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Palynologic and petrographic variation in the Pond Creek coal bed, Pike County, Kentucky
Org. Geochem.Vol. 17, No. 2, pp. 153-159, 1991
0146-6380/91 $3.00+ 0.00 Copyright © 1991 PergamonPress plc
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Palynologic and petrographic variation in the Pond Creek coal bed, Pike County, Kentucky CHARLES T. HELFRICH1 and JAMESC. HOWER2 IEastern Kentucky University, Richmond, KY 40475, U.S.A. 2Center for Applied Energy Research, University of Kentucky, Lexington, KY 40511-8433, U.S.A.
(Received 25 January 1990; accepted 15 July 1990) Abstract--Recent studies of the petrology and ash geochemistry of the Pond Creek coal bed (Middle Pennsylvanian Breathitt Formation) in Pike and Martin Countries, Kentucky, have defined vertical and lateral trends that are related to the development of the northeast-trending Belfry anticline contemporaneous with the deposition of the Pond Creek peat. To the northwest of the anticline the coal bed has a high-CaCO3 middle zone and a high Fe 2O3-high sulfur upper zone. To the east of the anticline, particularly in the Lick Creek and Jamboree 7½' quadrangles, the coal bed exhibits a distinctive petrographic zonation. In the latter area, the usual megascopic sequence is a basal durain followed by a bright clarain-durain/dull clarain-bright clarain-bone-bright clarain-durain sequence. The palynology of the Pond Creek coal bed was investigated in six sets of bench/lithotype samples from the Lick Creek and Jamboree 7~' quadrangles. The low-vitrinite basal durain (zone 1) has a palynomorph assemblage which reflects the importance of tree ferns and herbaceous lycopods. The easternmost site has a bright clarain below the durain. The latter lithotype has a fair diversity of palynormph groups and also has the highest percentage of arborescent lycopod forms of any bench below the bone (zone 5). The bright zone 2 above the durain has the grestest maceral group range and the greatest floral diversity of any of the lithotypes. The zone 3 dull lithotype has increased amounts of herbaceous lycopods and decreased amounts of arborescent lycopods, sphenopsids and tree ferns. The zone 4 bright lithotypes are generally over 80% vitrinite and, in general, exhibit a dominance of arborescent lycopods although sphenopsid, tree fern and small fern forms exhibit varying importance. The high-ash bone (zone 5) has 71.6-77.0% vitrinite. This lithotype is marked by a dominance of herbaceous lycopods at the expense of arborescent lycopods and sphenopsids. The zone 6 bright clarain is marked by an increase in arborescent lycopods and a large decrease in herbaceous lycopods. The low-vitrinite terminal durain has an assemblage with high percentages of herbaceous lycopods and low percentages of arborescent lycopods as well as increase in tree fern spores over zone 6. In general, the petrology and palynology trends are predictable. Dull lithotypes have abundant herbaceous lycopod representation and bright lithotypes have abundant arborescent lycopod representation. The greatest deviation from this simple pattern is within the zone 4 bright lithotypes, where diverse palynomorph assemblages occur among the high-vitrinite benches. Overall, the greatest floral diversity appears to have occurred near the base of the coal bed.
Key words--Kentucky, Pond Creek coal, coal petrology, palynology, depositional environments
INTRODUCTION The Pond Creek coal bed (Middle Pennsylvanian Breathitt Formation), also known as the Lower Elkhorn within the study area and correlative with the Blue Gem, Path Fork and Imboden coals mined elsewhere in southeastern Kentucky, is one of the most extensively mined coals in the Eastern Kentucky coal field. Within the study area of the Lick Creek and Jamboree 7½' quadrangles [geologic maps by McKay and Alvord (1969) and Outerbridge and Van Vloten (1968), respectively], the Pond Creek is generally overlain by siltstone and fine-grained sandstones. In previous studies of the Pond Creek through Pike and Martin Counties, Kentucky, little evidence of marine influence in the Lick Creek/Jamboree area was encountered (Hower and Pollock, 1988; Hower and Bland, 1989).
Kosanke (1967) studied the palynology of the Pond Creek coal bed at its type locality in the Belfry 7½' quadrangle. Overall, the coal was dominated by arborescent lycopod genera (Lycospora) and herbaceous lycopod genera (Densosporites, Cristatisporites), which along with Laevigatosporites (sphenopsid) and Granulatisporites (fern) contributions account for almost 89% of the palynomorphs. A generic summary for forms occurring in quantities greater than 1% in any of the five benches is presented in Table 1. In this study we are re-examining the petrography of a limited portion of Hower and Pollock's (1988) study area with the addition of palynology as an analytical tool. Vertical and lateral variations in the palynology and in the maceral composition will be used to help to understand the complexities involved in the development of the Pond Creek swamp. 153
154
CHARLEST. HELFRICHand JAMESC. HOWER Tablel. Genedcsummaryofmiospo~sfrom thePond C~ekcoal ~d, Belf~quadrangle,Pike County, Kentucky(afterKomnke, 1967) SAMPLE THICKNESS
(cm)
Ahrensisporites Cristatisporites Densosporites Dictyotriletes Endosporites Granulatisporites Laevigatosporites Lycospora Punctatisporites Savitrisporites
83-B (top)
83-C
83-D
83-E
83-F
21.59
20.32
29.21
33.02
31.75
0.8 2.8 39.6 0.4 0.4 2.4 1.2 48.8 0.8 . .
4.0 8.8 28.4 3.2 0.4 0.8 1.6 51.2 -. . .
0.4 2.4 34.8 3.2 -3.2 18.8 34.8 0.8 . . .
0.8 -25.2 0.8 0.8 2.8 5.6 62.4 0.8
2.4 34.0 11.6 0.4 3.6 5.2 18.0 19.4 1.6 1.6
Only includesgenera occurringat >1% abundance in at least one bench. PROCEDURE
The coal samples were collected from fresh exposures in five underground mines in the Lick Creek and Jamboree 7½' quadrangles (Figs 1 and 2). Sites 3661, 3671, 3597 and 3606 were included in a study by Hower and Pollock (1988). Sites 3772 and 3783 were sampled after the completion of the latter study. Wherever possible the delineation of benches was made at lithologic breaks. Benches are numbered from the top of the coal bed, as in the following example of a six bench set: 1/6 (top), 2/6 . . . . 5/6, 6/6 (bottom). The lithologic zones discussed in the text were first delineated in a geochemical study (Hower Johnson "XJ""""~ .x ~
Martin
Ft.oyd
DISCUSSION Studies of the petrography (Hower and Pollock, 1988) and geochemistry (Hower and Bland, 1989) of the Pond Creek coal bed in Pike and Martin Counties, Kentucky, have defined vertical and spatial trends which appear to be related to the development
J~'^(~
~" '" " ~ P " " " ]
and Bland, 1989) and were numbered in depositional sequence from the base of the coal bed. The petrographic and chemical analyses were performed at the University of Kentucky Center for Applied Energy Research.
/
~
WEST VIRGI"NIA
('/
Pike
t
/
'
/
~,r" t..~
b)"x, t ~
/
/
/1
rt )
37* 45~
/
oo "
/
•
>
$'/
,
%
I
I
0 0
p821~45'
//
i
miles kilomeVes
82 =30' J.
20 82 = J
82 ° 0 O'
Fig. 1. Location of Lick Creek and Jamboree 7½' quadrangles within Pike County, Kentucky, with the location of the Belfry anticline.
155
Petrology and geochemistry of Pond Creek coal, Kentucky X
I
Lick Creek
Jamboree
37* 30~/82" t7'
92"15'
37" 30'/8 2"
SampLe Sites
• 3597
•3783 3772 •
1 0 0 • •
mL km
t I
3671
37*27'/8 2"
3661
11'
\
I
Fig. 2. Samples sites within portions of the Lick Creek and Jamboree 7~' quadrangles. of the northeast-trending Belfry anticline contemporaneous with the deposition of the Pond Creek peat. The Belfry anticline (see Fig. 1) is the only major structure to interrupt the northwestward monoclinal dip of the Pond Creek horizon. To the northwest of the anticline the coal bed has a highCaCo 3 middle zone and a high-Fe203-sulfur upper zone. A thin, high TiO2-high zirconium zone in the lower third of the coal bed is indicative of elastic influx into the swamp. The main bed of the Pond Creek coal bed and the separation between the main bed and the rider both thin across the anticline. To the east of the anticline, particularly in the Lick Creek
and Jamboree quadrangles, the coal bed exhibits a distinctive petrogrpahic zonation. In general, the usual megascopic sequence is a basal durain followed by a bright clarain-durain/dull clarain-bright clarain (at some sites dulling upwards to clarain)-bonebright clarain-durain sequence. The generalized lithologic profiles for the six sites in this study are shown in Fig. 3. Certain iithologies, particularly the thin durain at the top of the coal bed, could not always be collected as an individual bench. Each lithologic zone (italic numbers in Fig. 3) could be collected at a minimum of two of the six sites, with the exception of zone "0" which was
Megoscopic Profites
bright ctoroin
:~'::'~:~:
ctoroin fusoin I duroin ,
,
duLLc(orain bone
Im
I
SAMPLE NO.
3661
SEPARATION (kin)
367'1 20
E
3597 4.4
3783
5772
1.6
1.3
3606 1.9
•
Fig. 3. Generalized megascopic profiles of the six sites. Wherever possible the division of benches (tick marks on the right-hand side of the column) was made at lithologic breaks. The lithologic zones (italic numbers) were delineated in the geochemical study (Hower and Bland, 1989).
156
CHARLEST. HELFRICHand JAMESC. HOWER Table 2. Form genera by palynomorph group
Arbcrescent lycopods Cappasporites Crassispora Lycospora Cordaites Florinites Ferns Acanthotriletes Apiculatisporis Apiculatisporites Dictyotriletes Granulatisporites Leiotriletes Lophotriletes Microreticulaltisporites Punctatisporites Raistrickia Savitrisporites Herbaceous lycopods Anapiculatisporites Cingulizonates Cirratriradites Cristatisporites Densosporites Endosporites Spencersporites
present only at site 3606. Zone 4, collected in multiple benches at four sites, and zone 5 were each collected at all six sites. The palynomorph genera identified in the study were assigned to groups, based on discussions in Smith and Butterworth (1967) and Traverse (1988) and references cited therein, as shown in Table 2. The group maceral petrography and the palynology for the six sites are summarized in Table 3. The greatest floral diversity, as well as the greatest diversity between sites, occurs in the basal zones 1 and 2 and, at site 3606, zone "0". At various sites the basal zones were dominated by either arborescent lycopods, herbaceous lycopods or tree ferns. Zone "0", bench 9/9 at site 3606, has a fair palynologic diversity although arborescent lycopod spores are more abundant than in any bench below the uppermost bright clarain (bench 2/9; bench 3/9 is a fusain). The basal durain (zone I), with maceral group composition from V22.2Is57L22.1 t o V38.2149.gLll.9 , has a diverse palynomorph assemblage reflecting the importance of tree ferns and herbaceous lycopods. Zone 2 bright lithotypes comprise the basal zone at sites where the zone l durain is absent. Zone 2 has the greatest maceral group range (V62.3127.sL9. 9 to Vs3,4I8.4L8.2) and the greatest floral diversity of any of the zones. In general, while arborescent lycopods show an increase over the basal durain, no distinctive palynologic composition is common to the six sites. The zone is thinnest in the west, increases in thickness to site 3772 and then decreases in thickness to the east. Zone 3, the thin dull z o n e (V62.4130.0L7. 6 to V739I~9.2L6.9), increases in thickness to the east. (The zone is present as a 0.9 cm bone within bench 6/6 at
Sphenopsids Calamospora Laevigatosporites Reticulatisporites Vestispora Tree ferns Cyclogranisporites Fabasporites Punctatosporites Thymospora Torispora Verrucosisporites Unknown affinity Ahrensisporites Alatisporites Grumosisporites Hymenospora Mooreisporites Planisporites Pustulatisporites Reinschospora Schofites Tripartites* Triquitrites Wilsonites *possible contamination
site 3671.) The bench is the first bench with some lateral consistency in palynology, generally being dominated by herbaceous lycopod forms. Zone 4, composed of bright lithotypes with over 80% vitrinite (except bench 5/7 at site 3783), is thickest in the western sites. Most sites have abundant fusains within the bright lithotypes. Site 3783 has less fusain and has a 5.2 cm pyrite band within the zone, the only megascopic pyrite observed in the Pond Creek east of the anticline. The following discussion of the palynology of zone 4 will progress through the sites from west to east. At site 3661 arborescent lycopods are important in the lower half of the zone but decrease at the expense of sphenopsids, small ferns and tree ferns in bench 5/8 and herbaceous lycopods in bench 4/8. Site 3671 exhibits similar trends with the dominant arborescent lycopod forms of bench 5/6 decreasing in favor of increasing herbaceous lycopods and sphenopsids in bench 4/6 and herbaceous lycopods in bench 3/6. Note that at the latter two sites arborescent lycopod forms are still more abundant than herbaceous lycopod forms. Site 3597 is represented by a single bench with a dominance of arborescent lycopods with secondary importance of sphenopsid forms. Site 3772 has relatively constant amounts of arborescent lycopod forms through the four benches. Secondary trends indicate rising and falling amounts of herbaceous lycopod, sphenopsid, fern and cordaites. Zone 4 at site 3783 has a basal zone with low arborescent lycopods and high herbaceous lycopods and sphenopsids. Arborescent lycopods and sphenopsids along with ferns and tree ferns increase upwards into the middle bench. Arborescent lycopods and sphenopsids, along with herbaceous lycopods,
3607 3608 3609 3610 3611 3612 3613 3614 3615
3784 3785 3786 3787 3788 3789 3790
3773 3774 3775 3776 3777 3778 3779 3780 3781 3782
3598 3599 3600 3601 3602 3603
3672 3673 3674 3675 3676 3677
3662 3663 3664 3665 3666 3667 3668 3669
KCER#
W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF W.C. I OF 2 OF 3 OF 4 OF 5 OF 6 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF 9 OF i0 O F W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF 9 OF
BENCH
9 9 9 9 9 9 9 9 9
7 7 7 7 7 7 7
i0 i0 i0 I0 i0 i0 i0 i0 i0 i0
6 6 6 6 6 6
6 6 6 6 6 6
8 8 8 8 8 8 8 8
5 4 3 2 1 "0"
7 6
6,7 5 4 4 4 2,3 2
6,7 5 4 4 4 4 3 2 2 1
7 6 5 4 2 1
6,7 5 4 4 4 2,3,4
7 6 5 4 4 4 3,4 2
LITH. ZONE 87.0 13.0 84.9 73.9 86.7 91.9 84.8 87.4 83.4 81.2 80.2 73.2 81.0 86.6 87.4 81.5 74.8 29.7 73.7 73.4 81.0 65.9 32.8 78.5 81.1 75.6 80.8 87.0 83.8 82.1 73.9 80.1 71.6 38.1 75.4 77.7 77.0 85.5 81.2 75.1 62.4 68.2 68.1 70.9 81 . 3 2.8 71.6 82.5 73.9 62.3 22.2 62.5
152 1 19 28 17 7 18 45 14 129 22 14 13 17 30 30 133 6 20 24 52 24 6 134
40 52 51 96 07 01 29 Ii 94 54 40 33 41 70 02 48 i0 10 73 08 12 08 10 37 22 25 26 52 6 71 11 58 7 92 12 50 2 13 14 02 27 74 3 05 1 2 2 94 24 38 19 81 20 73 13 72 15 85 16 1 5 10 06 1 7 0 69 2 74 21 34 2 13 21 64 49 38 10.06 27.43 4.57 31.39
VITS
THICKNESS (CM) 7.7 38.0 9.0 16.8 6.5 4,1 8.0 5.6 6.9 9.9 13.8 18.6 11.0 6.3 5.7 11.7 16 .0 34.5 19.7 19.3 8.6 18.8 44.3 12.7 12.5 16.6 11.3 8.1 8.6 11.6 15.0 10.3 18.7 47.4 13.9 13.0 16.1 8.2 10.1 15.1 23.9 17.2 19.9 17.4 10.7 97.2 20.4 9.6 18.2 20.5 47.8 22.1
[NERTS
0.9 9.5 1.4 0.i 1.4 1.2 3.6 2.2 1.5 2.4 i.i 0.i 0.7 2.1 3.0 1.4 2.5 5.8 2.4 0.7 4.1 6.1 5.0 2.6 2.2 0.2 2.4 1.6 2.9 2.1 4.2 4.1 4.4 2.6 4.6 2.4 0.i 1.5 4.0 4.1 6.1 7.4 3.6 4.3 2.8 0.0 0.2 3.4 0.5 7.3 7.9 8.3
MIC
30.0 4.2 6.7 6.3 9.2 17.9 6.2 4.2 7.6 5.5 3.3 4.7 4.2 6.9 5.5 5.3 11.9 6.1 6.9 6.8 4.8 4.7 5.7 7.6 7.2 8.4 7.1 5.1 0.i 7.8 4.5 7.4 9.9 22.1 7.1
6.7
4.4 39.5 4.7 9.2 5.4 2.8 3.6 4.8 8.2 6.5 4.9 8.1 7.3 5.0 3.9 5.4
LIP
7.99 13.73 5.30 24.93 8.10 1.96 532 245 689 950 1371 27 33 1166 227 147 639 12 24 1266 888 2846 203 441 789 1017 786 2368 11.10 206 154 182 296 668 539 36 86 12 22 i0 79 27 3 7 945 316 240 618 354 1020 765 615 417 28 32 467 1186 327 492 271
DRY ASH
0.0 0.8 0.0 0.8
1.5 0.4 0.0 0.0 0.4 1.8
0.2
43.2 44.2 2.8 2.9 4 .1 52.9
0.0 0.0 0.0 0.0 0.0 0.0 0.7 0.0 I.i 0.7 1.2 1.0 0.0 0 .4 0.4 0.5 0.3 0.0 0.5 1.7 0.4 0.5 1.8 2.0 0.8 1.5 0.4 0.4 1.1 3 .I 0.0 0.0 5.3 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0
CRD
53.6 21 .8 82.3
64.4 10.8 77.1 48.5 57.0 61.8 84.0 89.5 46.2 62.0 81.3 42.9 63.1 61.9 77.4 74.5 40.7 12.9 76.0 43.9 58.9 16.8 11.5 44.1 79.8 48.9 68.3 66.8 63.9 66.4 20 .8 39.3 37.4 9.2 46.2 68 .7 40.8 53.1 50.2 24.2 3.7
ALC
7 14 12 11 13 11
3 5 8 6 6 15 4 3 3 6 5 5 5 7 3 5 7 13 6 i0 I0 14 11 9 6 7 2 11 5 9 5 3 16 15 11 5 7 i0 16 6 14 0 8 3 4
FRN
6 7 2 6 9 7
9 0 3 6 7 1 4 8 8 8 2 7 1 9 9 9 6 5 0 3 8 0 9 0 5 7 8 9 3 2 5 3 4 9 6 7 9 5 3 2 7 2 4 5 5 1 6 5 2 5 10
44.3 32.5 66.1 69.9 39.7 5.8
9 0 9 9 2 9
6.0 1.2 8.3 0.7 3.7 17.9 4.7 1.5 7.5 4.5 4.5 0.8 2.5 14.9 5.4 10.1 5.8 1.3 5.6 0.7 5.9 3.7 8.1 3.3 7.6 1.1 6.8 12.3 8.4 5.0 0 4 4 4 9 2 i0 3 4 7 9 8 3 0 7 4 4 6 2 7 4 0 0 1 3 8 1 2 7 2
SPH
23.9 81.2 5.3 43.4 31.1 0.4 4.0 3.4 41.0 23.8 6.9 47.4 27.9 14.0 11.7 7.3 41.8 70.8 10.4 41.0 21.1 53.6 21.3 38.5 4.2 37.9 21.3 6.7 20.5 13 .7 70.4 50.4 8.4 23.6 34.6 14.3 45.7 27,5 24.0 65.4 72.1 0.2 30.4 70.0 4.2
HLC
0.8 0.0 0.0 0.7 1.5 0.4 0.0 0.8 0.0 1.5 0.5 1.9 1.0 0.0 0.1 0.2 1.8 0.2 0.5 1.7 0.1 0.2 0.0 2.9 0.4 0.4 0.0 0.4 0.0 0.8 0.7 0.0 0.0 0.0 2.1 0.8 0.7 1.6 1.9 0.8 1.8 0.0 1.0 0.0 0.8 1.5 0.4 1.2 0.4 0.4 0.0
0.0 1.9 11.8 12.3 36.3 16.8
UNK
1 0 1 9 1 1 0 0 0 0 4 4 2 2 1 1 0 4 0 7 0 5 0 3 0 4 0 9 1 1 1 5 2.0 1.3 i.i 0.8 2.8 11.2 45.4 0.2 0.8 2.6 0.4 1.5 0.8 1.9 2.2 2.6 23.3 39.5 0.7 0.8 1.9 0.0 3.0 0.8 3.7 0.2 2.0 3.5 0.4
TFN
VlT--vitrinites, INERT--inertinites, MlC--micrinite, LIP--liptinite, ALC--arborescent lycopods, CRD---cordaites, FRN--ferns, HLC--herbaceous lycopods, SPH--sphenopsids, TFN--tree ferns, UNK--unknown affinity.
3606
3783
3772
3597
3671
3661
SITE
Table 3. Group macerals, ash content and plant a~nities of Pond Creek coal bed ~mples
_q
8
o
o
158
CHARLEST. HELl:RICHand JAMESC. HOWER
increase in abundance to the top bench while small ferns and tree ferns decrease in abundance. The easternmost site, 3606, is represented by a single bench in which both arborescent and herbaceous lycopods are abundant. Zone 5, the bone lithotype (71.6-77.0% vitrinite), tends to be thicker in the east. There is little lateral variation in palynomorphs with herbaceous lycopod forms dominating. Zone 6, the upper bright zone (V73.7122.1L4, 2 to Vsl.3II3,6Ls.I) with abundant fusains (note that the 2.1 cm fusain at site 3606 was collected as a separate bench), is of relatively constant thickness across the study area. This lithotype shows significant increases in arborescent lycopod and sphenopsid forms and decreases in herbaceous lycopod and fern forms compared to the underlying bone lithotype. The thin terminal durain (zone 7) is present at all of the study sites as well as at whole channel sites from the same mines. The durain could not be collected individually at every site. At site 3671, for example, the durain is only 0.3 cm thick. The durain is absent to the west of the study area. In a mine in the Lick Creek quadrangle between site 3661 and the Belfry anticline a 3.3 cm bone (V84.3Ii3.7 L2.0) above a 1.5 cm siltstone was found at only one of the three sites sampled. The group maceral composition of the durain ranges from V13.01,17.sL39,5 to W29.7140.3L30.0 and is dominated by duroclarite and vitrinertoliptite microlithotypes. The palynomorph assemblages are dominated by herbaceous lycopod forms with tree ferns also showing an increase above the level of the underlying bright lithotypes. Overall the bright lithotypes record a rather different environment of deposition than the dull lithotypes. The herbaceous-lycopod-dominated dull zones, with clastic maceral and, in the zone 5 bone lithotype horizon, clastic mineral assemblages, indicate deeper water deposition than the aborescentlycopod-dominated bright zones. The bright lithotypes, particularly zones 4 and 6 with abundant fusains, indicate an environment generally more elevated than the dull zones and also susceptible to fluctuations of the watertable. The fusains may indeed represent the continued truncation of the peat as it rose above the water table. The zone 4 bright lithotypes were collected in sufficient detail to determine some of the vertical and lateral floral variation. As noted above there was a continual rise and fall in importance of various plant groups throughout the time of zone 4 deposition. The two sites closest to the Belfry anticline, Lick Creek sites 3661 and 3671, show indications of a greater importance of a relatively "dry land" flora: tree ferns, ferns and sphenopsids; particularly towards the top of the zone. This may point to a greater elevation for the latter sites; particularly in comparison to site 3783 where the sequence was
interrupted by the pyrite band, the only hint of any marine or brackish influence seen in the study area. Comparison of the zone 4 samples does show some lateral variability which possibly can be attributed to variations in elevation related to the development of the Belfry anticline at the time of peat deposition.
CONCLUSIONS
The primary conclusions of the study of the palynology and petrology of the Pond Creek coal bed in the Lick Creek and Jamboree 7½' quadrangles, Pike County, Kentucky are as follows: 1. The Pond Creek coal bed can be divided into seven lithologic zones which exhibit varying degrees of lateral continuity. The upper four zones have the greatest continuity across the study area. 2. The palynomorph content of the basal zone-zone 2 bright lithotypes at three sites, zone 1 durain at two sites and the zone "0" clarain at the easternmost site--shows considerable floral diversity within and between the sites. Apparently, the initial development of the Pond Creek swamp was considerably different at the six sites and the floral diversity continues to be complex up to the zone 3 dull lithotypes, which are dominated by herbaceous lycopods. 3. Zone 4, bright lithotypes with over 80% vitrinite (with one exception), is dominated by arborescent lycopod palynomorphs. Variations in sphenopsids, ferns, tree ferns and herbaceous lycopods within this assemblage point to vertical variations in the water level through the lifetime of zone 4. Some evidence for a greater importance of relatively "dry land" plants to the west and the presence of a pyrite parting within the lithotype at one of the eastern sites hints at the development of the Belfry anticline at the time of peat deposition. 4. The upper lithotypes--the high-ash bone lithotype of zone 5, the zone 6 bright lithotypes (with abundant fusains) and the thin zone 7 durain-continue the trend of the association of herbaceous lycopods with dull lithotypes and arborescent lycopods with bright lithotypes. The dull lithotypes with clastic mineral and maceral assemblages suggest allochthonous, deeper water deposition than the bright lithotypes, particularly zones 4 and 6 with abundant fusains.
SUMMARY
The relationship between the palynologic and petrographic characteristics and the Belfry anticline provide several lines of evidence for the growth of the
Petrology and geochemistry of Pond Creek coal, Kentucky anticline contemporaneous with the development of the Pond Creek swamp: 1. The basal lithotypes (zones "0", 1 and 2) as a unit generally thicken to the east. Parts of this trend, such as the absence of the zone 1 durain at the two western sites, are attributable to relief at the base of the swamp. Overall, the thickening does suggest some regional differences in relief. 2. The clastic lithotypes, zones 3 and 5 (and perhaps the thin zone 7), generally increase in thickness to the east. 3. The thick zone of bright lithotypes comprising zone 4 is thickest in the west, closest to the anticline. As noted above, the palynomorph composition suggests that the westernmost sites had a greater contribution from a relatively "dry land" flora than did the eastern sites. Together with the relative submergence, possibly indicative of a brackish or marine influence, seen in the thick pryite at one of the eastern sites, the evidence points to the relative elevation of the western sites. The relative elevation apparently provided a favorable site for peat deposition as well as for the repeated truncation of the swamp by fires, seen in the abundant pyrofusinite fusains.
159
The cycles of peat deposition, deeper-water clastic deposition, alternating with relatively elevated and stable episodes of bright lithotype deposition, appear to have been controlled by relative relief imposed by the contemporaneous development of the Belfry anticline.
REFERENCES Hower J. C. and Bland A. E. (1989) Geochemistry of the
Pond Creek coal bed, Eastern Kentucky coal field. Int. J. Coal Geol. 11, 205-226. Hower J. C. and Pollock J. D. (1988) Petrology of the Pond Creek coal bed in eastern Kentucky. Org. Geochem. 12, 297-302. Kosanke R. M. 0967) Palynological investigations in the Pennsylvanian of Kentucky--IV. U.S. Geological Survey Open-file Report. McKay E. J. and Alvord D. C. (1969) Geologic map of the Lick Creek quadrangle, Pike County, Kentucky. U.S. Geological Survey Map GQ-716, 1:24,000. Outerbridge W. F. and Van Vloten R. (1968) Geologic map of part of the Jamboree quadrangle, Pike County, Kentucky. U.S. Geological Survey Map GQ-775, l : 24,000. Smith A. H. V. and Butterworth M. A. (1967) Miospores in the coal seams of the Carboniferous of Great Britain. Spec. Pap. Palaeont. 1. Traverse A. (1988) Paleopalynology. Unwin Hyman, London.
0146-6380/91 $3.00+ 0.00 Copyright © 1991 PergamonPress plc
Printed in Great Britain. All rights reserved
Palynologic and petrographic variation in the Pond Creek coal bed, Pike County, Kentucky CHARLES T. HELFRICH1 and JAMESC. HOWER2 IEastern Kentucky University, Richmond, KY 40475, U.S.A. 2Center for Applied Energy Research, University of Kentucky, Lexington, KY 40511-8433, U.S.A.
(Received 25 January 1990; accepted 15 July 1990) Abstract--Recent studies of the petrology and ash geochemistry of the Pond Creek coal bed (Middle Pennsylvanian Breathitt Formation) in Pike and Martin Countries, Kentucky, have defined vertical and lateral trends that are related to the development of the northeast-trending Belfry anticline contemporaneous with the deposition of the Pond Creek peat. To the northwest of the anticline the coal bed has a high-CaCO3 middle zone and a high Fe 2O3-high sulfur upper zone. To the east of the anticline, particularly in the Lick Creek and Jamboree 7½' quadrangles, the coal bed exhibits a distinctive petrographic zonation. In the latter area, the usual megascopic sequence is a basal durain followed by a bright clarain-durain/dull clarain-bright clarain-bone-bright clarain-durain sequence. The palynology of the Pond Creek coal bed was investigated in six sets of bench/lithotype samples from the Lick Creek and Jamboree 7~' quadrangles. The low-vitrinite basal durain (zone 1) has a palynomorph assemblage which reflects the importance of tree ferns and herbaceous lycopods. The easternmost site has a bright clarain below the durain. The latter lithotype has a fair diversity of palynormph groups and also has the highest percentage of arborescent lycopod forms of any bench below the bone (zone 5). The bright zone 2 above the durain has the grestest maceral group range and the greatest floral diversity of any of the lithotypes. The zone 3 dull lithotype has increased amounts of herbaceous lycopods and decreased amounts of arborescent lycopods, sphenopsids and tree ferns. The zone 4 bright lithotypes are generally over 80% vitrinite and, in general, exhibit a dominance of arborescent lycopods although sphenopsid, tree fern and small fern forms exhibit varying importance. The high-ash bone (zone 5) has 71.6-77.0% vitrinite. This lithotype is marked by a dominance of herbaceous lycopods at the expense of arborescent lycopods and sphenopsids. The zone 6 bright clarain is marked by an increase in arborescent lycopods and a large decrease in herbaceous lycopods. The low-vitrinite terminal durain has an assemblage with high percentages of herbaceous lycopods and low percentages of arborescent lycopods as well as increase in tree fern spores over zone 6. In general, the petrology and palynology trends are predictable. Dull lithotypes have abundant herbaceous lycopod representation and bright lithotypes have abundant arborescent lycopod representation. The greatest deviation from this simple pattern is within the zone 4 bright lithotypes, where diverse palynomorph assemblages occur among the high-vitrinite benches. Overall, the greatest floral diversity appears to have occurred near the base of the coal bed.
Key words--Kentucky, Pond Creek coal, coal petrology, palynology, depositional environments
INTRODUCTION The Pond Creek coal bed (Middle Pennsylvanian Breathitt Formation), also known as the Lower Elkhorn within the study area and correlative with the Blue Gem, Path Fork and Imboden coals mined elsewhere in southeastern Kentucky, is one of the most extensively mined coals in the Eastern Kentucky coal field. Within the study area of the Lick Creek and Jamboree 7½' quadrangles [geologic maps by McKay and Alvord (1969) and Outerbridge and Van Vloten (1968), respectively], the Pond Creek is generally overlain by siltstone and fine-grained sandstones. In previous studies of the Pond Creek through Pike and Martin Counties, Kentucky, little evidence of marine influence in the Lick Creek/Jamboree area was encountered (Hower and Pollock, 1988; Hower and Bland, 1989).
Kosanke (1967) studied the palynology of the Pond Creek coal bed at its type locality in the Belfry 7½' quadrangle. Overall, the coal was dominated by arborescent lycopod genera (Lycospora) and herbaceous lycopod genera (Densosporites, Cristatisporites), which along with Laevigatosporites (sphenopsid) and Granulatisporites (fern) contributions account for almost 89% of the palynomorphs. A generic summary for forms occurring in quantities greater than 1% in any of the five benches is presented in Table 1. In this study we are re-examining the petrography of a limited portion of Hower and Pollock's (1988) study area with the addition of palynology as an analytical tool. Vertical and lateral variations in the palynology and in the maceral composition will be used to help to understand the complexities involved in the development of the Pond Creek swamp. 153
154
CHARLEST. HELFRICHand JAMESC. HOWER Tablel. Genedcsummaryofmiospo~sfrom thePond C~ekcoal ~d, Belf~quadrangle,Pike County, Kentucky(afterKomnke, 1967) SAMPLE THICKNESS
(cm)
Ahrensisporites Cristatisporites Densosporites Dictyotriletes Endosporites Granulatisporites Laevigatosporites Lycospora Punctatisporites Savitrisporites
83-B (top)
83-C
83-D
83-E
83-F
21.59
20.32
29.21
33.02
31.75
0.8 2.8 39.6 0.4 0.4 2.4 1.2 48.8 0.8 . .
4.0 8.8 28.4 3.2 0.4 0.8 1.6 51.2 -. . .
0.4 2.4 34.8 3.2 -3.2 18.8 34.8 0.8 . . .
0.8 -25.2 0.8 0.8 2.8 5.6 62.4 0.8
2.4 34.0 11.6 0.4 3.6 5.2 18.0 19.4 1.6 1.6
Only includesgenera occurringat >1% abundance in at least one bench. PROCEDURE
The coal samples were collected from fresh exposures in five underground mines in the Lick Creek and Jamboree 7½' quadrangles (Figs 1 and 2). Sites 3661, 3671, 3597 and 3606 were included in a study by Hower and Pollock (1988). Sites 3772 and 3783 were sampled after the completion of the latter study. Wherever possible the delineation of benches was made at lithologic breaks. Benches are numbered from the top of the coal bed, as in the following example of a six bench set: 1/6 (top), 2/6 . . . . 5/6, 6/6 (bottom). The lithologic zones discussed in the text were first delineated in a geochemical study (Hower Johnson "XJ""""~ .x ~
Martin
Ft.oyd
DISCUSSION Studies of the petrography (Hower and Pollock, 1988) and geochemistry (Hower and Bland, 1989) of the Pond Creek coal bed in Pike and Martin Counties, Kentucky, have defined vertical and spatial trends which appear to be related to the development
J~'^(~
~" '" " ~ P " " " ]
and Bland, 1989) and were numbered in depositional sequence from the base of the coal bed. The petrographic and chemical analyses were performed at the University of Kentucky Center for Applied Energy Research.
/
~
WEST VIRGI"NIA
('/
Pike
t
/
'
/
~,r" t..~
b)"x, t ~
/
/
/1
rt )
37* 45~
/
oo "
/
•
>
$'/
,
%
I
I
0 0
p821~45'
//
i
miles kilomeVes
82 =30' J.
20 82 = J
82 ° 0 O'
Fig. 1. Location of Lick Creek and Jamboree 7½' quadrangles within Pike County, Kentucky, with the location of the Belfry anticline.
155
Petrology and geochemistry of Pond Creek coal, Kentucky X
I
Lick Creek
Jamboree
37* 30~/82" t7'
92"15'
37" 30'/8 2"
SampLe Sites
• 3597
•3783 3772 •
1 0 0 • •
mL km
t I
3671
37*27'/8 2"
3661
11'
\
I
Fig. 2. Samples sites within portions of the Lick Creek and Jamboree 7~' quadrangles. of the northeast-trending Belfry anticline contemporaneous with the deposition of the Pond Creek peat. The Belfry anticline (see Fig. 1) is the only major structure to interrupt the northwestward monoclinal dip of the Pond Creek horizon. To the northwest of the anticline the coal bed has a highCaCo 3 middle zone and a high-Fe203-sulfur upper zone. A thin, high TiO2-high zirconium zone in the lower third of the coal bed is indicative of elastic influx into the swamp. The main bed of the Pond Creek coal bed and the separation between the main bed and the rider both thin across the anticline. To the east of the anticline, particularly in the Lick Creek
and Jamboree quadrangles, the coal bed exhibits a distinctive petrogrpahic zonation. In general, the usual megascopic sequence is a basal durain followed by a bright clarain-durain/dull clarain-bright clarain (at some sites dulling upwards to clarain)-bonebright clarain-durain sequence. The generalized lithologic profiles for the six sites in this study are shown in Fig. 3. Certain iithologies, particularly the thin durain at the top of the coal bed, could not always be collected as an individual bench. Each lithologic zone (italic numbers in Fig. 3) could be collected at a minimum of two of the six sites, with the exception of zone "0" which was
Megoscopic Profites
bright ctoroin
:~'::'~:~:
ctoroin fusoin I duroin ,
,
duLLc(orain bone
Im
I
SAMPLE NO.
3661
SEPARATION (kin)
367'1 20
E
3597 4.4
3783
5772
1.6
1.3
3606 1.9
•
Fig. 3. Generalized megascopic profiles of the six sites. Wherever possible the division of benches (tick marks on the right-hand side of the column) was made at lithologic breaks. The lithologic zones (italic numbers) were delineated in the geochemical study (Hower and Bland, 1989).
156
CHARLEST. HELFRICHand JAMESC. HOWER Table 2. Form genera by palynomorph group
Arbcrescent lycopods Cappasporites Crassispora Lycospora Cordaites Florinites Ferns Acanthotriletes Apiculatisporis Apiculatisporites Dictyotriletes Granulatisporites Leiotriletes Lophotriletes Microreticulaltisporites Punctatisporites Raistrickia Savitrisporites Herbaceous lycopods Anapiculatisporites Cingulizonates Cirratriradites Cristatisporites Densosporites Endosporites Spencersporites
present only at site 3606. Zone 4, collected in multiple benches at four sites, and zone 5 were each collected at all six sites. The palynomorph genera identified in the study were assigned to groups, based on discussions in Smith and Butterworth (1967) and Traverse (1988) and references cited therein, as shown in Table 2. The group maceral petrography and the palynology for the six sites are summarized in Table 3. The greatest floral diversity, as well as the greatest diversity between sites, occurs in the basal zones 1 and 2 and, at site 3606, zone "0". At various sites the basal zones were dominated by either arborescent lycopods, herbaceous lycopods or tree ferns. Zone "0", bench 9/9 at site 3606, has a fair palynologic diversity although arborescent lycopod spores are more abundant than in any bench below the uppermost bright clarain (bench 2/9; bench 3/9 is a fusain). The basal durain (zone I), with maceral group composition from V22.2Is57L22.1 t o V38.2149.gLll.9 , has a diverse palynomorph assemblage reflecting the importance of tree ferns and herbaceous lycopods. Zone 2 bright lithotypes comprise the basal zone at sites where the zone l durain is absent. Zone 2 has the greatest maceral group range (V62.3127.sL9. 9 to Vs3,4I8.4L8.2) and the greatest floral diversity of any of the zones. In general, while arborescent lycopods show an increase over the basal durain, no distinctive palynologic composition is common to the six sites. The zone is thinnest in the west, increases in thickness to site 3772 and then decreases in thickness to the east. Zone 3, the thin dull z o n e (V62.4130.0L7. 6 to V739I~9.2L6.9), increases in thickness to the east. (The zone is present as a 0.9 cm bone within bench 6/6 at
Sphenopsids Calamospora Laevigatosporites Reticulatisporites Vestispora Tree ferns Cyclogranisporites Fabasporites Punctatosporites Thymospora Torispora Verrucosisporites Unknown affinity Ahrensisporites Alatisporites Grumosisporites Hymenospora Mooreisporites Planisporites Pustulatisporites Reinschospora Schofites Tripartites* Triquitrites Wilsonites *possible contamination
site 3671.) The bench is the first bench with some lateral consistency in palynology, generally being dominated by herbaceous lycopod forms. Zone 4, composed of bright lithotypes with over 80% vitrinite (except bench 5/7 at site 3783), is thickest in the western sites. Most sites have abundant fusains within the bright lithotypes. Site 3783 has less fusain and has a 5.2 cm pyrite band within the zone, the only megascopic pyrite observed in the Pond Creek east of the anticline. The following discussion of the palynology of zone 4 will progress through the sites from west to east. At site 3661 arborescent lycopods are important in the lower half of the zone but decrease at the expense of sphenopsids, small ferns and tree ferns in bench 5/8 and herbaceous lycopods in bench 4/8. Site 3671 exhibits similar trends with the dominant arborescent lycopod forms of bench 5/6 decreasing in favor of increasing herbaceous lycopods and sphenopsids in bench 4/6 and herbaceous lycopods in bench 3/6. Note that at the latter two sites arborescent lycopod forms are still more abundant than herbaceous lycopod forms. Site 3597 is represented by a single bench with a dominance of arborescent lycopods with secondary importance of sphenopsid forms. Site 3772 has relatively constant amounts of arborescent lycopod forms through the four benches. Secondary trends indicate rising and falling amounts of herbaceous lycopod, sphenopsid, fern and cordaites. Zone 4 at site 3783 has a basal zone with low arborescent lycopods and high herbaceous lycopods and sphenopsids. Arborescent lycopods and sphenopsids along with ferns and tree ferns increase upwards into the middle bench. Arborescent lycopods and sphenopsids, along with herbaceous lycopods,
3607 3608 3609 3610 3611 3612 3613 3614 3615
3784 3785 3786 3787 3788 3789 3790
3773 3774 3775 3776 3777 3778 3779 3780 3781 3782
3598 3599 3600 3601 3602 3603
3672 3673 3674 3675 3676 3677
3662 3663 3664 3665 3666 3667 3668 3669
KCER#
W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF W.C. I OF 2 OF 3 OF 4 OF 5 OF 6 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF 9 OF i0 O F W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF W.C. 1 OF 2 OF 3 OF 4 OF 5 OF 6 OF 7 OF 8 OF 9 OF
BENCH
9 9 9 9 9 9 9 9 9
7 7 7 7 7 7 7
i0 i0 i0 I0 i0 i0 i0 i0 i0 i0
6 6 6 6 6 6
6 6 6 6 6 6
8 8 8 8 8 8 8 8
5 4 3 2 1 "0"
7 6
6,7 5 4 4 4 2,3 2
6,7 5 4 4 4 4 3 2 2 1
7 6 5 4 2 1
6,7 5 4 4 4 2,3,4
7 6 5 4 4 4 3,4 2
LITH. ZONE 87.0 13.0 84.9 73.9 86.7 91.9 84.8 87.4 83.4 81.2 80.2 73.2 81.0 86.6 87.4 81.5 74.8 29.7 73.7 73.4 81.0 65.9 32.8 78.5 81.1 75.6 80.8 87.0 83.8 82.1 73.9 80.1 71.6 38.1 75.4 77.7 77.0 85.5 81.2 75.1 62.4 68.2 68.1 70.9 81 . 3 2.8 71.6 82.5 73.9 62.3 22.2 62.5
152 1 19 28 17 7 18 45 14 129 22 14 13 17 30 30 133 6 20 24 52 24 6 134
40 52 51 96 07 01 29 Ii 94 54 40 33 41 70 02 48 i0 10 73 08 12 08 10 37 22 25 26 52 6 71 11 58 7 92 12 50 2 13 14 02 27 74 3 05 1 2 2 94 24 38 19 81 20 73 13 72 15 85 16 1 5 10 06 1 7 0 69 2 74 21 34 2 13 21 64 49 38 10.06 27.43 4.57 31.39
VITS
THICKNESS (CM) 7.7 38.0 9.0 16.8 6.5 4,1 8.0 5.6 6.9 9.9 13.8 18.6 11.0 6.3 5.7 11.7 16 .0 34.5 19.7 19.3 8.6 18.8 44.3 12.7 12.5 16.6 11.3 8.1 8.6 11.6 15.0 10.3 18.7 47.4 13.9 13.0 16.1 8.2 10.1 15.1 23.9 17.2 19.9 17.4 10.7 97.2 20.4 9.6 18.2 20.5 47.8 22.1
[NERTS
0.9 9.5 1.4 0.i 1.4 1.2 3.6 2.2 1.5 2.4 i.i 0.i 0.7 2.1 3.0 1.4 2.5 5.8 2.4 0.7 4.1 6.1 5.0 2.6 2.2 0.2 2.4 1.6 2.9 2.1 4.2 4.1 4.4 2.6 4.6 2.4 0.i 1.5 4.0 4.1 6.1 7.4 3.6 4.3 2.8 0.0 0.2 3.4 0.5 7.3 7.9 8.3
MIC
30.0 4.2 6.7 6.3 9.2 17.9 6.2 4.2 7.6 5.5 3.3 4.7 4.2 6.9 5.5 5.3 11.9 6.1 6.9 6.8 4.8 4.7 5.7 7.6 7.2 8.4 7.1 5.1 0.i 7.8 4.5 7.4 9.9 22.1 7.1
6.7
4.4 39.5 4.7 9.2 5.4 2.8 3.6 4.8 8.2 6.5 4.9 8.1 7.3 5.0 3.9 5.4
LIP
7.99 13.73 5.30 24.93 8.10 1.96 532 245 689 950 1371 27 33 1166 227 147 639 12 24 1266 888 2846 203 441 789 1017 786 2368 11.10 206 154 182 296 668 539 36 86 12 22 i0 79 27 3 7 945 316 240 618 354 1020 765 615 417 28 32 467 1186 327 492 271
DRY ASH
0.0 0.8 0.0 0.8
1.5 0.4 0.0 0.0 0.4 1.8
0.2
43.2 44.2 2.8 2.9 4 .1 52.9
0.0 0.0 0.0 0.0 0.0 0.0 0.7 0.0 I.i 0.7 1.2 1.0 0.0 0 .4 0.4 0.5 0.3 0.0 0.5 1.7 0.4 0.5 1.8 2.0 0.8 1.5 0.4 0.4 1.1 3 .I 0.0 0.0 5.3 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0
CRD
53.6 21 .8 82.3
64.4 10.8 77.1 48.5 57.0 61.8 84.0 89.5 46.2 62.0 81.3 42.9 63.1 61.9 77.4 74.5 40.7 12.9 76.0 43.9 58.9 16.8 11.5 44.1 79.8 48.9 68.3 66.8 63.9 66.4 20 .8 39.3 37.4 9.2 46.2 68 .7 40.8 53.1 50.2 24.2 3.7
ALC
7 14 12 11 13 11
3 5 8 6 6 15 4 3 3 6 5 5 5 7 3 5 7 13 6 i0 I0 14 11 9 6 7 2 11 5 9 5 3 16 15 11 5 7 i0 16 6 14 0 8 3 4
FRN
6 7 2 6 9 7
9 0 3 6 7 1 4 8 8 8 2 7 1 9 9 9 6 5 0 3 8 0 9 0 5 7 8 9 3 2 5 3 4 9 6 7 9 5 3 2 7 2 4 5 5 1 6 5 2 5 10
44.3 32.5 66.1 69.9 39.7 5.8
9 0 9 9 2 9
6.0 1.2 8.3 0.7 3.7 17.9 4.7 1.5 7.5 4.5 4.5 0.8 2.5 14.9 5.4 10.1 5.8 1.3 5.6 0.7 5.9 3.7 8.1 3.3 7.6 1.1 6.8 12.3 8.4 5.0 0 4 4 4 9 2 i0 3 4 7 9 8 3 0 7 4 4 6 2 7 4 0 0 1 3 8 1 2 7 2
SPH
23.9 81.2 5.3 43.4 31.1 0.4 4.0 3.4 41.0 23.8 6.9 47.4 27.9 14.0 11.7 7.3 41.8 70.8 10.4 41.0 21.1 53.6 21.3 38.5 4.2 37.9 21.3 6.7 20.5 13 .7 70.4 50.4 8.4 23.6 34.6 14.3 45.7 27,5 24.0 65.4 72.1 0.2 30.4 70.0 4.2
HLC
0.8 0.0 0.0 0.7 1.5 0.4 0.0 0.8 0.0 1.5 0.5 1.9 1.0 0.0 0.1 0.2 1.8 0.2 0.5 1.7 0.1 0.2 0.0 2.9 0.4 0.4 0.0 0.4 0.0 0.8 0.7 0.0 0.0 0.0 2.1 0.8 0.7 1.6 1.9 0.8 1.8 0.0 1.0 0.0 0.8 1.5 0.4 1.2 0.4 0.4 0.0
0.0 1.9 11.8 12.3 36.3 16.8
UNK
1 0 1 9 1 1 0 0 0 0 4 4 2 2 1 1 0 4 0 7 0 5 0 3 0 4 0 9 1 1 1 5 2.0 1.3 i.i 0.8 2.8 11.2 45.4 0.2 0.8 2.6 0.4 1.5 0.8 1.9 2.2 2.6 23.3 39.5 0.7 0.8 1.9 0.0 3.0 0.8 3.7 0.2 2.0 3.5 0.4
TFN
VlT--vitrinites, INERT--inertinites, MlC--micrinite, LIP--liptinite, ALC--arborescent lycopods, CRD---cordaites, FRN--ferns, HLC--herbaceous lycopods, SPH--sphenopsids, TFN--tree ferns, UNK--unknown affinity.
3606
3783
3772
3597
3671
3661
SITE
Table 3. Group macerals, ash content and plant a~nities of Pond Creek coal bed ~mples
_q
8
o
o
158
CHARLEST. HELl:RICHand JAMESC. HOWER
increase in abundance to the top bench while small ferns and tree ferns decrease in abundance. The easternmost site, 3606, is represented by a single bench in which both arborescent and herbaceous lycopods are abundant. Zone 5, the bone lithotype (71.6-77.0% vitrinite), tends to be thicker in the east. There is little lateral variation in palynomorphs with herbaceous lycopod forms dominating. Zone 6, the upper bright zone (V73.7122.1L4, 2 to Vsl.3II3,6Ls.I) with abundant fusains (note that the 2.1 cm fusain at site 3606 was collected as a separate bench), is of relatively constant thickness across the study area. This lithotype shows significant increases in arborescent lycopod and sphenopsid forms and decreases in herbaceous lycopod and fern forms compared to the underlying bone lithotype. The thin terminal durain (zone 7) is present at all of the study sites as well as at whole channel sites from the same mines. The durain could not be collected individually at every site. At site 3671, for example, the durain is only 0.3 cm thick. The durain is absent to the west of the study area. In a mine in the Lick Creek quadrangle between site 3661 and the Belfry anticline a 3.3 cm bone (V84.3Ii3.7 L2.0) above a 1.5 cm siltstone was found at only one of the three sites sampled. The group maceral composition of the durain ranges from V13.01,17.sL39,5 to W29.7140.3L30.0 and is dominated by duroclarite and vitrinertoliptite microlithotypes. The palynomorph assemblages are dominated by herbaceous lycopod forms with tree ferns also showing an increase above the level of the underlying bright lithotypes. Overall the bright lithotypes record a rather different environment of deposition than the dull lithotypes. The herbaceous-lycopod-dominated dull zones, with clastic maceral and, in the zone 5 bone lithotype horizon, clastic mineral assemblages, indicate deeper water deposition than the aborescentlycopod-dominated bright zones. The bright lithotypes, particularly zones 4 and 6 with abundant fusains, indicate an environment generally more elevated than the dull zones and also susceptible to fluctuations of the watertable. The fusains may indeed represent the continued truncation of the peat as it rose above the water table. The zone 4 bright lithotypes were collected in sufficient detail to determine some of the vertical and lateral floral variation. As noted above there was a continual rise and fall in importance of various plant groups throughout the time of zone 4 deposition. The two sites closest to the Belfry anticline, Lick Creek sites 3661 and 3671, show indications of a greater importance of a relatively "dry land" flora: tree ferns, ferns and sphenopsids; particularly towards the top of the zone. This may point to a greater elevation for the latter sites; particularly in comparison to site 3783 where the sequence was
interrupted by the pyrite band, the only hint of any marine or brackish influence seen in the study area. Comparison of the zone 4 samples does show some lateral variability which possibly can be attributed to variations in elevation related to the development of the Belfry anticline at the time of peat deposition.
CONCLUSIONS
The primary conclusions of the study of the palynology and petrology of the Pond Creek coal bed in the Lick Creek and Jamboree 7½' quadrangles, Pike County, Kentucky are as follows: 1. The Pond Creek coal bed can be divided into seven lithologic zones which exhibit varying degrees of lateral continuity. The upper four zones have the greatest continuity across the study area. 2. The palynomorph content of the basal zone-zone 2 bright lithotypes at three sites, zone 1 durain at two sites and the zone "0" clarain at the easternmost site--shows considerable floral diversity within and between the sites. Apparently, the initial development of the Pond Creek swamp was considerably different at the six sites and the floral diversity continues to be complex up to the zone 3 dull lithotypes, which are dominated by herbaceous lycopods. 3. Zone 4, bright lithotypes with over 80% vitrinite (with one exception), is dominated by arborescent lycopod palynomorphs. Variations in sphenopsids, ferns, tree ferns and herbaceous lycopods within this assemblage point to vertical variations in the water level through the lifetime of zone 4. Some evidence for a greater importance of relatively "dry land" plants to the west and the presence of a pyrite parting within the lithotype at one of the eastern sites hints at the development of the Belfry anticline at the time of peat deposition. 4. The upper lithotypes--the high-ash bone lithotype of zone 5, the zone 6 bright lithotypes (with abundant fusains) and the thin zone 7 durain-continue the trend of the association of herbaceous lycopods with dull lithotypes and arborescent lycopods with bright lithotypes. The dull lithotypes with clastic mineral and maceral assemblages suggest allochthonous, deeper water deposition than the bright lithotypes, particularly zones 4 and 6 with abundant fusains.
SUMMARY
The relationship between the palynologic and petrographic characteristics and the Belfry anticline provide several lines of evidence for the growth of the
Petrology and geochemistry of Pond Creek coal, Kentucky anticline contemporaneous with the development of the Pond Creek swamp: 1. The basal lithotypes (zones "0", 1 and 2) as a unit generally thicken to the east. Parts of this trend, such as the absence of the zone 1 durain at the two western sites, are attributable to relief at the base of the swamp. Overall, the thickening does suggest some regional differences in relief. 2. The clastic lithotypes, zones 3 and 5 (and perhaps the thin zone 7), generally increase in thickness to the east. 3. The thick zone of bright lithotypes comprising zone 4 is thickest in the west, closest to the anticline. As noted above, the palynomorph composition suggests that the westernmost sites had a greater contribution from a relatively "dry land" flora than did the eastern sites. Together with the relative submergence, possibly indicative of a brackish or marine influence, seen in the thick pryite at one of the eastern sites, the evidence points to the relative elevation of the western sites. The relative elevation apparently provided a favorable site for peat deposition as well as for the repeated truncation of the swamp by fires, seen in the abundant pyrofusinite fusains.
159
The cycles of peat deposition, deeper-water clastic deposition, alternating with relatively elevated and stable episodes of bright lithotype deposition, appear to have been controlled by relative relief imposed by the contemporaneous development of the Belfry anticline.
REFERENCES Hower J. C. and Bland A. E. (1989) Geochemistry of the
Pond Creek coal bed, Eastern Kentucky coal field. Int. J. Coal Geol. 11, 205-226. Hower J. C. and Pollock J. D. (1988) Petrology of the Pond Creek coal bed in eastern Kentucky. Org. Geochem. 12, 297-302. Kosanke R. M. 0967) Palynological investigations in the Pennsylvanian of Kentucky--IV. U.S. Geological Survey Open-file Report. McKay E. J. and Alvord D. C. (1969) Geologic map of the Lick Creek quadrangle, Pike County, Kentucky. U.S. Geological Survey Map GQ-716, 1:24,000. Outerbridge W. F. and Van Vloten R. (1968) Geologic map of part of the Jamboree quadrangle, Pike County, Kentucky. U.S. Geological Survey Map GQ-775, l : 24,000. Smith A. H. V. and Butterworth M. A. (1967) Miospores in the coal seams of the Carboniferous of Great Britain. Spec. Pap. Palaeont. 1. Traverse A. (1988) Paleopalynology. Unwin Hyman, London.