 (0.03)
85.2 (0.33) 86.3 (1.10) 87.7 87.2
0.6 (0.04) 0.5 (0.03) 0.5 0.5
0.08 (0.02) 0.06 (0.02) 0.10 0.10
0.02 (0.02) 0.01 (0.01) 0.04 0.08
0.02 (0.02) 0.00 (0.00) 0.10 0.02
0.01 (0.01) 0.01 (0.01) 0.00 0.00
10
KS 6.7 (0.90) 7.2 5.00
81.2 (0.78) 81.5 (1.01) 91.5 82.6
15.5 (0.82) 12.8 (1.12) 3.3 10.5
0.3 (0.04) 0.3 (0.05) 0.1 0.2
0.15 (0.05) 0.05 (0.06) 0.05 0.04
0.08 (0.03) 0.00
0.00 (0.00) 0.02 (0.00) 0.05 0.01
0.01 (0.01) 0.01 (0.01) 0.19 0.02
5
semifusinite cutinite
3
vitrinite semifusinite cutinite
2
vitrinite semifusinite fusinite cutinite
1
vitrinite semifusinite fusinite cutinite
of macerals
Values are in wt%. Numbers observations (n) 2 5.
of
from north Elk Valley coalfield
in parentheses
are standard
(0.00) 0.07 0.00
deviations,
computed
where
10 5
5 5
5 1 2
5 1 1
the number
of
M. Mastalerz, R.M. Bustin / International Journal of Coal Geology 33 (I 997143-59
51
Table 3 FUR-derived Seam
ratios for selected macerals Maceral
CH,
(bands used for integration
/(CH, +CHJ
explained
in the text)
c=o/c=c
C=O/(CH, +CH,)
R,, (%‘c)
South Elk Valley coaljield: Seam D
vitrinite semifusinite
0.64 (0.18) 0.40 (0.47)
0.56 (0.3 1) 0.57 (0.67)
0.74 (0.46) 1.03 (0.51)
1.3 2.0
Seam C
vitrinite semifusinite
0.33 (0.18) 0.48 (0.45)
0.42 (0.22) 0.42 (0.33)
0.80 (0.32) 0.97 (0.44)
1.5 2,s
Seam B
vitrinite semifusinite
0.36 (0.2 CHZ=O
0.60 (0.32) 0.64 (0.3 1)
0.80 (0.36) 0.73 (0.34)
I .3 2.0
Seam A
vitrinite semifusinite
0.43 (0.32) 0.47 (0.41)
0.45 (0.22) 0.52 (0.63)
0.74 (0.5 I) 0.7 I (0.39)
I.2 2.0
vitrinite cutinite semifusinite
0.49 (0.22) 0.41 (0.13) 0.53 (0.41)
0.56 (0.44) 0.67 (0.13) 0.56 (0.25)
3.00 (1.31) I .24 (0.62) 2.03 (0.45)
0.9 0.2
Seam 3
vitrinite cutinite semifusinrte
0.47 (0.17) 0.37 (0.09) 0.45 (0.32)
0.30 (0.14) 0.40 (0.09) 0.34 (0.4 I)
1.16(0.21) 0.51 (0.14) 0.70 (0.38)
0.9 0.3 1.7
Seam 2
vitrinite cutinite sporinite semifurinite fusinite
0.49 0.27 0.40 0.36 0.55
0.31 0.70 0.68 0.49 0.60
1.71 1.40 0.75 I .25 I .76
0.9 0.4 0.2
vitrinite cutinite semifusinite fusinite
0.63 (0.25) 0.46 (0.08) 0.46 (0.48) 0.63
I)
North Elk Valley coalfield Seam 4
Seam
1
Each value represents brackets.
(0.26) (0.11) (0.09) (0.24)
a mean of IO analyses,
(0.19) (0. IO) (0.1 I ) (0.29)
0.34 (0.19) 0.66 (0. IO) 0.45 (0.32) 0.61 except fusinite
I .4
(0.21) (0.07) (0.1 I) (0.30)
I .-I 2.1
1.57(0.26) 0.90 (0.07) 2.52 (0.63) 0.78
(2 analyses),
standard
0.9 0.5 1.7 1.7 deviation
is given in
4.2.3. Cutinite
Liptinite is rare in seams of the south Elk Valley coalfield due, at least partly, to the higher coal rank than in the north Elk Valley coalfield. In the north Elk Valley coalfield, cutinite is abundant (Fig. 4B) and its elemental composition varies from seam to seam similarly to vitrinite and semifusinite (Table 2). Cutinite in seams 1 and 4 has higher oxygen content and lower carbon content than the cutinite in seams 2 and 3. Carbon content of cutinite is higher than that of vitrinite and slightly higher or comparable to that in semifusinite, except seam 4, where C content of cutinite is substantially lower than in semifusinite. Macerals other than already described are uncommon in the samples studied or they are of very small size and because of that no elemental data have been obtained.
52
M. Mastalerz, R.M. Bustin/International
Journal
qf Coal Geology 33 (1997143-59
CH3 KHZ + CH3
,’ 0
0.1
,’
0.2
,’
,’
0.3
0.4
,’
0.5
0.6
0.7
semifus. Wcutinite Illlvitrinite
Fig. 5. FTIR-derived ratios of vitrinite, semifusinite and cutinite in the seams of the north Elk Valley coalfield (seams l-4). Ratio values are the same as in Table 3.
The above results show that each maceral (vitrinite, semifusinite and cutinite) varies with respect to C and 0 contents even between samples of very similar rank. This is particularly apparent for samples from the north Elk Valley coalfield. At the reflectance range from 0.92% to 1.O%, C content of vitrinite ranges from 70% to 84% and 0 content from 25% to 8%. The same range of variations exists even for seams with almost identical R, (samples from seams 2-4). Variations in elemental composition of semifusinite are of the same magnitude as vitrinite; variations within cutinite are somewhat smaller but still substantial. The coals from the south Elk valley coalfield represent higher rank (R, 1.33- 1.44%) than those from the north Elk Valley coalfield and smaller variations in elemental composition between vitrinite and semifusinite, are, at least partly, a function of higher rank. 4.3. Functional
group distribution
Fig. 5 and Fig. 6 and Table 3 present parameters derived from micro-FTIR spectra of vitrinite, semifusinite and cutinite for the coals studied. The parameters calculated are: (1) a ratio of CH,/(CH, + CH,) in the 2800-3000 cm-’ region; (2) C=O/(CH, + CH,); and 3) C=O/C=C in the 1550-1750 cm-‘. The first ratio is related to the length of aliphatic chains (Pradier et al., 1992) whereas the last two reflect the degree of oxidation of organic matter.
M. Mastalerz, R.M. Bustin/International
Journal
of Coal Geology 33 (1997) 43-59
S?
CH3lCH2 + CH3
seam A
C=QICHZ + CH3
0
0.2
0.4
0.6
0.6
1
1.2
Fig. 6. FTIR-derived ratios of vitrinite and semifusinite A-D). Ratio values are the same is in Table 3.
in the seams of the south Elk Valley coalfield (seams
For the vitrinite in samples from the north Elk Valley coalfield, CH,/(CH2 + CH,) ratio is N 0.5 for seams 4, 3 and 2 and increases to 0.63 in seam 1 (Fig. 5) reflecting the vitrinite of seam 1 has shorter aliphatic chains. The C=O/C=C and C=O/(CH, + CH,) ratios of vitrinite are greatest in the topmost seam 4, indicating more advanced oxidation of the vitrinite of this seam compared to others. In cutinite, the lowest CH,/(CH, + CH,) ratio occurs in seam 2, whereas the highest occur in seam 1, again suggesting shortest aliphatic chain of cutinite in the latter. The C=O/C=C and C=O/(CH, + CH,) ratios are lowest in seam 3, indicating the lowest oxidation level. Seams 4 and 2 show the greatest oxidation of cutinite. Semifusinite shows comparable CH,/(CH, + CH,) ratio for all seams, except a lower value in seam 2. The C=O/C=C and C=O/(CH2 + CH,) ratios are lowest in seam 3, similar to cutinite. In the south Elk Valley coalfield, vitrinite has the highest CH,/(CH, + CH,) ratio in seam D (Fig. 6) suggesting the shortest aliphatic chains. The C=O/C==C ratio is higher in seams D and B than in the other two. The C=O/(CH, + CH,) ratio is comparable in all seams, which suggests a similar oxidation level. Semifusinite in all seams shows comparable CH,/(CH, + CH,) ratio except seam B, whose semifusinite shows no detectable CH, (Table 3). The C=O/C=C ratio is highest in seam B, whereas C=O/(CH, + CH,) is highest in seams D and C. In addition to the ratios discussed above, the values of CH,/CH, in 2900-3000
54
M. Mastalerz, R.M. Bustin/International
Vitfinite
Ro (36
Journal of Coal Geology 33 (1997) 43-59
:i1:/:3-
0
“Eli”““““““““““’
0.5
1
CH3 EH2
0
Semifusinite
Ro (%
05 CH3/CH2
15
2
25
3
35
0
'(2800-2biO)
1 CH3
(2900-3000)
2
0
0.5 C%
2 /CH2
1 /CH2
3
4
(2900-3000)
1.5
2
2.5
3
3.5
(2800-2900)
Fig. 7. Relationships between reflectance and CH, /CH, ratios for vitrinite and semifusinite from all the samples studied. For calculation of these ratios, the following band integration areas (in cm-‘) were used: 2850 (CH,), 2870 (CH,), 2925 (CH,) and 2955 (CH,).
cm-’ and CHJCH, in 2800-2900 cm-’ for vi&mite, semifusinite and liptinite have been plotted against reflectance in order to determine the evolution of CH, and CH, groups as well as their individual bands with maturation. Fig. 7 shows an increase in CHJCH, ratio with maturation in vitrinite. Comparisons of CHJCH, ratios in the 2800-2900 and 2900-3000 cm-’ regions suggest that it is the 2800-2900 cm-i region that contributes to the increase in CHJCH, ratio with rank. The bands in the 2900-3000 cm-’ region do not correlate with R,. Plots for semifusinite show very weak to non-existent correlation between FTIR-derived functional group ratios and reflectance (Fig. 7). Fig. 8 depicts relationships for liptinite group. Because of a limited number of analyses on individual liptinite macerals, cutinite, sporinite and resinite are grouped together. For this maceral group the only significant correlation has been obtained for R, and CH,/CH, in the 2900-3000 cm-’ region (r2 = 0.641, whereas there is no correlation between R, and CHJCH, in the 2800-2900 cm-’ region. The lack of correlation between reflectance and CH,- and CH,-related ratios implies that other factors than maturation strongly affect these ratios. One of the factors might be inhomogeneity of organic material. Because each maceral was considered separately, petrographic inhomogeneity can be ruled out. However, the fact that elemental and molecular chemistry of individual macerals vary from one seam to another, even though reflectance values are very similar implies that CH,- and CH,-related ratios should also vary from seem to seam. It should be mentioned here that for the seams studied, a
M. Mastalerz. R.M. Bustin /International Journal of Coal Geology 33 (1997) 43-59
55
Liptinite 06
0.5
04 03 0.2
t
................................................ ........ ............ ........... ..~..*.5:.......__._ .A’ r"0.64 ....
",
CH+CH2
(29’20-3000)
Ro(%) 0.6
05
t
I
?? ??? ? ? ? ? ? ? ? ?? ?? ? ? ? ? ? ??? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
~~
0.4 0.3 02 01
0
02
04
06
0.8
CH31CH2 (2800-2900)
Fig. 8. Relationships between reflectance studied. Ratios calculated as in Fig. 7.
and FTIR-derived
ratios for liptinite macerals
from all the samples
correlation between carbon content and reflectance for individual macerals is also poor. Positive, though very weak correlations were obtained for semifusinite and vitrinite (with r2 of 0.45 and 0.62, respectively). Better correlations between reflectance and carbon content were obtained for cutinite (r2 = 0.76) and inertodetrinite (r2 = 0.74). but these may not be significant because of small number of analyses (8 for each maceral). Weak correlations between reflectance and carbon content on a maceral scale were also noticed elsewhere (Mastalerz and Bustin, 1993a). The results obtained provide also information on the length and branching of aliphatic chains in individual macerals, which gives insight into maceral structure and is valuable from the oil and gas generation point of view. Assuming that higher ratio CH,/(CHz + CH,) represents shorter and more branched aliphatic chains, the results obtained (Table 3) show that of all the macerals studied cutinite has longest or least branched aliphatic chains. This is consistent with observations by Lin and Ritz (1993), who documented longer aliphatic chains for cutinite than for alginite. Sporinite in the coal studied shows shorter aliphatic chains than cutinite. Fusinite always had the shortest chains of all macerals. Vitrinite is usually characterized by longer aliphatic chains than semifusinite. there are examples, however, where semifusinite is comparable to vitrinite with respect to chain length. Such a semifusinite has usually low reflectance and, thus, is likely reactive. Perhaps the reactivity is related to the length of aliphatic chains and, if this
56
M. Mastalerz, R.M. Bustin/International
Journal of Coal Geology 33 (1997143-59
suggestion is correct, FTIR would be a very useful technique to determine semifusinite reactivity versus non-reactivity. This problem, however, requires further study. 4.4. Remarks on coal (peat) deposition The coals of the Mist Mountain Formation were deposited in an protected from marine incursion. This is inferred from sedimentological elastic sediments associated with the seams (Bustin and Dunlop, 1992) as their low sulphur content (Gibson, 1985). It has been suggested that the developed on a broad, relatively flat coastal marsh-swamp complex, remaining part of the section is related to fluvial (flood plain)-dominated
environment studies of well as from oldest seams whereas the environment,
cutinite
. 4000
. 3600
. 3200
. 2600
.
.
.
2400
2000
1600
Wavenumber
. 1200
3600
3200
2800
2400
. 400
(cm-‘)
, . . . . . . .
4000
. 600
2000
Wavenumber
1600
1200
I
600
400
(cm“)
Fig. 9. FTIR spectra of vitrinite and cutinite from seams 3 and 4. Assignment of bands: 2925 and 2856 cm- ’ - CH,; 1738 and 1711 cm-’ - C=O; 1610 cm-’ - C=C; 1448 cm-’ - CHZ; and 812 cm-’ compounds containing rings with two neighbouring C-H groups. Note large reduction of aliphatic stretching bands in the 2800-3000 cm-’ region for both vitrinite and cutinite in seam 3 due to oxidation.
M. Mastalerz, R.M. Bustin / International Journal
of Coal Geology 33 (19971 43-S9
57
with changeable influence of active alluvial channels (Bustin and Dunlop, 1992). The mentioned earlier vertical trend in maceral composition of the seams throughout the formation may reflect a change from the dominance of herbaceous vegetation (high-inertinite coals) to more arborescent vegetation (high-vitrinite coals) with time. In the south Elk Valley coalfield, all the seams studied come from the high inertinite portion of the Mist Mountain Formation. Semifusinite in these coals often occurs in extensive, regular layers, suggesting local exposure to very dry (likely wildfire) conditions. In the north Elk Valley coalfield, only seam 1 is inertinite-rich. Lower seams, not sampled for this study, have high inertinite content; from 40% to 48% (Dawson and Clow, 1992). Younger seams in the north Elk Valley coalfield are vitrinite-rich with common cutinite, whereas inertinite occurs as rare irregular fragments. This suggests lack of aerial exposure of peat surface even though most material comes from arborescent vegetation and one could expect drier swamp conditions than prevailing earlier when more herbaceous vegetation was dominant. Elemental and molecular data from the seams studied do not favour drier, and consequently, more oxidizing environment for vitrinite-rich coals. The vitrinite-rich samples from the seams of the north Elk Valley coalfield sections do not show evidence of oxidation, and vitrinite in those samples has lower C=O/C=C and C=O/(CH, + CH,) ratios than vitrinite in inertinite-rich coals in both coalfields. These two ratios are expected to be higher in more oxidized material due to formation of oxygenated groups. This suggests that there was higher oxidation during formation and preservation of the inertinite-rich coals (peats), representing the lower portion of the Mist Mountain Formation. Vitrinite-rich seam 4 in the north Elk Valley section has unique chemical characteristics. This seam has unusually low C content in vitrinite and cutinite associated with distinctly elevated 0 content. Much higher C=O/(CH, + CH,) and C=O/C=C ratios in this seam relative to other seams suggest high proportion of oxygenated groups, with high contribution of those formed due to the consumption of CH, and CH, during oxidation (Fig. 9). These observations suggest that weathering and oxidation influenced coal chemistry.
5. Conclusions (1) Inertinite-rich coal seams in the lower portion of the Mist Mountain Formation reflect the dominance of herbaceous vegetation and a climate with distinct seasonality and frequent aerial exposure, whereas vitrinite-rich coals in the upper part of the formation depict more arborescent vegetation and consistently humid conditions. (2) Individual macerals are inhomogeneous with regard to C and 0 content, and C=O/C=C and CH,/CH, ratios. In the case of the seams studied, this inhomogeneity results from the geochemical character of a depositional environment as well as post-depositional oxidation. (3) Coal macerals vary substantially with regard to the length and branching of aliphatic chaines; for these from the Mist Mountain Formation, cutinite had the longest or least branched aliphatic chains, and was followed by sporinite, vitrinite, semifusinite and fusinite.
58
M. Mastalerz, R.M. Bustin/International
Journal of Coal Geology 33 (1997) 43-59
Acknowledgements Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research and an NSERC operating grant to Bustin. Comments by Drs. A. Aihara, A. Dutcher, M. Kruge and P. Robert are greatly appreciated.
References Bustin, R.M. and Dunlop, R.L., 1992. Sedimentological factors affecting mining, quality, and geometry of coal seams of the Late Jurassic-Early Cretaceous Mist Mountain Formation, southern Canadian Rocky Mountains. Geol. Sot. Am., Spec. Pap., 267: 117-138 Bustin, R.M., Cameron, A., Grieve, D. and Kalkreuth, W., 1985. Coal Petrology, Its Principles, Methods and Applications. Geol. Assoc. Can., Short Course Notes, 2nd ed. Bustin, R.M., Mastalerz, M. and Wilks, K.R., 1993. Direct determination of carbon. oxygen and nitrogen content in coal using the electron microprobe. Fuel, 72: 181-185. Cameron, A.R., 1972. Petrography of Kootenay coals in the Upper Elk River and Crowsnest areas, British Columbia and Alberta. Proc. 1st Geol. Conf. on Western Canadian Coal, Edmonton, Alta., Res. Count. of Alberta, Info. Ser. No. 60, pp. 31-46. Dawson, F.M. and Clow, J.T., 1992. Coalbed methane research, Elk Valley Coalfield. In: B.D. Ryan and J. Cunningham (Compilers), The Canadian Coal and Coalbed Methane Geoscience Forum, Parksville, B.C., pp. 57-72. Donald, R.L., 1984. Sedimentology of the Mist Mountain Formation in the Fording River area. southeast Canadian Rocky Mountains. M.Sc. Thesis, University of British Columbia, Vancouver, B.C., 186 pp. Dunlop, R.L. and Bustin, R.M., 1987. Depositional environments of the coal-bearing Mist Mountain Formation, Eagle Mountain, southeastern Canadian Rocky Mountains, Bull. Can. Pet. Geol., 35: 389-415. Dyrkacz, G.R., Bloomquist, C.A.A. and Solomon, P.R., 1984. Fourier transform infrared study of high purity maceral types. Fuel, 63: 5366542. Dyrkacz, G.R., Bloomquist, C.A.A. and Rustic, L., 1991, An investigation of the vitrinite maceral group in microlithotypes using density gradient separation methods. Energy Fuels, 5: 155% 163. Gibson, D.W., 1985. Stratigraphy, sedimentology, and depositional environments of the coal-bearing Jurassic-Cretaceous Kootenay Group, Alberta and British Columbia. Geol. Surv. Can., Bull. 357, 108 pp. Gibson, D.W. and Hughes, J.D., 1981. Structure, stratigraphy, sedimentary environments and coal deposits of the Jura-Cretdceous Kootenay group, Crowsnest Pass area, Alberta and British Columbia. Field Guides Geol. Miner. Deposits, Calgary ‘81, Geol. Assoc. Can.-Mineral. Assoc. Can.-Can. Geophys. Union, pp. I-39. Hughes, J.D. and Cameron, A.R., 1985. Lithology, depositional setting and coal rank - Depth relationships in the JurassiccCretaceous Kootenay Group at Mount Allen, Cascade Coal Basin, Alberta. Geol. Surv. Can., Pap. 81-11, 41 pp. Landais, P. and Rochdi, A., 1990. Reliability of semiquantitative data extracted from transmission microscopy-Fourier transform infrared spectra of coal. Energy Fuels, 4: 290-295. Lin. R. and Ritz, G.P., 1993. Reflectance FT-IR microspectroscopy of fossil algae contained in organic-rich shales. Appl. Spectrosc., 47: 265527 1. MastaJerz, M. and Bustin, R.M., 1993a. Variation in elemental composition of macerals; an example of the application of electron microprobe to coal studies. Int. J. Coal Geol., 22: 83-99. Mastalerz, M. and Bustin, R.M., 1993b. Variation in maceral chemistry within and between coals of varying rank: an electron microprobe and micro-Fourier transform infra-red investigation. J. Microsc., 17lt2): 153-166. Mastalerz, M. and Bustin, R.M., 1995. Application of reflectance micro-Fourier transform infrared spectrometry in studying coal macerals: comparison with other Fourier transform infrared techniques. Fuel, 74: 5366542.
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Painter, P.C., Snyder, R.W., Starsinic, M., Coleman, M.M.. Kuehn, D.W. and Davis, A., 1981. Concerning the application of FTIR to the study of coal: a critical assessment of band assignments and the application ot spectral analysis programs. Appl. Spectrosc., 35: 475-485. Pouchou, J.L. and Pichoir, F., 1991. Quantitative analysis of homogenous or stratified microvolume applying the model “PAP”. In: K.F.J. Heimich and D.E. Newbury (Editors), Electron Probe Quantitation. Plenum. New York, NY, pp. 31-75. Pradier, B.. Landais. P., Rochdi. A. and Davis, A., 1992. Chemical basis of fluorescence alteration of crude oils and kerogens, II. Fluorescence and infrared micro-spectrometric analysis of vitrinite and liptinite. Org. Geochem., 18: 241-249. Rochdi, A., Landais, P. and Burneau, A., 1991. Analysis of coal by transmission FAIR microspectroscopy: methodological aspect. Bull. Sot. GCol. Fr., 162: 1555162. Stout, S.A., 1992 Chemical fingerprinting of individual macerals in situ using laser micropyrolysis-GCMS. 9th Annu. Meet., Sot. Org. Petrol., Abstr. Prog., University Park, PA, p.59. Wang, S.H. and Griffith, P.R., 1985. Resolution enhancement of reflectance IR spectra of coals by Fourier self-deconvolution. I CH stretching and bending modes. Fuel, 64: 229-236.