Chemistry and origin of minor and trace elements in vitrinite concentrates from a rank series from the eastern United States, England, and Australia

International Journal of Coal Geology, 13 ( 1989 ) 481-527 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

481

C h e m i s t r y and origin of minor and trace e l e m e n t s in v i t r i n i t e c o n c e n t r a t e s from a r a n k series from the e a s t e r n U n i t e d States, England, and Australia PAUL C. LYONS 1, CURTIS A. PALMER 1, NEELY H. BOSTICK 2, JANET D. FLETCHER 1, FRANK T. DULONG 1, FLOYD W. BROWN 1'*, ZOE ANN BROWN 1'*, MARTA R. KRASNOW 1, and LISA A. ROMANKIW 1

1U.S. Geological Survey, MS 956, National Center, Reston, VA 22092, U.S.A. ~U.S. Geological Survey, MS 972, Denver Federal Center, Denver, CO 80225-0046, U.S.A. (Received August 3, 1988; revised and accepted December 2, 1988)

ABSTRACT Lyons, P.C., Palmer, C.A., Bostick, N.H., Fletcher, J.D., Dulong, F.T., Brown, F.W., Brown, Z.A., Krasnow, M.R. and Romankiw, L.A., 1989. Chemistry and origin of minor and trace elements in vitrinite concentrates from a rank series from the eastern United States, England, and Australia. In: P.C. Lyons and B. Alpern (Editors), Coal: Classification, Coalification, Mineralogy, Trace-element Chemistry, and Oil and Gas Potential. Int. J. Coal Geol., 13: 481-527. A rank series consisting of twelve vitrinite concentrates and companion whole-coal samples from mined coal beds in the eastern United States, England, and Australia were analyzed for C, H, N, 0, ash, and 47 trace and minor elements by standard elemental, instrumental neutron activation analysis (INAA), and direct-current-arc spectrographic (DCAS) techniques. The reflectance of vitrinite, atomic H : C and 0 : C, and ash-free carbon data were used to determine ranks that range from high-volatile C bituminous coal to meta-anthracite. A van Krevelen (atomic H:C vs. 0 : C ) diagram of the vitrinite concentrates shows a smooth curve having its lowest point at H:C =0.18 and O:C =0.01. This improves the van Krevelen diagram by the addition of our vitrinite concentrate from meta-anthracite from the Narragansett basin of New England. Boron content (400-450 ppm) in two Illinois basin vitrinite concentrates was about an order of magnitude higher than B contents in other concentrates analyzed. We attribute this to marine origin or hydrothermal activity. The alkaline-earth elements Ca, Mg and Ba (DCAS) have higher concentrations in our vitrinite concentrates from bituminous coals of the Appalachian basin, than they do in vitrinite concentrates from the marine-roofed bituminous coals of the Illinois basin; therefore, a nonmarine origin for these alkaline-earth elements is postulated for the Appalachian basin coals. An ion-exchange mechanism due to high concentrations of these elements as ions in diagenetic water, but probably not recent ground water, may be responsible for the relatively high values of these elements in Appalachian concentrates. Higher concentrations of Ni and Cr in one of the English vitrinite concentrates and of Zr in the Australian concentrate probably indicate organic association and detrital influence, respectively. *Present address: U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508, U.S.A.

0166-5162/89/$03.50

© 1989 Elsevier Science Publishers B.V.

482 Br and W generally show organic association in the vitrinite concentrates. U and V have a tendency toward organic association in our samples. Ca shows organic association in the U.S. coal samples, but was inorganically associated in the English and Australian coal samples. Ba, Mn, Se and Sr show mixed organic-inorganic associations in all samples. In the English and Australian samples, nearly one-half of the trace elements analyzed were organically associated. A1, Cs, K, Si and some heavy rare-earth elements (Yb, Lu ) are positively correlated with major silicate minerals found in the whole coals and generally showed strong inorganic (mineral-matter) association in coals from the eastern United States. Br concentrations correlate with inertinite content for all coal samples which is consistent with the organic affinities of this element. For the samples studied, the trace-element chemistry appears to be generally unrelated to factors such as rank, age, marine or nonmarine roof rocks, or origin from particular groups of plants such as lycopods or tree ferns. However, concentrations of elements in tissues of a living tree fern indicate that some elements in the Pittsburgh coal bed, which was dominated by tree-fern precursors, could have had their source in tree-fern xylem. A definite provincialism for the vitrinite concentrates from the eastern United States is indicated by marked concentration differences in rare-earth-element patterns that allow discrimination between coal basins or provinces. To a lesser extent, provincialism or basinal differences is indicated by high or similar concentrations of such elements as B, Ba, Co, Cu, Hf, Na, Ni, Sb, Th, U, V and W.

INTRODUCTION V i t r i n i t e is t h e m a j o r m a c e r a l of E u r a m e r i c a n b i t u m i n o u s coals a n d a n t h r a cites a n d is t h e p r e d o m i n a n t m a c e r a l o f t h e coal l i t h o t y p e s v i t r a i n a n d clarain. R e l a t i v e l y little is k n o w n a b o u t t h e m i n o r - a n d t r a c e - e l e m e n t c h e m i s t r y of v i t r i n i t e s worldwide because m o s t p r e v i o u s studies dealt with coal ash a n d whole coals (e.g., G o l d s c h m i d t , 1935, 1937; J o n e s a n d Miller, 1939; H o r t o n a n d Aubrey, 1950; A l p e r n a n d Quesson, 1956; Zubovic et al., 1961, 1980; Clark a n d Swaine, 1962; S w a n s o n et al., 1976; G l u s k o t e r et al., 1977; Swaine, 1985). C h e m i c a l d a t a o n v i t r i n i t e c o n c e n t r a t e s can yield i n f o r m a t i o n o n t h e source of e l e m e n t s in coal a n d on t h e p a r t i t i o n i n g of e l e m e n t s d u r i n g p e a t i f i c a t i o n a n d diagenesis of coals. Also, such d a t a are of i n t e r e s t because v i t r i n i t e s m a y c o n t a i n e c o n o m i c a l l y significant a m o u n t s of c o m m e r c i a l sources of c e r t a i n elem e n t s such as the r a r e - e a r t h e l e m e n t s a n d Cr, Ni, a n d V, which are concent r a t e d in v i t r a i n ( G i b s o n a n d Selvig, 1944; Reynolds, 1948; H o r t o n a n d Aubrey, 1950). T h e p r i m a r y p u r p o s e s o f our r e s e a r c h o n v i t r i n i t e c o n c e n t r a t e s were: (1) to d e t e r m i n e t h e c o n c e n t r a t i o n s of t r a c e a n d m i n o r e l e m e n t s in a r a n k series f r o m several d i f f e r e n t coal basins a n d t h e i r p r o b a b l e organic a n d inorganic associations; (2) to d e t e r m i n e possible p r o v i n c i a l i s m of m i n o r a n d t r a c e e l e m e n t s associated with vitrinite; (3) to m a k e e l e m e n t a l c o m p a r i s o n s with possible v i t r i n i t e precursors; a n d (4) to suggest p r o b a b l e p r i m a r y or s e c o n d a r y processes t h a t c o n c e n t r a t e d or d e p l e t e d t r a c e a n d m i n o r e l e m e n t s in these vitrinite c o n c e n t r a t e s . P r o v i n c i a l i s m as used in this p a p e r refers to p r i m a r y controls (as o p p o s e d to s e c o n d a r y or p o s t d e p o s i t i o n a l c o n t r o l s ) r e l a t e d to local condi-

483 tions affecting different coal basins or provinces. Provincialism relates to different kinds and sources of sediments, paleoenvironmental and tectonic setting, and geochemical conditions during peat deposition. COALNOMENCLATURE The lithotype vitrain is a macroscopic constituent of coal. Although not precisely defined, it consists dominantly of macerals of the vitrinite maceral group and, thus, in a sense, is a vitrinite concentrate. Vitrite is a microlithotype and contains 95% or more vitrinite macerals (Stach et al., 1982). Vitrinite, as used in this paper, consists of the macerals telinite and collinite which are microscopically distinguishable. Most of the vitrinite concentrates analyzed for this paper consist predominantly of the maceral type telocollinite, which appears structureless (if not specially etched) in reflected light (Stach et al., 1982). For our purposes, particles that have a bright luster and a conchoidal or blocky fracture and that can be recognized and handpicked under a low-power (32 X ) binocular microscope are considered vitrain. Unavoidably, some particles belonging to the lithotype clarain (a less vitrinite-rich lithotype ) are also included in the vitrinite concentrates, although every attempt was made to eliminate particles having a finely banded or striated appearance, which is typical of clarain. PREVIOUS WORK Vitrinite

Relatively few reports are available on microprobe determinations of trace elements in vitrinite from the United States. Chen et al. (1981) and Minkin et al. (1979, 1982, 1987) have presented electron microprobe and PIXE (proton-induced X-ray emission) data on vitrinites from western and eastern United States coal beds. Minkin et al.'s data (1982) indicate that some elements, such as As, Cr, Ga, Mn, Ni, Se, V and Zn in the Pittsburgh coal bed of the eastern United States have relatively uniform concentrations in the vitrinite, liptinite, and inertinite maceral groups; however, Br, Ca, Ge and Sr were relatively enriched in the vitrinite, and Ti was relatively depleted in the vitrinite as compared to the other maceral groups. PIXE analysis of vitrinites in some high volatile bituminous coals from the western United States (Minkin et al., 1982) showed higher concentrations of As, Ca, Cr, Fe, Ga, Mn, Se, Sr and V than did vitrinites from the Pittsburgh and Western Kentucky No. 9 coal beds of the eastern United States. Qualitative laser-microprobe data indicate that two types of vitrinite in the Lower Bakerstown coal bed of the eastern United States have a different trace-element composition (Lyons et al., 1987 ); although A1, Fe, Ga, K, Mg, Na, Si and V were found in both banded

484 (part of vitrinite band) and nonbanded (corpocollinite) vitrinites, Ba, C1, F, Li, Sr and Ti were found only in the former. Alpern and Quesson (1956) used an autoradiography technique to determine the distribution of trace elements in coal macerals. Their work demonstrates that certain trace elements are clearly localized and more concentrated in desmocollinite than in telocollinite. The extractability in quinoline of twelve elements in whole coals from the Herrin coal was reported by Chyi and Palmer (1986). They found that quinoline preferentially attacks vitrinite while leaving the inertinite and liptinite (exinite) macerals unattacked. They also found that Cr and Co were the most extractable elements and, therefore, due to mass-balance considerations, the most likely elements to be associated with the vitrinite. Vitrain The literature contains only scattered data on minor and trace elements in vitrains. This lack of data is partly because vitrain concentrates per se are not used in coal technology and partly because of problems in separating vitrain from whole coal, cleaning it, and analyzing the small quantities of vitrain obtained or the even smaller quantities of its ash. Jones and Miller ( 1939 ) analyzed vitrain of probable sigillarian bark origin from cauldrons (kettle bottoms) in the English coal fields. They reported that the cleaned vitrains from cauldrons contained as much as 1.0 weight percent ash and that the ash of some contained higher concentrations of Ni and Ti (also relatively high V, according to Horton and Aubrey, 1950; see also, Crossley, 1947) than the ash of vitrains which were not associated with a cauldron. Also, Jones and Miller (1939) reported trace or minor concentrations of Cr, Ga and Ge in the English cauldron vitrains. High concentrations of Cr, Ni, Ti, and V were also reported by Reynolds (1948) in ash of vitrains from other English coalfields. Zubovic et al. (1964, 1966) reported trace- and minor-element concentrations in vitrains from the Illinois and Appalachian basins. Zubovic et al. ( 1964 ) found different concentrations of minor elements in four vitrain-band samples as compared to block (whole-coal) samples from the Eastern Interior Region of the United States. B, Be, Co, Ga, Ti and V were more concentrated in the vitrains than in the whole coal, and Cr, La, Mo and Zn were considerably less concentrated in the vitrains than in the whole coals; this distribution of trace elements is an indication of the organic affinities of the former and the inorganic affinities of the latter elements. Trace elements in three Kittanning vitrains from Ohio in the Appalachian basin were reported by Zubovic et al. (1966). They reported that the concentrations of B, Co, Cr, Ga, Ge, Mo, Ni and Y in the vitrain bands did not differ from concentrations in their respective companion block or whole coal; however, in the Lower Kittanning coal bed of

485

the Appalachian basin, La and Zn had higher concentrations in vitrain, whereas Cu, Ni, Sn and B were higher in the whole coal, indicating organic and inorganic association, respectively. Sink-float data on vitrains

Horton and Aubrey (1950) reported on minor elements in vitrains from the English Barnsley seam. Generally, B, Be, Cr, Ga, Ge, Mo, Ni, Sb, Ti, V and Zn were relatively concentrated in the lighter density (i.e., vitrinite-rich) fractions and, thus, had high organic affinities. Co, Cu and Pb either did not show any significant fractionation or were concentrated in the lighter fractions in one or two of the vitrains. Mn, P, Sn, and Zr were concentrated in the heavy fractions probably because they were associated with mineral matter. Curiously, the English Brockwell seam (Reynolds, 1948) showed much higher concentrations of V and Cr from a float separate than from the whole vitrain. These results are not consistent with these elements being trapped as homogeneously dispersed organometallic compounds in the vitrinite. The data suggest that V and Cr were concentrated in some other lighter maceral than the principal vitrinite maceral type (telocollinite) or in finely dispersed mineral matter in the float. For two English vitrains, Reynolds (1948) also reported B in high concentrations greater than 0.1 wt.%. Sink-float data on whole coals

Trace-element data on sink-float separates from whole coals have been reported (e.g., by Zubovic et al., 1960, 1961, 1966; Alpern and Morel, 1968; Gluskoter et al., 1977; Finkelman, 1980 ). These data are relevant because the float or low-density fractions concentrate mainly vitrinite and liptinite macerals, and useful interpretations have been made on organic and inorganic associations, which will be treated later in this paper. Finkelman (1980) pointed out that low-density fractions may also concentrate certain fine-grained minerals, so that interpretations about organic associations must be made cautiously. It is clear that earlier workers did not completely address the issue of organic and inorganic associations and that a new approach is desirable. Therefore, we decided to concentrate the major organic component of these coals, that is, the vitrinite, and compare their elemental concentrations with those in the whole coal that includes all of the mineral matter. SAMPLES AND SAMPLE PREPARATION

Table 1 summarizes the geographical and geologic data for the samples of this paper. The samples are from vitrinite-rich coals that range in age from Early Mississippian to Late Permian and range in rank from high-volatile C

Massachusetts Pennsylvania

West Virginia Maryland Maryland

Alabama West Virginia

Kentucky Indiana England England

Australia

LP-1 LP-2

LP-3 LP-4 LP-5

LP-6 LP-7

LP-8 LP-9 LP-17 LP-18

LP-19

Northern District

Ohio County Warrick County South Yorkshire South Yorkshire

Fayette County Kanawha County

Norfolk County North Umberland County Morgan County Allegany County Garrett County

County/District

aPennsylvanian ~ Upper Carboniferous. bMississippian ~ Lower Carboniferous.

State/Country

Sample no.

Sydney

Illinois Illinois East Pennine East Pennine

Warrior Appalachian

Meadow Branch Georges Creek Castleman

Narragansett Western Middle

Coal basin (b) or field (f)

Locality and stratigraphic data for vitrinite concentrates of this paper

TABLE1

b

b b f f

b b

f f f

b f

Homestead Lynnville Lofthouse Thurcroff

Holmes

Bettinger

Short Mountain

Masslite Bear Valley

Mine

Unnamed Pittsburgh Lower Bakerstown Cobb Raymond (Pittsburgh) No. 9 No. 5 Beeston Swallow Wood Liddell

A Mammoth

Bed

Late Permian

Middle Pennsylvanian Middle Pennsylvanian Westphalian A Westphalian B

Early Pennsylvanian Late Pennsylvanian

Early Mississippianb Late Pennsylvanian Late Pennsylvanian

Middle Pennsylvaniana Middle Pennsyvlanian

Age

Oo

k

0

200

600

]

400

I

r

800 KM

A

We r r i o r - ~ / j / ~ Basin

f

Fig. 1. Map showing the general location of the collecting sites of the coals from the eastern United States. Map modified from Trumbult (1960).

F

Oo

488

bituminous coal to meta-anthracite. Nine samples are from the eastern United States (Fig. 1 ); two are from the East Pennine coalfield, England; and one is from the Sydney basin, Australia. Most of the samples were collected from active mines and include as-mined samples from England and Australia and mine grab samples from the United States. The vitrinite concentrates were handpicked from coarsely crushed aggregates using a low-power (32 × ) binocular microscope. Grains showing any signs of mineral matter or other lithotype except vitrain were discarded. A second handpicking eliminated "impure" grains missed during the first handpicking. The vitrinite concentrates were crushed in an agate mortar and passed through 50-mesh brass sieves (0.297 mm openings). EXPERIMENTAL

The sample splits for C, H, N, and O analyses were dried in an oven at 110 °C and 1-2 mg were analyzed directly using a Perkin-Elmer* Model 240 Elemental Analyzer or a Carlo-Erba* Model 1106 Elemental Analyzer. The ash yield was determined after combustion at a temperature of 960-1000 °C by weighing the residue in a platinum boat. Duplicate or triplicate C-H-N-O-ash analyses were obtained on all samples. Analyses for total sulfur were made on selected vitrain samples of a few to several milligrams by using the Leco* SC-132 Sulfur Analyzer. Trace-element data were obtained by direct-current-arc spectrographic (DCAS) procedures that were described by Fletcher and Golightly (1985). Detection limits and other data are given in the Appendix. Ten-milligram samples of the vitrinite concentrates were used in all DCAS analyses. For the wholecoal samples, 100 mg of sample mixed with 100 mg of Li2CO3 and 50 mg of pure graphite powder were finely ground in an agate mortar. Because of limited amounts of vitrinite concentrates, 10 mg of sample were mixed with the 10 mg of Li2CO3 and 5 mg of graphite but were not ground in the agate mortar to conserve the sample. U.S. National Bureau of Standards (NBS) coal standard reference materials 1632, 1632a, and 1635 and homogeneous mixtures of oxides and carbonates diluted with Li2C03 were used as standards. Thirty elements were determined by instrumental neutron activation analysis (INAA) using techniques similar to those described by Palmer and Baedecker ( 1989 ). Aliquots of 0.7 to 250 mg were used depending on sample availability. U.S. National Bureau of Standards (1979, 1985) Standard Reference Materials 1632b (coal) and 1633a (fly ash) and powdered CaCO3 were used as standards. Careful attention was given to sample and standard geometries to *The use of trade or brand names is for descriptive purposes only and does not constitute endorsement of products by the U.S. Geological Survey.

489

increase the precision of the analyses. Samples were grouped by size so that distance from the detector could be adjusted to account for differences in sample height between samples and standards. The maceral group, pyrite, and other mineral-matter compositions of the TABLE 2 Maceral group and mineral data (vol.%) for samples of this paper Sample no.

Point counts (as determined)l

Vt ~

in 3

Lp3

py3

Mn 3 R~

VM 5

Point counts calculated to include mineral matter (based on ash content)

Maceral point counts (mineral-free basis )

Vt 3

Mn 3 Vt 3

In 3

Lp 3

Py~

In ~

LP 3

LP-1

wr 2 vit.

92? 6 98?

tr tr?

? tr?

3 5 5.0 0.5 <0.5

3

71? 96

tr? tr?

~ ?

1 0.2

24 3.3

LP-2

wr vit.

95? 95

2 tr?

? tr?

0 tr

2 5

2.6

8

90? 99

2 tr

0.0 0.0 tr <0.1

7.8 1.3

LP-3

wr vit.

91 99

9 1

0 0

0 0

tr 0

2.3

10

86 98

9 1

tr <0.1

0.05 0.0

4.6 0.6

91 99

9 1

0 0

LP-4

wr vit.

95 99

5 1

0 0

0 0

0 0

1.5

21

94 99

5 1

0.0 tr

0.03 0.03

1.4 0.4

95 99

5 1

0 0

LP-5

wr vit.

77 92

21 8

<0.5 tr

1 tr

1 tr

1.3

25

76 91

21 8

0.0 tr

0.3 0.2

2.7 0.8

78 92

22 8

<0.5 0

LP-6

wr vit.

89 98

7 <0.5

2 tr

1 1

tr 0

0.72

40

89 98

7 0.5

2 tr

0.2 0.1

1.2 0.4

90 99

7 <0.5

2 tr

LP-7

wr 91 vit. 100

5 0

1 tr

1 0

2 0

0.77

39

92 100

5 0

1 tr

0.4 0

1.2 93 0.3 100

6 0

1 tr

LP-8

wr vit.

91 99

3 tr

4 tr

0 0

2 tr

0.55 [47]

90 99

3 tr

4 tr

0.2 < 0.1

94 99

3 tr

4 tr

LP-9

wr vit.

90 96

4 2

3 tr

1 <0.5

2 tr

0.50 [50]

89 97

4 2

3 tr

0.5 <0.5

93 97

4 3

3 tr

LP-177 wr 71 vit. (98)

22 (1)

4 tr

1 tr

1 0

0.91

35

72 98

23 1

4 tr

< 0.5 <0.1

0.7 0.3

73 98

23 1

5 <0.5

LP-187 wr vit.

69 (95)

18 (2)

10 (1)

tr (0)

3 0

0.87

36

70 96

18 2

10 1

tr <0.1

1.3 0.5

72 (96)

18 (3)

10 (1)

LP-197 wr 83 vit. (99)

12 (0)

2 (1)

0 (0)

3 (0)

0.80

38

83 99

2 <0.5

<0.1 <0.1

12 (0)

2 (tr)

12 <0.25

2.8 0.1 3.5 0.2

3.5 86 0.6 (100)

tr = trace amount. ~Microscope area for anthracitic coal (LP-1 and LP-2 ); estimates by N. Bostick using techniques described in Bostick et al. (1987). All others based on 600-900 point counts. ewr = whole coal; vit. = vitrinite concentrate. ~Vt = vitrinite maceral group; In = Inertinite maceral group; Lp = liptinite maceral group; Py = pyrite; Mn = other mineral matter. 4Rr = m e a n random vitrinite reflectance is based on 90-140 measurements of each whole-coal sample by N.H. Bostick. (See Table 4, Rmax). 5VM, approximate volatile matter {calculated, dry ash free ) based on vitrinite reflectance. Values in brackets uncertain. 6Queried entries for LP-1 and LP-2 indicate values that were difficult to determine because of the high rank of the coal. VValues in parentheses were determined from very sparse preparations.

e,D C,

491

vitrinite concentrates and whole-coal samples (Table 2) were determined on polished preparations of particles in epoxy (Figs. 2A, 3A). For maceral-group analysis, we used a microscope area estimate (Bostick et al., 1987) and standard point-count (600-900 points) techniques using a petrographic microscope with oil-immersion objective at 600X magnification. The mean maxim u m vitrinite reflectance, Rmax, was determined by standard techniques described by the American Society for Testing and Materials (ASTM, 1978), although only 50 (not 100) measurements were made for each whole coal. Semiquantitative mineral analysis was made using a program currently operational on an IBM-PC utilizing data from an automated Philips X-ray diffraction (XRD) system. The quantification is based on user-determined factors derived from experimental relationships between mineral standards and an internal standard. Published use of the program for bulk-mineral analysis of Devonian shales of the Appalachian basin is reported in Hosterman and Whitlow (1983). The precision of the XRD analyses is + 10%. COMPOSITION AND RANK OF THE SAMPLES

The results of C, H, N, 0, S, and ash determinations are indicated in Tables 3A and 3B. Generally these data, except for the S contents, are based on duplicate, closely agreeing analyses. Because of the limited vitrinite concentrate sample size, the organic sulfur was not determined; however, for some samples, the organic sulfur was estimated from the vitrinite concentrates or whole-coal total-sulfur analyses (see Neavel, 1966). The ash content of the concentrates ranged from less than 0.3 to 5.2 wt.%; however, all but four vitrinite concentrates yielded 1% or less ash. Thus, the ash content of our vitrinite concentrates is comparable to the ash content of English vitrains, or the ash contents of their low-density fractions previously reported by Reynolds (1948), and Horton and Aubrey (1950). The high ash content in the vitrinite concentrate from LP-1 presumably is caused by fine-grained epigenetic minerals (Raben, 1979 ) that are difficult to separate by handpicking in this metamorphic rock. Table 2 shows that, on the basis of quantitative analysis and ash content, the vitrinite concentrates contained between 96 and 100 vol. % vitrinite, except LP-5 which contained 91 vol.% vitrinite and 8 vol.% inertinite. In contrast, the whole-coal samples contained 70-95 vol.% vitrinite, up to 23% inertinite, and up to 10% liptinite macerals (see Figs. 3A, B). Figure 4 is a plot of the Fig. 2. Polished grain mounts of LP -5 and LP -5wr (Lower Bakerstown coal bed ). Reflected white light, glycerine immersion. The whole coal (A) contains abundant inertinite (bright grains), whereas the vitrinite concentrate (B) has inertinite significantly reduced. At higher magnification (C), the inertinite remaining in the concentrate is seen to consist of oxidized planV tissues,which could be removed after finer crushing, and extremely fine micrinite-rich bands.

492

Fig. 3. Many coals are complex mixtures of organic components such as this vitrinite-rich coal (Liddell coal, Australia, LP-19wr) so interpretation of chemical data can be uncertain. Coarse, relatively uniform vitrain bands were picked from whole coals to concentrate vitrinite for this study. A. Polished preparation of whole coal; inertinite is bright and liptinite is dark; intermediate gray layers and groundmass are vitrinite. Reflected white light, glycerine immersion. B. Same area, self fluorescence under intense blue light; liptinite macerals are light and intertinite macerals are dark. 220 #m = width of field.

493 T A B L E 3A Reflectance (Rm,x), rank, elemental, a n d ash data for vitrinite concentrates of this paper Sample Rm~xl No. (%)

Rank 2 C~

H3

N3

LP-1 LP-2 LP-3 LP-4 LP-5 LP-6 LP-7 LP-8 LP-9 LP-17 LP-18 LP-19

ma a a/sa lvb mvb hvA hvA hvC hvC hvA hvA hvA

1.3 3.3 3.7 4.7 5.0 5.3 5.2 5.4 5.1 5.3 5.4 5.4

0.20 5.2 1.6 2.1 1.3 0.88 2.3 0.80 2.0 1.7 2.1 0.83 1.6 0.55 1.8 <0.3 1.8 0.44 2.0 0.66 1.6 0.96 2.2 1.3

5.6 2.8 2.6 1.57 1.28 0.74 0.74 0.51 0.52 0.95 0.84 0.80

88.1 88.6 90.2 87.8 86.1 78.8 78.4 76.8 74.1 82.4 81.6 77.9

Ash

Direct Organic Atomic Atomic Ash-free oxygen 4 sulfur 5 H : C O :C carbon 1.13 2.36 1.92 3.34 4.22 10.59 12.64 11.77 15.18 7.9 8.20 10.19

<0.1

0.4 0.76 0.5 0.6 1.1 0.7 0.5

0.18 0.44 0.49 0.64 0.69 0.80 0.79 0.84 0.82 0.77 0.79 0.83

0.01 0.02 0.02 0.03 0.04 0.10 0.12 0.12 0.15 0.07 0.08 0.10

92.9 90.5 91.0 88.5 87.6 79.5 78.8 77.0 74.4 82.9 82.4 78.9

All elemental a n d ash data in weight percent. Dash leaders ( - ) , no data. ' D a t a from Table 4. 2Rank is based on reflectance data in Table 4; m a = m e t a - a n t h r a c i t e ; a = a n t h r a c i t e ; sa = semianthracite; lvb = low-volatile b i t u m i n o u s coal; m v b = medium-volatile bituminous coal; hvA = high-volatile A b i t u m i n o u s coal; hvC = high-volatile C bituminous coal. 3C, H, a n d N determined by Z.A. B r o w n according to the m e t h o d given in Lyons et al. ( 1982 ). 4L.A. Romankiw, analyst; m e t h o d given in Lyons et al. ( 1982 ). 5Organic sulfur was estimated from total sulfur in whole-rock or vitrinite c o n c t n t r s t e . 6Chemically determined; pyritic sulfur, 0.7%; sulfate sulfur, 0.2%. T A B L E 3B Elemental a n d ash data (wt.%) for whole-coal samples of this paper Sample no.

C1

H'

N'

Ash'

LP-lwr LP-2wr LP-3wr LP-4wr LP-5wr LP-6wr LP-7wr LP-8wr LP-9wr LP-17wr LP-18wr LP-19wr

52.83 78.4 84.1 85.8 84.7 78.1 75.9 72.0 69.1 79.5 80.6 74.1

1.0 3.0 3.4 4.6 4.9 5.4 5.3 5.0 4.9 5.2 5.3 5.1

0.4 1.4 1.2 2.5 2.0 2.4 2.1 1.7 1.6 1.9 1.9 2.2

39.4 12.4 7.4 2.9 3.2 2.5 4.1 5.8 7.1 3.4 2.6 7.0

Oxygen 2 (by difference)

Atomic H :C

Ash-free carbon

4.8 4.9 4.2 5.2 11.6 12.6 15.5 17.3 10.0 9.6 11.6

0.22 0.46 0.48 0.65 0.69 0.83 0.84 0.83 0.86 0.78 0.79 0.83

87.13 89.4 90.8 88.4 87.5 80.1 79.1 76.4 74.4 82.3 82.7 79.7

'Z.A. Brown, analyst; C H N analyses, m e t h o d given in Lyons et al. ( 1982 ). 2Includes organic sulfur. 3Significantly low probably due to incomplete combustion of this m e t a m o r p h i c rock. Dashleader ( - ), unreliable du to u n c e r t a i n t y in carbon analysis.

494 i

I

LP-I

(I}

E CE_ (3) C) c-

"G rr

0.1

0.2

0.3

0.4

0,5

0.6

0.7

O,B

0.9

H:C atomic ratio

Fig. 4. Rmax vs. atomic H : C for the vitrinite concentrates of this paper. Data from Table 3A. TABLE 4 Reflectance data for whole-coal samples of this paper Sample No.

Rmaxa (%)

Standard deviation

LP-1 wr LP-2 wr LP-3 wr LP-4 wr LP-5 wr LP-6 wr LP-7 wr LP-8 wr LP-9 wr LP-17 wr LP-18 wr LP-19 wr

5.6 b 2.8 2.6 1.57 1.28 0.74 0.74 0.51 0.52 0.95 0.84 0.80

unknown 0.15 0.20 0.04 0.05 0.03 0.03 0.05 0.05 0.05 0.06 0.06

"R. . . . the mean maximum vitrinite reflectance, was determined by M.R. Krasnow on the basis of 50 measurements. (See Table 2, Rr. ) bFrom Raben (1979). m e a n m a x i m u m r e f l e c t a n c e (Rmax) vs. a t o m i c H : C r a t i o ( d a t a f r o m T a b l e 3 A ) for the vitrinite concentrates of this paper. The standard deviation for the r e f l e c t a n c e d a t a is 0.03 t o 0.06 f o r a l l t h e b i t u m i n o u s s a m p l e s a n d 0.15 a n d 0.20 for the anthracitic coals LP-2 and LP-3, respectively (Table 4). Figures 4 and 5 clearly show that LP-1 from the tectonically and metamorphically complex N a r r a g a n s e t t b a s i n is o f a m u c h h i g h e r r a n k t h a n L P - 2 a n d L P - 3 f r o m t h e

495 0.9 LP-18

0,8

i LP-18

LP'-8

•

• LP-9

0 0.7

0 0,6

E

O O .5

~

I_P-3

LP-2

(.30.4 0.3

0.~

ILP- 1 i 0.02

i 0.04

i 006

i 0.08

I 0.1

0.112

0.114

0,16

O:C atomic ratio

Fig. 5. Van Krevelen (H : C vs. 0 : C ) diagram of the vitrinite concentrates of this paper. Data from Table 3A.

Valley and Ridge Province of the eastern United States. The relative degree of coalification of the vitrinite concentrates LP-2 and LP-3, as shown in Figure 4, is about the same; however, LP-2 on the basis of reflectance and H: C atomic data, has a slightly higher degree of coalification (Table 3A). Figure 4 also shows a clustering of data points in the range for high volatile bituminous coal. Figure 5 is a van Krevelen diagram (atomic H: C vs. O:C) for the vitrinite concentrates. The major difference from van Krevelen's (1961) is that the LP-1 point gives a lower point of control for very high rank on the vitrinite curve. TRACE- AND M I N O R - E L E M E N T C H E M I S T R Y OF T H E V I T R I N I T E C O N C E N T R A T E S : R E S U L T S AND D I S C U S S I O N

General In general, the trace-element data obtained by INAA (Table 5A) and DCAS (Table 6A) indicate that the vitrinite concentrates from the same coal basin or coal region have similar element-for-element concentrations of most trace and minor elements. This uniformity is particularly true for A1, Co, Sb, Sc, Se, Th, U, W and the rare-earth elements. Some of the highest concentrations of certain elements are found in the U.S. vitrinite concentrates having the highest ash; these concentrations indicate inorganic association. A n example is the concentrate from the Narragansett basin of New England (LP-1), which has high concentrations of A1, As, C, Sb, Sc, V and the rare-earth elements. LP-8 (lowest ash content) has the lowest or among the lowest concentrations of A1, As, Br, Co, Cr, Hf, Hg, K, Na, Sb, Sc, Sr, Ta and the rare-earth elements; these

496 low concentrations indicate a lack of minerals. Elements in the vitrinite concentrates that appear to show little or no relationship to ash percent are Fe, Se, Th, V, W and Zn, which probably indicate differences related to basinal geochemistry or mineralization (e.g., Fe, V and Zn) or organic associations (Br and W). Some of the vitrinite concentrates, particularly those from England and Australia, show high concentrations of certain elements such as Br, Co, Cr, Sb, V and Zr which are not related to high ash content. These relatively high concentrations are not readily explainable, but most likely are related to basinal processes and mineralization and/or organic association. Vitrinite concentrates from the anthracitic coals from extensively folded and faulted coal beds (LP-1, LP-2 and LP-3) have high concentrations of certain elements (Table 4A and 6A) probably as a result of epigenetic mineralization. Elements that may have been derived from epigenetic mineralization are A1, Co, Sb, Sc, Th, V, W, and the rare-earth elements. Co, Cr, Ni, and V (Table 5A and 6A) generally do not have unusual concentrations in the analyzed vitrinite concentrates as compared to our whole coals and those U.S. coals reported by Zubovic et al. ( 1980 ). In general, the highest concentrations of these elements are in the coals with either the highest ash (LP-1 and LP-2) or the lowest ash (LP-9 and LP-17), which point to two different origins and/or modes of occurrence. The very low concentrations of A1 in Illinois basin and English vitrinite concentrates (Table 5A) are related to the very low ash contents of these samples. Such a relationship indicates a lack of clays in these concentrates. The unusually high concentrations of Cr, Ni and V, elements with moderate to high organic affinities (according to Zubovic et al., 1961) in samples LP-9, LP-17 and LP-18, three of the lowest ash vitrinite concentrates, are more consistent with an organic association. Silbermintz (1935) also reported unusually high concentrations of V (up to 4000 ppm) in bright-banded (vitrain- and clarain-rich), low-ash Jurassic coals of the Ural Mountains, U.S.S.R., which suggest basinal geochemical controls on V enrichment. Similar controls are suggested for the V data for LP-9, LP-17 and LP-19.

Organic and inorganic associations Assumptions Certain assumptions are made in this paper in regard to organic vs. inorganic associations. First, macerals of the liptinite maceral group are not regarded as generally enriched in most inorganically associated elements as compared to macerals of the vitrinite and inertinite maceral groups. Our analyses of resinites of the liptinite maceral group (unpubl. data) indicate that they are extremely depleted in all elements that we have examined with respect to the vitrinite concentrates reported here.

497

The second assumption is that inertinite macerals such as fusinite and secretinite (Lyons et al., 1986a) are generally enriched in certain elements compared to the liptinites and the vitrinites. Data in Chen et al. (1981) and Minkin et al. (1982) indicate in the Western Kentucky No. 9 coal that secretinite (their "inertinite") appears to be enriched in Ca, Sr and Mn and depleted in Cr, Ga, Ge, Ni, Ti, V and Zn compared with associated macerals. Our third assumption is that the liptinites, because of their relatively low amounts in the whole coals (less than 10 vol.% ), will not significantly bias the data on organically associated elements whether the liptinites are relatively concentrated in the whole coal or are inadvertently concentrated in the vitrinite concentrates. To significantly affect the results, elements in the liptinites would have to be present in concentrations 10-20 times higher than those in the vitrinites. Fourth, we assume that fusinite and other inertinite macerals, which often are intimately associated with minerals, are more concentrated in the whole coal than in the vitrinite concentrates (see Table 2). Therefore, any organically associated elements selectively enriched in these macerals would be interpreted as inorganically associated by our procedures. For example, elements such as Ca, Fe, Mn, Si and Sr, which generally are concentrated in inertinite macerals in bituminous coals relative to vitrinite, would tend to be considered inorganically associated by our procedures, although they could be partly organically bound in the coals. However, we think that these elements generally will be found in carbonates, sulfides, and silicates and, therefore, are inorganic in association. This last assumption is consistent with data and interpretations of Gluskoter et al. (1977) for coals of the eastern United States.

Trace- and minor-element organic and inorganic associations Organic and inorganic associations of trace elements in samples of this study are shown in Figures 6 and 7, which are plots of the ratio of concentration of the elements in the vitrinite concentrates relative to their concentration in the whole coals. Elements such as Br, which plots significantly above the line (error bars do not cross line), are considered to be organically associated, whereas those whose points that plot significantly below the line are inorganically (whole-coal or mineral-matter) associated. Those elements for which the ratios plot near the line, but not significantly above or below, are considered to have no particular organic or inorganic associations for that sample. Data for these plots are found in Tables 5A, 5B, 6A and 6B. Several elements show rather consistent organic associations. Foremost is Br (see Palmer et al., 1986, 1988 ) which is organically associated in all samples. W also plots above the line in all samples where detected. Where U was detected, it generally tends to be associated organically. Vanadium shows organic association or no preferred association in all vitrinite concentrates except in LP-6 and LP-18 where it is inorganically associated. Ca was above the line

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Fig. 6. Plot of ratio of minor- and trace-element content in vitrinite concentrates to that in whole coal to show organic and inorganic associations of selected elements in vitrinite concentrates from the eastern United States. Elemental concentrations in vitrinite concentrates and whole coals were determined by DCAS (open squares) and INAA (solid squares); data from Tables 5A, 5B, 6A, and 6B. Elements for which the ratio plots above the horizontal line have organic associations, and those for which the ratio plots below the line have inorganic associations. Error bars (see Appendix) are indicated by vertical lines through points. See Table 1 for sample data.

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Fig. 7. Plot of ratio of element content in vitrinite concentrates to that in whole coal to show organic and inorganic associations of selected element in vitrinite concentrates from England and Australia. Element concentrations in vitrinite concentrates and whole coal were determined by INAA (solid squares; Tables 5A and 5B ) and DCAS (open squares; Tables 6A, 6B ). Elements for which the ratio plots above the horizontal line have organic associations and those for which the ratio plots below the line have inorganic association. Error bars (see Appendix) are indicated by vertical lines through points. Coal beds: LP-17 = Beeston; LP-18 = Swallow Wood; LP-19 Liddell. See Table 1 for sample data.

500 TABLE 5A Concentrations of minor and selected trace elements in vitrinite concentrates of this paper as determined by instrumental neutron activation analysis (INAA) Element

Al (%) As (ppm)

LP-1

LP-2

0.85+5% 11.9_+5%

0.407_+4% 0.70_+16%

0.314_+3% 0.83_+8%

LP-4

LP-5

0.208_+3% 0.73_+10%

0.404_+3% 3.83_+4%

0.364_+3% 7.24_+6%

7.3_+8%

34.0_+5%

3.4_+21%

Co (ppm)

4.30_+6%

12.7_+5%

3.83_+2%

1.23_+5%

3.37_+4%

Cr (ppm)

16.9-+12%

22.7_+4%

6.4_+7%

6.71_+3%

5.80_+4%

2.12_+5%

0 . 1 8 _ + 1 8 % <0.090

0.067_+31%

0.047_+31%

0.336_+2%

0.266_+2%

Fe (%)

Hf (ppm)

0.58_+29%

0.28_+4%

0.419_+4%

0.055_+7%

0.86_+3%

0.59_+10%

0.106_+17% 0.20_+22%

<1

Hg (ppm)

<2

K (%)

<0.2

Na (%) Rb (ppm) Sb (ppm) Sc (ppm) Se (ppm) Sr (ppm) Ta (ppm) Th (ppm) U (ppm)

<0.5 0.065_+17%

0.038_+5% <60 2.93_+5% 4.99_+2% <9 <500

5.80<3% 4.1_+12% <200

<0.7 0.67<21% 1.08_+20%

V (ppm)

153_+7%

W (ppm)

<2

Zn (ppm)

<18

0.009_+5% <20 0.575<5%

0.18_+22% 2.19_+8% 1.66_+12% 56_+6% 2.59+12% <15

<0.1" 0.012-+17% 0.005_+4%

0.052_+13% <0.4 <0.1 0.041_+8%

84_+5%

LP-6

Br (ppm)

Cs (ppm)

4.62_+6%

LP-3

4.19_+5% 3.17-+5%

0 . 1 9 8 _ + 1 2 % 0.049_+14% <0.3 0.011_+23% 0.013_+3%

0.34+ 14% <0.015 0.006_+3%

<10 <8 <10 <5 0 . 4 0 0 _ + 5 % 0 . 0 6 8 _ + 4 4 % 0 . 1 8 8 _ + 9 % 0.171_+4% 1.94_+2% <1 77_+15% <0.09 0.48_+13% 0.50_+11% 17.7_+6% 2.18_+10% 10.2_+9%

1.32_+1% 1.07_+9% 75_+9%

1.05_+2%

0.454_+2%

0 . 7 5 _ + 1 1 % 3.62_+5% 55_+20% 89_+9%

0.05_+88% 0.51_+6%

0 . 0 6 2 _ + 1 4 % 0.021_+26% 0.70_+4% 0.16_+7%

0.374_+8%

0.40_+24%

0.109_+19%

8.4_+7%

5.0_+9%

0.93_+13%

0.69_+10%

12.9_+5% 0.56_+9% 7.0_+20%

24.1_+4%

2.74_+11%

La (ppm)

10.2_+4%

1.47_+4%

0.656_+4%

5.7_+20%

3.08_+3%

1.37_+3%

Ce (ppm)

16.4_+8%

4.35_+7%

2.6_+13%

8.3_+4%

5.8_+8%

2.7_+12%

Nd (ppm) Sm (ppm)

<50 1.96_+3%

Eu (ppm) Tb (ppm) Yb (ppm) Lu (ppm)

0.82_+17% <1 1.09-+12% 0.124_+22%

<20 <11 0.999_+3% 1.14_+2%

5.2_+23% <10 0.80_+13% 0.563_+2%

2.0_+27% 0.330_+3%

0.29-+15%

0.314-+6%

0.139-+8%

0 . 1 2 0 _ + 1 0 % 0.073-+10%

0.240_+13%

0.201_+5%

0.076_+16%

0.068_+13%

0.90_+8% 0.112_+11%

0.63-+6% 0.083_+8%

0.174-+10% 0.030_+8%

0.169-+11% 0.110_+11% 0 . 0 1 6 _ + 2 4 % 0.018_+12%

0.037_+22%

Analyses by C.A. Palmer assisted by J.S. Mee, U.S. Geological Survey. Values in weight percent ( % ) or parts per million

(ppm) as indicated in column 1.

(organic) in all U.S. coals where it was detected in both the vitrinite concentrate and the whole-coal samples, but was below the line (inorganic) in all the English and Australian coals. The organic association of Ca in the U.S. coals may be due to submicroscopic phosphates (see Palmer and Filby, 1984 ) formed from organic compounds during coalification. On the other hand, Cs, Cr and Ni (where determined), which show no preferential association or are inorganic in the U.S. coals, are organically associated in the English and Australian coals. The English and Australian coals were found to have many more elements

501

LP-7

LP-8

LP-9

LP-17

0.281 +_3%

0.084 + 3%

0.065 _+4%

1.42 _+6%

0.61 _+6%

1.56 _+8%

12.4 _+4%

8.2 _+5%

2.98 ± 4%

3.60 _+7%

59.3 _+5%

0.96 +_4%

0.977 _+2%

1.90 _+9%

4.7+_20% < 0.1

5.80+_3% 0.049_+ 22%

16.6_+9% < 0.3

0.079_+ 3%

6.90 +-3% 8.6_+ 10% < 0.2

LP-18 0.037_+ 25%

1.09 ± 5%

4.5 _+10%

1.55 _+17%

69 + 6% 5.6 _+6% 23.1 ± 10% < 1.00

0.051 _+4%

0.174 _+2%

0.295 ± 6%

0.437 _+3%

0.38 _+30%

0.116_+21%

0.098_+9%

0.33._+ 14%

0.163_+ 11%

1.12_+24%

<0.2

0.14±30%

<2

<0.04

0.008±26%

<0.1

0.012 _+3% <8

0.011 _+10% <5

0.060 +_3% < 18

0.66_+ 12% <0.1 0.014 _+4% < 13

<60

0.248_+ 7%

2.56_+ 3%

2.49 +_6%

4.48 _+4%

1.71 _+5%

3.29 _+2%

2.63 _+8%

1.77 _+14%

2.21 _+13%

0.27 _+6% < 0.3 12.0 _+7% 0.36+_ 19% <7

< 130

< 90

0.026 _+7% <40 0.97_+ 5% 2.44 _+4%

< 15

< 15

< 500

< 700

0.023 _+20%

0.162 +_13%

0.061 _+23%

0.49 _+2%

0.70 _+13%

0.54 ± 7%

1.40 _+14%

1.04 _+14%

0.47 _+8%

4.04 _+6%

1.71 _+9%

1.06 ± 24%

0.90 _+24%

13.7 _+4%

102 _+5%

0.77_+ 12%

1.16_+ 15%

51.7 _+4% 0.75± 18%

9.5_+5%

5.5_+ 19%

2.28 +_3%

0.36 _+26%

1.64 _+4%

1.36 _+4%

4.64 +_3%

0.71 ± 8%

3.2 _+13%

2.18 _+8%

<8

1.35± 14% <0.1

0.037 _+5%

1.11 ± 3 % 18 +_27%

0.131 _+24%

<0.2

0.127_+ 5%

38 _+22%

6.8±31% 0.61 _+32%

<3

1.03 _+2%

< 0.07

4.2 _+14% 4.9 +- 10%

<3

0.105 +_12% < 1

LP-19

<5

<15

<6

<13

<1

8.9 _+15%

<1

156 +_7%

<3

0.71 ±32%

108_+9%

48_+ 16%

3.65 _+5%

3.1 _+20%

< 14

< 12

<50

<30

0.563 _+3%

0.244 _+3%

1.80 ± 3%

0.478 _+3%

0.40 _+8%

0.117_+15%

0.078_+7%

0.541_+5%

0.140±7%

<0.36

0.073_+13%

0.068±6%

0.448_+4%

0.085_+21%

<1

0.167_+11%

0.317_+4%

1.15_+6%

0.272_+12%

0.024± 17%

0.053±6%

0.153_+9%

0.036_+17%

0.37_+31% <0.2

0.557 _+4% 0.30_+32% <1 0.80_+10% 0.136_+14%

associated organically than do the coals from the eastern United States (Figs. 6, 7). As, Ba, Br, Co, Cr, Cs, Fe, Hf, Hg, Mn, Ni, Sb, Se, Th, V, U, W and Zn are associated organically in one or more of the three English and Australian coals (Fig. 7). Elements such as A1, As, Co, Cs, Cu, Fe, Ga, Hf, Mn, Na, Ni, Sc, Si, Ta, Th, Ti and the rare-earth elements, are generally associated inorganically in our samples from the eastern United States. Several elements show mixed or variable associations. Ba, Mn, Sb, and Se are associated organically in three or four samples and are associated inorganically in most of the U.S. samples.

502 TABLE 5B Concentrations of minor and selected trace elements in associated whole-coal samples of this paper as determined by instrumental neutron activation analysis (INAA) Element

Al (%) As (ppm) Br (ppm)

LP-lwr 4.82_+3% 31.1"+2% 2.56_+4%

LP-2wr 2.52_+3% 2.07"+3%

10.5_+2%

24.1_+2%

Cr (ppm)

16.5_+3%

25.4_+3%

2.75"+2%

LP-4wr

1.27"+3% 2.26_+3%

1.97_+4%

Co (ppm) Cs (ppm)

LP-3wr

25.5"+3% 4.70_+2%

1.33"+4%

LP-5wr

0.659"+3% 1.50_+3% 2.66_+3%

0.481_+3% 9.71_+2% 68.7_+3%

LP-6wr 0.433_+3% 6.25"+2% 1.55_+6%

1.62_+2%

6.29_+3%

3.48_+2%

7.53_+3%

7.20_+2%

5.15_+3%

4.17"+3%

0.645_+3%

0.058_+17%

0.067_+20% 0.225_+5%

Fe (%)

3.40_+2%

0.125_+3%

0.093_+3%

0.057_+3%

0.740_+3%

0.463_+3%

Hf (ppm)

0.40_+8%

0.93_+4%

0.310_+5%

0.305_+6%

0.178_+6%

0.179_+5%

Hg (ppm) K (%) Na (%) Rb (ppm)

<1 1.05_+3% 0.258_+2% 60_+11%

Sb (ppm)

7.32-+2%

Sc (ppm) Se ( p p m )

10.3_+1% 1.56_+16%

Sr (ppm)

124_+11%

<1

<0.2

<0.3

<0.3

<0.3

0.353_+4% 0.058"+6% <0.04 0.016_+15% 0.017_+11% 0.033_+2% 0.014_+2% 0.042_+2% 0.013_+2% 0.009_+2% 18_+19% <16 <20 <19 4.6+32% 0.633-+2% 0.512"+4%

0.095-+9%

0.546"+3%

0.110_+11%

7.53-+3% 3.25-+5%

1.33_+2% 1.41-+7%

1.18_+ 2% 1.50-+5%

0.676_+2% 1.97_+4%

2.00-+3% 0.55-+22%

<80

73_+10%

52_+7%

46_+14%

109_+5%

Ta (ppm)

0.116-+9%

0.320_+5%

0.068_+9%

0.097±6%

0.051_+9% 0.052-+7%

Th (ppm)

0.882-+3%

1.06"+3%

0.673_+4% 0.523_+3%

1.66"+8%

4.36"+4%

U (ppm) V (ppm)

1.02_+8% 109_+8%

1.40-+4% 47.4"+6%

W (ppm) Zn (ppm)

1.32_+7% 32.8_+4%

0.79_+7% 9.4_+12%

1.00_+6% 4.28-+7%

0.36_+ 10% 7.4_+16%

8.92-+2%

2.21_+3%

4.99_+2%

La (ppm)

18.9"+2%

Ce (ppm) Nd (ppm)

34.3_+2% 15_+28%

17.2_+2% 8.1"+27%

0.33"+10% 0.31-+14% 18.5"+7% 12.7_+7%

0.40"+14% 7.8"+8%

0.17_+20% 6.0_+9%

0.79"+9% 64.5-+2%

0.58_+7% 2.95+7%

3.02_+ 2%

5.44_+5% 7.42_+2% 5.37_+4% <14 <11 <20

2.98_+2% 5.11 _+2% <8

Sm (ppm)

3.94_+2%

2.36_+2%

1.61_+2%

0.842_+2%

0.685_+2%

Eu (ppm)

0.978_+3%

0.452_+3%

0.323"+3%

0.143_+4%

0.126_+3%

0.103_+3%

Tb (ppm)

0.594 _+3 %

0.341 _+3 %

0.246 "+5%

0.093 _+3 %

0.085 _+5 %

0.066 _+7%

0.18"+28%

0.207_+12%

Yb (ppm)

1.55_+5%

1.26_+4%

0.71-+5%

0.322"+5%

Lu (ppm)

0.139"+13%

0.191_+7%

0.084_+7%

0.036"+31%

<0.04

0.596_+2%

0.024"+ 12%

Analyses by C.A. Palmer assisted by J.S. Mee, U.S. Geological Survey. Values in weight percent ( % ) or parts per million

(ppm) as indicated in column 1.

With some exceptions, the organic and inorganic associations determined by this study are consistent with previously reported data. Br and W in this study are generally organic in their association as they were in studies by Gluskoter et al. (1977). However, because As is one of the most inorganically associated elements in coals of the eastern United States (Gluskoter et al., 1977; Kuhn et al., 1980 ), it is surprising that As in this study is associated organically in LP-6 and in the English and Australian samples. These exceptions most likely indicate very finely disseminated pyrite in the vitrinite or an association

503

LP-7wr 0.646 ± 3% 30.6 ± 2%

LP-8wr

LP-9wr

LP-17wr

LP-18wr

LP-19wr

0.849 ± 3%

1.22 ± 3%

0.484 ± 3%

0.639 ± 3%

1.07 + 3%

0.95 ± 4%

2.70 ± 7%

8.34 ± 2%

2.95 ± 3%

0.69 + 18%

4.94 ± 3%

2.58 ± 3%

1.35 ± 5%

1.11 _+3%

2.08 ± 1%

3.00_+ 3%

5.26 ± 4%

8.69 ± 2%

0.114 ± 10%

0.657 ± 2%

1.01 ± 3%

0.351 ± 2%

1.05 ± 4%

0.867 ± 2%

0.229 _+4%

0.376 ± 3%

0.210 ± 8%

0.334 ± 4%

0.392 ± 5%

0.229 _+7%

0.309 ± 5%

0.93 + 7%

< 0.23 ± 21%

< 0.3

14.3 ± 2% 0.663 ± 3%

< 1

49.9 ± 3%

49.5 ± 3%

2.55 ± 4%

2.31 ± 2%

6.55 ± 3%

7.15 ± 2%

9.67 ± 2%

2.64 ± 6%

0.056 ± 21%

0.262 ± 5%

0.399 + 4%

0.46 ± 16%

< 0.4

5.36 ± 3%

< 0.3

0.029 ± 14%

0.134+_5%

0.106 +_6%

0.022 + 15%

0.56_+9%

0.053 ± 10%

0.008 ± 2%

0.010 ± 2%

0.045 ± 3%

0.032 ± 2%

0.041 ± 2%

0.046 ± 2%

< 12

10.7 ± 10%

11..0 ± 26%

< 18

< 21

< 17

0.075 ± 10%

0.099 _+5%

0.296 ± 5%

1.23 ± 2%

1.08 ± 3%

0.351 ± 3 %

1.19 ± 3%

1.80 ± 2%

6.65 ± 3%

1.75 ± 2%

3.23 ± 2%

2.40 ± 3%

0.54 ± 9% 41 ± 11%

0.45 +_16% <40

3.17 ± 4% <80

1.24 ± 5% 36±26%

0.77 ± 15% 46± 15%

<1 213 _+9%

0.065 ± 6%

0.102 +_4%

0.103 ± 8%

0.057 ± 6%

0.066 +_13%

0.779 ± 2%

1.26 ± 3%

3.74 ± 3%

1.25 ± 3%

0.956 ± 3%

1.64 _+3 %

0.22 + 20%

0.468 ± 6%

3.75 ± 4%

1.47 ± 4%

0.82 ± 17%

0.57 ± 10%

8.9 ± 8% 0.252 ± 12% 4.0 ± 8%

14.6 ± 7% 0.49 ± 9% 38.7 ± 2%

66 ± 5% 0.50 ± 10%

36.7 ± 5% 0.49 ± 26%

10.5 ± 5%

3.9 ± 11%

3.24 ± 2%

4.36 ± 2%

15.7 ± 2%

4.91 ± 2%

5.90 + 2%

7.66 ± 2%

36.2 ± 3%

8.05 ± 3%

< 10

<9

0.666 ± 2%

0.921 ± 2%

0.120 ± 4%

0.173 ± 3%

27± 14% 12.3± 3% 2.21 ± 3%

<17

27.5 ± 5% 0.29 _+26% 10.9 ± 10% 7.54 ± 2% 13.9 ± 2% < 19

0.110 ± 5%

22.5 ± 6% 0.44 ± 9% 11.3 ± 7% 5.96 + 2% 10.3 + 2% <11

1.42± 2%

1.95± 2%

1.36± 2%

0.285 ± 3%

0.417 ± 3%

0.256 + 4%

0.070 _+11%

0.127 ± 4%

1.06± 3%

O.191 ± 3%

0.256 ± 3%

0.173 ± 4%

0.226 ± 9%

0.564 ± 3%

2.10 ± 7%

0.44 ± 10%

0.56 ± 7%

0.751 _+4%

0.028 ± 13%

0.062 ± 12%

0.257 ± 7%

0.050 ± 12%

0.067 ± 18%

0.093 ± 10%

of As with possibly organic matter rather than with pyrite, which, as reported by Minkin et al. (1984), contains as much as 1.5 wt.% As. LP-7 does show a strong inorganic association of both As and Fe, which probably indicates that the As is in the pyrite crystal structure. The strong organic association of Zn, a bioessential element, in three samples (LP-3, LP-18, LP-19) is notable because Zn normally has a strong theoretical inorganic association (Zubovic et al., 1961 ) and is not found organically associated in whole-coal, sink-float sets (Gluskoter et al., 1977). However, it is conceivable that Zn can be complexed organically as a porphyrin because it

86 < 10 19

2.69

Ca/Mg

7.27

< 40 24 3,200 <5 7 14 1,100 440 8 5 4,400 100 19 < 10 < 10 7.70

<1 < 40 160 <2 470 <2 <5 10 7 750 5 < 10 61 5 2 2 3,800 210 <2 27 < 10 < 10 7.60

<1 < 40 42 <2 1,900 <2 <5 7 2 3,400 2 < 10 250 10 6 <2 6,400 470 <2 10 15" < 10 8.11

<1 44 240 <2 3,000 <2 <5 2 7 2,700 <2 < 10 370 24 2 <2 990 45 <2 < 10 < 10 < 10 11.0

<1 54 70 <2 1,100 <2 <5 5 <2 550 <2 < 10 100 5 <2 <2 2,400 100 <2 14 < 10 < 10

LP-1 was n o t analyzed due to inadequate sample quantity. All data in parts per million. - = n o t detected or determined. Analyst: J.D. Fletcher. *Visual determination.

8,900 680

160 6 28

16 27 34 700

< 40 120 430

Ag B Ba Bi Ca Cd Co Cr Cu Fe Ga Ge Mg Mn Ni Pb Si Ti T1 V Zn Zr 7.66

<1 450 2 <2 360 <2 <5 7 < 2 1,600 3 < 10 47 4 <2 <2 150 45 <2 19 < 10 < 10 <40 20 23 10 10 36 4,600

24 8 31 650 150 76 < 10 < 10 0.96

400 12 36O <5 19 12 2,500

88 6 12 2,000 430 140 < 10 20 4.09

1.11

57 22

2,100 330

180 5 93

10 45 19 700

2OO

<40 28

3.30

36

50

3,600 320

200 3 3

8 7 12 900

66O

<40 50

C o n c e n t r a t i o n s of m i n o r a n d selected trace e l e m e n t s in vitrinite c o n c e n t r a t e s of t h i s paper as d e t e r m i n e d by direct-current-arc spectrographic (DCAS) techniques LP-9 LP-17 LP-18 LP-19 Element LP-2 LP-3 LP-4 LP-5 LP-6 LP-7 LP-8

T A B L E 6A

<1 < 40 86 <2 770 <5 8 21 39 30,000 32 < 10 2,600 370 50 20 70,000 270 <2 87 20* < 20

Ag B Ba Bi Ca Cd Co Cr Cu Fe Ga Ge Mg Mn Ni Pb Si Ti T1 V Zn Zr

<1 < 40 120 <2 140 <5 16 30 40 1,300 22 < 10 730 3 41 13 35,000 1,800 <2 50 <20 53

LP-2wr <1 < 40 30 <2 2,100 <5 6 9 13 1,100 9 < 10 650 7 10 5 20,000 320 <2 21 <20 < 20

LP-3wr <1 < 40 80 <2 370 <5 <5 8 6 630 10 < 10 76 4 5 5 8,400 700 <2 16 <20 22

LP-4wr

All data in parts per million. Analyst: J.D. Fletcher. *Visual determination.

LP-lwr

Element <1 < 40 22 <2 1,400 <5 7 5 9 8,600 6 < 10 270 10 21 7 6,800 410 <2 13 60* < 20

LP-5wr <1 45 180 <2 2,000 <5 5 4 11 4,800 4 < 10 380 15 4 <5 2,800 300 <2 8 <20 < 20

LP-6wr <1 78 36 <2 750 <5 <5 5 6 10,000 4 < 10 310 14 2 <5 9,600 420 <2 13 <20 < 20

LP-7wr <1 330 24 <2 220 <5 <5 11 6 3,900 6 23 590 10 8 <5 16,000 700 <2 20 <20 < 20

LP-8wr <1 260 20 <2 340 <5 <5 18 24 10,000 9 < 10 520 11 20 12 20,000 530 <2 76 <20 < 20

LP-9wr <1 < 40 15 <2 220 <5 <5 9 54 10,000 6 < 10 75 5 12 13 6,200 300 <2 46 <20 < 20

LP-17wr <1 < 40 52 <2 1,600 <5 12 16 32 2,600 5 10 420 150 20 4 10,000 320 <2 39 <10 26

LP-18wr

<1 < 40 50 <2 5,200 <5 10 3 15 6,000 5 4 1,300 73 < 10 3 30,000 730 <2 31 14" 31

LP-19wr

Concentrations of minor and selected trace elements in associated whole-coal samples of this paper as determined by direct-current-arc spectrographic (DCAS) techniques

TABLE 6B

¢91

506 can substitute for Fe and Mg which are well known in porphyrins such as hemoglobin and chlorophyll, respectively. Because Cr, Cs and Hf typically have inorganic associations (Gluskoter et al., 1977), their organic association in the English a n d / o r Australian samples was not expected. Cr has some capacity to form organometallic complexes (Reynolds, 1948; Zubovic et al., 1961 ), but Cs and Hf apparently would have little affinity for such complexing. Cr tends to occur in the coal float samples from the Appalachian basin (Zubovic et al., 1966), which probably indicates organic association, whereas Cs and Hf tend to occur in sink samples, which indicates inorganic association (Gluskoter et al., 1977). However, floating material may be inorganically associated and sinking material may be organically associated in some cases because the sinking and floating properties are to some extent related to the size and distribution of mineral grains in coal. Although data are lacking, generally there is no relationship between Ga and A1 (Table 5A and 6A ); a positive relationship like that between Si and A1 would be expected if Ga was substituting for A1 in clay minerals (Nicholls, 1968). Martin et al. (1986) showed a lack of congruent spatial relation between Al and Ga using secondary ionization mass spectrometry (SIMS) imaging techniques on vitrinite from Cape Breton Island, Nova Scotia, Canada; the lack of congruency means that these elements do not occur together in the same microregion. The high concentrations of Co, Cu, Ni, and Zr in LP-2 are related positively to higher ash content (Table 3A) and probably, except perhaps for V, can be attributed to mineral matter in this sample (see also data in Medlin et al., 1975). The relatively high concentrations of U, V, and W in LP-9 from the Illinois basin, Zn which is notably higher in LP-18 and LP-19, and Se contents between 0.7 and 4.1 p p m (where detected) for vitrinite concentrates (Table 5A) most likely result from organic complexing. Trace elements in modern plants Goldschmidt (1935) delineated the principal processes responsible for the enrichment of trace and minor elements in coal. These processes are concentration by plants, concentration during peat degradation, and concentration by mineralization in peat. Very little work has been related to concentration of elements in vitrains, although Goldschmidt (1935) noted that vitrain or clarain are more enriched in "rare" elements than the lithotype durain, which is vitrinite-poor. The subject of primary concentration of trace and minor elements by plants is very difficult to deal with because most species of the peat-producing plants of Carboniferous and Permian ages have long been extinct. Thus, their capacity to concentrate certain elements can only be surmised from analyzing organs and tissues from related modern plants. The trace-element contents of modern plants from the Okefenokee Swamp, Georgia, a subtropical peat-forming en-

507

vironment, were reported by Casagrande and Erschull (1976, 1977). The reported concentrations of some of the trace elements in Okefenokee peat (e.g., Cr, Cu, Mn and Zn) have a similar range of concentrations for the same elements in the vitrinite concentrates of this paper. However, the ranges for Ba, Co, Fe and Ni are quite different which probably reflects different concentrations in the swamp waters and the surrounding rocks of the Okefenokee as compared with late Paleozoic swamps. Vitrinite concentrates (LP-4 and LP-7) that are from the Pittsburgh (Raymond) coal bed originated in peat dominated by tree ferns, as is indicated by the microflora (Kosanke, 1943; Cross, 1952), megaflora (Gillespie and Pfefferkorn, 1979 ), and coal-ball studies (Phillips and Peppers, 1984). Tree ferns can be considered the closest modern analog of the peat-forming plants that gave rise to the Pittsburgh peat. Table 7 shows analytical results from samples of vitrinite and vitrain from the Pittsburgh coal bed, as well as tissue samples from a modern tree fern. Although we cannot assume that the vitrinite and vitrains are from the same plant species or genus, nevertheless, certain generalizations can be made about TABLE 7 Selected elemental data ( p p m ) for vitrinite a n d vitrains from t h e P i t t s b u r g h coal bed in West Virginia (WV) a n d M a r y l a n d ( M D ) a n d tissue from a modern tree fern E l e m e n t or ash Ash (wt.%) As Br Ca Co Cr Cu Fe Ga Ge La Mn Ni Se Sr Ti V Zn

Vitrinite (WV)I

<1 50 1,200 18 3 400 9 7 3 4 5 58 49 20 20

---no data. 1From M i n k i n et al. (1982). 2From Tables 5A a n d 6A, this paper. -

Vitrain ( L P - 7 ) (WV)2

Vitrain (L~'-~) (MD)2

Tree-fern xylem

0.55 1.4 8.2 1,100 0.96 4.7-5 <2 510-550 <2 < 10 2.3 5 <2 <1 38 100 14 <7

0.80 0.7 3.4 470 1.0 6.7-10 7 750 5 < 10 6 5 2 1.1 75 210 27 7

<0.8, < 4 2.6 4,000-6,900 0.6-5 < 20-21 1,000

6-8 28-57 <6, <60 55-84 180 < 1 85-95

508 the samples of the Pittsburgh coal bed, which are from three different areas in the Appalachian basin. The Ca, Ti and Fe in the Pittsburgh vitrinite/vitrain samples generally can be attributed to mineral matter such as calcite, aluminosilicates, and pyrite, respectively. The concentrations for As, Co, Fe, Mn, Ni, Sr and V in the three Pittsburgh samples are reasonably consistent, a probable indication of some common origin. Ni and V, elements known to have moderate to high organic affinities in coal (Zubovic et al., 1961 ), could be primary in origin. Data for Br, Cr, Ga, Se, Ti and Zn in the Pittsburgh coals (Table 7) show more dispersion. This may be related partly to localized geochemical conditions in the Pittsburgh swamp or to selective elemental enrichment or entrapment in certain tissues or organics of the peat-forming plants. The tree-fern xylem shows some commonality and differences in elemental concentrations as compared to the Pittsburgh vitrinite (Lyons and Palmer, 1988) and vitrains (Table 7). Co, La, Se and Sr are similar in concentrations in both the xylem and Pittsburgh vitrinite concentrate, but Na, Ca, C1, K, Mn and Zn are higher in the xylem (Lyons and Palmer, 1988). The first three elements and C1 would be expected to be easily mobilized in peat waters, and, thus, be depleted in the peat. However, A1 and Sm are significantly lower in the xylem. Because concentrations of Br in this study have consistent values in analyzed tree-fern tissues (Lyons et al., 1986b) and because Br is known to have organic affinity in coal, we speculate that the higher concentrations of Br in the vitrinite concentrate samples in this study may have resulted from selective Br enrichment in certain lignin-based compounds at the expense of more degradable organic compounds such as cellulose (Horton and Aubrey, 1950; Hatcher and Breger, 1981 ). This idea, of course, is speculative.

Rare-earth element chemistry Figure 8 shows the INAA patterns for the rare-earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu ), normalized to shale (Haskin et al., 1968 ), for vitrinite concentrate samples from the eastern United States. The rare-earth patterns comprise four distinct groups as indicated below: Group 1: LP- 1 k(meta_ anthracite, Narragansett basin, Fig. 8A ) Group 2:LP-2 and LP-3 (anthracitic coals, Valley and Ridge Province, Fig. 8B) Group 3 : L P - 4 through LP-7 (high volatile A to low volatile bituminous coals, Appalachian Plateaus Province, Fig. 8C ) Group 4:LP-8 and LP-9 (high volatile C bituminous coal, Eastern Interior Basin (Illinois basin, Fig. 8D) LP-1 (Fig. 8A) shows a positive Eu anomaly compared to shale. The rareearth-element patterns for shales are generally very similar to those for coals (Fleet, 1984). Rare-earth-element patterns for various kinds of plant matter generally show a much larger negative Eu anomaly with respect to chondrites

509

OO5

o

[

i ....

I

II"',,

/

• LP-2

OOl < tlJ _..1 <

La Ce Pr Nd Pm Sm Eu Gd ~

Oy H? Er Trn Y~ Lu

C.

KEY • LP-4 • LP-5 • LP-6

o o

La ~ro P' Nd Pm ~m Eu Gd T~ Dy 149

Er Trn Y~

Lu

D

•

oo°

o o2 ool

Fig. 8. Rare-earth-element patterns of vitrinite concentrates from the eastern United States. A. LP-1, meta-anthracite, Narragansett basin. B. LP-2 and LP-3, anthracitic coals, folded Appalachians. C. LP-4 through LP-7, high-volatile A to low-volatile bituminous coals, Appalachian Plateaus. D. LP-8 and LP-9, high-volatile C bituminous coals, Illinois basin. Vertical lines through symbols are error bars determined by INAA. Data normalized to shale (Haskin et al., 1968). Nd data was not plotted for samples where only upper limit was determined and was not used in determining the pattern due to missing data and high errors. La

Ce

Pr

Nd

Pm ~m

Eu

Gd

Tb

Dy

H0

Er

Tm Yb

Lu

0,5

O 0.2 rr

LU --J fl.

<

0.1

0.05

tf)

5J

._J 0.0~

< I

CO 0 , o '

Fig. 9. Rare-earth-element patterns of selected vitrinite concentrates from England (LP-17 and LP-18) and Australia (LP-19). Data normalized to shale (Haskin et al., 1968). Vertical lines through symbols are error bars determined by INAA.

510

(Koyama et al., 1986) than do shales (Haskin et al., 1968). None of the rareearth-element patterns in our study have negative Eu anomalies; thus, they, are more similar to patterns for shales than to patterns for plants, which indicate inorganic (mineral-matter) affinities for the rare-earth elements. The rare-earth-element patterns of LP-2 and LP-3 (Fig. 8B) from the folded Appalachians are very similar and, when compared to patterns for coal from other areas in the eastern United States, they indicate depletion in light rare-earth elements and distinctly contrast with the relatively flat (undifferentiated with respect to shale) rare-earth-element patterns of LP-4 through LP-7 (Fig. 8C) from the Appalachian Plateaus. The patterns for samples LP-8 and LP-9 from the Illinois basin (Fig. 8D ) are very similar to each other and reflect depletion in the light rare-earth elements, like LP-2 and LP-3, but have a lower Ce:La ratio. This is probably due to a depletion in Ce for these samples which will be discussed in the next section. The rare-earth patterns for the English and Australian vitrinite concentrates are shown in Figure 9. One of the English vitrains (LP-17) shows an apparent Ce anomaly. Marine and nonmarine influences on trace elements

In general, we find few relationships between unusually high or low concentrations of certain trace elements and the presence of marine (LP-5, LP-6, LP-8, LP-9) or nonmarine (LP-1, LP-2, LP-3, LP-4, LP-7) roof rocks. Boron may be a paleosalinity indicator in the Illinois basin. Our marineinfluenced coal samples from the Illinois basin are characterized by high concentrations of B (400-450 ppm for vitrinite concentrates and 260-330 ppm in the companion whole coals). High concentrations of B (100-400 ppm) have been reported in vitrains of the Western Kentucky No. 9 and the slightly younger Illinois No. 6 coal bed (Zubovic et al., 1964). Most of the B concentration in the vitrains do not relate positively with ash and Si contents. Also, the range of concentrations reported for B in illite in the Illinois basin (Bohor and Gluskoter, 1973) are too low (76-200 ppm) to account for the concentrations of 400-450 p p m in the vitrains. Thus, the boron is probably associated or chemically combined with the organic matter in the vitrains and may be due to selective entrapment of B from marine waters (Bohor and Gluskoter, 1973 ). This conclusion is partly consistent with the organic association of B in the Lloyd sove Seam, Nova Scotia, Canada, and The Svea seam, Spitzbergen, Norway (Nicholls, 1968). However, high concentrations of B can also result from hydrothermal activity (e.g., see Jin and Qin, 1989). Kear and Ross (1961) found up to 1500 ppm B in the ash of New Zealand coals. However, it should be noted that LP-5 and LP-6 do not have particularly high B, but this may imply less marine influence during or following the deposition of the peat or other mechanisms for boron concentration.

511

The rare-earth-element pattern of the two vitrinite concentrates from the Illinois basin (Fig. 8D) may also indicate marine origin. These patterns are generally similar to those of anthracites (Fig. 8B ) in this study; however, they are significantly depleted in Ce. This may suggest sea water entrapment or exchange because sea water is very depleted in Ce (Fleet, 1984). The high Na concentration and high V (102-140 ppm) in LP-9 is perhaps a result of a marine influence; for example, an exchange of Na + from sea water with the alkaline-earth elements (particularly Ca 2+ ). Such an ion-exchange also would be expected to elevate Mg in the clays (Berner, 1971), but the relatively low Mg content (88 ppm) and the lack of clays in this vitrinite concentrate places considerable doubt on a marine origin for Na. Na in Illinois basin coals is probably mainly due to NaC1 (Gluskoter and Rees, 1964), perhaps trapped in fluid inclusions in the minerals (E.W. Roedder, pers. commun., 1988). Although the evidence presented here for marine activity is not particularly strong, our data suggests that coals from the Illinois basin formed under a greater marine influence than did coals reported here from the Appalachian basin.

Correlations by coal bed Elemental data for vitrinite and vitrains from the Indiana No. 5 coal bed and its correlative, the Western Kentucky No. 9, and from the Illinois No. 6 coal bed are summarized in Table 8. Even though at least an order of magnitude difference exists in the ash contents shown in Table 8, the concentrations of Ga in all but one case are similar and, thus, indicating probable organic association or a uniform mineral distribution. Except for one sample, Co also shows a narrow range of concentrations that does not relate to ash content. In the vitrinite concentrates, B ranges from 100 to 400 ppm, which is normally high for coals of the Illinois basin (Zubovic et al., 1964 ). The respective concentrations of Cr, Ga, Ge, Se, Ti and Zn are highest in the Western Kentucky No. 9 vitrinite sample (Minkin et al., 1982 ). Even though the vitrinite appears to be optically "pure" material, the higher concentrations found using PIXE might indicate subsurface impurities in the vitrinite as compared with the bulk analyses of the vitrinite concentrates, or, possibly, inaccuracies in the various techniques. PIXE analyses are on limited areas (6-10/tm), whereas the other techniques used are bulk analysis.

Basinal differences A comparison between the vitrains, vitrinites, and vitrinite concentrates from the Illinois and Appalachian basins indicates interesting similarities and differences (Tables 7 and 8). Vitrinite concentrates from the Illinois and Appa-

512 TABLE8 E l e m e n t a l d a t a ( p p m ) for certain vitrains, vitrinite, a n d vitrinite c o n c e n t r a t e s from t h e Illinois No. 6 coal bed, t h e W e s t e r n K e n t u c k y No. 9 coal bed, a n d t h e I n d i a n a No. 5 coal bed in t h e Illinois basin Element

Illinois 1 (No. 6)

A s h (wt.%) As B Be Br Co Cr Cu Ga Ge La Mn Mo Ni Se Sn Sr Ti V Y Zn

3.34 400 1.3 0.7 7.7 6.7 3 7.7 * 3.3 6.7 * 94 7.7 3 16

W. Ky 1 No. 9 2.56

100 1

3.20 130 2.1

W. K y 2 (No. 9)

2

11 5.1 16 13 2.6 67 *

1.1 8 9.6 2.6 2.9 3.2

2.3 23

1.9 4.5

2.6 150 21 2.6 5.1

5.4 210 9 3.2 *

27 5 11 70 14 18 7 9 1,200 28 200

W. K y 3 (No. 9) (LP-8) <0.3 0.61 450 3.0 1.0 6-7 <2 3 < 10 0.4 4 <2 2.6 18 45 14-19 9.5

IN 3 (No. 5) (LP-9) 0.44 1.56 400 3.6 1.9 17-19 12 1.6 6 12 1.8 < 130 430 102-140 5.5

= no d a t a or insufficient sample. 1Vitrain d a t a from Zubovic et al. (1964). 2Vitrinite; d a t a f r o m M i n k i n et al. (1982). ~Data f r o m Tables 5A a n d 6A, vitrinite concentrates, t h i s paper. *Below limit of detection. -

lachian basins have similar ranges of concentrations of V (except for one sample, LP-9), Cr, Cu, Ga and Zn. Sr is higher in the Pittsburgh vitrains. These similarities may indicate primary concentrations in the plant matter but not fractionization for these elements by lycopod and tree-fern wood or tissues. Tables 5A and 6A show that the vitrinite concentrates from the Appalachian basin have, in general, similar Ca/Mg ratios (weight percent basis, Table 6A) and higher concentrations of the alkaline-earth elements Ba, Ca, Mg, and Sr than do vitrains from the Illinois basin. These higher concentrations do not relate to the ash content of the concentrates (Table 3A) and most likely indicate greater amounts of carbonate, clays, or other minerals in these Appalachian vitrinite concentrates. The Appalachian vitrinite concentrates that have

513 higher concentrations of these elements were probably less influenced by marine conditions than were those in the Illinois basin; thus, a nonmarine mechanism to concentrate Ba, Ca, Mg, and Sr is indicated. An ion-exchange mechanism involving clays and ground-water activity (Hildebrand, 1986) is one possibility. However, a comparison of modern ground-water chemical data for the Anthracite region (LP-2, Barker, 1984) and for Ohio County, Kentucky (LP-8, Faust et al., 1980) shows that Ca and Mg are actually in greater concentrations in recent ground water in the Kentucky area rather than in the Anthracite region. Thus, these data do not support a modern ground-water origin for Ca and Mg in the vitrains. These elements were most likely concentrated during diagenesis or metamorphism. The Illinois Basin and Pittsburgh vitrains generally show similarity in concentrations of Co, Cu, Ga, Ge, and Zn but are lower in Cu, Ni, and V and higher in Cr and Ti concentrations than the English vitrains (Horton and Aubrey, 1950). In general, on an ash-normalized basis, the concentrations of such elements as Cr, Cu, and Ni in the vitrinite concentrates approach the typical concentrations of these elements in peats from raised bogs (Hochmoors), which are typically ash-poor (Naucke, 1980). These elements typically form insoluble compounds under reducing conditions and, thus, would be expected to be ash related and conserved in peats during peatification and early diagenesis (see Shotyk, 1988 ). The high amounts of Ti and Ni in British cauldron vitrains of lycopod origin, as compared to seam vitrains, was noted in a previous section (Jones and Miller, 1939; Reynolds, 1948). The comparison of the data from different coal basins shows that vitrains of different ages have similar concentrations of many of the same elements, which indicate no preferential fractionization by different plant groups. The implications are either that the plant tissues have concentrated elements in a similar way in peat of the coal-forming swamps of different regions or that the organic matter has chelated or has otherwise fixed these elements in the same way (see Zubovic et al., 1961 ).

Mineral, maceral-group, trace-element, and Rmaxcorrelations As previously stated for our study, the great majority of trace elements analyzed are inorganically associated in coals of the eastern United States, whereas the English and Australian coals show about half the trace elements to be associated organically. In order to understand the inorganic associations, the concentrations of the minerals in each whole coal were determined using semiquantitative X-ray diffraction analysis (Table 9 ). As expected, there is no relationship between the mineral content and rank (Table 3A) except for LP-1 which shows that the kaolinite has been transformed to chlorite due to high temperatures. Pearson (parametric) and Spearman (nonparametric) correlations for mineral composition, minor and trace elements, low-temperature ash, and Rmax of

514 TABLE 9 Semiquantitative mineralogy of low-temperature ash for whole-coal samples of this study (values are wt.% of ash) Sample

Quartz

Feldspar

LP- lwr LP-2wr LP-3wr LP-4wr LP-5wr LP-6wr LP-7wr LP-8wr LP-9wr LP-17wr LP-18~r LP-19wr

35 10 20 10 20 5 10 25 10 <5 15 25

<5 <5 <5 <5 <5 15 <5 <5 <5 <5 <5

Illite 15 30 10 15 10 10 20 10 <5 15 10

Chlorite

Kaolinite

40 <5 <5 <5 <5 <5 10 <5 <5 50 <5 <5

60 60 70 40 20 25 40 50 60 50

Calcite

Pyrite 5 -

<5 <5 5 5 102

25 60 501 101 25 45 5 <5

Siderite <5 <5 <5 <5 <5 <5 <5 <5

1Coquimbite [Fe2 (SO4)3 + 9H20 ] is present. 2Ankerite [Ca(Fe +2, Mn, Mg) (CO3)2] is present. - = n o t detected. TABLE 10 Pearson and Spearman correlations between semiquantitative mineralogy, low-temperature ash and Rm~xwith minor- and trace-element concentrations in whole-coal samples. Correlations are positive and significant at the 95% confidence level for both Pearson (parametric) and Spearman (nonparametric) correlation coefficients Quartz Feldspar Illite Kaolinite Chlorite Calcite Siderite Pyrite Low-temperature ash Rm~x (vitrinite reflectance)

Al, Cs, Mg*, Si* No significant correlation A1, Cr, Cr*, Cs, Ga*, K, Ni, Pb*, Rb, Si* Al, Cs, Hf, Ni*, Rb, Sc, Si*, Ta, Ti*, Yb, Lu Rb No significant correlation Th As, Pb* A1, Cs, Mg*, Rb, Si* Ga*, Sb

*Determined by direct-current-arc spectroscopy; all others were determined by instrumental neutron activation analysis. t h e w h o l e c o a l s a r e s h o w n i n T a b l e 10 u s i n g t e c h n i q u e s s i m i l a r t o t h o s e d e scribed by SAS (1982). We have chosen to refer to the significant correlations b e t w e e n v a r i a b l e s o n l y i f t h e r e l a t i o n is p o s i t i v e a n d s i g n i f i c a n t a t t h e 9 5 % l e v e l i n b o t h t h e P e a r s o n a n d S p e a r m a n . T h i s d e c i s i o n is d u e t o t h e s m a l l s a m p l e size, u n t e s t e d n o r m a l i t y o f t h e d a t a d i s t r i b u t i o n s , a n d i n c o m p l e t e d a t a . I f t h e c o r r e l a t i o n is s i g n i f i c a n t f o r t h e p a r a m e t r i c a s w e l l a s f o r t h e s t a t i s t i c a l l y more robust nonparametric correlations, the variables certainly are statistically associated. The low-temperature ash (LTA) content correlates at the

515

95% confidence level (CL) with generally inorganically associated elements. Both quartz and low-temperature ash correlate with the elemental suite A1, Cs, Mg and Si; low-temperature ash also is associated with Rb. Illite is correlated with all of the aforementioned elements, except Mg, plus Cr, Ga, K, Ni and Pb. Kaolinite is correlated with Al, Cs, Ni and Rb like in illite, plus the rare-earth elements Yb and Lu, and also with Hf and Sc. Pyrite is correlated with As and TABLE llA Interelement correlations, arranged alphabetically (except rare-earth elements) by element. Elements are positively and significantly correlated (confidence level--95% ) in the vitrinite concentrates for both Pearson (parametric) and Spearman (nonparametric) correlation coefficients As: Ca*: Co: Cr: Cr*: Cu*: Cs: Fe: Fe*: Hf: Hg: K: Mg*: Ni*: Sb: Sc: Si*: Ta: Ti*: Th: U: V: V*: W: Zn:

Fe, Sb Mg* Cr, Cu, Hg, K, Sc, Th, Zn Co, Cr*, K, Ni*, Sc, Ta, Ti*, Th, V*, Eu, Tb, Yb, Lu Cr, Cs, Ni*, Sc, Ta, Th, Eu, Tb Co Cr*, Hf, Sb, Ta, Zn, Tb, Lu Fe*, As, Hg Fe, Hg Cs, Ta, Th Co, Fe, Fe*, Sm Co, Cr Ca* Cr, Cr*, Sb As, Cs, Ni* Co, Cr, Cr*, Ta, Ti*, Th, U, V, V*, W, Sm, Eu, Tb, Yb, Lu Ti* Cr, Cr*, Cs, Hf, Sc, Th, Ti*, W, Sm, Eu, Tb Cr, Sc, Si*, Ta, Th Co, Cr, Cr*, Hf, Sc, Ta, Ti* Sc, V*, Tb, Yb, Lu Sc, Eu, Tb, Yb, Lu Cr, Sc, U, Eu, Tb, Yb, Lu Sc, Ta Co, Cs

La:

Ce

Ce: Sm: Eu: Tb: Yb:

La Hg, Sc, Ta, Eu, Tb, Yb Cr, Cr*, Sc, Ta, V, V*, Sm, Tb, Yb, Lu Cs, Cr, Cr*, Sc, Ta, V, V*, U, Sm, Eu, Yb, Lu Cr, Sc, U, V, V*, Sm, Eu, Tb, Lu Cr, Cs, Sc, U, V, V*, Eu, Tb, Yb

Lu:

(No correlations with A1, Ba*, Br, Na, Nd, Rb, Se and Sr.) *Determined by direct-current-arc spectroscopy; all others were determined by instrumental neutron activation analysis.

516 TABLE 11B Interelement correlations, arranged alphabetically (except rare-earth elements) by element. Elements are positively and significantly correlated (confidence level = 95% ) in the whole-coal samples for both Pearson (parametric) and Spearman (nonparametric) correlation coefficients. See Table 10 for correlations of mineral content with trace-element concentrations AI: As: Ca*: Co: Cr: Cr*: Cu*:

Cs: Fe: Fe*: Ga*: Hf: K: Mg*: Na: Ni*: Pb*: Rb: ab: Sc: ai*: Sr: Ta: Th: U: V: V*:

La:

Ce: Nd: Sin: Eu: Tb: Yb: Lu:

Cr, Cr*, Cs, Ga*, K, Mg*, Na, Rb, Sc, Si*, V, V*, Ce, Yb Fe, Fe* ar Ni*, Sc A1, Cr*, Cs, Ga*, Ni*, Sc, Si*, Ta, Th, V, V*, La, Ce, Yb, Lu A1, Cr, Cs, Ni*, ac, Th, V, V*, La, Ce, Tb, Yb, Lu Ni*, V, V* A1, Cr, Cr*, K, Mg*, Rb, Sc, Si*, V, V*, Ce, Yb As, Fe* As, Fe Al, Cr, K, Ni*, Pb, Rb, Sc, Ta, V, V*, Yb Ta, Th A1, Cs, Ga*, Mg*, Rb, Sc, Si*, V, V*, La, Ce A1, Cs, K, Rb, Sc, Si* A1, Ni*, Rb, Sc, ai*, v, V*, La, Ce Co, Cr, Cr*, Cu*, Ga*, Na, ab, Sc, V, V*, La, Ce, Lu Ga*, Rb Al, Cs, Ga*, K, Mg*, Na, Pb, Sb, Si* Ni*, Rb, V, V* A1, Co, Cr, Cr*, Cs, Ga*, K, Mg*, Na, Ni*, ai*, Ta, Th, V, V*, La, Ce, Sin, Eu, Tb, Yb, Lu A1, Cr, Cs, K, Mg*, Na, Rb, Sc, V, V*, La, Ce, Yb Ca* Cr, Ga*, Hf, Sc, Th Cr, Cr*, Hf, Sc, Ta, V*, U, La, Ce, Sm, Eu, Tb, Yb, Lu Th, V, V*, La, Ce, am, Eu, Tb, Yb, Lu A1, Cr, Cr*, Cu*, Cs, Ga*, K, Na, Ni*, Sb, Sc, Si*, V*, U, La, Ce, Sm, Eu, Tb, Yb, Lu Al, Cr, Cr*, Cu*, Cs, Ga*, K, Na, Ni*, Sb, Sc, ai*, Th, V, U, La, Ce, Sin, Eu, Tb, Yb, Lu Cr, Cr*, K, Na, Ni*, Sc, Si*, Th, V, V*, U, Ce, Sm, Eu, Tb, Yb, Lu A1, Cr, Cr*, Cs, K, Na, Ni*, Sc, Si*, Th, V, V*, U, La, am, Eu, Tb, Yb, Lu Eu, Tb, Yb Sc, Th, V, V*, U, La, Ce, Eu, Tb, Yb, Lu Sc, Th, V, V*, U, La, Ce, Nd, Sm, Tb, Yb, Lu Cr*, Sc, Th, V, V*, U, La, Ce, Nd, Sin, Eu, Yb, Lu A1, Cr, Cr*, Cs, Ga*, Sc, Si*, Th, V, V*, U, La, Ce, Nd, Sin, Eu, Tb, Lu Cr, Cr*, Ni*, Sc, Th, V, V*, U, La, Ce, Sm, Eu, Tb, Yb (No correlations with Br, Hg, ae, Zn.)

*Determined by direct-current-arc spectroscopy; all others were determined by instrumental neutron activation analysis.

517

Pb. Chlorite is associated with Mn, Ba and Rb and siderite with Th. Feldspar and calcite are not correlated with any elements because there are not enough samples with real values. Most of the reported values (Table 9) are less than 5% of the low-temperature ash, an acceptable lower limit for semiquantiative X-ray diffraction. Correlation of K with illite should be expected, and indicates a specific mineral association. The relation of As and Pb with pyrite could also be physicochemical. It should be noted that an expected correlation would be between pyrite and Fe. For some peculiar reason, pyrite is significantly correlated with Fe but only for the parametric Pearson correlations, and not for the nonparametric Spearman rank correlations. Correlations with major minerals may be due to physical characteristics (size and specific gravity) rather than specific physicochemical mineral associations. For example, Palmer and Filby (1984) have shown that many lithophilic trace elements such as the rare-earth elements Th, Hf, Ta and Ti are primarily associated with clay-sized heavy accessory minerals such as rutile, rare-earth phosphates, and zircon even though they correlate with clays. These correlations are due to intermixing of these minerals rather than actual mineral association. Finkelman (1980) also suggests that the rare-earth elements are primarily associated with rare-earth phosphates in coal. Table l l A and l l B show the Pearson and Spearman interelement correlation coefficients in the vitrinite concentrates and whole-coal samples, respectively. Many of the interelement correlations in the whole coals are not found in the vitrinite concentrates. For example, A1 and Si which correlate with twelve elements in the whole coal (Table l l B ) are not correlated or correlated with only one element in the vitrinite concentrates (Table 11A). On the other hand, W only shows correlations with Sc and Ta in the concentrates. The differences in correlations are due to the lack of aluminum silicates in the concentrates and the relative concentration of W in the vitrinite concentrates which is consistent with organic association (Figs. 6 and 7). Statistical correlations of the maceral-group estimates (Table 2) for the whole coals with the trace-element concentrations in whole coals (Tables 5B, and 6B ) were made. Inertinite content correlates in whole-coal samples with Br concentrations which is consistent with the dominant organic affinities of this element in the samples studied. At the 95% CL there were no positive correlations between the vitrinite-group compositions and the elemental concentrations. Rmax positively correlates with Ga and Sb. The reasons for these correlations are not clear and merit further investigation. CONCLUSIONS

There appears to be little or no relationship between the rank, age and floral composition of the coals and the minor- and trace-element chemistry of the

518 vitrinite concentrates. The vitrinite concentrates analyzed for this paper generally show only a few major differences when compared to whole-coal analyses of the eastern United States as reported in this paper and by Zubovic et al., ( 1980 ). The lack of differences is because all these coals are vitrinite-rich and, therefore, are not very different in vitrinite content as compared to the vitrinite concentrates. The high B content of vitrains from the Illinois basin and the high Sb content of English and Australian vitrinite concentrates are about an order of magnitude higher than those in the other vitrinite concentrates analyzed. Most of the B concentration probably is n o t due to associated illite because the B concentration in the vitrains does not correlate positively with ash and Si contents. Thus, the boron is probably associated or chemically combined with the organic matter in the vitrains and is probably of marine or hydrothermal origin. Some vitrinite concentrates show high or low concentrations of certain elements relative to the whole-coal analyses. V has notably high concentrations at least several times higher than the mean for whole coals from the eastern United States (Swanson et al., 1976; Gluskoter et al., 1977). These data support a mixed organic-inorganic origin for most of the V. Comparison of analyses of vitrains from the Appalachian basin with those from the Illinois basin shows that there are higher concentrations of the alkaline-earth elements Ba, Ca, Mg and Sr in the former, which most likely indicate higher amounts of carbonate, clays, and other minerals and a nonmarine origin (possibly an ionexchange mechanism) of these elements in the vitrinite concentrates from the Appalachian basin. The English and Australian coals show organic association of As. The highest concentrations of Ni and Cr occur in one of the English vitrinite concentrates and the highest Zr occurs in the Australian vitrinite concentrates. These anomalies probably indicate differences in the water chemistry and surrounding peatland rocks for these coal basins. Many elements that show correlations in the whole coals do not show correlations in the vitrinite concentrates. This is mainly due to the lack of aluminum silicates and the presence of vitrinite-associated elements in the vitrinite concentrates. Statistical correlations between the mineral composition and concentrations of minor and trace elements in the whole coals indicate that many elements are associated with major silicate minerals. Arsenic and Pb are correlated with pyrite in the whole coals. Chemical data reported in this paper suggest that Br and W are the most organically associated elements. Ca, U, and V have a tendency toward organic association in all coals. Na is associated organically in three samples. Arsenic shows strong inorganic association in most samples. Zn has a strong organic association in two vitrinite concentrates, one from England and one from Australia. As, Br, Cr, Hf, Hg, Sb, and V show organic associations in the English and Australian coals. Most other elements, including Th and the rare-earth elements, show inorganic associations in these coals.

519 The following elements show dominantly inorganic association in all the coals: A1, As, Co, Cs, Cu, Fe, Hf, La, Mg, Ni, Si, Ti, Th and Yb. Basinal geochemical signatures are indicated by the rare-earth-element data. Provincialism is indicated by the elevated concentrations of B, Ba, Co, Cu, Ni, Sb, U, V, Zr and other elements in the vitrinite concentrates from certain coal basins. Some of these high concentrations are probably related to deformation or epigenetic mineralization; for example, the high concentrations of certain elements such as A1, As, Sb, V, and the rare-earth elements in our samples occur in the most deformed and highest rank coals of the eastern United States. Our preliminary data indicate that living tree ferns histologically fractionate certain elements, such as A1, Ba, Ca, Co, Cr, K, La, Na, Se, Sm and Zn, and that concentrations of elements in tree-fern xylem, particularly Ca, Ce, Co, La, Sc and Sr, are similar to the concentrations in the vitrinite concentrate from the Pittsburgh coal bed, which is consistent with entrapment during the peat stage. ACKNOWLEDGEMENTS We thank A.H.V. Smith of the University of Sheffield, England, for supplying samples of the English and Australian coals. The manuscript was critically reviewed by D.W. Golightly, W.H. Orem, M.J. Bergin, R.B. Finkelman, P.J. Aruscavage, and J.A. Minkin, all of the U.S. Geological Survey. J.S. Mee, U.S. Geological Survey, assisted with the INAA analysis. APPENDIX

Precision and accuracy of chemical analyses The precision of the analyses for each sample is best determined by multiple analyses of each element in each sample. However, because of limited sample and cost, this was not practical. The precision for DCAS is _ 10 percent for concentrations greater than five times the detection limit (Tables A-1 and A2 ). An estimate of the precision of the INAA technique was obtained by analyzing as many samples as possible in duplicate (Palmer and Baedecker, 1989 ). For very small samples, such as the handpicked vitrinite concentrates, precision was estimated by analyzing duplicate standard reference samples. The concentrations of elements in these reference samples were established by several analytical techniques and were used to provide an estimate of the accuracy of the INAA technique. Table A-3 shows data for duplicate INAA analyses of NBS standard reference materials 1632b (coal) and 1633a (fly ash). The relative errors reported are one sigma errors based on counting statistics. Each sample was counted for as long as 2 hours and as many as six times to obtain the best statistics for elements of various half-lives. If the elemental concen-

520 TABLE A-1 Precisionlof direct-current-arc spectrographic (DCAS)techniquesfor vitrinite concentrates of this paper Wavelength (nm)

Element

Limit of detection (ppm)

5 × limit 1 (ppm)

265.248 249.773 455.403 315.887 345.350 425.435 327.396 302.107 294.364 277.983 285.213 279.482 341.476 283.306 251.920 309.840 318.341 334.502 327.926

A1 B Ba Ca Co Cr Cu Fe Ga Mg Mg Mn Ni Pb Si Ti V Zn2 Zr

2000 40 2 20 5 2 2 200 2 200 10 2 2 2 200 10 10 10 10

10000 200 10 100 25 10 10 1000 10 1000 50 10 10 10 1000 50 50 50 50

1Relative precision above 5 Xlimit is _+10%. 2The background at the wavelength region of Zn 334.502 was so dense that it was necessary to visually determine this element; thus, optimum precision was not obtained. t r a t i o n was d e t e r m i n e d in m o r e t h a n I count, the n u m b e r o f c o u n t s is r e p o r t e d in p a r e n t h e s e s a f t e r the e r r o r as s h o w n in T a b l e A-3. T h e N B S certified a n d n o n c e r t i f i e d values also are i n c l u d e d in Table.A-3 for b o t h 1632b a n d 1633a. T h e relative e r r o r s for t h e values were c a l c u l a t e d f r o m the absolute e s t i m a t e d u n c e r t a i n t y given by t h e U.S. N a t i o n a l B u r e a u o f S t a n d a r d s Certificates of Analysis (U.S. N a t i o n a l B u r e a u of S t a n d a r d s , 1979,1985). T h e p r e c i s i o n was w i t h i n 2 sigma o f t h e c o u n t i n g statistical e r r o r in all cases, e x c e p t S m in 1632b ( T a b l e A-3) where, despite t h e low c o u n t i n g statistical errors, t h e lowest value is 10% below t h e weighted average b a s e d on the ratio of inverse squares o f t h e relative errors. T h e largest c e r t a i n t y was in Nd, w h e r e c o u n t i n g statistical e r r o r s were as high as 30%, a n d in H g t h a t was d e t e c t e d in only one c o u n t of 1632b a n d n o t at all in 1633a. T h e a c c u r a c y of t h e I N A A d a t a in this p a p e r was assessed b y c o m p a r i n g the w e i g h t e d average o f values o b t a i n e d in this s t u d y with N B S certified a n d noncertified values. In general, m o s t values agreed w i t h i n t h e statistical errors. Only t h r e e values differed f r o m e x p e c t e d values b y m o r e t h a n 15%. T h e y were Rb in 1632b (6.1 p p m c o m p a r e d to N B S certified values of 5.05 p p m ) , a n d Sr

521 TABLE A-2 Precision 1 of direct-current-arc spectrographic (DCAS) techniques for whole coals of this paper Wavelength (nm)

Element

Limit of detection (ppm)

5 × limit (ppm)

265.248 249.773 455.403 315.887 345.350 425.435 327.396 259.837 317.5042 294.364 265.118 285.2133 277.983 279.482 293.9302 341.476 283.306 251.920 243.5164 309.840 316.257 318.341 334.502 327.926

Al B Ba Ca Co Cr Cu Fe Fe Ga Ge Mg Mg Mn Mn Ni Pb Si Si Ti Ti V Zn ~ Zr

2000 40 15 70 5 2 4 500 4000 4 10 10 70 4 30 2 5 700 2000 10 40 8 20 10

10000 200 75 350 25 10 20 2500 20000 20 50 50 350 20 150 10 25 3500 10000 50 200 40 100 50

1Relative precision above 5 ×limit is _+10%. 2Only used for LP-lwr. :~Only used for LP-17wr. ~Only used for LP-lwr and LP-2wr. 5The background at the wavelength region of Zn 334.502 was so dense that it was necessary to visually determine this element; thus, optimum precision was not obtained.

and Sb in 1633a (Sr 980 ppm compared to NBS certified 830 ppm; and Sb 5.59 ppm compared to recommended NBS value of 7 ppm). Table A-4 shows a similar study for A1, Ca, Mn, Ti and V. The U.S. Geological Survey (USGS) standard rock AGV-1 was analyzed as a control. Because it was not run in duplicate, the only estimate of precision is based on counting statistics. For example, Ti in AGV-1 was 0.42% compared to 0.62%, the recommended USGS value. Ti actually agrees with the recommended USGS value within the counting statistical errors (sigma = 42 % ), and the other four values agree within 2 sigma.

As (ppm) sigma (%) Ba (ppm) sigma (%) Br (ppm) s,gma (%) Co (ppm) sigma (%) Cr (ppm) s,gma (%) Cs (ppm) s,gma (%) Fe(%) sigma (%) Hf (ppm) s,gma (%) K(%) sigma (%) Na (%) s,gma ( % ) Rb (ppm) s,gma (%) Sb (ppm) sigma ( % ) Sc (ppm) sigma (%) Se (ppm) sigma ( %) Sr (ppm) sigma ( % )

Element

3.73 3(3) 62 13(3) 20.4 6 2.28 6(5) 11.6 4(5) 0.50 9(5) 0.747 2(5) 0.43 8 0.080 5(3) 0.057 2(3) 6.9 13 0.219 4 2.18 3(5) 1.31 13(%) 180 13(2)

Control NBS 1632b (a) 4.15 6 62 15 18.2 6 2.25 4(2) 11.0 4(2) 0.400 7(2) 0.751 2(2) 0.463 6(2) 0.067 13 0.055 3 5.6 12 0.190 7(2) 2.00 2(2) 1.31 12{2) 97 14

Control NBS 1532b (b) 3.80 5 62 10 19.3 6 2.26 4 11.3 3 0.43 2 0.749 2 0.451 5 0.078 6 0.056 2 6.1 10 0.211 7 2.05 4 1.31 9 102 10

Weighted average NBS 1632b 3.72 2 68 3 17.0 * 2.29 7 11.00 * 0.44 2 0.76 6 0.43 * 0.075 4 0.052 2 5.05 2 0.24 * 1.90 * 1.29 9 102 *

NBS 1632B NBS value 144.2 2(4) 1350 4(4) 2.46 5(3) 43.8 2(4) 188 2(6) 9.8 4(6) 9.36 2(6) 7.2 7(6) 1.81 2(4) 0.186 2(4) 143 6(4) 5.5 7(6) 39.5 2(6) < 15 (6) 960 9(2)

Control NBS 1633a (a)

Precision and accuracy of instrumental neutron activation analysis (INAA) data of this paper

TABLE A-3

151.9 2(2) 1440 7(2) 2.64 5(3) 43.3 3(~) 191 3(3) 10.9 6(3) 10.02 2(3) 6.89 3(3) 1.72 4(2) 0.197 2(2) 117 15(2) 5.60 2(3) 41.9 2(3) 11.3 21 1010 12

Control NBS 1633a (b) 3

3 0.190 3 139 8 5.59 2 40.6 3 11.3 21 980 7

1.79

4 2.55 5 43.6 2 189 2 10.0 2 9.7 4 6.94 3

1370

148

Weighted average NBS 1633a

3

11.3 6 83O 4

4O

1.88 3 0.170 6 131 2 7

2 9.4 1 7.6

11

196

46

145 10 1500

NBS 1633a NBS value

¢91 b~

7(2) 4.51 3 8.4 4(2) 4.6 30 0.818 3 0.176 7(2) 0.104 8(2) 0.46 9 0.056 9

11.5

14.1

7(4) 4.78 3(3) 8.9 4(5) 7.2 24(2) 0.928 2(3) 0.212 6(4) 0.108 19.(5) 0.393 8(3) 0.052 8(3)

0.167 8(2) 1.36 3(2) 0.45 11 0.44 17 -

Control N B S 1632b (b)

0.145 16(2) 1.47 3(5) 0.46 7(3) 0.46 8(3) 0.37 27

Control NBS 1632b (a)

11 4.63 3 8.64 3 5.6 23 0.90 6 0.197 10 0.104 8 0.41 8 0.054 6

12.5

0.162 7 1.41 4 0.455 6 0.45 8 0.37 27

Weighted average N B S 1632b

-

-

0.87 * 0.17 * -

7 5.1 * 9 *

11.9

1.34 3 0.432 3 0.48 * -

-

NBS 1632B NBS value

Control NBS 1633a (b) 2.34 8(3) 26.9 2(3) 10.3 4(2) 6.1 6(2) 238 4(3) 87.7 2(2) 180 3(3) 60 15(2) 20.4 2(2) 3.82 7(3) 2.7 12(3) 8.76 3(2) 1.13 5(2)

Control NBS 1633a (a) 1.80 17(6) 25.4 3(6) 10.7 3(4) 5.6 6(4)

210 8(6) 84.5 2(4) 166 3(6) 77 7(4) 18.4 6(4) 3.76 3(6) 2.35 4(6) 7.99 3(4) 1.02 10(4)

4(5) 86.0 2 171 4 73 10 20.2 4 3.77 3 2.37 4 8.2 5 1.11 4

232

2.20 11 26.4 3 10.6 3 5.86 5 -

Weighted average NBS 1633a

4

180

0.160 6 220 5

10.2 1

-

-

N B S 1633a N B S value

Error limits are one standard deviation based on counting statistics alone. Number in parentheses is number of individual results, based on repetitive counts, averaged to yield expressed result. NBS values for standard reference materials 1632b (coal) and 1633a (fly ash) are from the U.S. National Bureau of Standards (1979, 1985 ). Average values are weighted average based on inverse-squared ratio of errors *NBS value given above symbol is not certified and should be used for information only.

Ta (ppm) sigma ( % ) T h (ppm) sigma ( % ) U (ppm) s,gma (%) W (ppm) sigma (%) Hg (ppm) sigma ( % ) Zn (ppm) sigma ( % ) La (ppm) sigma (%) Ce (ppm) sigma (%) Nd (ppm) sigma ( % ) Sm (ppm) sigma ( % ) Eu (ppm) sigma ( % ) Tb (ppm) sigma ( % ) Yb (ppm) sigma ( % ) Lu (ppm) slg~la ( % )

Element

O1 bO

524 TABLE A-4 Estimate of precision for short-lived isotopes of this paper as determined by instrumental neutron activation analysis (INAA) Sample

Control AGV-1

AGV- 1 USGS value

A1 (%) sigma (%) Ca (%) sigma (%) Mn (ppm) sigma (%) Ti (%) sigma ( % ) V (ppm) sigma ( % )

8.67 2 2.9 22 750 22 0.42 41 133 9

9.13 * 3.5 * 750 * 0.62 * 125 *

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