Coal deposits of the Newark rift system

Chapter 27

Coal deposits of the Newark rift system ELEANORA I. ROBBINS, GERALD P. WILKES and DANIEL A. TEXTORIS ABSTRACT Detailed biostratigraphic analysis, updated knowledge of the subsurface, calculation or recalculation of resources using updated distribution data, and reinterpretation of depositional environments using data from modern swamps of active rifts have been applied to the coal deposits of the Newark rift system. Bituminous coal mined from Newark rift-system basins played an important role in the early economic history of the United States. More than ten million short tons were mined from the Richmond and Deep River basins, and our resource estimates suggest that about 4 billion tons of coal remain in the Richmond, Deep River, Dan RiverDanville, Farmville, and Taylorsville basins. However, the coal beds are faulted, dips are steep, methane explosions have been a major factor in loss of lives, and the sulfur content of many beds is high. For these reasons, the coal probably never will be mined again, even though methane may be a future economic resource. The dominant plants found in the coal beds are horsetails, quillwort-like plants, and cycadeoids. A characteristic suite of palynomorphs including Calamospora nathorstii, Convolutisporites affluens, Cyclotriletes oligogranifer, Tigrispontes dubius, Colpectopollis ellipsoideus, Plicatisaccus badius, 'Placopollis raymondii' (Koob, 1961), and Cycadopites 'sp. 103' (Cornet, 1977) in the coal beds and associated carbonaceous shales shows that the main stage of peat accumulation occurred during the middle Carnian age of the Late Triassic (as used by Cornet, 1977). The environments in which the Late Triassic peat accumulated are typical of those around modern rift lakes. River delta swamps, lake fringe swamps, and the filling-in stage of lake death swamps appear to have been the most important depositional environments.

Introduction Most of the tectonic basins of the Newark rift system of eastern North America (Burke, 1976; Van Houten, 1977; Robbins, 1981; Ziegler, 1983) are known to include coal-bearing strata. Coal occurs primarily as extensive beds in the Richmond, Deep River, Dan River - Danville, Farmville, and Taylorsville basins; coal stringers or coalified logs have been found in the Culpeper and Hartford basins (Shaler and Woodworth, 1899; Stone, 1910; Reinemund, 1955; Weems, 1980b; Wilkes, 1982). Coal also has been reported in the Gettysburg and Newark basins (Frazer, 1880; Lyman, 1895), but its presence has not been confirmed. Figure 27-1, which shows the location of known coal deposits in these basins, also shows that the major locus of peat deposition was restricted to the area from central North Carolina through Virginia and into the subsurface of Maryland. Drilling in buried rift-like basins that appear to follow the same trend under South Carolina, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana and Texas has not uncovered any additional coal (Applin, 1951; Maher, 1971; Daniels et al., 1983; Gawloski, 1983). The age of the coals has been determined on the basis of palynomorphs, plant fossils, fish, and reptile remains in the coals and in the underlying and overlying beds. Cornet (1977), Fontaine (1883), Olsen et al. (1982), Robbins (1982), Schulz and Hope (1973), and Weems (1980b) have shown that deposits of coal are limited to the Carnian age of the Late Triassic.

650

E.I. Robbins, G.P. Wilkes and D.A. Textoris

Resource estimates have been reported for coal in two of the basins. Reinemund (1955) calculated that more than 2 million short tons of coal were mined and that more than 110 million tons remain in the Deep River basin. Lucas et al. (1981) calculated that more than 8 million short tons were mined and more than 3.5 million tons remain in the Richmond basin. No compilations on the coal-bearing facies of all of the the rift basins have been reported since the work of Roberts (1928), although Robbins (1985) presented a short paper on coal palynostratigraphy for a workshop on current knowledge of the early Mesozoic basins of the eastern United States. This paper presents a modern assessment of the coal deposits of the Newark rift system including; (1) a detailed biostratigraphic analysis of the cöal-bearing units; (2) updated knowledge on subsurface distribution of coal; (3) calculated or recalculated coal resources utilizing updated distribution data; and (4) reinterpretation of depositional environments using data from modern swamps in active rifts. To make this assessment, samples of coal, impure coal, and carbonaceous shale were analyzed for palynomorph content, thermal alteration and vitrinite reflectance, and pyrite and sulfur content; chemical analyses and resource data were tabulated for several of the basins; and six depositional environments resulting in peat deposits near rift lakes were identified. Because the coal deposits are not presently mined, a section has been included to show their importance to the early economic history of the United States.

EXPLANATION ■*■ Coal localities * Exposed basins { - Buried basin 1 2 3 4

BASINS Hartford Newark Gettysburg Culpeper

5 Taylorsville

6 7 8 9 10 11

Richmond Farmville Briery Creek Dan R i v e r Danville Deep River

500 km

Fig. 27-1. Map of exposed and partially buried Newark rift system basins showing location of coal deposits (Modified from Froelich and Olsen, 1983).

Trilete and monolete spores Aratrisporites flmbriatus A. saturnii cf. Callialasporites Calamospora nathorstii Camerosporites pseudoverrucatus Concentricisporites sp. Convolutisporites affluens Cyathidites minor Cyclotriletes oligogranifer Deltoidospora hallii D. magna Dictyophyllidites mortonii Discisporites niger Neoraistrickia sp. Polycingulatisporites spp. Punctatisporites major P. sp. Pyramidosporites traversei Reticulatisporites sp. Stereisporites perforatus Tigrisporites dubius Todisporites major Triletes klausii Tuberculatisporites hebes Verrucosisporites cheneyi Zebrasporites corneolus Unidentified spores

Sample number: Lithology:

Deep River

Farmville - Briery Creek

Richmond

Taylorsville

27

5 3

1

1

3

1 2

-

1

(1)

-

1

3

1

(1)

-

(2)

-

2

2

18

15

35

-

11

1

1

1

73

1

-

1

77

2 5

8

(1)

4

3

32

7

6

4

8

18

1

5

2

5

7

1

1

1

-

20

1

1

2

2

2

8 -

3

599 602 613 819 827 876 779 780 821 822 823 824 875 733 734 754 755 756 757 758 830 877 883 s i s c s c s s i i i i c c c c i i i i c s i

Dan RiverDanville

Palynomorphs in coal-bearing strata of Triassic basins

TABLE 27-1

ON

o o

Sample number: Lithology:

(continued)

Bisaccate pollen Alispontes grandis A. ovatus A. parvus A. thomasii A. sp. Brachysaccus neomundanus Colpectopollis ellipsoideus Colpectopollis 'sp. 142' (Cornet, 1977) Haplosporites varius Klausipollenites gouldii K. schaubergerii Lunatisporites sp. Microcachryidites 'sp. 143' (Cornet, 1977)

Deep River

Farmville - Briery Creek

Richmond

Taylorsville

-

-

-

-

-

-

7

6 (5)

(4) 29 4

-

poll[en 12 — — 3 12 2 5 1 - (5) 1 7 2 2

-

-

-

1

4

1

15 7

-

-

-

(1)

-

-

3

-

10

-

1

-

(1)

-

-

19

-

— — 8 7 7 7 - (6) 18 -

— -

-

-

-

2

-

-

1

2

-

17

-

-

-

-

-

-

-

-

-

-

-

-

-

-

_ -

-

— — _ 16 -

-

-

-

-

10

-

5

-

4

-

(7)

_

_

_ _

_ _

-

-

_ _ _

-

-

1

-

(1)

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

1 8

— —— -

-

-

-

_

_ 2

32 26

-

1

4

7

5 (3) 4

-

-

-

-

-

(7) _

-

-

-

13

-

-

-

-

-

-

_

-

-

-

-

42

-

-

_

_

-

-

-

-

-

-

_

-

-

-

-

-

-

-

-

-

-

-

3 -

8

15

13

-

4

-

12 (2)

1

6

-

-

-

-

17

-

-

-

5

4 18 8 (2) 1

-

19

-

-

599 602 613 819 827 876 779 780 821 822 823 824 875 733 734 754 755 756 757 758 830 877 883 1 1 1 [ s i i c c c c i i i i c s c s c s s s

Dan RiverDanville

Monosaccate, circumpolloid, and inaperturate A raucariacites fissus A. sp. Corollina meyeriana Enzonalasporites vigens Guthoerlisporites cancellosus Paracirculina scurrilis Parillinites pauper Patinasporites densus Praecirculina granifer Vallasporites ignacii Monosaccate sp. A (Robbins, 1982) Unidentified round grains

TABLE 27-1

E.I. Robbins, G.P. Wilkes and D.A. Textoris

1

-

-

-

118

200

Other Volvox-type cysts Grains degraded beyond recog.

Total:

-

-

20

-

-

3

15

29

1

2

7

5

57

-

-

-

-

(1)

-

-

4

-

(1)

-

-

5

1 1 4

4 53

5 46

-

3 4

2

-

-

-

-

-

-

-

-

-

-

(1)

-

-

-

-

-

96

-

4

-

-

-

-

-

-

-

-

15 85

-

-

-

-

-

-

-

-

-

98

-

2

-

-

-

-

-

-

-

-

61

1

-

3

-

-

1 4

-

-

-

-

-

100

-

-

-

-

-

-

-

-

-

100 100 100 100 100 100 100 100 100 100

91

-

-

-

-

-

-

-

-

1 6

6 2

1

1

-

-

-

-

-

-

-

-

-

3

5

3

1

-

-

-

-

-

-

-

-

-

6

4

2

5

1

6

9

15

-

-

-

-

-

-

-

-

4 1

2

19

-

(2)

-

-

-

-

-

16

-

-

-

100 100 100 100 100

20

-

-

-

-

-

-

-

= not seen in samples; ( ) = possible identification; c = coal; i = impure coal; recog. = recognition; s - carbonaceous shale.

100 200

92

-

-

-

-

-

4

-

1

-

5 3 12

-

-

1

-

-

-

2

17 5

3

12

-

-

15 1 3

-

-

10

-

-

-

-

-

Monosulcate and plicate pollen Cycadopites detenus C. subgranulosus C. wielandii C. 'sp. 103' (Cornet, 1977) C. sp. Equisetosporites sp. Ginkgocycadophytus sp. Monocolpopollenites sp. Monosulcites sp. A (Robbins, 1982) M. spp. Ovalipollis ovalis 'Placopollis raymondii' (Koob, 1961) 'P. sp. Tetrad 39' (Cornet, 1977) Zonizonasulculate sp. Unidentified prolate grains

Pityosporites devolvens P. inclusus P. scaurus P. sp. A (Robbins, 1982) P. spp. Platysaccus sp. Plicatisaccus badius Protodiploxypinus sp. Protohaploxypinus sp. Sulcatisporites australis Triadispora verrucata Vitreisporites pallidus Unidentified bisaccates

1

43

-

-

-

-

-

-

-

-

-

4

19

-

-

-

-

-

-

-

-

100 100 100

20

-

10

-

-

-

-

20

-

-

-

1

2

3

-

1

8 2

2

3

8

-

-

-

-

-

-

-

100 100

11

-

-

-

-

-

-

-

-

-

18

S u)

C/5
o

D.

O o £L

654

E.I. Robbins, G.P. Wilkes and D.A. Textoris

Fig. 27-2. Maps and cross sections of basins showing coal-bearing units, deep wells, and sample localities. Note scale changes on maps. Cross sections are diagrammatic and not drawn to scale. A. Dan River - Danville basin. From Mundorff, 1948; Meyertons, 1963; Thayer, 1970; John Allan, North American Exploration, pers. commun., 1985; North Carolina Geological Survey Section, pers. commun., 1985. Wells: 1 = Danville Well Co. Halsey No. 1 (Well 37 in Mundorff, 1948) ( Total depth [TD] 163 ft, coal present); 2 = Z.V. Jones Co. Martin No. 1 (Well 166 in Mundorff, 1948) (TD 99 ft, coal present); 3 = 5. Stafford Co. Grogan No. 1 (Well 168 in Mundorff, 1948) (TD 177 ft, coal present); 16 = North American Exploration NCRO-1 (TD 480

655

Coal deposits

Materials and methods Samples. Coal and impure coal samples were processed by means of standard palynological treatment as outlined by Doher (1980). Carbonaceous shales were processed according to the treatment outlined by Robbins and Traverse (1980). Carbonaceous shales are defined here as black shales in which HC1 and HF treatment produces residues that are more than 60 volume percent organic matter, the dominant tissues being wood cells. Only carbonaceous shales surrounding coal or impure coal are discussed. Appendix 1 gives locality and lithology information, and Figure 27-2 shows the locations of each sample and each well discussed in this paper. Species identification and botanical relationships. Palynomorphs identified in the coals and carbonaceous shales are reported for each sample (Table 27-1). Relative frequencies of each taxon are shown by 100-grain-counts in all samples except for samples 599 and 613. In these two samples, 200-grain-counts were performed (Robbins, 1982). Some of the age/environment restricted, diagnostic, and characteristic palynomorphs identified in the samples are shown in Plates 27-1 and 27-2. Preservation of the palynomorphs is excellent in all the basins except for the Dan River - Danville basin. Figures 1 and 9 of Plate 27-1 were included to show the presence of important taxa in the Dan River - Danville coals even though their preservation is poor. Botanical relationships of all taxa are shown in Table 27-2. Color of palynomorphs and thermal alteration index. Palynomorph color can be used to establish the degree of maturation of rocks and can be correlated with approximate Thermal Alteration Index (TAI) and Vitrinite Reflectance (R0) values. Color was noted on bisaccate pollen whenever possible and has been reported along with TAI and R0 values in Table 27-3. Palynomorph color was determined after HCl-HF treatment but before the application of Schulze's solution which is oxidant that acts as a bleach. Pyrite content. Pyrite is a serious but common contaminant of coal. When coal is burned, sulfur from the pyrite easily can be released into the atmosphere. Large chunks of pyrite can be removed mechanically from coal stock, but small enmeshed crystals are difficult to remove during beneficiation. The mode of occurrence, therefore, is important and has been reported in Table 27-4. As the HN0 3 in Schulze's solution eliminates most of the pyrite and forms new pyrite ghosts in tissues, data were collected on pyrite after the rocks were sub—*► ft, coal absent); 17 = North American Exploration NCST-1 (TD 628 ft, coaly shale present); 18 = North American Exploration NCST-2 (TD 804 ft, coal present). B. Taylorsville basin. From Richards, 1974; Weems, 1980; R.E. Weems, USGS, written commun., 1983; H.J. Hansen, Maryland Geological Survey, written commun., 1983, 1985. Wells: 13 = Washington Gas Light PG-Fd 61 (TD 1725 ft, coal present); 14 = Washington Gas Light CH-CE 37 (TD 2014 ft, coal absent); 15 = J.S.C. Drilling Co. Thompson No. 1 (TD 3250 ft, coal absent). C. Farmville basin. From Wilkes, 1982, VDMR, written commun., 1984. Wells: 16 = VDMR Johns Dam Well 42 (TD 44.5 ft, coal absent); 17 = VDMR Coffey No. 3 (TD 180 ft, coal absent); 18 = Tidewater Oil and Gas Corp. Fork Well No. 2 (TD 1518 ft, coal present). D. Richmond basin. From Wilkes et al., 1981; B. Goodwin, College of William and Mary, written commun., 1983; B. Cornet, Houston, Tex., written commun., 1984. Wells: 4 = Cornell/Geminoil Bailey No. 1 (TD 7140 ft, coal present); 5 = Merrill Natural Resources Cashion No. 2 (TD 1675 ft, coal present); 6 = Froehling and Robertson, Inc. Tuckahoe Village West No. 1 (TD 106.3 ft, coal present); 12 = Cornell/Geminoil Horner No. 1 (TD 6328 ft, coal present). E. Deep River basin. From Reinemund, 1955; Bell et al., 1974; Bain and Harvey, 1977; Bain and Brown, 1981; Brown et al., 1985; unpubl. data. Wells: 7 = USGS Sears No. 1 (New Hill Well) (TD 3750 ft, coal absent); 8 = Beutel and Assoc. Dummitt-Palmer No. 1 (TD 953 ft, coal present); 9 = SEPCO Butler No. 1 (TD 4200 ft, coal present); 10 = Chevron Groce No. 1 (TD 5348 ft, coal present); 11 = SEPCO Hall No. 1 (TD 4622 ft, coal absent).

656

E.I. Robbins, G.P. Wilkes and D.A. Textoris

657

Coal deposits

jected to HCl-HF treatment and before Schulze's solution treatment. Pyrite was identified by its brassy color under reflected light. The content of pyrite was estimated and reported as 'estimated percent'. Chemistry. Coal rank is determined on the basis of corrected values for carbon content, volatile matter, and calorific value. These parameters have been reported for 3 of the basins in Table 27-5. Sulfur analyses available for 4 of the basins are reported in Table 27-6. Most of these analyses are very old and were performed during the active stages of mining in the basins. No standard collecting method was used and the quality of samples is unknown. Nevertheless, the tables represent a body of data that might be useful in terms of burial history, future mining prospects, or ore deposit potential. Resources. Resources have been calculated here in a variety of ways because of the wealth of data from some basins and the paucity of data from others. Table 27-7 is a compilation of resource data for the Richmond, Deep River, and Dan River - Danville basins. Resources were not calculated for the Farmville/Briery Creek or Taylorsville basins because there were no data on coal distribution and thickness. Depositional analogs. Six depositional environments that have resulted in peat deposits along modern rift lakes have been identified (Weir, 1950; Robbins, 1982, 1983). Peatdepositing swamps may form on river deltas, such as the delta of the Selenga River into Lake Baikal in Siberia; in fringes around lakes, such as Lake Hula in Israel; within embayments where rivers feed into lakes, such as Lake Kivu in Rwanda; within depressions that remain after lakes are filled, such as the Bahi Swamp in Tanzania; along low-gradient rivers that feed lakes, such as the Kazinga Channel between Lakes George and Edward in Uganda; and at the swampy confluence of rivers, such as the 'delta' region of the Sacramento Valley in California. Information from those studies have been applied to help analyze the depositional environments that resulted in the coals.

PLATE 27-1 Restricted, diagnostic, and characteristic palynomorphs from the coal-bearing basins (All palynomorphs x 1000, unless otherwise noted; sample number in parentheses) 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Stereisporites perforates,

Dan River - Danville basin (599).

Tigrispontes dubius, Taylorsville basin (877). Convolutisporites affluens, Richmond basin (758). Aratrisporites fimbriatus, Richmond basin (734). Deltoidospora magna, Deep River basin (827). Cyclotriletes oligogranifer, Richmond basin (733). Polycingulatisporites sp., Taylorsville basin (883). Calamospora nathorstii, Richmond basin (733). Equisetosporites sp., Dan River-Danville basin (613). Praecirculina granifer, Farmville basin (824). Paracirculina scurrilis, Deep River basin (876). 'Placopollis raymondiV (Koob, 1961), Farmville basin (824). 'Placopollis sp. Tetrad 39' (Cornet, 1977), Taylorsville basin (877) ( x 500). Ovalipollis ovalis, Farmville basin (780).

658

E.I. Robbins, G.P. Wilkes and D.A. Textoris

11

10

•

i*W

659

Coal deposits

Richmond basin The coal-bearing interval in the Richmond basin of Virginia (Fig. 27-2) is the 'Productive Coal Measures' (Shaler and Woodworth, 1899). The attitude of the coal beds ranges from nearly horizontal to 40°, dipping to the west. Three major coal beds have been identified in the basin and several coals of local extent or unminable thickness also have been noted (Roberts, 1928). The thickest persistent coal bed is the lowermost coal, the Black Heath, which Lyell (1847) reported as 40 feet thick at the Black Heath Pit near Midlothian. More commonly, it occurs as two splits separated by as much as 10 feet of shale and siltstone parting. The upper split commonly is 12 feet and the lower split commonly is 14.5 feet (Heinrich, 1878). In outcrop, roof and floor rock are carbonaceous shale or arkosic sandstone, depending on their location in the coal field. Analyses of coal in the basin show that it ranges in rank from subbituminous A to anthracite (Table 27-5). The majority of these old analyses fall in the high-volatile A to medium-volatile bituminous range. Natural coke occurs close to intrusive diabase sills. Eight samples of coal and impure coal were processed for palynomorphs. Figure 27-2 shows their location in the basin and Table 27-1 lists the taxa including Calamospora nathorstii, Cyclotriletes oligogranifer, and Convolutisporites affluens, and 'Placopollis raymondii' (Koob, 1961) that are diagnostic for middle Carnian, but the abundance of Aratrisporites in the lowest coal suggests it may be older. Among these are 18 taxa that have not been observed yet in the coals of the other basins but that have been identified in other lithologies. Detailed palynological analyses resulting in correlation have been made by Bruce Cornet (pers. commun., 1985) on core samples of coals. Deep wells show that three periods resulted in coal deposits in the basin (Fig. 27-2). Only the earliest and latest periods left thick coals. The oldest coal bed crops out at Midlothian and Winterpock. The coal is well developed at depth and can be correlated across the southern part of the basin. It was found between depths of 6,200 and 6,700 feet in the Cornell/Geminoil Bailey No. 1 well. Spores such as Aratrisporites and Calamospora dominate the palynoflora of the oldest coal, but mono-

PLATE 27-2 Restricted, diagnostic, and characteristic palynomorphs from the coal-bearing basins (All palynomorphs x 1000, unless otherwise noted; sample number in parentheses) 1 2 3 4 5 6 7 8 9 10 11

Sulcatisporites australis, Dan River-Danville basin (613). Alispontes ovatus, Richmond basin (830). Colpectopollis ellipsoideus, Taylorsville basin (877). Alispontes parvus, Deep River basin (876). Klausipollenites gouldii, Dan River-Danville basin (613). Plicatisaccus badius, Deep River basin (827). Cycadopites 'sp. 103' (Cornet, 1977), Deep River basin (827). Zonizonasulculate sp., Taylorsville basin (877). Plant cuticle from coalified log, Culpeper basin (882). Volvox-Wke algal cysts, Farmville basin (779). Wood cell from coalified log, Culpeper basin (882).

E.I. Robbins, G.P. Wilkes and D.A. Textoris

660 TABLE 27-2

Botanical relationships and edaphic significance of palynomorphs in coal-bearing strata (kingdom Phyta)

Division

Order

Family

Chlorophycophyta Bryophyta? Microphyllophyta Microphyllophyta Pteridophyta do do do do do Arthrophyta Pteridophyta or Arthrophyta Pteridospermophyta do do Cycadophyta or Ginkgophyta do do do do do do do do do Coniferophyta or Gnetophyta Coniferophyta or Pteridospermophyta do do do do do do do do do Coniferophyta do do do do do do do

-

-

Taxon

Edaphic significance

Volvox-type cysts Stereisporites perforatus Pleuromeiaceae Aratrisporites fimbriatus Pleuromeiaceae Aratrisporites saturnii Cyathidites minor Dicksoniaceae Dictyophyllodites mortonii Matoniaceae Todisporites major Osmundaceae Zygopteridaceae Verrucosisporites cheneyi Punctatisporites major Punctatisporites sp. Calamospora nathorstii Reticulatisporites sp. -

Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte

Caytoniales Glossopteridales

-

-

Vitreisporites pallidus Protohaploxypinus sp. Guthoerlisporites cancellosus

None None Xerophyte

-

-

Cycadopites detenus Cycadopites subgranulosus Cycadopites wielandii Cycadopites 'sp. 103' (Cornet, 1977) Cycadopites sp. Ginkgocycadophytus sp. Monocolpopollenites sp. Monosulcites sp. A (Robbins, 1982) Monosulcites sp. Equisetosporites sp.

Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Hydrophyte Unknown

Voltziales

-

Lycopodiales Lycopodiales Filicales do do do do do

-

Corystospermales do Alisporites grandis do A lisp orites ova t us do Alisporites parvus do Alisporites thomasii do Alisporites sp. Colpectopollis ellipsoideus do do Colpectopollis 'sp. 142' (Cornet, 1977) do Haplosporites varius do Sulcatisporites australis Voltziales Triadispora verrucata Coniferales Cheirolepidaceae; Corollina meyeriana do Patinasporites densus Pinaceae? do do Pityosporites devolvens do Pityosporites inclusus do do do Pityosporites scaurus do do Pityosporites sp. A (Robbins, 1982) do do Pityosporites spp.

None None None None None None None Unknown None Xerophyte Xerophyte Xerophyte None None None None None

661

Coal deposits TABLE 27-2 (continued)

Edaphic significance

Division

Order

Family

Taxon

Coniferoplhyta do do do do do do do do do do do do do (conifer?) Unknown (pteridophyte?) (do) (do) (do) Unknown do

Coniferales do do do do do do do do do do do -

Pinaclae? Araucariaceae Araucariaceae Podocarpaceae? Podocarpaceae -

-

-

-

-

Protodiploxypinus sp. Araucariacites fissus Araucariacites sp. Brachysaccus neomundanus Platysaccus sp. Enzonalsporites vigens Paracirculina scurrilis Klausipollenites gouldii Klausipollenites schaubergerii Parillinites pauper Praecirculina granifer Vallasporites ignacii cf. Callialsporites Lunatisporites sp. Camerosporites pseudoverrucatus Concentricisporites sp. Convolutisporites affluens Cyclotriletes oligogranifer Deltoidospora hallii Deltoidospora magna Discisporites niger Microcachyridites 'sp. 143' (Cornet, 1977) Monosaccate sp. A (Robbins, 1982) Neoraistrickia sp. Ovalipollis ovalis 'Placopollis raymondii' (Koob , 1961) 'Placopollis sp. Tetrad 39' (Cornet, 1977) Plicatisaccus badius Polycinculatisporites sp. Pyramidosporites traversei Tigrisporites dubius Trilites klaussii Tuberculatisporites hebes Zebrasporites corneolus Zonizonasulculate sp.

do do do do do do (pteridophyte?) Unknown (lycopod?) (pteridophyte?) Unknown (lycopod?) Unknown

None Unknown Unknown None None Xerophyte Unknown None None Unknown Unknown Xerophyte Unknown Unknown Unknown Unknown Unknown Unknown Hydrophyte Hydrophyte Unknown None Unknown Hydrophyte None Unkown Unknown Unknown Unknown Unknown Unknown Unknown Unknown Unknown Unknown

1

Taxonomic classification from: Bold et al., 1980; Taylor, 1981; Sources for botanical relationships: Schöpfet al., 1944; Couper, 1958; Archangelsky and Gamerro, 1967; Bharadwaj and Venkatachala, 1968; Jung, 1968; Pfefferkorn et al., 1971; Dunay, 1972; Douglas, 1973; Clement-Westerhof, 1974; Gensel et al., 1975; Scheuring, 1976; Cornet, 1977; Good, 1978; Grauvogel-Stamm, 1978; Stone, 1978; Ash, 1980; Grauvogel-Stamm and Grauvogel, 1980; Schopf and Askin, 1980; Taylor, 1981; Litwin, 1985; A. Traverse, written commun., 1985. 2 Edaphic significance from: Visscher and van der Zwan, 1981. sulcate pollen is common; leaves of Macrotaeniopteris

and stems oi Equisetites dominate the

megaflora. The middle coal is lenticular in its development, forms stringers in several deep wells, and appears in wells near the surface at the southeastern edge of the basin. Sculptured osmundaceous fern spores dominate the palynoflora of rocks associated with the middle coal and

662

E.I. Robbins, G.P. Wilkes and D.A. Textoris

monosulcate pollen is rare. The coal that crops out in the northwestern part of the basin contains a flora most similar to the middle coal zone of the deeps wells. The youngest coals are found in the Winterpock area where they are separated from the oldest coals by a north trending fault. The youngest coal is found at about 1,100 feet in the MNR Cashion No. 2 well. In the youngest coal, articulate spores dominate over fern spores. Aratrisporites is only a minor part of the palynoflora, as are other sculptured spores and monosulcate pollen. The oldest and middle coals are associated with distinct sandstone sequences. Geophysical TABLE 27-3 Thermal alteration of palynomorphs in coal-bearing strata of Triassic basins Color of bisaccate (or other) pollen

Culpeper 887 (c)

-

Thermal alteration index (TAI*)

Approximate value of vitrinite reflectance

-

Dan River - Danville 599 (s) 602 (i) 613 (s)

dk med org bn (v dk med org bn) v dk bn

3 3/3 + 4-

1.7

Deep River 819 (c) 827 (s) 876 (c)

(med org bn) dk med org bn dk bn

33 3+

1.1 1.3 1.5

med org bn med org bn (dk med org bn) (It med org bn)

333 2+

1.1 1.1 1.3 0.9

(It med org bn)

2+

0.9

med bn (dk bn) med org bn med org bn dk med org bn dk med org bn dk med org bn

33+ 333 3 3

1.1 1.5 1.1 1.1 1.3 1.3 1.3

dk med org bn med org bn

3 3-

1.3 1.1

Farmville - Briery Creek 779 (s) 780 (s) 821 (i) 822 (i) 823 (i) 824 (i) 875 (c) Richmond 733 (c) 734 (c) 754 (c) 755 (i) 756 (i) 757 (i) 758 (i) 830 (c) Taylorsville 877 (s) 883 (i)

-

-

-

-

1.3 1.3- 1.5

- , no data available; c = coal; i = impure coal; s = carbonaceous shale; bn = brown; dk = dark; It = light; med = medium; org = orange; v = very. * TAI from Pearson (1981). ** R from Staplin (1977).

663

Coal deposits TABLE 27-4 Pyrite content of acid-insoluble residues from coal-bearing strata of Triassic basins Estimated Crystal form percent (%) octa fram Culpeper 887 (c)

X(0)

Dan River - Danville 599 (s)

< 1

602 (i)

5

613 (s)

10

Deep River 819 (c)

< 1

827 (s)

5

876 (c)

1

Farmville - Briery Creek < 1 779 (s) < 1 780 (s) 0 821 (i) 822 (i) 0 0 823 (i) 824 (i) < 1 10 875 (c) Richmond 733 (c) 734 (c) 754 (c) 755 (i)

< 1 < 1 < 1 5

756 (i)

1

757 (i) 758 (i) 830 (c)

< 1 1

Taylorsville 877 (s) 883 (i)

det, enm det, enm

enm

det, enm det, enm, enm

—

det, enm

det,

det det

-

det det

det det

-

det, enm det, enm det

pyrito

enm

enm, enm enm

det

enm, enm

det

enm

enm enm

det, enm

enm

enm enm

-

-

-

-

det, enm

—

" enm, enm enm enm

hexag

det

det,

enm

-

det

det

det

-

det det det

det, enm

enm

-

enm

det

enm enm

enm

-

1 < 1

det det, enm

enm enm

det enm

det

det

—

x « i)

rect

det

enm

-

-

mass

cube

enm det

det det

c = coal; i = impure coal; s = carbonaceous shale; - = not present; X = no data in HCl-HF (data in Schultze solution); det = detrital; enm = enmeshed; enm = enmeshed ghost; fram = framboids; hexag = hexagonal prisms; mass = masses with indistinguishable crystal faces; octa = octahedrons; pyrito = pyritohedrons; rect = rectangular prisms.

Meta-anthracite Anthracite Semianthracite Low vol Bitum Med vol Bitum High vol Bitum High vol A Bitum High vol B Bitum High vol C Bitum Subbitum A Subbitum B Subbitum C Lignite A Lignite B

Anthracite < 2 2-8 8-14 14-22 22-31 > 31 > 31

-

-

Volatile matter dmmf

> 98 92-98 86-92 78-86 69-78 < 69 < 69

Fixed carbon dmmf

unknown > 14,000 13,000--14,000 11,500--13,000 10,500--11,500 9,500- -10,500 8,300--9,500 6,300- -8,300 < 6,300

— -

Calorific value BTU/lb mmmf

-

-

-

1

3 19 2

_ -

— 3 1 6 15 5

Clo

Car

Richmond

-

29 4

-

2 3

_ -

Mid

-

1

— -

Dur

-

2 5 4

-

Gul

Deep River

Number of analyses in basins

-

-

1

1 2

3 3 7 12 7 24

Rock

_

Cum

Stock

-

2 1

—

Dan River

Car = Carbon Hill mining district; Clo = Clover Hill mining district; Cum = Cumnock coal bed; dmmf = dry mineral matter free; Dur = Durham subbasin; Gul = Gulf coal bed; Mid = Midlothian mining district; mmmf = moist mineral matter free; Rock = Rockingham County; Stok = Stokes County; vol = volatile.

Lignite

Subbituminous

Bituminous

Group

Class

Classification of Triassic coals by rank [Classification from American Society for Testing Materials, 1982. Data from references listed on Table 27-6]

TABLE 27-5

a

o

E.I. Robbins, G.P. Wilkes and D.A. Textoris

665

Coal deposits

data suggest these large sandstone bodies are deltaic complexes, so the coals may be the result of deposition on deltas where large river systems entered lakes (Bruce Cornet, Houston, Tex., personal commun., 1985). TABLE 27-6 Sulfur content of Triassic coals [?, coal bed may not be correct] Sulfer content of whole rock (as received, wt.%) Dan River - Danville basin 3 Rockingham Co., NC Stokes Co., NC

0.49, 0.58, 2.23, 4.76 0.82, 2.70, 5.56

Deep River basin b Durham subbasin Chatham Co., NC

0.6

Sanford subbasin, Cumnock coal bed, top bench Chatham Co., NC 1.2, 1.8, 1.8, 1.8 Moore Co., NC 2.5 Cumnock coal bed, main bench Chatham Co., NC Lee Co., NC Moore Co., NC County unknown

1.1, 1.1, 1.6, 2.1, 2.19, 2.2, 2.2, 2.3, 2.4, 2.5, 2.5, 2.5, 2.8, 2.89, 3.4, 4.0, 4.3 1.3?, 1.3?, 1.77?, 1.8, 1.8, 1.9, 1.99?, 2.0, 2.9, 4.6, 4.9, 5.3 2.9, 3.0, 3.2, 3.5 0.92, 0.99, 1.44, 2.03, 2.13, 2.75

Cumnock coal bed, lower bench Chatham Co., NC 1.42, 1.7, 2.2, 2.34, 2.7, 2.7, 2.88, 2.9, 3.1, 3.2, 3.4, 3.8, 4.1 Gulf coal bed Chatham Co., NC Gettysburg basinc Lancaster Co., PA Richmond basin Carbon Hill Mining Dist., Goochland and Henrico Cos., VAd Clover Hill Mining Dist., Chesterfield Co., VAe

1.37, 1.7, 2.5, 3.33, 3.4, 3.69, 3.72, 3.9, 4.18, 4.9, 7.08 0.5 0.08, 0.137, 0.235, 0.33, 0.466, 0.427, 0.6, 0.603, 0.63, 0.63, 1.04, 1.04, 1.050, 1.100, 1.128, 1.129, 1.13, 1.159, 1.3, 1.31, 1.32, 1.4, 1.43, 1.5, 1.54, 1.585, 2.000, 2.089, 2.16, 2.2, 10.00 0.48, 0.51, 0.63, 0.85, 0.87, 1.01, 1.04, 1.09, 1.11, 1.32, 1.46, 1.61, 1.92, 1.98, 2.36, 2.38, 2.44, 3.02, 4.39, 4.46, 4.65, 4.73, 4.99, 6.14, 7.22 0.59

Deep Run (Springfield) Mining Dist., Henrico Co., VAf Midlothian Mining Dist., 0.04, 0.058, 0.20, 0.377, 1.014, 1.04, 1.07, 1.263, 1.3, 1.39, 1.52, 1.53, Chesterfield Co., VA8 1.60, 1.69, 1.627, 1.7, 1.760, 1.785, 1.8, 1.91, 1.957, 1.97, 2.10, 2.12, 2.2, 2.210, 2.23, 2.286, 2.29, 2.371, 2.38, 2.449, 2.67, 2.741, 2.797, 2.89, 2.90, 3.555, 4.08, 4.59, 4.70 Sources of data: a Stone (1910). b Chance (1885) and Clarke (1887) in Reinemund (1955); Woodworth (1902); Campbell and Kimball (1923); Reinemund, (1955). c Frazer (1880). d Heinrich (1878); Eby and Campbell (1926, 1944); Roberts (1928); Woolfolk (1828, 1901), Johnson (1846), Robertson (1873), d'Invilliers (1904), Miller (1913); Jones (1916) and Wadleigh (1934) in Lucas et al. (1981). e Robertson (1873) in Roberts (1928); Ansburner (?) in Lucas et al. (1981); Virginia Division of Mineral Resources, unpub. data. f U.S. Geological Survey, unpubl. data. 8 Clarke (1887); Roberts (1928), Eby and Campbell (1944); Johnson (1846), Robertson (1873), Heinrich (1878) Raymond (1883), d'Invilliers (1904), Wortham (1916), and Treadwell (1928) in Lucas et al. (1981).

666

E.I. Robbins, G.P. Wilkes and D.A. Textoris

TABLE 27-7 Resources of coal in Triassic basins Basin

Resources

Dan River- Danville remaining*

(short tons) 69,120,000

Deep River

remaining

139,664,000

Richmond

mined remaining

2,206,000 3,561,000,000

mined Total mined: Total remaining:

> 8,000,000

Reference or basis for calculation Calculated from estimated areal extent of 32 mi, semianthracite rank, and hypothetical thickness of 18 inches Textoris (1985) using method of Wood et al. (1983) Reinemund (1955) Lucas et al. (1981) using coal zone method that assumed 106 mi 2 are underlain by coal 30 feet thick (see discussion in Wood et al. (1983) Lucas et al. (1981)

> 10,206,000 3,769,784,000

* Unmined.

During the life of the field, more than 8 million tons of coal were produced from the lowest coal. A study by Lucas et al. (1981) calculated resources to be 3.561 billion short tons, most of which are at unrecoverable depths (Table 27-7). Methane resources for the Richmond basin are reported to be 700 billion cubic feet, and the reserve may be as much as 350 billion ft3 (Lucas et al., 1981). Deep River basin Coal is found in the Cumnock Formation in the Deep River basin of North Carolina and South Carolina (Fig. 27-2). The Deep River basin, for the purposes of this paper, is divided into three subbasins: the Durham to the north, the Sanford in the middle, and the Wadesboro to the south. Coal crops out primarily within the Sanford subbasin but outcrops also have been located in the southern part of the Durham subbasin (Reinemund, 1955). Minor occurrences of thin coal have been noted in the lower and upper Pekin Formation (Reinemund, 1955; Cornet, 1977; Gore, 1986b). Even though the subject comes up periodically in the literature, no coal beds have been located within the Wadesboro subbasin. The coal beds of the Deep River basin dip mainly 10° to 48° southeast, and locally have variable reverse attitudes in structurally disturbed zones. As many as seven thin coal beds have been seen in cores. Syndepositional faulting has caused local thinning and thickening of the beds. Postdepositional faulting has offset some of the coals, and minor diabase dikes and sills have intruded others. Oil shows in the Cumnock Formation are reported from almost 30% of the drill holes described in Reinemund (1955). The coals are found near the base of the Cumnock Formation and consist mainly of 2 persistent beds usually about 28 to 40 feet apart in the outcrop and mined areas (Fig. 27-3). In the subsurface, the coals thin to the southeast and south where they interfinger with sandstones and conglomerates. The lower coal, the Gulf coal bed, is commonly confined to one bench which may be as much as 3 feet thick. It underlies an area of about 22 mi 2 , and is thickest and of best quality in the northern part of the Sanford subbasin (Reinemund, 1955).

667

Coal deposits

It also has been identified in the center of the basin at a depth of 2,591-2,592 feet in the SEPCO Butler No. 1 well (D.G. Ziegler, SEPCO, written commun., 1985). Dark-gray shale or 'blackband' (black shale with siderite nodules) are the dominant roof and floor-rock lithologies, although in places a rooted underclay has been observed (Hope, 1975). Sandstone also is found as floor rock beneath the Gulf coal. The Cumnock, which is the upper coal, generally occurs in three beds over an area of nearly 75 mi 2 (Reinemund, 1955). The middle bed is the most extensive of all the subsurface coals. The Cumnock coal is best developed in the northern part of the Sanford subbasin where the middle bed may be nearly 9 feet thick. The Cumnock coal was penetrated at a depth of 2,670 feet in the Chevron Groce No. 1 well and at 2,511 - 2,515 feet in the SEPCO Butler No. 1 well. Another coal may have been encountered at 2,478 - 2,480 feet in the SEPCO Butler No. 1 well (D.G. Ziegler, SEPCO, written commun., 1985). Black slate, 'blackband', black shale, or gray shale are reported to form both floor and roof rock of the Cumnock coal. Rooted underclay also has been noted. Analyses are available for rank of the Cumnock coal. The coal ranges in rank from subbituminous A in the Durham subbasin to anthracite in the Sanford subbasin (Table 27-5). The majority of these old analyses fall in the high-volatile to medium-volatile bituminous range. Igneous rocks have coked the coal for several tens of feet at contacts (Reinemund, 1955).

Red or brown siltstone,

Sanford Fm

claystone & sandstone

-Gray siltstone Black & gray shale

.CUMNOCK COAL BED -GULF COAL BED

Cumnock Fm

N

J G r a y siltstone

Red or brown siltstone, Pekin Fm

i^j

claystone & sandstone

CO

?f 111

a

-Gray conglomerate Metamorphic rocks

800 400 L

0 feet

Fig. 27-3. Generalized stratigraphic section of Triassic formations in the western part of the Sanford subbasin of the Deep River basin (From Reinemund, 1955).

668

E.I. Robbins, G.P. Wilkes and D.A. Textoris

Three samples of Cumnock coal and carbonaceous shale were processed for palynomorphs. Figure 27-2 shows their location and Table 27-1 lists the taxa identified from these samples including Plicatisaccus badius and Cycadopites 'sp. 103' (Cornet, 1977) that are diagnostic for the middle Carnian. Among these are 6 species that have not been observed yet in the coals of the other basins but that have been identified in other lithologies. Traverse's (1986) samples from Gulf and Bethany Church further restrict this unit to the late Julian (late middle Carnian) ammonite stage. Drilling by the U.S. Geological Survey and others in the basin, as well as detailed studies of regional sedimentation, paleoclimate, paleontology, and tectonic activity have made it possible to interpret depositional environments not only for the coals of the Cumnock Formation but also for the underlying Pekin Formation and overlying Sanford Formation (Figure 27-3). On the basis of an extensive well-preserved megaflora in the upper Pekin Formation near Gulf, N.C., Hope (1975) concluded that the siltstones and mudstones had accumulated in swamps and floodplains on which grew a community of ferns, seed ferns, horsetails, cycads, and cycadeoids. Conifers and other gymnosperms that are characteristic of a tropical humid climate grew on the nearby uplands. Gensel (1986) determined that the climate during late Pekin time was warm, probably moist with seasonal rainfall, based on the presence of cycads and the fossil fern Phlebopteris. Alluvial fans, whose deposition was seasonally and tectonically controlled, spread out from the east onto an alluvial plain during late Pekin time. Streams meandered over the plain and formed deltas into lakes which responded to seasonal distribution of rainfall by enlarging or shrinking. During deposition of the Cumnock Formation, more moisture and less tectonic activity allowed lake-fringe swamps to extend well into a shallow anoxic lake where gray and black siliciclastic muds were settling. Reinemund (1955) believed that the ponding forming a lake in the Sanford subbasin was caused by blockage along the Colon cross structure by a greater accumulation of alluvialfan sediment. Ziegler (1983) defined these events as fitting a wet climate/closed drainage model. Then the lake apparently deepened and the muds, which eventually became organicrich shales several hundred feet thick (Fig. 27-3), drowned the swamps. The lake may have been around 15 miles wide and 20 miles long (Gore, 1986a). Ultimately, alluvial sedimentation from the southeast filled the basin with the siliciclastics of the Sanford Formation (Robbins and Textoris, 1986). During commercial exploitation of the Deep River Coal Field, more than 2 million tons of coal were produced, primarily from the middle bed of the Cumnock coal. A study by Textoris (1985) calculated the remaining resources to be 139,664,000 short tons (Table 27-7). Beutel (1982) reported on feasibility studies to produce methane from the Cumnock and Gulf coal beds as well as from the thick, organic-rich shales associated with them. The objective of that project was to fracture these beds, and to obtain enough natural gas for use by 12 local brick companies. The Do well Division of Dow Chemical performed a fracture treatment in the Dummitt-Palmer No. 1 well. The results are still being studied, but before fracturing, 2,995 cm 3 /g of natural gas was extracted from the black shale, 9,015 cm 3 /g from the Cumnock coal, and 7,379 cm 3 /g from the Gulf coal. Dan River - Danville basin Coal is found in the middle and lower members of the Cow Branch Formation of Meyertons (1963) in the Dan River - Danville basin of North Carolina and Virginia (Fig. 27-2). Coal also may occur in the upper member. The coal beds dip 18° to 73° to the west (Thayer, 1970).

Coal deposits

669

The thickest persistent coal bed is at the southern end of the basin in the lower member of the Cow Branch Formation in North Carolina in the vicinity of Germantown, Pine Hall, and Walnut Cove (Olmsted, 1824; Stone, 1910; Pickett, 1962) (Fig. 27-2). It crops out along the southeastern edge of the basin. Emmons (1856) reported a 4-foot bed; Stuckey (1965) cited an 1887 report by Robson of a 9-foot-thick bed. The coal in the lower member appears to extend from Germantown to Eden, and borrow pits have revealed two beds (Stone, 1910). In the subsurface, 2 feet of coal were penetrated at 105 feet in the Danville Well Co. Halsey No. 1; thickness was not reported for coal in the J. Stafford Co. Grogan No. 1 (Mundorff, 1948). Less than an eighth of an inch of coal was reported in the North American Exploration NCST-2 corehole at 122 feet. In outcrop, the underclay of the lower member is gray, and the roof rock is a dark-purple shale and gray-orange siltstone (Pickett, 1962). The thickness of coal in the middle member of the Cow Branch Formation is unknown. Mundorff (1948) reported its presence in the Z.V. Jones Co. Martin No. 1 well. A coaly interval in the upper member of the Cow Branch Formation was reported around Leakesville (Eden) by Rogers (1884) and Stone (1910). Today, at the Sollte Quarry in Eden, N. C , bright silver-colored slickensided pods in this upper member suggest the former presence of coal that might have served as graphite-like slip planes on intraformational faults (Robbins, 1982). Analyses of Cow Branch coal show that it ranges in rank from high-volatile bituminous to anthracite (Table 27-5). The majority of these old analyses rank the coal primarily as semianthracite. Three samples of impure coal and carbonaceous shale were processed for palynomorphs. Figure 27-2 shows their location in the basin and Table 27-1 lists the taxa identified from these samples; none of these are restricted to the middle Carnian. However, other shales which surround the coal but are not carbonaceous contain Colpectopollis ellipsoideus that is restricted to the middle Carnian (Robbins, 1982). Among the taxa in the impure coal and carbonaceous shale are 16 species that have not been observed yet in the coals of the other basins but that have been identified in other lithologies. The lack of extensive drilling in the basin, poor outcrop exposure, and the steep dip of the beds make it difficult to determine the depositional environment of the coals. Areal extent and lateral facies relationships are part of the evidence used to differentiate between the types of coals that could be expected to the found in tectonic basins. If coal in the lower member bed is continuous, the unit might represent the final filling-in stage of the lake based on its areal extent. Resources have not been calculated formally in the Dan River-Danville basin because of sparse subsurface data. Stone (1910) examined all known exposures of coal in the lower member, and reopened a number of pits. He concluded that the coal is generally thin and discontinuous, even though it has been found at four localities along strike, over a possible distance of 32 miles. If, in the future, the lower member of the Cow Branch Formation proves to be continuous, remaining resources may be on the order of 69,120,000 million short tons (Table 27-7). Farmville and Briery Creek basins The coal-bearing interval in the Farmville and Briery Creek basins of Virginia (Fig. 27-2) is the 'coal measures' of Wilkes (1982). The strata in the basins dip 10° to 60°NW; the dip of the exposed coal beds is generally less than 20°. The total number of individual coal beds

670

E.I. Robbins, G.P. Wilkes and D.A. Textoris

is unknown, but 7 were reported by Rogers (1884) in a drill hole north of Farmville. Coal outcrops are confined to the southern portion of the Farmville basin but are extensive in the Briery Creek basin. The thickest coal reported in the Farmville basin is 3 feet (Daddow and Bannon, 1866). Where it was mined, the average thickness of coal was 18 inches. At an outcrop near one of the mines, three coals range from 0.9 to 1.3 feet thick. Floor rock for each bed is dark-gray shale which grades into the coal. Roof rock is black shale or gray sandstone that either grades into or is in sharp contact with the coal. In the Briery Creek basin, excavations for the spillway of the Brushy Creek Water Management Project, 2 miles south of Hampden Sydney, exposed a bed of coal 1 foot thick. South of this in the Briery Creek drainage, a coal 1.1 feet thick can be observed grading above and below into black silty shale. Elsewhere in the basin, roof and floor rock is carbonaceous siltstone that grades above or below into coal. No analyses of coal in either basin have been reported. The color of the organic tissues and the ease of degradation in Schulze's solution indicate that the rank will be bituminous, similar to that in the Richmond basin. Six samples of impure coal and carbonaceous shale from the Farmville basin and 1 sample of coal from the Briery Creek basin were processed for palynomorphs. Figure 27-2 shows their locations in the basins and Table 27-1 lists the taxa identified from these samples including 'Placopollis raymondiV (Koob, 1961) which is restricted to the middle Carnian. Among these are four species that have not been observed yet in the coals of the other basins but that have been identified in other lithologies. Furthermore, cysts similar to those of the green alga Volvox were identified (Plate 27-2 no. 10). The globular cysts average 15 μπι in diameter. Processing of the coaly rooks from the Farmville basin in both the acid and the acid followed by the base treatments resulted in an unusual occurrence. Copious amounts of humic acids leaked from the rock chips and continued to leak even after 20 water washes. In contrast, a typical refractory coal might require 10 water washes at most to remove the humic acids. The lack of drilling in these small basins, the paucity of outcrops, and the lack of data on lateral extent of the coal beds make it difficult to interpret the invironment in which the coal-precursors accumulated. However, the interfingering of coal beds with dark shale suggests an alternation of swamp and lake environments, a situation that would most likely occur along the margin of a lake. Therefore the coal may be the preserved remains of a fringingswamp plant community. We did not calculate resources for the Farmville and Briery Creek basins. The thinness of the exposed section did not warrant a calculation, but a drill hole less than 1000 feet in depth in the southern end of the Farmville basin might provide the kinds of data that are necessary to calculate resources. Taylorsville basin Coal in the Taylorsville basin of Virginia and Maryland (Fig. 27-2) is found in the Falling Creek Member of the Doswell Formation (Weems, 1980b). The coal beds dip 15° to 60° to the north and northwest (Weems, 1981, 1986). Two coal-bearing intervals which were once mined have been identified at the southern end of the basin, one stratigraphically in the middle of the unit and the other at the top (Weems, 1980b, 1981, 1986). Most of the Taylorsville

Coal deposits

671

basin is unexplored because its entire northeastern end, which extends into Maryland, is covered by Coastal Plain sediments. The Washington Gas Light PG-Fd 61 well near the inferred northern end of the basin penetrated coal and coal streaks between depths of 1,673 and 1,686 feet (H.J. Hansen, Maryland Geological Survey, written commun., 1983). At the surface, no coal bed is known to be thicker than a few inches (Rogers, 1884; R.E. Weems, USGS, written commun., 1985). No rank determinations are available for the Taylorsville basin coals. The color of the tissues and the ease of degradation in Schulze's solution indicate that the rank will be bituminous, similar to that in the Richmond basin. Two samples of impure coal and carbonaceous shale were processed for palynomorphs. Figure 27-2 shows their location in the basin, and Table 27-1 lists the taxa identified from these samples including Colpectopollis ellipsoideus and 'Placopollis raymondiV (Koob, 1961) that are restricted to the middle Carnian. Among these are 9 taxa that have not been observed yet in the coals of the other basins but that have been identified in other lithologies. Because much of the Taylorsville basin probably is buried under Coastal Plain sedimentary cover, it is difficult to determine the regional geometry that might aid in the interpretation of the environment of deposition of the thin coals. Furthermore, only a few drill holes penetrate the lakebed sequence to help determine the lateral extent of the coal-bearing Falling Creek Member. The topmost coal defines the end of lacustrine sedimentation in the basin and therefore probably represents a deposit from the final filling in stage of the lake (R.E. Weems, USGS, pers. commun., 1985). Because data concerning the distribution and thickness of coal in the Taylorsville basin are sparse, no resources were calculated. Other basins Culpeper basin. Coalified logs occur in the Manassas Sandstone in the Culpeper basin at Seneca Falls State Park, Md. One such log was processed through the acid/base treatment (sample 887). Neither pyrite nor palynomorphs were present, but the wood cells had distinct bordered pits typical of conifers (Plate 27-2, no. 11) and cuticle is present (Plate 27-2, no. 9). The ease of degradation in Schulze's solution indicates that the coal is of low rank. Palynomorphs in fine-grained rocks interbedded with the sandstone are of earliest Late Carnian age, based on the presence of Bhardwajispora jansonii and Platysaccus triassicus. Lee (1977, 1979) was told of coal in the Waterfall (Bull Run) Formation (of Lindholm, 1979) in the Middleburg Quadrangle, Va., but was unable to find either excavations or outcrops to confirm the report. Coal in the Waterfall Formation would be of Pliensbachian (Early Jurassic) age (Cornet, 1977). I.A. Breger reported to A. J. Froelich (USGS, pers. commun., 1985) that coalified plant tissue in conglomerate of the Waterfall Formation was lignite in rank. Lee (USGS, written commun., 1985) also has noted a streak of coal less than 1/4 inch thick in the Triassic beds west of the City of Frederick, Md. Gettysburg basin. Coal has been reported but not verified from two localities in York County, Penn., along the eastern edge of the central part of the Gettysburg basin (Fig. 27-1). An analysis in Frazer (1880) would indicate the coal at Liverpool (now Manchester) to be low-volatile bituminous on the basis of fixed carbon content. R.C. Smith (Pennsylvania Geol. Survey, personal commun., 1985) was told of a coal locality along an old railroad grade at Mount Hope. These coal beds would be in the lower New Oxford Formation of Carnian age that dips 38°N at the Manchester locality and 29°NE at the Mount Hope locality.

672

E.I. Robbins, G.P. Wilkes and D.A. Textoris

No thickness information is available for either locality in York County. Lignite has been reported at one locality in Adams County (Anonymous, 1886). Hartford basin. Coalified logs have been collected by J.J. Heilman (Wallingford, Conn., written commun., 1984) in the Hartford basin in East Haven, Conn, at the contact between the New Haven Arkose and the Talcott Basalt. On the basis of stratigraphic position and the presence of abundant Corollina meyeriana, the coalified logs are Hettangian (Early Jurassic) in age (as used by Cornet and Traverse, 1975). Newark basin. Coal stringers have been reported in a dozen localities in Bucks and Montgomery Counties in the southern end of the Newark basin in eastern Pennsylvania (Lyman, 1895) (Fig. 27-1). No analyses are available, nor has any of the coal been recovered for this study. Coalified logs were noted by Kümmel (1898) in the lower Stockton Formation in New Jersey, which is middle Carnian in age (Cornet, 1977). History of mining Richmond basin. The first record of coal in the United States is from Colonel W. Byrd who patented 344 acres of coal land near Manakin in the Richmond basin in 1701 (Byrd, 1886). It is probable that French Huguenot settlers knew of the coal even before 1701. The coal field was developed rapidly, and in 1745 the Richmond basin became the location of the first commercial coal production in North America. In 1758, 9 tons of coal were transported by ship from Hampton to New York; later in that century, street lamps in New York, Philadelphia, and Boston were fueled by coal gas derived from the flourishing Virginia coal industry near Richmond. Mostly due to a restrictive market and competition from foreign coal, the mines produced less than 1,000 tons of coal through the 1700's. In 1794, however, a tariff was imposed on imported coal, and the owners of the Richmond mines responded by expanding and establishing a solid market on the east coast. Then, in 1833, an earthquake killed two miners (MacCarthy, 1958). Until about 1850, the coal field experienced great activity as evidenced by many new shaft and slope mines. Interstate transportation of coal from the Richmond Coal Field was interrupted in 1860 by unrest preceding the Civil War. Production during the war years primarily was directed to the Confederate war effort, and cannon foundries in Richmond exclusively used the Black Heath coal. An explosion in the Brighthope Pit 1 mile south of Winterpock killed 66 miners in 1867 due to a methane accumulation ignited by an open flame in an unventilated part of the mine (Heinrich, 1878). The market for Richmond coal declined in 1883 when the Norfolk and Western Railroad opened the Pocahontas Coal Field in Virginia and West Virginia. By the time the last large mine closed in the 1920's, production had been sporadic for years. Deep River basin. The most complete mining history of the Deep River Coal Field was written by Reinemund (1955). The earliest record of coal useage in the Sanford subbasin is 1775 in the Village of Gulf, N.C. The first commercial shaft was the Egypt mine at Cumnock in the 1850's, and shortly thereafter an explosion killed three miners at the Cumnock mine. During the Civil War, the Confederate Army took over the Cumnock mine and supplied coal for blockade runners in Wilmington, N.C. The mine was sealed near the end of the war to prevent the northern armies from exploiting the coal; during this time the mine was flooded by water from the Deep River. The mines were reopened in the early 1890's, and a series of gas explosions and floodings claimed the lives of more than 200 miners. After World War II, there were further efforts to mine the coal commercially, but the last major mine was flooded and closed in 1953.

673

Coal deposits

Dan River - Danville basin. Emmons (1856) reported that coal from Germantown was used by local blacksmiths. Coal was mined at the old Wade Plantation south of Eden and used during the Civil War (Stone, 1910). Farmville and Briery Creek basins. A mine north of Farmville was active during the Civil War and produced coal for local use. Although this mine was reopened periodically until the 1950's, no significant quantities of coal were produced (Wilkes, 1982). In the Briery Creek basin, coal was worked from a small pit in 1833. Taylorsville basin. There are reports that coal was mined in the basin as long ago as the 1830's (Rogers, 1884; Woodworth, 1902). Traces of more recent mines and pits have been located and mapped in both the Hanover Academy and Ashland Quadrangles (Weems, 1981, 1986). Weems (1980b) was unable to locate production data from these and concluded that there was probably no more than local use of the coal. Culpeper basin. A farmer in Louden County reported that coal was dug for domestic use during the Civil War (K.Y. Lee, USGS, written commun., 1985). Lee was unable to find either excavations or outcrops to confirm the report. Gettysburg basin. The coal at Manchester reported by Frazer (1880) may have been mined by Benjamin Gross (Marian Hewitt, Manchester, PA., pers. commun., 1985). Interpretations and conclusions Although the coal deposits of the Newark rift system are not considered to be of economic importance at present, the remaining coal resources are not inconsequential. More than 10 million short tons have been mined, and according to our calculations, almost 4 billion tons of coal remain in the isolated basins. Most of the palynomorphs identified in the coal-bearing samples are from taxa that have long time ranges and therefore are not diagnostic for specific age. However, taxa that are restricted in time to the middle Carnian age of the Late Triassic (as used by Cornet, 1977) were identified from each basin. These include Calamospora nathorstii, Convolutisporites affluens, Cyclotriletes oligogranifer, Tigrisporites dubius, Colpectopollis ellipsoideus, Plicatisaccus badius, 'Placopollis raymondiV (Koob, 1961), and Cycadopites 'sp. 103' (Cornet, 1977) (Plates 27-1 and 2). These indicate that the time of major deposition of coal occurred during the middle Carnian. The palynoflora in the coal of the Richmond, Taylorsville, and Farmville basins represents assemblages of predominantly middle Carnian age; the basal coal in the Richmond basin contains a distinct microflora and is the oldest Triassic that has been recognized in the eastern United States (Cornet, 1977; Olsen et al., 1982). The palynofloras of the Deep River and Dan River - Danville basin coals are clearly younger than those in the Richmond - Taylorsville Farmville sequence (Cornet, 1977), but detailed correlation of all of these assemblages with the type section in Europe is a problem because of a variety of factors. Among the important factors are: (1) The Carnian sequence of the rift is much thicker stratigraphically than the European type section (Cornet and Olsen, 1985); (2) The Carnian type section in Europe is marine and therefore is zoned primarily on the basis of ammonite content (Kümmel, 1979). Correlation of palynomorphs with ammonites has been quite successful in Arctic Canada and northwestern Europe (Fisher, 1979; Visscher and Brugman, 1981); (3) Swamp flora respond to edaphic conditions that typically can allow relict plants to live

674

E.I. Robbins, G.P. Wilkes and D.A. Textoris

in swamps even though they have become extinct elsewhere (Gillespie et al., 1978); and (4) The flora of isolated rift basins in the continental interior easily could have been different from that growing elsewhere along low lying coastal plains (Manspeizer and Cousminer, in press). Until further studies resolve local differences between the late middle Carnian and the early late Carnian along the east coast of the United States, we cannot be certain that the coalbearing sequences in the Deep River and Dan River - Danville basins are late middle Carnian rather than early late Carnian in age. The palynomorphs in these coal-bearing sequences are from bryophytes, lycopods, ferns, articulates, seed ferns, conifers, cycadeoids and cycads, and some are of unknown affinities (Table 27-4). Conclusions about edaphic requirements of these fossil plants can be drawn. Certainly the presence of megafossils of Macrotaeniopteris spp., Equisetosporites sp., and fern fronds in the coals of the Richmond basin (Fontaine, 1883) shows that true cycads, horsetails and ferns and/or tree ferns grew in the swamps. Because Visscher and van der Zwan (1981) compared floras in Carnian coals to those in evaporites, information can be added from the palynomorphs themselves (Table 27-2) even though it is difficult to assess which palynomorphs are the remains of plants that grew in closed-canopied swamps or were carried into open-canopied swamps by the wind or both. Aratrisporites, Calamospora, and Cycadopites are typical of hydrophytic assemblages elsewhere, and probably were shed by plants that grew in the swamps. Corollina, Patinaspontes, and Triadospora have xerophytic affinities elsewhere and are probably best interpreted as the remains of conifers that grew on drier horst uplands surrounding the rift. Three plants probably composed the bulk of the peat in the Newark rift system swamps (B. Cornet, Houston, Tex., pers. commun., 1984): Equisetites, which were giant reed-like horsetails that had thick, 3- to 4-inch diameter stems (Fontaine, 1883) and whose presence is indicated by Calamospora; Isoetes-like quillworts that produced Aratrisporites and were several feet tall (Retallack, 1975); and Macrotaeniopteris, cycadeoids that shed abundant small willow-like leaves and probably produced monosulcate pollen. This association also is present in Australian coals (de Jersey, 1962). Coal is common in Carnian sequences, and in particular middle Carnian sequences, around the world. The data of Visscher and van der Zwan (1981) show coal deposits in Austria, Poland, Germany, Svalbard Island in the Arctic Ocean, Siberia, and the Caucasus region between the Black and Caspian Seas. The middle Carnian coal of the eastern United States now must be added to this list. Furthermore, plant fossils in the coals of the Chinle Formation in Arizona, Utah, and western New Mexico also are of middle Carnian age (Ash, 1980; S.R. Ash, Weber State College, pers. commun., 1985), as are the Ipswich and equivalent coals in Australia (de Jersey, 1962; Banks, 1978; Laseron, 1984). These data suggest that the Carnian was a time of swamp conditions and peat-forming plant communities around the world. In contrast, deposits of coal do not occur after middle Carnian times within the Newark rift system. The reason for their absence is not clear, and may be related to causes as divergent as plant anatomy, earthquake frequency, or global sea level changes. Peat swamps may not have been present, they may have been uncommon, or perhaps peat was not preserved. It is not unreasonable to suggest that the composition of the swamp flora may have affected peat accumulation. The distinctive plant association in middle Carnian coals is not present in later assemblages; there may have been a change from woody plant dominants in the swamps to herbaceous plants that formed other lithologies such as organic-rich shales in-

Coal deposits

675

stead. By the late Carnian, quillwort-like plants that produced Aratrisporites fimbriatus and the thick-stemmed horsetail that produced Equisetites both dropped out. This change is mirrored elsewhere; a large number of hydrophytic species dropped out in Arctic Canada at the end of the middle Carnian. However, some familiar elements of the east coast flora are found in late Carnian to Liassic (Early Jurassic) coals of higher latitudes such as Greenland and Southern Australia (Harris, 1937; Playford and Dettman, 1965; Stevens, 1981). But the conifers in the coals of Greenland are different; they have tree rings (Harris, 1937) which indicate growth in a seasonally changing climate rather than in a perennially moist swamp. Other possible explanations for the restriction of coal in time might be climatic or tectonic changes. A global eustatic sea-level fall may be implicated; it may have been caused by climatic or tectonic events. A worldwide drop in sea level is recognized at the LadinianCarnian stage boundary, and other ones are postulated at other Triassic stage boundaries (Biddle, 1984). A drop in base level easily could have affected local water tables. Availability of water in the form of high water tables, in the distribution of rainfall, and in the amount of rainfall are major selective forces creating distinctive plant communities today. Diagnostic vertebrates, diagnostic plant species, and the presence of lithologies formed in playa lakes suggest a general drying trend after the middle Carnian along the entire Newark rift system (Wheeler and Textoris, 1978; Cornet and Olsen, 1985). The cause of the drying trend is usually attributed to climate (Cornet and Olsen, 1985; Textoris and Holden, 1986), but tectonic changes that cause water tables to drop affect groundwater discharge into modern rift swamps. The rift environment is one in which earthquake activity is very common (Robbins, 1982), so a model based on tectonics and water-table fluctuations also might account for the lack of post-middle Carnian swamps. Intrabasinal and syntectonic faulting may have controlled major sedimentation patterns, as shown for Lake Malawi in East Africa (Ebinger et al., 1984), but there is insufficient subsurface information to support or refute these ideas in regard to their effect on coals in the Newark rift system. Our data also show an apparent restriction of coal in space. The significant coal deposits are located in Virginia and central North Carolina. The swamps of the middle Carnian may have been distributed along the Triassic equatorial belt where humidity could have been one of the factors that enhanced peat deposition just as it does today (Clymo, 1983). In the present-day tropics along the equator, humidity is a major factor that favors maintenance of rain-forest habitat (Trewartha, 1954; Ingram, 1983). Paleomagnetic data show that the North American plate began to shift northward in latest Triassic time (Robinson, 1973; Smith and Briden, 1977; Ziegler et al., 1977), and perhaps the lakes along which peat accumulated earlier were next shifted into a climatic regime that was not conducive to the maintenance of swamp conditions or to the preservation of peat. Two words of caution must be entered, however: the distribution of coal may be an artifact of the distribution of known middle Carnian sequences; and peat deposition rarely is governed by latitude. Nevertheless, peat deposits do appear to be localized in modern rifts: the locus of peat deposition in the Dead Sea rift is the Lake Hula region at latitude 33°N (Brenner et al., 1978), and in the San Andreas rift the locus is the 'delta' region at latitude 38°N (Weir, 1950). Most coals in the basins are high volatile bituminous in rank, but rank ranges from subbituminous A in the Richmond and Deep River basins to anthracite in the Richmond, Deep River, and Dan River - Danville basins (Table 27-5). The presence of lignite also has been reported in the Taylorsville basin (Rogers, 1884). A variety of indicators including rank of coals, color of tissues, clay mineralogy, and porosity suggest that the individual basins have been subjected to different degrees of burial or to varying temperatures. Rank also has been affected by proximity to intrusive and extrusive igneous bodies in the basins.

676

E.I. Robbins, G.P. Wilkes and D.A. Textoris

Only two types of analyses are available on the sulfur content of the coals - the chemistry of whole coal, and the pyrite content of acid-insoluble residues. Chemical analyses (Table 27-6) on whole coal show that sulfur content ranges from a trace to more than 10% in the Richmond basin. In the acid residues of coals, the pyrite content ranges from none in the Farmville basin to 10% in the Briery Creek basin (Table 27-4). We did not correlate sulfur and pyrite content because analyses were not performed on the same samples and because variability in both data sets is large. The crystal forms of pyrite in these coals and associated carbonaceous shales are octahedrons, framboids, cubes, pyritohedrons, hexagonal prisms, rectangular prisms, and masses with indistinguishable crystal faces (Table 27-3). Many are detrital grains, but individual crystals commonly are enmeshed in the tissues (Plates 27-1 and 2), which suggests anaerobic bacteria at work and which will make beneficiation difficult if the coals are to be utilized in the future. There are also enmeshed crystal ghosts than indicate the former presence of pyrite. The crystal form of pyrite in coal may be useful in determining rank and therefore in approximating heat flow in a basin. Lovering (1949) showed that the transition of pyrite from framboids and cubes to the pyritohedral crystal form occurred in a hydrothermal gradient across the East Tintic District, Utah. Plant tissues in coals and other lithologies in the Dan River - Danville basin contain abundant pyritohedral holes; the tissues throughout most of the basin range from dark brown to black; the coal rank is predominantly semianthracite; and the clay minerals are 2-M illite and chlorite (Robbins and Traverse, 1980; Robbins, 1982; Thayer et al., 1982). The Dan River - Danville basin clearly has been subjected to high heat flow, higher than in the other basins (de Boer and Snider, 1979). Furthermore, pyrite is present but rare (Table 27-4), and pyrite crystal-ghosts predominate (Plates 27-1 and 2). Some hydrologic and/or thermal event has removed much of the sulfide. Coals subjected to such events may potentially become low-sulfur but high-rank coals. The presence of an alga indistinguishable from Volvox, which today requires organic nutrients (Hutchinson, 1967), and the presence of copious amounts of humic acid leaking from its coaly rocks suggest that something unusual occurred in the swamps of the Farmville basin. The virtual lack of pyrite in the Farmville basin samples (Table 27-4) adds to the idea that the chemistry of the swamp was not typical. The copious leaking of humic acid alone suggests either that the rocks of the basin may have been subjected to long intervals of weathering or the swamp(s) was a closed basin into which plant degradation products poured, these served as nutrients for heterotrophic algae, and then these products were precipitated. Whereas innumerable data are available because of mining activities in the Richmond and Deep River basins, the northern ends of the Farmville and Taylorsville basins are the least studied and could contain potentially economic coal. More data are needed from these areas because thick coals may exist in the subsurface. Because of the methane content of the coals, faulting, sulfur content, and the dip of the beds, the coals probably never will be mined again. However, abundant methane in the coals actually may be brought into production on a commercial scale in the Richmond and possibly also in the Deep River basin. Acknowledgements This paper would not have been possible without the help of John Allan, H.J. Hansen, K.Y. Lee, and D.G. Ziegler who provided unpublished information; Bruce Cornet who checked species identifications and provided unpublished data on the megafossils in the

677

Coal deposits

coals; Frank Delong who wrote the algorithm for the calculation of rank classification data; Bruce Goodwin and J.J. Heilman who provided samples; R.M. Kosanke who processed two intractable samples; the North Carolina Geological Survey Section who provided access to their files; J.R. SanFilipo who provided field support; R.C. Smith and J.P. Wilshusen who provided locality information; P.A. Thayer who provided field support and locality information; and R.E. Weems who provided field support and unpublished data. Reviews by A.J. Froelich, Alfred Traverse, and H.L. Cousminer greatly strengthened this paper. Partial support for D.A. Textoris came from U.S. Geological Survey Grant 14-08-000l-G-970, and a grant from the University Research Council of the University of North Carolina.

APPENDIX l Sample lithology and locality information [carb = carbonaceous; imp = impure] Sample No. Lithology

Field No.

IVi' Quadrangle

Dan River - Danville basin 599 carb. shale 602 imp. coal 613 carb. shale

8007ER8 ) 8007ER9 ) Walnut Cove, NC 7806ER51 Mayodan, NC

Deep River basin 819 Cumnock coal 827 carb. shale 876 Cumnock coal

-

Goldston, NC Colon, NC Goldston, NC

Farmville and Briery Creek basins 8210ER2 779 carb. shale 780 carb. shale 8210ER6 821 imp. coal 8210ER1 822 imp. coal 8210ER3 823 imp. coal 8210ER5 8210ER7 824 imp. coal 875 coal Richmond basin 733 coal

8208ER18

Midlothian, VA

coal

8208ER23

Hallsboro, VA

754

coal

-

Winterpock, VA

755 756 757 758 830

imp. imp. imp. imp. coal

Taylorsville basin 877 carb shale 883

imp. coal

\

1>

Midlothian, VA

{

I 8211ER2 8211ER8

Stone (1910) locality 9 NC 65 & US 111 Meas. Sec. D (Thayer, 1970) US 220 & NC 704 Bethany Church near Gulf Carolina Mine, 1 mi NE of Cumnock Bethany Church near Gulf

\ j Γ VA 600 1000 ft N of VA 637 Farmville, VA f \ ) Hampden Sydney, VA VA 706 3050 ft W of US 15

734

coal coal coal coal

Sample locality

Hanover Academy, VA

VA 652, 3000 ft S of James River, from dump Grove shaft, 3050 ft on dirt road from power plant on VA 754 MNR Cashion # 1 , 1128.0 ft, on VA 603 W of Winterpock TVW # 1 , 32.3 ft TVW # 1 , 33.8 ft i TVW # 1 , 34.3 ft > in shopping center, TVW # 1 , 35.9 f t \ G a y t o n Rd. TVW # 1 , 38.5 ft Beech Creek trib. near power line

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E.I. Robbins, G.P. Wilkes and D.A. Textoris

References American Society for Testing and Materials, 1982. Annual Book of ASTM Standards; Part 26, Gaseous Fuels; Coal and Coke; Atmosphere Analysis. ASTM, Philadelphia, PA, pp. 203-480. Anonymous, 1886. History of Cumberland and Adams County, republished as History of Adams County. Warner, Beers, and Co., Knightstown, IN, p. 304. Applin, P.L., 1951. Preliminary report on buried pre-Mesozoic rocks in Florida and adjacent States. U.S. Geol. Surv., Circ. 91, 28 pp. Archangelsky, S. and Gamerro, J.C., 1967. Pollen grains found in coniferous cones from the Lower Cretaceous of Patagonia (Argentina). Rev. Palaeobot. Palynol., 5: 179-182. Ash, S.R., 1980. Upper Triassic floral zones of North America. In: D.L. Dilcher, and T.N. Taylor, (Editors), Biostratigraphy of Fossil Plants. Dowden, Hutchinson, and Ross, Stroudsburg, PA, pp. 153-170. Bain, G.L. and Brown, C.E., 1981. Evaluation of the Durham Triassic basin of North Carolina and techniques used to characterize its waste-storage potential. U.S. Geol. Surv., Open-File Rep. 80-1295, 132 pp. Bain, G.L. and Harvey, B.W., 1977. Field guide to the geology of the Durham Triassic basin. Carol. Geol. Soc. Field Trip Guideb., Raleigh, NC, Oct. 7 - 9 , 1977, 83 pp. Banks, M.R., 1978. Correlation chart for the Triassic System of Australia. Aust. Bur. Miner. Resour., Geol. Geophys., Bull. 156C, 39 pp. Bell, H., Ill, Butler, J.R., Howell, D.E. and Wheeler, W.H., 1974. Geology of the Piedmont and Coastal Plain near Pageland, South Carolina and Wadesboro, North Carolina. Carol. Geol. Soc. Field Trip Guideb., S. C. Dev. Board, Columbia, SC, 1974, 23 pp. Beutel, R.A., 1982. Final report to U.S. Department of Energy and North Carolina Energy Institute on Deep River development project for unconventional gas-exploratory drilling and completion. R.A. Beutel and Associates, Inc., Chapel Hill, NC, 18 pp. Bharadwaj, D.C. and Venkatachala, B.S., 1968. Suggestions for a morphological classification of sporae dispersae. Rev. Palaeobot. Palynol., 6: 4 1 - 5 9 . Biddle, K.T., 1984. Triassic sea level change and the Ladinian- Carnian stage boundary. Nature, 308: 631 - 6 3 3 . Bold, H.C., Alexopoulos, C.J. and Delevoryas, T., 1980. Morphology of Plants and Fungi, 4th ed. Harper and Row, New York, NY, 819 pp. Brenner, S., Ikan, R., Agron, N.A. and Nissenbaum, A., 1978. Hula Valley peat: Review of chemical and geochemical aspects. Soil Sei., 125: 226-232. Brown, P.M., et al., 1985. Geologic map of North Carolina. N.C. Dep. Nat. Resour. Community Dev., Geol. Surv., Raleigh, NC, 1:500,000. Burke, K., 1976. Development of graben associated with the initial rupture of the Atlantic Ocean. Tectonophysics, 36: 9 3 - 1 1 2 . Byrd, W., 1886. Letter to the Colonial Council re. The Huguenots at Manakin, reprinted. In: R.A. Brock (Editor), Documents relating to Huguenot Emigration to Virginia. Virginia Historical Society. Campbell, M.R. and Kimball, K.W., 1923. The Deep River coal field of North Carolina. N. C. Geol. Econ. Surv., Bull., 33: 87. Clarke, F.W., 1887. Report of work done in the Division of Chemistry and Physics. U.S. Geol. Surv., Bull., 42: 146. Clement-Westerhof, J.A., 1974. In situ pollen from gymnospermous cones from the Upper Permian of the Italian Alps - a preliminary account. Rev. Palaeobot. Palynol., 17: 6 3 - 7 3 . Clymo, R.S., 1983. Peat. In: A.J.P., Gore (Editor), Mires: Swamp, Bog, Fen, and Moor. Ecosystems of the World, V. 4. Elsevier, Amsterdam-New York, pp. 159-224. Cornet, B., 1977. The palynostratigraphy and age of the Newark Supergroup. Ph.D. Dissertation, Pennsylvania State University, University Park, PA, 501 pp. Cornet, B. and Olsen, P.E., 1985. A summary of the biostratigraphy of the Newark Supergroup of eastern North America with comments on Early Mesozoic provinciality. 3rd Congreso Latinoamericano de Paleontologia. Mexico. Symposio sobre Floras del Triasico Tardio, Su Fitogeografia y Paleoecologia, Memoria, pp. 6 7 - 8 1 . Cornet, B., Traverse, A., 1975. Palynological contribution to the chronology and stratigraphy of the Hartford basin in Connecticut and Massachusetts. Geosci. Man, 11: 1 - 3 3 . Couper, R.A., 1958. British Mesozoic microspores and pollen grains: A systematic and stratigraphic study. Palaeontographica, Abt. B, 103: 7 5 - 1 7 9 . Daddow, S.L. and Bannon, B., 1866. Coal, iron, and oil, In: Practical American Miner. Lippincott, Philadelphia, PA, pp. 47, 395, 402, 403.

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