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dissertation entitled

PALYNOLOGIC INVESTIGATION OF THE MORENO HILL FORMATION

(UPPER CRETACEOUS), WEST—CENTRAL NEW MEXICO

presented by

Kurtis C. Kelley

has been accepted towards fulﬁllment of the requirements for

Master of Sciencedegree in Botany and Plant Pathology

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PALYNOLOGIC INVESTIGATION OF THE MORENO HILL FORMATION

(UPPER CRETACEOUS), WEST-CENTRAL NEW MEXICO

Kurtis C. Kelley

A THESIS

Submitted to Michigan State University in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

Department of Botany and Plant Pathology

1987 ABSTRACT

PALYNOLOGIC INVESTIGATION OF THE MORENO HILL FORMATION (UPPER CRETACEOUS), WEST CENTRAL NEW MEXICO

Kurtis C. Kelley

One outcrop and three subsurface coal-test well-sections

were sampled for palynologic analysis in the Upper

Cretaceous Rio Salado Tongue of the Mancos Shale, Atarque

Formation and Moreno Hill Formation from the Fence Lake area

of west-central New Mexico.

A potential problem with contamination of samples by a

Middle Cretaceous, fossiliferous drilling-mud was encount-

ered and resolved.

Palynologic correlation was made between sections based

on local pollen-spore occurrence and range, cluster analy-

sis, and relative frequency peaks of selected pollen-spore groups. These correlations resulted in the establishment of

six palynologic zones.

The abrupt occurrence of marine microfossils in the upper part of the Lower Moreno Hill Formation indicates a marine transgression into the study area not previously identified.

Analysis of five recurring pollen-spore assemblages and other micro- and macroscOpic-sized plant detritus included in these sediments indicates the presence of a diverse land flora occupying shifting habitats on the prograding sediment buildup. ACKNOWLEDGMENTS

I would like to express my sincere thanks to Professor

Aureal T. Cross for the considerable amount of time and

labor he put into the the development of this thesis and for

his concern and efforts in assuring that my family and I did

not starve in the process. I would also like to express my

appreciation to Professor Ralph Taggart and Professor

Chilton Prouty for their aid during the research and writing of this manuscript.

I am very grateful to the United States Geological Survey and the New Mexico Bureau of Mines and Mineral Resources for

the generous grants they awarded in partial support of this thesis project and to the Department of Botany and Plant

Pathology and the Department of Geological Sciences of

Michigan State University for their financial support in the form of graduate assistantships.

Finally I would like to thank Dr. Abolfazl Jameossanaie,

Kyle Walden and Feng Bing Cheng for their aid and no small measure of moral support.

11 TABLE OF CONTENTS:

I. BACKGROUND AND PURPOSE ...... OOOOOOOOOOOOOOO H

Objectives ...... Previous Studies ...... Geology and stratigraphy ...... Palynology ...... Geology ...... Atarque Sandstone......

Moreno Hill Formation ...... \DUU‘bUUD-I

II. METHODS AND PROBLEMS ...... OOOOOOOOOOOOOOOOO 11

Source of Samples ...... 11 Preparation Procedure ...... 14 Analytical Methods ...... 15 Quantitative Analysis ...... 17 Unknown or unidentifiable species .... 17 Analytical Problems ...... 18 Stratigraphic distribution of palynomorphs ...... 18 Drilling mud contamination ...... 19 Weathered vs. unweathered samples .... 19

III. RESULTS OF STUDY 0...... OOOOOOOOOOOOO 21

Resolution of Drilling Mud Contamination Problem ...... 21 The Relative Representation of Palynomorphs in Weathered vs. Unweathered Samples ...... 22 Problem of Representation of Palynomorphs from Well-cuttings ...... 24 Palynologic Zonation of Principal Reference Sections ...... 26 Selection of pollen-spore assemblages 26 Zonation of the Moreno Hill outcrOp section ...... 26 Rio Salado zone ...... 26 Atarque zone ...... 27 Lowest coal zone (AnteIOpe) ...... 28 Middle coal zone (Lower Rabbit) ... 29 Upper coal zone (Upper Rabbit) .... 29 Zonation of well 517-25-1 ...... 30 Cerro Prieto coal zone ...... 30 Lower Rabbit coal zone ...... 31 Upper Rabbit coal zone ...... 31

111 Zonation of well 519-21-1 ...... 32 Rio Salado zone ...... 32 Atarque zone ...... 32 Lower zone of the Lower Member of the Moreno Hill Fm...... 33 Upper zone of the Lower Member of the Moreno Hill Fm...... 33 Upper Moreno Hill Member ...... 34 Cluster Analysis ...... 46

IV. PALYNOLOGICAL CORRELATION ...... 52

Rio Salado Zone ...... 54 Atarque Zone ...... 55 Coal Zone A (Antelope) ...... 56 Coal Zone B (Cerro Prieto) ..... 60 Coal Zone C (Lower Rabbit) ..... 61 Coal Zone D (Upper Rabbit) ...... 64 Correlation To Other Wells and Outlying

outcrop sections ...... OOOOOOOOOOOOOOOO 65

V. PALEOENVIRONMENTAL INTERPRETATIONS 67

Pollen-Spore Assemblages ...... 71 Assemblage l. Off-shore marine shale and siltstone (Figure 20) ...... 71 Assemblage 2. Near-shore or brackish shale and siltstone (Figure 21) .... 77 Assemblage 3. Fern-dominated shale (Figure 22) ...... 77 Assemblage 4. Angiosperm-dominated shale (Figure 23) ...... 78 Assemblage 5. Interbedded coal and shale (Figure 24) ...... 79 Other Dispersed MicroscOpic-Sized Plant Detritus ...... 79 Paleoecological Reconstruction ...... 81

VI. CONCLUSIONS 00...... OOOOOOOOOOOOOOOOOO 9O

BIBLIOGRAPHY O...... OOOOOOOOOOO...... OOOOOOOOOOOO 92

APPENDIX 1. List of Samples used and Abbreviated

Lith01°81c Description ...... OOOOOOOOOOOOOOIOO 102

APPENDIX II. Species List ...... 105

PLATES 0.0.0.0....O0.0...... OOOOOOOOOOOOOOOOOO 110

iv LIST OF FIGURES

FIGURE

Map of New Mexico indicating area of study ..... p. 2

Diagram showing stratigraphic relationships in

BtUdy area O...... OOIOOOOOOIOOOOOOO00.0.0000...

Stratigraphic cross-section from Moreno Hill to

Gallup area OOOOOOOOOIOOOOOO...... OOOOOOOOOOOOO.

Diagram showing measured sections and sample intervals from the Moreno Hill locality ......

Map showing sample localities and extent of

Gretaceous outcrop exposure ...... OOOOOOOOOOOOOO 12

Diagram showing generalized stratigraphic columns and sample intervals of the four principal reference sections ...... 13

Diagram showing local range and occurrence of selected pollen and spores from the principal

reference sections ...... OOOOOOOOOOO...... OOOOOO 36

Diagram of well 519-21-1 showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage ...... 37

Diagram of well 519-21-1 showing the frequency of major gymnosperm groups relative to the total

gymnosperm pOPUIation 000...... OOOOIOOOOOO 38

10. Diagram of the Moreno Hill section showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage .. 39

11. Diagram of the Moreno Hill section showing the frequency of major gymnosperm groups relative to the total gymnosperm population .... 40

12. Diagram of well 517-25-1 showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage .. 41

13. Diagram of well 517-25-1 showing the frequency of major gymnosperm groups relative to the total gymnosperm population .... 42

V 14. Diagram of the USGS well #1 showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage .. 43

15. Diagram of the USGS well #1 showing the frequency of major gymnosperm groups relative to the total gymnosperm population .... 44

16. Diagram of the principal reference sections with lines indicating correlations between sections based on relative abundance peaks of selected pollen-spore groups and taxa ...... 45

17. Diagram resulting from cluster analysis ...... 50

18. Diagram of the principal reference sections showing stratigraphic and geographic distribution of sample clusters indicated in Figure 17 ...... 51

19. Diagram of the principal reference sections indicating palynologic zones of correlation ..... 53

20. Pollen-spore Assemblage 1 of off-shore marine shale and siltstone ..... 72

21. Pollen-spore Assemblage 2 of near-shore or brackish shale and siltstone ...... 73

22. Pollen-spore Assemblage 3 of fern-dominated shale in the Lower Member of the Moreno Hill Fm., Moreno Hill section ..... 74

23. Pollen-spore Assemblage 4 of angiosperm dominated shale in the Lower Member of the Moreno Hill Fm.. 75

24. Pollen spore Assemblage 5 of interbedded coal and shale in the Lower Member of the Moreno Hill Fm.. 76

vi Palynological Investigation of the Moreno Hill Formation

(Upper Cretaceous), west-central New Mexico

Kurtis C. Kelley

BACKGROUND AND PURPOSE

A project of geologic subsurface mapping of the Atarque

and Moreno Hill formations was begun several years ago by

the New Mexico Bureau of Mines and Mineral Resources and the

U.S. Geological Survey as part of a larger mapping project

in the San Juan and Zuni Basins in New Mexico. The Moreno

Hill Formation is principally a non-marine sequence, in part

interdigitated with marine strata. Palynological analysis

is a useful method for age determination and biostratigraphic correlation of these rocks. Sampling for

palynological analysis of the Moreno Hill Formation was

initiated in 1979 under the direction of Prof. A.T. Cross of

Michigan State University. The writer joined this project

in 1981 to make a detailed palynologic analysis of these

rocks as the tapic of a Master of Science thesis.

Objectives:

The fundamental purpose of the palynologic study of the

Atarque and Moreno Hill Formations in the Fence Lake area of west-central New Mexico is to provide useful data in the

subsurface mapping of this region (Figure l) and to assist

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-... too 200 km ___1 l I . I \ n IOOrm

area of study. of New Mexico indicating FIGURE 1 - Map and landward Tree Hermanos Formation Seaward extent of Shale are D-Cross Tongues of Mancos extent of Pescado and fig. 1.) Molenaar and Cobban, 1983, indicated. (after Hook, in resolving some of the stratigraphic problems. This type

of analysis is particularly significant in non-marine

sediments where correlation using marine invertebrates is

not possible.

Specifically, the objectives are:

(1) Determine the local stratigraphic range of pollen and

spore taxa contained in these rocks.

(2) Document pollen-spore assemblages of coal zones.

(3) Provide data on environments of deposition.

(4) Identify any marine or near-marine invasions into the

area during the Upper Cretaceous Atarque and Moreno Hill

time.

(5) Correlate strata based on the biostratigraphic data

gained through this study.

(6) Compare and contrast the palynologic content of

various types of samples studied (outcrops, well-cuttings).

(7) Verify the importance of recognizing contaminants

introduced during drilling.

Previous Studies:

Geology and stratigraphy: The stratigraphy of the

Moreno Hill and Atarque Formations has recently been described in detail by McLellan and others (1982, 1983a,

1983b, 1983c). Other paleontological and stratigraphic studies in west-central New Mexico pertinent to this study include 0.J. Anderson, 1981, 1982a, 1982b; Campbell, 1981,

1984; Campbell and Roybal, 1983; Cobban and Hook, 1979, 1983; Gadway, 1959; Hook and Cobban, 1979, 1980, 1981; Hook,

Cobban and Landis, 1980; Hook, Molenaar and Cobban, 1983;

Molenaar, 1973, 1983; Pike, 1947; Roybal and Campbell, 1981; and Sears, 1925. The lower Member of the Moreno Hill

Formation in the Fence Lake area appears to range in age from Middle to Early-late Turonian based on marine megafossils found in the Atarque and Rio Salado Formations and in the upper Tres Hermanos Formation to the north and west (Cobban and Hook, 1983; Hook and Cobban, 1983; McLellan et a1., 1983a).

Palynology: There are relatively few publications describing pollen and spores from Turonian rocks in North

America. Previous studies on the palynology of Cretaceous rocks in Western North America are outlined in detail by

Jameossanaie (1983). Palynological reports particularly pertinent to this study, on the basis of both age and location are: Brown and Pierce, 1962; Burgess, 1971;

Griesbach, 1956; Griggs, 1970; Nichols and Jacobson, 1982;

Orlansky, 1971; Romans, 1972, 1975; Sarmiento, 1957; Stone,

1967; Thompson, 1969; Tschudy, 1961, 1976, 1980, and Upshaw,

1959, 1963, 1964. Most palynological studies of Cretaceous strata in the western United States are of much younger formations. Debra Dufek is completing a PhD dissertation at this time on the Ferron coals of Castle Valley, Utah which are of nearly comparable age. This study is the first palynological investigation to be performed on rocks in the

Zuni Basin. Geology:

The Atarque and Moreno Hill Formations in Cibola and

Catron Counties, New Mexico, represent a sequence of Lower

Cretaceous marginal marine and non-marine sediments located stratigraphically between the Rio Salado Tongue of the

Mancos Shale and the Tertiary Fence Lake gravels (Figure 2).

To the north and east, the Atarque Formation is laterally equivalent to the Atarque Member of the Tres Hermanos

Formation. The Moreno Hill Formation is laterally equivalent, in part, to the Tres Hermanos Formation, the

Pescado Tongue of the Mancos Shale in the Zuni Basin

(equivalent to the D-Cross Tongue in the Acoma Basin), the

Gallup Sandstone, the Mesa Verde Formation, and possibly the lower Crevasse Canyon Formation (Hook et a1., 1983),

(Figures 1 and 3). The Salt Lake Coal Field is located in the Zuni Basin. The Zuni Basin is separated from the San

Juan Basin to the north by the Zuni Uplift. Goals in the

Salt Lake Coal Field are distributed locally and are included in the Moreno Hill Formation. They are, in ascending order, the Antelope, Cerro Prieto, Rabbit, and

Coyote coals.

Atarque Sandstone: The outcrOp section of Atarque

Sandstone was measured and sampled at the base of Moreno

Hill along Route 32, Cibola County, New Mexico (Figure 4).

It is 92 ft. thick in this section. The base of this section is in the SW 1/4 sec.7, T4N, R18W. This appears to be only several hundred feet east of the designated A . o C Tertiary Fence Lake Formanon .' AL, ‘ 11

Upper Cretaceous

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FIGURE 2 - Diagram showing stratigraphic relationships 1n study area. (after Anderson, 1982a)

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_ ‘l -'. “ . I I .1- I. g __ 05132" '- ”1“ H Mancos Shale I ¥ «— ﬁlo Salado—v <—Atarque Fm. Moreno Hlll Fm. V Tongue (Lower mbr.) IMdduI Sandstone Figure 4 - Diagram showing measured sections and sample intervals from the Moreno Hill locality. Lines are drawn between equivalent stratigraphic units. Bracketed zones to the left of each individual measured section indicate' rock units from which samples were collected. Pb numbers indicate productive samples.

principal reference section (McLellan et a1., 1983a) and

about 1.5 miles northwest of the measured section at Moreno

Hill studied by Molenaar (1973).

The Atarque is a regressive series of coastal-barrier

bars which prograded northeastward into the Mancos seaway

(Hook et a1., 1983; McLellan et a1., 1983a). The Atarque in

this section is represented by a series of interbedded

sandstones, siltstones and shales. The basal sandstone unit

is even-bedded and lies conformably on the Rio Salado Tongue

of the Mancos Shale. The top of the Atarque here is a two-

foot thick, extensively burrowed, root-penetrated sandstone

which weathers to a purplish color in zones. To the north

and east, beyond the landward pinchout of the Pescado or D-

Cross Tongue of the Mancos, the Atarque Sandstone is

referred to as the Atarque Member of the Tres Hermanos

Formation (Hook et a1., 1983).

Moreno Hill Formation: The Moreno Hill Formation

consists primarily of a series of non-marine, interbedded

sandstones, siltstones, shales and coals. The siltstones

and sandstones are of fluvial origin, laterally

discontinuous, and probably represent channel and crevasse

splay deposits. The shales, carbonaceous shales, and coals

are thought to have been deposited in interchannel

bottomlands and fresh-water marsh or swamp environments as

overbank and peat deposits on prograding coastal or delta

plains of low relief. Hook et a1. (1983) characterize the

Tres Hermanos Member of the Tres Hermanos Formation, which 10 is the lateral equivalent of part of the lower Moreno Hill

Formation, in that way. The Fence Lake Formation, of middle

Tertiary age, unconformably overlies the Moreno Hill

Formation in the study area. This formation is primarily composed of unconsolidated sandstones and conglomerates deposited after deep erosion of the Moreno Hill rocks

(McLellan et al., 1982b, 1983a). The Upper Member of the

Moreno Hill Formation is not present at the Moreno Hill section or in wells USGS #1 and 517-21-1 to the east. It is, however, present on well 519-21-1. 11

METHODS AND PROBL§§§

Source of Samples:

Samples were obtained from outcrOps and rock chips from

coal test wells (Figures 5 and 6, and Appendix 1). Initial

palynological sampling of the Salt Lake Coal Field was

conducted from outcrop sections during the summer of 1979 by

Prof. Aureal T. Cross of Michigan State University. In the

summer of 1981, the writer joined Dr. Cross in New Mexico

where we measured and sampled an additional 650 feet of

outcrop section of the Atarque and the Lower Moreno Hill

strata (Figure 6). Dr. Cross returned to the study area

during the summers of 1982 and 1983 for additional measurements and sampling.

OutcrOps were selected for sampling on the basis of

overall stratigraphic coverage, the extent of continuous vertical eXposure, and on a visual assessment of the degree of weathering. Trenches were dug in an attempt to obtain

samples minimally affected by deep, surface weathering.

Sample wells were selected on the basis of the proximity of the wells to the outcrOps in order to provide an east- west trending transect of samples through the Salt Lake Coal

Field. Samples used in this study include rock chips from coal test wells 519-21-1, 517-34-1 and 517-25-1.

Collections spanned the upper part of the Rio Salado

Tongue of the Mancos Shale, the Atarque and the Moreno Hill

Formations. The Fence Lake (Tertiary) gravels overlie the 12

FIGURE 5 — Map showing sample localities and extent of Cretaceous outcrop exposure. (after Campbell, 1981, fig. 1) 13

and

.I .. ‘ . .' .

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I ‘-n sections.

I ll -1

Hull USGS l . I-°

reference : a . stratigraphic

principal

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intervals

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‘l 1.00!) impom‘] 50-01 ' In (“no“) we -. InOIVlV WI 1"“ ON’IOH mono; 00"" 0" lav: IJNIffi [0-0.4

FIGURE

sample

Moreno Hill Formation unconformably in the study area.

Preparation Procedure:

(1) Crush entire sample to about 1mm. Mix thoroughly and measure out a representative 10 gram aliquot.

(2) Place sample in a 90 ml polyprOpylene centrifuge tube and cover with 102 HCl to about 5 cm depth. Let stand,

stirring occasionaly until reaction with carbonates ceases

(5 to 60 minutes).

(3) Wash 3 times, each wash followed by centrifugation and pipetting off supernatant liquid.

(4) In ice bath, slowly add 52% HF to a depth of about 10 cm taking care not to allow reaction to get hot enough to boil. Either place tube in ice bath or add HF over crushed ice in tube with residue. Allow HF to react with sample for

18 to 24 hours.

(5) Wash 3 times by centrifuging and pipetting off supernatant liquid or decanting.

(6) If the sample is very carbonaceous or coaly, transfer sample to 40 ml glass centrifuge tube and cover with

Schulze' solution (1 part KC103 + 5 parts HNO3) to 5 cm depth. Allow oxidation to continue from 5 minutes to 48 hours or until spores are free. Intermittent examination of temporary mounts of residue are made to determine length of

time required. Most claystones, shales and siltstones did not recieve this treatment but preparation continued directly to step 7 from step 5.

(7) Add 52 KOH to a depth of 8 cm in the centrifuge tube 15

and allow to react for 5 minutes, stirring occasionally.

(8) Wash until clear.

(9) Stain to moderate intensity with Safranin O.

Centrifuge and decant (Do not overstain).

(10) Transfer sample to 10 dram vial and fill with BBC

(hydroxyethyl cellulose, Fisher Scientific Co.). Suspend

sample by stirring and allow to settle for 24 hours. Draw off liquid and repeat until liquid is clear; this removes fine particles and clays.

(ll) Dilute the REC (which contains the residue) with water to give satisfactory concentration of residue on slide. Place coverglass on warming table and spread a bead of diluted residue on coverglass surface. Allow to air dry.

Place 1 or 2 drops of Kleermount mounting resin or other sealant on center of coverslip and lower microscope slide to touch drop of resin. The coverslip will be drawn onto the slide. The slide is then turned over (coverglass up) and allowed to dry on the warming table for 48 hours.

Analytical Methods:

All of the mounted residues were studied and palynomorphs identified using 54x or 95x oil immersion objectives and 10x or 15x oculars on a Leitz Orthomat microscope, Michigan

State University number G62667. The magnification required for accurate identification was determined after making 4 separate counts using 25x dry, 40x dry, 54x oil immersion and 95x oil immersion lenses on several samples. The raw 16

data from those counts were then subjected to Chi Square

analysis to determine if there were significant differences

in the species data obtained on the same sample using

different magnifications. In all cases, an unacceptable

margin of difference was indicated except between the 54x

and 95x oil immersion objectives, which showed no

significant differences. Two factors causing these results

are the greatly increased resolution gained over the lower

power dry objectives by using the higher power oil immersion

lenses and the small size and very fine sculpturing of the

exine of many pollen grains and spores found in these

samples. The resolution possible using the 40x objective is

not sufficient to differentiate many of the sculpture

patterns, particularly on eroded or otherwise poorly

preserved grains.

Four vertical traverses were made for each slide,

beginning at 3 mm from the upper left corner of the cover

slip. Each successive traverse was made 5 mm to the right

of the previous traverse. A maximum of 50 pollen grains and

spores were counted in any single traverse. This was

continued for each sample at least until a species-area

curve for that sample leveled off. Most leveled off between

90 and 140 specimens. Counts were continued to at least 200

in all but 3 samples. These samples were either largely monotypic, in which case the slides were still scanned for

other species, or the entire macerated portion of the sample

yielded less than 200 grains. In samples which were 17

dominated by one or two species, additional counts were made

to gain information otherwise masked by the dominant

species. All slides were scanned for rare species.

Quantitative Analysis:

After completing the identification (Appendix II) and

tabulation of palynomorph abundances, the raw species data were grouped into 16 categories and subjected to Cluster

Analysis following the procedures of Jameossanaie (1983).

The groups differentiated are: "tricolpate pollen"; ”tricolporate pollen"; "Phimopollenites"; ”Liliaceae” (monocolpate

pollen); ”Taxodiaceous pollen”; Classopollis/

Exesipollenites"; "other gymnosperms"; ”inaperturate grains

of uncertain affinity"; "Gleicheniaceous spores";

"Schizaeaceous spores"; "other ferns"; "Bryophytic spores";

"Lchpodiaceous spores"; "acritarchs"; "dinoflagellates";

"other marine grains". This analysis was performed by Dr.

Abolfazl Jameossanaie, using a modification of the Chi

Square test as a similarity index, on an Apple II computer.

Unknown or unidentifiable species: Identification of fossil palynomorphs is not always possible. Biodegradation prior to burial, poor preservation, imprOper maceration, and physical distortion or damage during burial, weathering or sample preparation are some of the factors contributing to the difficulty of identification. In many such cases, identification to a specific morphospecies is not possible and such entities can only be assigned to a higher taxonomic 18

level such as genus, family, or, in some cases, larger general groups such as "angiosperm", ”pollen", "dinoflagellate” or ”trilete spore”. These catagories can be very useful in some applications. Palynomorphs are always assigned to the lowest taxonomic level possible.

"Unknown” grains are those palynomorphs that have characters that may permit identification by students who have more experience or knowledge. These are designated as

"unknown sp. 1", "unknown sp. 2" etc., and included in the total count.

Analytical Problems:

Stratigraphic distribution of palynomorphs: Strati- graphic range information for palynomorphs can be misleading when based on well-cutting samples. Two major factors may affect such samples: caving of rock from uncased walls of the hole as drilling proceeds, and the introduction of foreign pollen contained in the water or the mud used in drilling.

Rock chips from levels higher in the well than the stratigraphic levels of samples being collected may occur in the samples. For this reason, only the youngest occurrence or tap of the stratigraphic range can be considered reliable. Caution should be exercised when identifying earlier limits of stratigraphic ranges from samples collected from drill cuttings. 19

Drilling mud contamination: Well-cutting samples, contaminated by a fossiliferous drilling mud, can present a

problem in many phases of pollen-spore analysis. Palyno- morphs introduced in a drilling mud made from rocks of a very dissimilar age can generally be recognized and therefore readily dealt with. However, the presence of palynomorphs in a drilling mud composited of rock of the same age, or of an age closely approximating that of the strata being studied, can affect both the qualitative and quantitative information being collected. Similarly, drilling mud thinners, used to counteract thickening of drilling mud by clay particles, may contain very large numbers of pollen and spores. In a paper by Traverse and

Clisby (1961), the pollen and spore content of various commercial mud-thinners was investigated. Most were found to be fossiliferous and, in one case, an oxidized lignite,

"Carbonox”, contained over 4 million pollen and spore grains per gram of thinner.

The possibility of sample contamination by foreign pollen and spores introduced through the drilling-mud can be a sobering experience and was encountered in this study. (See

"Resolution of Drilling Mud Contamination Problem” at the beginning of the "RESULTS" section).

Weathered vs. unweathered samples: Weathering of exposed rock can have an influence both on the relative number of productive samples from outcrop sections and on the identification of palynomorphs. Weathering may, also, 20

selectively destroy spores (Cross, 1964). The effects of this on pollen-spore analysis should be considered. (See

”The Relative Representation of Palynomorphs in Weathered vs. Unweathered Samples" in ”RESULTS” section). 21

RESULTS OF STUDY

Resolution of Drilling Mud Contamination Problem:

One sample of drilling mud was sent following the

original request for samples of the muds used in drilling

the coal test wells considered for this study. After

further inquiry, it was discovered that well 519-21-1 was

drilled using a mixture of seven different commercial muds

and mud thinners, one of which proved to be compounded from

a very fossiliferous bentonitic clay apparently of Albian or

Aptian age. This is relatively close to the preliminary

early-late Cretaceous palynological age determination for

the Moreno Hill Formation which was based on information

from the Moreno Hill outcrOp and on air-drilled samples.

After a thorough study of the drilling mud, it was determined that the drilling mud contained 81 palynomorph

species and that only 10 of these were also common to the

strata penetrated by well 519-21-1. These ten taxa also occur in rock from the outcrOp and/or air-drilled well samples. The remaining 71 drilling mud palynomorphs, which overwhelmingly dominated the drilling mud sample, were not found anywhere in the Moreno Hill samples. This indicated that the extensive palynoflora of the drilling mud could be entirely excluded from analysis and would not likely significantly affect the quantitative information obtained from the Moreno Hill samples, particularly when included in larger groupings where 10 species common to the drilling mud 22 flora are of minor significance. Stratigraphic range distribution data for these 10 species were not used for correlation purposes. The 10 pollen and spore species are:

Acritarch type 1; Alisporites sp.; Classopollis sp. A.;

Cycadopites spp. A and B; Rousea georgensis; Taxodiaceae-

pollenites; Tricolpites spp. A and C; and Unknown sp. A.

The Relative Representation of Palynomorphs in Weathered vs.

Unweathered Samples:

Weathering of the exposed rock in the Moreno Hill samples appears to present a significant problem in making a palynological analysis both in the identification of grains and in the relative number of productive samples. This does not, however, appear to be a problem in the well samples.

43 outcrop samples from the Moreno Hill locality along Route

32, and 90 samples of well-cuttings from two wells were originally prepared for this study using standard palynologic techniques. More than 80% of the well- cuttings samples yielded pollen and spores in sufficient numbers and of satisfactory condition for study. Only 22 of the 43 outcrop samples or about 512 were similarly suitable for study.

All major genera represented in the subsurface wells are also found in the outcrop section at Moreno Hill. However, certain grains, commonly found in samples from the subsurface wells, are noticably rare or difficult to identify in outcrop sample preparations. The most noticable 23 of these grains are the angiosperm pollen yyssapollenites

and the spore genera Stereisporites, Distverrusporites and

Cingutriletes. No obvious reason for the rarity of

Nyssapollenites in outcrop sample preparations is

understood. Nyssapollenites appears to have a relatively

thick exine. The lack of this pollen in samples from outcrOp exposures may be due, in part, to a particular susceptibility of the exine to secondary oxidation caused by deep weathering of surface or near-surface sediments.

Stereisporites, Distverrusporites and Cingutriletes are

believed to have affinities with plants in the order

Sphagnales. The relatively thin, distal and proximal faces of these grains were often observed, in slide preparations,- in various states of degradation, and were sometimes completely absent, leaving only the cingulum or thicker exine of the equatorial region. Without the proximal and distal faces of these spores, identification is difficult and often impossible.

In general, palynologic preparations of outcrop samples which were countable were rated only as ”fair“ or "good”.

This rating is based on the abundance and physical condition of palynomorphs in slide preparations and indicates that significant degradation was apparent on pollen and spore walls. Besides size, shape, aperture configuration, and staining qualities, exine sculpturing is critical for the accurate identification of fossilized palynomorphs. The loss or partial destruction of exine ornamentation features, 24

either because of oxidation before entrapment in sediments,

later weathering, poor preservation, diagenetic alteration,

or improper laboratory preparation makes the identification

of palynomorphs to lower taxonomic ranks difficult. The net

result is the placement of grains into larger categories

such as "angiosperms" or ”trilete spores” because not enough

sculpturing patterns remain for assignment to species or

genera.

Well-chip samples were generally rated as "good" or

"exellent" indicating a minimum of exine degradation and the

preservation of sufficient characters for critical

identification.

Problem of Representation of Palynomorphs from Well-

cuttings:

Though palynologic preparations from subsurface rock-chip

samples yielded better results overall, than from outcrop

samples, the sampling resolution is considerably less accurate. Rock-chip samples were collected in five- foot

intervals, regardless of lithologic breaks. This often results in more than one rock-type being included in a single sample. This is a distinct disadvantage when compared to the fine sampling resolution possible when

taking lithologically constrained samples from rock outcrOps.

A good example of just this type of problem, drawn from this study, concerns the palynologic analysis of the coals. 25

Coal samples from the outcrop section at Moreno Hill Were collected as distinct lithologic units. Pollen and spores were absent or so severly degraded that no or only questionable identifications could be made. Larger plant tissues, such as cuticle and woody fragments, were, however, distinguishable, even in highly degraded states, based on their gross structure. In this case, no reliable pollen- spore data of the coal could be obtained but potentially useful information was gained on specific coal seams by the presence and general abundances of larger plant tissues.

In contrast to the outcrop samples, the highest percentage of coal in any single rock-chip sample from the subsurface wells, in this study, is about 352. The rest of the sample is primarily shale fragments representing strata interbedded with the coals. Pollen and spores are abundant and generally in very good condition but represent not only the coal but also the shale. In this case, different depositional environments are represented in the pollen spore data of a single sample and this presents the problem of separating the probable constituents of each. (See discussions in "PALEOENVIRONMENTAL INTERPRETATIONS” section under ”Assemblage 5. Interbedded coal and shale" and also

”Paleoecological Reconstruction"). 26

Palynologic Zonation of Principal Reference Sections:

Selection of pollen-spore assemblages: Zonation and correlation of the lower Moreno Hill Formation is based on individual palynomorph occurrence and range (Figure 7); on relative abundance of individual species, genera and selected groups of palynomorphs; and on comparative gymnosperm frequencies (Figures 8 through 15). Grouping pollen and spores into larger categories, such as "angiosperms",

"ferns", ”inaperturate grains of uncertain affinity", and

”Classopollis and Exesipollenites" is considered useful in

indicating general local environmental trends. Disregarding other groups and comparing the relative abundances of individual gymnosperms may further assist in defining environments and vegetation in and around the peat swamps that were the source of coal deposits. Gymnosperms were separated into four groups; (1) "Cycads" (cycad-like pollen), (2) "Taxodiaceaepollenites", (3) "Classopollis/

Exesipollenites", and (4) "bisaccates". The first three

groups were the most useful.

Zonation of the Moreno Hill outcrop section:

Rio Salado Zone: Pb 13587-13592. The Rio Salado

Zone is characterized by a very high frequency of pollen of the ClassoPOIIislExesipollenites complex (24-532). Palyno-

morphs assignable to marine algae (acritarchs and dinoflagellates) are rare (less than 12). Angiosperms are common (11-372) and the frequency of ferns is generally low 27

(0-41). Inaperturate grains of uncertain affinity range between 102 and 351. Tricolpites sp. D is found throughout

this zone (0.5-32) but is absent or very rare through the rest of the section. The microfossil flora of the Rio

Salado zone is generally low in diversity (between 10 and 15 different species in each sample). Cluster analysis groups all the samples in this zone together with Pb 13116, which is from the lowermost coal zone of the Moreno Hill Formation

(deposited directly at the tap of the Atarque Fm. in this section) as a distinct cluster. This is probably due in a large part to the very high frequency of Classopollis.

Atarque Sandstone Member: Pb 13493-13494). An abrupt change in the microfossil flora occurs above the Rio

Salado sediments in the Atarque Sandstone sedimentary complex. ClassOpollis, the dominant palynomorph in the Rio

Salado samples in the Moreno Hill outcrop section, is only a minor constituent in the Atarque (0-72). Angiosperms are low (1-72); fern spore frequency is generally unchanged; and marine dinoflagellates and acritarchs gain complete dominance. The lowest sample (Pb 13493) contains a diverse assortment of marine algal grains (acritarchs and dinoflagellates) that comprise 47% of the palynomorphs present. Pb 13494 contains less than 21 of these marine forms and is dominated by inaperturate grains of uncertain affinity. These unknown grains mask the importance of the marine component. Removing the inaperturate grains of uncertain affinity from consideration, sample Pb 13493 28 yields more than 952 marine taxa with the remaining material representing terrestrially derived pollen and spores.

Lowest Coal Zone (Antelope): Pb 13111-13121. The lowest coal zone in the Moreno Hill outcrop section is distinctly different from the Atarque and from any of the coal zones further up-section. The relative frequencies of inaperturate grains of uncertain affinity, ferns, and

ClassOpollis fluctuate widely through this zone, and marine

algae are absent.

Inaperturate grains of uncertain affinity are dominant

(602) in the lowest sample in this zone (Pb 13111).

Angiosperm pollen are common (27%); and Classopollis and

ferns are low at 12 and 4X, repectively. The shale sample immediately below the first coal bench (Pbl3112) shows a dramatic increase in the relative abundance of fern spores

(931). Between the first and second coal benches, in sample

Pb 13116, Classopollis is again dominant (422). This

dominance of Classopollis, together with the other plant

constituents (222 angiosperms, 182 inaperturate grains of uncertain affinity, and 62 ferns), makes this palynoflora very similar to that of the Rio Salado samples and cluster analysis groups them together. Following the second coal

(sample Pb13120), ferns are again the dominant palynomorph group (372) along with 372 inaperturate grains of uncertain affinity, 212 angiosperms and less than 12 Classopollis.

The highest sample in this zone (Pb 13121) is dominated by

982 inaperturate grains of uncertain affinity. It is 29 important to note that this coal zone is overwhelmingly fern-dominated when these inaperturate grains of uncertain affinity are removed from consideration.

Middle Coal Zone (Lower Rabbit): Pb 13127-13135.

The middle coal zone can be distinguished from the lower coal zone by a much higher relative abundance of angiosperms

(752 in Pb 13127 gradually decreasing upward to 162 in Pb

13132 and increasing again to 742 in Pb 13135), and a much lower frequency of ferns (4-341) and inaperturate grains of uncertain affinity (5-352). Cycad- like pollen is usually important in these samples and generally dominate the gymnospermous population. In the lower coal zone,

Taxodaceaepollenites and ClassOpollis are the dominant

gymnosperm taxa.

Upper Coal Zone (Upper Rabbit): Pb13136-13141.

The upper coal zone is similar to the middle coal zone in having a high but decreasing angiosperm relative abundance

(81-48%), a generally low to moderate frequency of fern spores (1-121) and a low to moderate frequency of inaperturate grains of uncertain affinity (0-162). The upper two samples in this zone contain marine acritarchs though they are rare (0.5-12). The comparative gymnosperm diagram (Fig. 9) shows a shift from the cycad-type pollen dominated middle coal zone to an alternating ClassOpollis-

Taxodiaceaepollenites-Classopollis pattern.

The palynoflora of the basal sample in this zone (Pb

13136) is notably different from that of the rest of this 30

zone. This sample appears to contain more than 992 of a

single algal-like cyst (unknown sp. 248), whose morphology

and affinities are not understood, but appears to represent

a marine or brackish water organism. This palynomorph was

found in only one other sample (from well 517-25-1) where

its relative frequency is 231 and where it is found

associated with marine acritarchs and unknown sp. 249.

Zonation of Well 517-25-1:

Cerro Prieto Coal Zone: Pb 13636-13628. The

lowest sample in this zone (Pb 13636) has the lowest

angiosperm frequency (291) for this well section, except for

sample (Pb 13619) at the t0p. It lacks Phimopollenites, which appears to be a good marker species for the rest of

this zone. Above this lowest sample of the Cerro Prieto

coal zone, a diverse angiosperm flora dominates (42-802).

Inaperturate grains (6-122) and ferns (2-172) are both generally in low percentages. Cycad-type pollen and the

ClassOpollis/Exesipollenites complex both reach a maximum

for samples from this well. Cycad-types decrease from 162 in Pb 13636 to less than 12 above the main coal and the

ClassOpollis/Exesipollenites complex follows a similar pattern of decline from 152 to 02. One dinoflagellate (sp.

7) was found in Pb 13631 just below the main coal. Its significance is conjectural but it may have been recycled.

Cycad-type pollen tends to dominate the gymnospermous population, in this well, through this and the lower Rabbit coal zone above. 31

Lower Rabbit Zone: Pb13627-13623. The lower

Rabbit Zone is palynologically very similar to the Cerro

Prieto Zone but PhimOpollenites is rare and occurs only in

the lower three samples (Pb 13627-13625). The cycad complex, while important (1-102), is not as common as in the

Cerro Prieto. It peaks above the main coal in this zone rather than below it. Angiosperms are dominant, comprising

56 to 69% of the population; ferns are 5-142; inaperturate grains, 7-92; and the Clas30pollislExesipollenites complex is less than 32.

The lower Rabbit Zone is very similar to the Moreno Hill middle coal zone in diversity and overall pollen-spore frequency distribution. There is a very high peak for cycad-like pollen on the comparative gymnosperm diagram in this zone from both the well and the outcrop (Figure 12).

Of particular note is the number of palynomorphs either restricted to or ending in the samples in and just above the main coal in the lower Rabbit Zone (Pb13626-l3625) in well

517-25-1 and just above the coals in the middle coal zone of the Moreno Hill section (Figure 7).

Upper Rabbit Zone: Pb 13951, 13622-13619. The upper Rabbit Zone is also angiosperm dominated (52-622) and inaperturate grains are low (4-92) except in the upper sample (Pb 13619) where angiosperm frequency drops to 252 and inaperturate grains are 392. Ferns fluctuate between 13 and 32, and the ClassOpollis[Exesipollenites complex does not exceed 42. 32

Zonation of Well 519-21-1: Distribution of the palynomorphs in the rock-chip samples (well-cuttings) of the

Moreno Hill, Atarque and Rio Salado Formations here is generally too gradual or "blended” to make a clearly defined zonation of this section. This may be attributable in part to the limited stratigraphic section studied but is more probably due to mixing of cuttings during drilling and sample recovery. Zonation of this section is therefore less precise, although reasonable correlation to the Moreno Hill

Outcrop Section is possible on the basis of general trends in pollen-spore frequency.

Rio Salado Zone: (Pb 13185- 13170). The Rio

Salado zone here is characterized by a low frequency of marine algal cysts (less than 0.6%). The relative frequency of pollen in the Cla380pollis/Exesipollenites complex is high (261) in the lowest sample (Pb 13185) and decreases upward to 22 in Pb 13170. There is a very low frequency of cycad-type pollen (less than 22). Ferns range from 9-172; inaperturate grains of uncertain affinity increase upward from 262 to 39X. Angiosperm pollen (11-372) generally shows low diversity here (6-8 species in counts of 200 specimens).

Both Classopollis and Taxodiaceaepollenites are dominant in

the gymnosperm population (27-742 and 23-842 respectively).

Atarque Zone: Pb 13206, 13202). The Atarque Zone, in this well, is very similar to the Rio Salado zone. It differs in having a slightly higher relative abundance of marine acritarchs and dinoflagellates (0.5-1!) and a 33 consistantly low frequency of pollen in the ClassoPOIIis/-

Exesipollenites complex (32). This zone is further

characterized by having a high comparative gymnosperm frequency of Taxodiaceaepollenites (68-792). Fern frequency

ranges from 10 to 142.

Lower zone of the Lower Member of the Moreno Hill

Fm.: Pb 13198-13194. This zone, at the base of the Moreno

Hill Formation, is very similar to the Atarque zone below.

The cluster diagram (Figure 17) also shows these samples linking very closely to the Atarque samples. In general, this zone has a slightly higher frequency of marine microfossils (<1-3Z). The relative frequency of angiosperm pollen is variable (29-472). Fern spore frequency ranges from 72 to a distinct peak of 262 in sample Pb 13197.

Pollen from the C1a830pollislExesipollenites complex is

uncommon (<1-4Z). Taxodiaceaepollenites ranges from 44 to

912 relative to the gymnospermous population. The 912 high for Taxodiaceaepollenites occurs as a pronounced peak in Pb

13195. Inaperturate grains of uncertain affinity range from

192 to a peak of 341 in Pb 13195.

Upper zone of the Lower Member of the Moreno Hill

Fm.: Pb 13193-13190, 13406. Five closely spaced samples represent this zone. This zone is overlain, unconformably, by the Moreno Hill ”Middle Sandstone". The most significant difference between this zone and the zones below is the lack of a marine palynoflora here and overall lower relative frequency of inaperturate pollen of uncertain affinity. 34

The average relative frequency for the angiosperms is the highest in this section, ranging from 39 to 572. Ferns show

slight fluctuations but range between 17 and 292.

Inaperturate grains of uncertain affinity (8-182) and pollen

percentages of the Clas80pollis/Exesipollenites complex are

low (0-72).

Shifts in the relative abundances of Taxodiaceae-

pollenites and ClassoPOllis compared to the other plants in

the gymnospermous papulation appear to be more significant

than frequency variation in the larger groupings cited above. Taxodiaceaepollenites increases through this zone to

a peak of more than 992 in Pb 13190 then abruptly decreases

to a low of 182 in the sample just above (Pb 13406) which is

the youngest sample in this zone. Classopollis, however,

decreases through this zone from 332 in Pb 13193 to less

than 12 in Pb 13190 then shows an abrupt increase to 752 in

Pb 13406. Cycad-type pollen percentages remain low (<1-

162).

Upper Moreno Hill Member: Pb 13400. Only one

sample was studied in this section above the Middle

Sandstone Member of the Moreno Hill Formation. The Middle

Sandstone is comprised of massive medium- to coarse-grained arkosic sandstones (McLellan et al., 1983a) and identifiable by electric log data in subsurface wells (Roybal and

Campbell, 1981).

Sample Pb 13400 has a high relative frequency of angiosperms (492) and low frequencies of ferns (132); 35 inaperturate grains of uncertain affinity (162); and pollen in the Classopollis/Exesipollenites complex (142). Compara- tive gymnosperm frequencies indicate a high relative abundance of Classopollis (812) and low frequencies of

cycad-like pollen (62) and Taxodeaceaepollenites (62). One acritarch was also found in this sample while scanning slides for rare species, but its significance is uncertain. 36

A 0

sp.

sp. rites

sp.

n11¢1te:

ites 519-21-1

.c>.u.c>

ndici

i 11 A

:2 TriIetcs Tricol - O O U 0 tan I..." I362! monolD) IJOII IJQSI c J .2 " '3624 Rabbit S IJOIS senate) E I362. lib}? E uaoao 132351 IJOJI :30): 036)) 13614 iasac

Intel.” 100011)

Atarque Fitnuﬂwon

RI. Salado Tongue (Mancos an)

FIGURE 7 - Diagram showing local range and occurrence of selected pollen and spores from the principal reference sections. 37

P {All

'lNCI

000.! : .‘L " {75. [mutate ._. 3:; gram 0! ox ...... -' i .' Anion-eras Fem Classopollis! mu“ . 134:! ﬁrm n 2 ' Emimllauu Atrium W one manta-tun : +7 moo - -‘ 2 ‘s’.= 312:. . - F" " um ‘ . n

O- 33:33 , A‘ 3 3'2: ' " “‘2 ' '1 -- -— .543: F F ' 3 3190/ g: mo: —— . ..— I!

'4- 13206 ‘_ . p I — - "5, 11170 :.;_ 7_ - z 2.35 i O " 7 -.—._:. -—1 , ‘ __.__ .

g g muo :-:-;-— ‘ .- ...— — ~ < " " a 9 ‘3‘” P I . — _ \u .

7:.“ u s. ".1 0 so 100.

Percent of Total Pollen-Spores Assemblage

FIGURE 8 - Diagram of well 519-21-1 showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correla— tion (Figure 16). These labels are used in Figure 16 to designate “correlation lines” between samples, in other sections, where corresponding peaks in the relative abundance of a particular group or taxon occurs.

Hell 519~2I-I

mu Fine!

1 U05.’

Mlll .54 (grads ‘fuod. Clossoml I u hurrah-s

'3‘“ :37'7: p I l

MOIINO

lumen?

LO-Ov

L [

993

83-“:

AVAIOU!

I W ‘l ', “.1 c;'| I I! l I l

mucus V U .- u- M

TH“

3:833]!

I! I!

(Monet) sauoo

no o 5. no! ;

Percent of Gymnosperm Population

FIGURE 9 - Diagram of well SlQ-Zl-l showing the frequency of major gymnosperm groups relative to the total gymnosperm population. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate ”correlation lines“ between samples, in other sections, where corresponding peaks in the relative abundance of a particular group or taxon occurs.

Hill Inaperturate KT .1 ”“5 guns at {3 f Imam-ens Ferns Clamlllsl maria" Toh' "3'"! a L- A (again-«Hal m thw 61-00mm 0"” “WWW" DH! .. H F «P r Far I 7

I)!” =;_-'f: _ _ I

I3:31“~- 1:1. ‘-

p ' m “"35nno/ Z: L‘2: J” ' P I I

: '.." . um ‘ .7 E nm>xrf P rt. Ean .. 1312|>.:.'I' ‘2’ : m'u/ 73;, P = 3 ' oa .... , $.17

l]!7l\ :31 l 13:20:}, .7... (h ' limo --. 1:- . .L- I?" _ 751' 9

mn t/ .... F V L— I

13494 fag—4; m j S o o = ‘ 2 '* ”"3 'i-vi': —--"' . P r "" ‘m

ma 7}. Lii: n — — P law ””2/I) 9|“ if}:"'3‘?! n. ‘_ _ . . 3 ._ 5 (‘51-; ‘ '— ma.“ 3 5'; 13590? -.:‘_i‘: — I 1— _ m I ( 0 2 :2}: ‘3; '35" 3f:.3'~7:1_ ‘_ — (m o"-— t? - ."? I :II ". : : i ...... IJSII -.:- 1 I 4— — Imu. '

0 30 loo: 0 "3. "'7 “' [WW--

Percent of Total Pollen-Spore Assemblage

FIGURE 10 - Diagram of the Moreno Hill section showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate ”correlation lines“ between samples, in other sections, where corresponding peaks in the relative abundance of a particular group or taxon occurs.

’T‘v‘w 9 -_. . , . u .' g _. ;-'_-' Tuod. Clasmlln hurrah-s

13139 =: .:‘.::'."‘5.73. . T4

min._ 34:? CM I'JIJb / __., : — p IJIJS 1.“ 12". — z fa .. niazf‘ﬁgw C L 2 i IJI'JI__ » r _ _- n: ;almv 13m); 2:p-r- f" F- r ... :.‘ 3 / A . '- 01 "M: _.l.-..., li l ..‘23- , :

" l IJ'7Im.) :43!—..- 2 and --“=- - Cl'2 l3"? 5." .73 b—J—u gnu" +23” 2 L— - 13494 -+ an :'. 1.. o3 , ' “:4 . :- I1M93 “v.37: - I

1353 7K ._-.;;.. _ 135925: =:-;_:;— b " g numb-ﬁe L 1'5”; 135907712 _ n<92“ z . 1 3” ..r:_ 01 '35.? tor} an“ . o"~ :37," - J 1m. anti—3.4,...... “—— -—_.‘. _—-—-' ' I002 Percent of Gymnosperm Population

FIGURE 11 - Diagram of the Moreno Hill section showing the frequency of major gymnosperm groups relative to the total gymnosperm population. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate "correlation lines“ between samples, in other sections, where corresponding peaks in the relative abundance of a particular group or taxon occurs.

Hall Inaperturate 3017-25-1 . gram 0! him * Fens Classopollis! “If“!!! 1.4.! time Emin'lni.” minim Mus Other acupunctu- nuq :-';

13670\ ~‘-..'- 13:.7|_‘_:-.-—— .. _ I3(.22/~_ ‘ 1395 L/ mm : um 3575:!“- .= H; 1 3626/ 13627/ j.,3-.;

uno\ 72'] mn§ . i maoﬂ‘ ' ' 32347 " t h I mm' 4/ L mm 3 - 1m . .______l_..._... 0 So too:

Percent of Total Pollen—Spore Assemblage

FIGURE 12 - Diagram of well’Sl7-25-l showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate "correlation lines" between samples, in other sections, where corresponding peaks in the relative abun— dance of a particular group or taxon occurs. Hull 517-25-1

(grads Iaxod. Classmllns Ilsarrues

P???‘ '36!” :u-‘t.~.‘ °-1w ‘_ _

'JhMN' 0 .mn;:-- V 13022,. ”:.‘ lval/ 52:7; .

1m: ; "I II- l3m4,\ ‘2 : 13675,: ” '. .3076/ ...... 1302/2/ .._-.‘_:

umo\ 'f' I3(.W"\‘ .- nun:d ""2 3,; ,'. ‘..6.J".< 7" . nun ...“:rI/-nun/3,4 :.‘. -._ '4 ' s ' on mm none. 1

Percent of Gymnosperm Population

FIGURE 13 - Diagram of well 517-25-1 showing the frequency of major gymnosperm groups relative to the total gymnosperm population. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate ”correlation lines" between samples, in other sections, where corresponding peaks in the-relative abundance of a particular group or taxon occurs. 43

Inaperturate cram at rem cmm-oms/ mun rug! Mm [resinous-Ines Minus Was Other onawlnrtou

L___c L. L LL I 0 50 1007-

Percent of Total Pollen-Spore Assemblage

FIGURE 14 - Diagram of the USGS well #1 showing relative frequencies of pollen and spore groups relative to the total pollen-spore assemblage. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate “correlation lines" between samples, in other sections, where corresponding peaks in the relative abun— dance of a particular group or taxon occurs.

Classopollis Ulsarcues E L... i

Percent of Gymnosperm Population

FIGURE 15 - Diagram of the USGS well #1 showing the frequency of major gymnosperm groups relative to the total gymnosperm population. Letter and letter-number labels on diagram indicate peaks in the relative abundance, of palynomorph groups, which are considered useful for correlation (Figure 16). These labels are used in Figure 16 to designate “correlation lines" between samples, in other sections, where corresponding peaks in the relative abundance of a particular group or taxon occurs.

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peaks

number

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Cluster Analysis:

The cluster analysis diagram (Figure 17) illustrates

several groups or ”clusters" of samples which "link”

together at relatively high levels of community similarity

based on the particular palynomorph groupings used. Lower

horizontal lines linking two samples or sub-clusters

(previously linked samples) in the diagram indicate higher

level linkage or more closely similar community assemblages.

The clustering technique used here will eventually link all

samples to the diagram, even samples with no or very few taxa in common. The fifteen samples on the bottom of the diagram, for example, show linkages at relatively low levels. Except for the relatively high level linkage between samples Pb 13136 and Pb 13951, the linkages of the remaining 13 samples are probably not statistically meaningful (Jameossanaie, personal communication).

Cluster A contains the two samples from the western well

(519-21-1), immediately above and immediately below the

Moreno Hill Middle Sandstone Member, and also Pb 13141, which is the uppermost productive sample from just below the

Middle Sandstone Member on the Moreno Hill outcrOp section.

Pb 13141 contains marine microfossils. Pb 13406 and Pb

13400 lack marine microfossils.

Cluster B is composed of shale and siltstone samples from the well furthest west (well Sl9-21-1). It contains all of the Atarque samples, the uppermost sample from the Rio

Salado and, the six closely spaced samples from the base of 47

the Moreno Hill Formation.

The clustering here generally appears to indicate both geographic position, perhaps reflecting proximity to a particular plant community or similar source areas for water

transported palynomorphs, and a nearshore or brackish water depositional environment. As stated earlier, well 519-21-1 has a consistantly higher relative frequency of Taxodiaceae-

pollenites than the other sections. All of the samples in

Cluster B, except Sample Pb 13193, contain marine microfossils Pb 13193 contains no marine grains but lies immediately above uppermost marine sample (Pb 13194) in this cluster.

Cluster C is primarily comprised of subsurface (From coal-test wells), shale and carbonaceous shale samples from the Lower Rabbit Zone with the exception of Pb 13190 from the lower Upper Rabbit zone and Pb 13180 from the Rio

Salado. Two of the samples, Pb 13623 and Pb 13191, also contain coal. These two samples are both from the upper part of the Lower Rabbit Zone in wells 517-25-1 and $19-21-

1, respectively. All three samples from USGS well #1 are included. All of the samples included in Cluster B have a high relative abundance of tricolporate pollen and, except for Pb 13180, similar stratigraphic position.

The group of samples included in Cluster D are all outcrop samples from the Upper Rabbit Zone or are in close association with the Middle Sandstone. The Moreno Hill section, section 7/27/82 II, section 7/30/82 I, and section 48

7/30/82 11 are all represented here. Four of the six samples contain marine microfossils. This cluster appears to represent a wide geographical area and possibly a brackish or nearshore environment which may be associated with the Pescado Tongue, a transgressive wedge of the Mancos

Shale. All of these samples also have a very high relative frequency of tricolpate angiosperm pollen. Because all of the samples were collected from outcrOps, selective degradation of palynomorphs caused by surface weathering may be a factor in the clustering.

With the exception of Pb 13116, all of the samples included in Cluster K are from the Rio Salado Tongue of the

Mancos Shale at the Moreno Hill outcrOp section. All of these samples, including Pb 13116, contain a high relative abundance of ClassoPOllis. The cluster here appears to

represent a nearshore or near offshore depositional environ— ment.

Besides the four major clusters just discussed there are several two-sample cluster or high level linkages clusters

E-J, L; Figure 17). These are commonly lithologically similar samples from the same zone in a single section or from separate sections at similar stratigraphic positions.

They generally agree very closely with correlations already suggested.

Figure 18 is a diagram of the 4 principal reference sections indicating the stratigraphic and geographic distribution of the various clusters. The letter designations of 49 samples on Figure 18 correspond to the same letter designation for clusters in Figure 17. The dashed lines between sections on Figure 18 are drawn to indicate significant cross-section clustering.

The point should be made here that, although the clustering analysis of the samples used in this study generally agree with the correlations made between sections and the paleoenvironmental interpretations, no new or useful information was actually gained by performing this analysis.

All of the resulting clusters were expected prior to the computer analysis. Modification of the cluster analysis, such as using other available similarity indexes and proportional weighing of linking samples, and regrouping of the palynomorphs may increase the value this statistical technique for future use in the study area. .50

‘ - Association with Middle Sandstone Cluster A Member of Moreno Hill Fa.

Near-shore marine or brackish Cl ster B subsurface " west well (519-21-1) high Taxodiaceae llenites

Lower Rabbit Zone Cluster C Subsurface high tricolporate angiosperm pollen

Near-margg: o; brackish Upper a t one Cluster D outcrop high tricolpate angiosperm.pollen

_ Cluster 5 ' Cluster F 5:::: Cluster 6 ‘ 1.: Cluster H . ll: Cluster I a... La, g; ‘ Ii : Cluster J

n.3,.7 a...... oo—‘

- 1159) *9?» Marine ' ' °a=: Rio Salado Tongue of Mancos

. high Classopollis

i l...

Cluster L

i—1

FIGURE 17 - Diagram resulting from cluster analysis. The degree of community similarity decreases to the right of the diagram. m=marine

51‘ A-L)

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stratigraphic n

PALYNOLOGICAL CORRELATION

Three lines of analysis of palynological data from shale and siltstone samples were used in correlating the sections studied; 1) palynomorph occurrence and range, 2) palynomorph relative frequency and 3) cluster analysis. Figures 8 through 15 show relative frequency diagrams for selected, grouped pollen-spore assemblages in the four principal sections studied and comparative diagrams of the gymnospermous component alone for the four sections. Figure

16 is a composite of the four sections with correlation letter-number designated lines drawn between sections which correspond to letter-number designated relative abundance peaks illustrated in Figures 8 through 15. Figure 7 indicates spore and pollen occurrence and range which are considered useful. Figure 17 is the cluster diagram resulting from analysis of the data set. Figure 18 is a diagram of the four principal reference sections showing stratigraphic and geographic relationships between clusters or high-level linking samples. Figure 19 is a composite diagram of the four principal reference sections showing suggested palynologic zones of correlation based on information in Figures 7 through 18 and from the discussion below.

A sedimentary complex of offshore, nearshore, and four coal-bearing zones are differentiated in the sections 53 indicating

I F .. -- . , E a) In. :~ H uoIv '-k. r.”. .l ..2?;2 mu - 3 — c: .‘ 4 l . .7. a"... '. . .‘1 .‘A ill)! ‘- 0‘ v .. . g 2 m a

517-25-1 I A I )‘u 2’ a "' '- a g ' "‘ 5 '5 a) , l' u) n u S r- .

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K - 19

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19-21-1

AOOGfl :.‘”...... 01 j (semen) ’flOIViV e um nun: ._L Hi "It! ONIIOfl mono: oovws on

FIGURE

palynologic

54 studied (Fig. 19) based on the fossilized palynoflora of these sediments.

Rio Salado Zone:

The oldest zone studied here, present in both the Moreno

Hill outcrop section and well 519-21-1, is primarily a thick, gray shale sequence representing the upper Rio Salado

Tongue of the Mancos Shale. Palynologically this zone is generally low in diversity (10-15 species) and differentiated based on a high relative abundance of members of the ClassopollislExesipollenites complex, neither parent

plant of which are indigenous to this environment. This zone also has a low frequency but consistent presence of marine acritarchs and dinoflagellates (generally less than

1%).

The sediments here are considered to have been deposited in a relatively near-offshore environment. Classopollis and

Exesipollenites pollen generally appear to increase in

relative abundance in sediments deposited further from shore. This seemingly anomalous distribution is, however, a common occurrence in other Cretaceous sediments (Thompson,

1969). A similar pattern of mangrove pollen distribution was described in a study of modern offshore sediments in front of the Orinoco delta by Muller (1959). Srivastava

(1976) and Pocock and Jansonius (1961) have suggested that the plant represented by Classopollis (Cheirolepidiaceae)

may have occupied a habitat similar to the coastal habitat 55 occupied today by mangrove (RhizoPhora). In Muller's study, the relative abundance of mangrove pollen to other land- derived palynomorphs was shown to increase with increased distance seaward for more than 100 km from the source area in the mangrove thickets on the seaward edge of the Orinoco

Delta. This distribution pattern is against the prevailing wind direction and appears to be the result of water currents which result in a decreasing concentration of mangrove pollen offshore per unit of water but an increasing relative abundance offshore to the total pollen and spore assemblage.

A similar distribution pattern of modern pine pollen was studied in bottom sediments in the Gulf of California by

Cross and others (1966). The ”hinterland" habitat of pine is in sharp contrast to the strandline habitat of mangrove, yet, between Muller's 1959 study and Cross and others' 1966 study, there is considerable similarity in the pollen distribution patterns in offshore sediments from these two taxa.

Atarque Zone:

This zone is also present in both the Moreno Hill outcrop section and well 519-21-1. The base of this zone is identified by an abrupt decrease in the relative frequency of pollen of the Classopollis[Exesipollenites complex in the

Moreno Hill section and an average lower percentage in well

519-21-1. There is also a slight to great increase in the 56

relative abundance of acritarchs and dinoflagellates in the

Atarque compared to the Rio Salado below. In well 519- 21-1

the frequency of marine algae ranges from less than 11 to 22

although such micrOplancton cysts are always encountered in

a palynomOph count of 200. In the Moreno Hill outcrop

section the frequency of these grains ranged from more than

11 to 471. The lower relative abundance in well 519-21-1 may be due, in part, to mixing of strata in the rock-chip

samples.

The high frequency of acritarchs and dinoflagellates in

the Atarque zone may indicate a nearshore environment. The higher frequency of these marine microfossils might be explained by a higher nutrient level availability for the microplancton derived from terrestrial drainage, or from nearshore waters which, due to such factors as salinity, temperature, or circulation could result in increased papulation. Selective winnowing of the pollen and spores by local water currents could also be a factor.

Coal Zone A (Antelope):

This coal zone is present in the Moreno Hill outcrOp section and in well 519-21-1. In the Moreno Hill section, the base of this zone can be distinguished from the Atarque zone by the absence of marine algae (acritarchs and dinoflagellates) and a very significant increase in the frequency of Taxodiaceaepollenites relative to other members

of the gymnospermous population. Fern spores are dominant 57 in the shale layer below the first main coal bench (Pb

13112) and the shale layer above the upper coal bench (Pb

13120). AngiOSperm pollen frequency remains low throughout this zone. In the gymnospermous fraction, the relative frequency of Taxodiaceaepollenites decreases through the

coal layers as ClassoPOllis abundance increases but

Taxodiaceaepollenites rebounds to almost 1002 of the

gymnospermous pollen just above the upper coal bench. This may indicate that a taxodiaceous vegetation occupied sites adjacent to or in areas of peat accumulation. The frequency of inaperturate grains of uncertain affinity also appear to be high below and above the two benchs of coal but low in frequency through the coal accumulations.

It is curious to note that the lower four samples at the base of the Moreno Hill Formation in well 519-21-1 (Pb

13198-13195) contain marine microfossils. The patterns of relative frequency shifts of pollen and spores, though not magnitude, correspond very closely to those in coal zone A of the Moreno Hill outcrop section (Pb 13112-13120) (Figures

8 and 9). This may indicate a time-line crossing facies boundaries suggesting that a coal-forming swamp existed at the locality of the Moreno Hill section penecontemporaneously with sediment accumulation in a nearshore environment at the location of the 519-21-1 well.

Coal zone A (Ante10pe) is significantly different from other coal zones present in the four principal sections studied, both on the basis of relative abundance of grouped 58 pollen and spores, and on the comparative frequency of gymnosperms alone. There is a question as to whether this coal zone could be the same as the lowest coal zone reached during drilling in well 517-25-1, which is in a comparable stratigraphic position. One explanation of the disparity between their respective palynofloral compositions is variation of local habitat or environmental conditions, such as water level, which could have controlled the local vegetation. The magnitude of difference between these two zones from different sections, however, appears too great.

Although migrating or narrow zones of vegetation are not generally detected palynologically in the peat of the

Everglades swamp-marsh complex (Cohen and Spackman, 1972), the zones of vegetation here may not have been narrow and may have stood undisturbed for a sufficient length of time to build up peats with a significantly different pollen- spore assemblage. The interbedded shale units generally reflect a broader region of source vegetation. A common explanation for such a representation is that it is due to the influx of muddy water into the peat swamp where the water-transported palynomorphs settle out of the muddy waters along with the suspended mineral sediments. Besides the significant difference between a low angiosperm, very high, fern-dominated assemblage in the Moreno Hill section and the angiosperm-dominated assemblage in well 517-25-1, there is a very high relative abundance of cycad-type pollen in well 517-25-1, compared to other gymnosperms and to the 59

total pollen-spore papulation. Cycad-type pollen comprises

162 of the total palynoflora at the base of well 517-25-1

and generally decreases to less than 12 in the sample

immediately above the main coal of the lower coal zone

(Cerro Prieto). Cycad-type pollen is absent or rare in the

lower coal zone of the Moreno Hill outcrop section, except in the sample (Pb 13116) between the two main coal benches where it is about 32.

The lower coal zone in well 517-25-1 is considered to be part of the Cerro Prieto coal zone (Campbell, 1981). This zone thickens for about 3 miles to the southwest of well

517-25-1 toward the Moreno Hill outcrop with the thickest coals trending northwest-southeast. Beyond this point the coals split and thin to the west and are not considered to extend as far as the Moreno Hill Outcrop section (Campbell,

1981; Campbell and Roybal, 1983). 60

Coal Zone B (Cerro Prieto):

Coal Zone B is found in well 517-25-1 and may include the lowest coal in USGS #1 well (4N 17W, sec. 4). However, the coal in USGS #1 is tentatively placed above Coal Zone B; the reasons for this are given below in the discussion of Coal

Zone C (Lower Rabbit).

In addition to the features in the discussion above which distinguish this zone from Coal Zone A, this zone contains the fossil pollen PhimOpollenites. This grain appears to be

derived from a plant restricted to this zone up to and including the shale unit immediately above the main coal in

Coal Zone C (Lower Rabbit). In well 517-25-1 the relative abundance of this pollen type ranged from 0.51 to 91, the highest occurring just above the thickest coal bench.

This zone is distinguished generally on the basis of comparative gymnosperm pollen content. It contains a high relative abundance of cycad-type pollen and a very low frequency of Taxodiaceaepollenites. Angiosperms dominate

the pollen-spore population of this zone. Two palynomorphs first appear in the upper part of this zone in sediments which bracket the thin upper coal. Rousea sp. A first occurs in the shale between the 3 ft. thick, lower coal bench and the thin (less than 1 ft. thick) upper coal bench.

An unidentified trilete spore, species 151, first occurs either at or just above the upper coal. 61

Coal Zone C (Lower Rabbit):

This coal-bearing zone of shales, coal and some sandstone is found in all four sections studied, though in well 519-

21-1 it is barren of coal. In many ways this zone is very similar to Coal Zone B (Cerro Prieto). It can be distingushed, however, on the bases of pollen and spore ranges and by the increase in the frequency of Taxodiaceae-

pollenites relative to other gymnosperms. Eleven palyno-

morphs have either their terminal or only occurrence in this zone (Figure 7).

Correlation of this zone between sections is based primarily on patterns of change in the comparative frequencies of gymnosperms. Cycad-type pollen increases from the base of this zone to a peak just above the main coals (above the upper 16" coal in the Moreno Hill outcrOp section and above the 6'6" two-bench coal in well 517-25-1 and just above the upper of the two coals studied in USGS well #1). Although well 519-21-1 does not contain coals in this zone, a peak in the relative frequency of angiosperm pollen for that section (Pb 13194) is correlated to a high angiosperm peak in the Moreno Hill outcrOp section (Pb

13127). This is considered significant more on the basis of its sequential occurrence following very high peaks in both

Taxodiaceaepollenites and inaperturate grains of uncertain

affinity at the top of coal zone A (Ante10pe) than on magnitude of the peak itself.

Wells 517-25-1 and USGS coal test well #1 both show a 62

similar pattern in relative frequency shifts of cycad-like

pollen, Taxodiaceaepollenites and ClassOpollis. This

pattern is evident in the samples from the main coal bed in

well 517-25-1 but above the main coal in USGS well #1. This

might be explained by: mixing of cuttings during the

drilling operation; a time difference between coal deposi-

tion at the two sites; the lack of sample data below the main coal in USGS well #1, which would allow seeing the

overall larger pattern of change at that level; or the

placing of the lower coal in USGS #1 below the C Coal Zone.

The difference in the relative abundance trends for angiosperms compared to the total palynoflora between

sections is puzzling. Pollen and spore relative abundance

shifts in Well 519-21-1 and in the samples from the outcrop section are generally very closely similar in trends; both peak in angiosperm frequency at the base of Coal Zone C, following the peak in the frequency of inaperturate grains of uncertain affinity at the tap of Coal Zone B. Both these sections show a decline in relative angiosperm frequency through this zone. Well 517-25-1 and USGS well #1 both indicate a minor role for angiosperms in the peat swamp itself. This may be due to local differences in environmental conditions within the coal swamp. The loss of data through weathering of samples in the outcrop may be a factor.

The correlation of USGS well #1 to the Moreno Hill

Section and other wells studied, remains more problematical. 63

In this case the occurrence of rare species aids in stratigraphic placement. In USGS well #1, Phim0pollenites was not encountered in the normal count of 200 specimens but was found in the lower two samples while scanning the slides more extensively for rare species. The occurrence of

Phimopollenites places the lower two samples in USGS well #1

below Pb 13625 of well 517-25-1. The presence of Tricol- pites sp. E places the lowest sample in USGS well #1 (Pb

12726) at or above Pb 13628 of well 517- 25-1. Tricolpites

sp. B appears earlier in the section at Moreno Bill. The presence of Distverrusporites antiguasporites in the USGS

well sample PB 12726 and in the next sample above (Pb

12729), indicate correlation at or below Pb 13627 in well

517-25-1. The presence of Cicatricosisporites sp.A places these lower two samples from USGS well #1 between Pb 13627 and Pb 13624. The presence of Appendicisporites sp. A indicates correlation of Pb 12729 at about the position of

Pb 13627 in well 517-25-1. The presence of Biretisporites

8p. D places the lowest sample in USGS well #1 with Pb 13127 in the outcrop locality. This particular series of palynological "bracketing" would indicate that both the lowest samples from coal zone C (Lower Rabbit) in the Moreno Hill outcrop and at least the lower two samples in USGS well #1 correlate most nearly with the lowest sample in Coal Zone C from well 517-25-1 to the northeast. This indicates that the lower coal penetrated in USGS well #1 may have been removed by erosion at the site of well 517-25-1 before 64 deposition of the sandstone unit at the top of coal zone B.

Alternate explanations may be that the main coal in USGS # 1 belongs in the upper part of Coal Zone B above the main bench of coal or a significant span of time separated peat accumulation at the two locations. The range data in Figure

7 also appears to place the lower two samples from the

Moreno Hill outcrop C Coal Zone in an intermediate position between Coal Zone B and C in well 517-25-1.

Coal Zone D (Upper Rabbit):

Coal zone D is found in three sections; well 519-21-1, the Moreno Hill outcrop, and well 517-25-1. The base of this zone is marked by the peculiar environmental facies indicated by the abundance of unidentified sp. 248, which is resticted to Pb 13136 in the Moreno Hill outcrop section and to Pb 13951 from well 517-21-1. Concurrent with or immediately following this restricted appearance of unidentified sp. 248 is an increase in the abundance of

ClassOpollis followed by a surge of Taxodiaceaepollenites,

which is, in turn, followed by an increase of Classopollis,

and decrease of Taxodiaceaepollenites, and the abrupt

appearance of marine acritarchs. This pattern of change is apparent in all three of these sections except in well 519-

21-1 where only a single marine acritarch was found. This was in sediment immediately above the Middle Sandstone

Member, rather than below it. 65

Correlation to Other Wells and Outlying Outcrop Sections:

During the course of this study several other outlying outcrop sections and several samples from one other coal test well were investigated in addition to the four primary sections (well 519-21-1, Moreno Bill outcrop, USGS coal test well #1 and well Sl7-25-l). The palynological data from these sections have not been subject to the same detailed analysis as the primary sections though most of the samples from the outcrOp sections were included in the clustering analysis.

Samples from the only coal-bearing zone in a coal test well (well 517-34-1) located in section 34, TSN, R17W at a depth of 170 to 191 ft. (elevation 6740 to 6721 ft.) were briefly examined and were generally found to have a very high percentage of Classopollis and fern spores. Based on

limited data the coal zone represented by these samples appears to be the most similar to samples in coal zone A

(Antelope) of the Moreno Hill outcrOp section.

Several samples from two outcrop sections (Pb 13698 and

13699 from outcrop 7/30/82 I in sections 14 and 23, T2N,

R16W; and 13701 & 13702 from outcrOp 7/30/82 11 in sec.8,

T2N, R17W) (Figure 5) are considered to be part of the Upper

Member of the Moreno Hill Formation above the Middle

Sandstone (Cross, personal communication). Three of these samples Pb 13698, 13699 & 13702) were subject to cluster analysis. Two of these (13698 & 13702) were grouped very closely with Pb 13139 from above the coals in coal zone D of 66

the Moreno Hill outcrOp section. The lowest sample (Pb

13698), from the 7/30/82 I outcrOp section, contains marine acritarchs and dinoflagelates (32).

Three samples from two other outcrOp localities (Pb 13440 from 7/27/82 I in sec. 6, T2N, R17W; and Pb 13445, 13448 from 7/27/82 II in sec. 33, T3N, R18W) were collected from below the top of the Moreno Hill Middle Sandstone Member.

All three of these samples contain marine acritarchs and/or dinoflagellates. In section 7/27/82 11 the lowest sample,

19 ft below the Middle Sandstone, Pb 13445, also contains what appears to be some type of algal cyst (unknown sp. 248) which was also found at only one stratigraphic level from both well 517-25-1 (Pb 13951) and the Moreno Hill outcrOp section (Pb 13136). Without further analysis of the palynological data from these three samples,the palynoflora appears to fit the general model for coal zone D very closely. Cluster analysis groups both samples from 7/27/82

II with samples from the D coal zone in the Moreno Hill outcrop and, curiously, links the Pb 13440 from 7/27/82 II with Pb 13494 from the marine Atarque zone at Moreno Hill. 67

PALEOENVIRONMENTAL INTERPRETATIONS

Workable reconstructions of plant communities based on pollen, spores and other microscOpic plant detritus recovered from ancient sediments must be in accord with the sedimentary regime indicated by those rocks. The coal- bearing rocks of the Moreno Hill Formation, discussed earlier, appear to represent depositional environments of prograding coastal or delta plains of low relief. Broad interchannel bottomland and freshwater swamp or marsh environments in which overbank and peat deposits accumulated are represented by the varying thicknesses of shale, carbonaceous shale and coal. Stream channels and crevasse splays are indicated by numerous laterally discontinuous freshwater sand and siltstone deposits. Often such sandstones lie unconformably on the underlying rock indicating fluvial scouring. This general depositional system has some characteristics in common with the lower Mississippi delta of today (Kolb and Dornbush, 1975) or perhaps it is more nearly comparable to the smaller deltaic systems protected behind the barrier system along the coast of Texas (LeBlanc and Hodgson, 1961).

The Atarque Formation, which lies immediately beneath the

Moreno Hill Formation, is considered to be a series of coastal-barrier sandstone or shoreface deposits (McLellan and others, 1983a; Hook and others 1983). It is probably the result of a primarily non-deltaic, northeastward prograding shoreline with local areas dominated by deltaic 68

sedimentation. The shoreline configuration was probably very digitate and embayed and the sea very shallow. (Hook and others, 1983).

In a prograding deltaic system major distributaries build out into coastal waters. Crevassing and splay formation on the delta and tidal and wave action offshore, results in a gradually infilling between the major distributaries (Blatt, and others, 1980). While still open to the sea such sites may maintain brackish or near-marine environmental characteristics. As the water level in the interdistributary areas shallows, the elevation gradient from the generally higher natural levee of the distributary to the lower interdistributary area provides a range of habitat conditions for plants with different requirements leading to the establishment of various vegetation zones. Marsh or swamp communities may become established on wet, boggy sites. If clastic influx is restricted by vegetation or other means and peat accumulation keeps abreast of or exceeds local subsidence, the peat swamp will thrive and peat accumulation may continue with no or only minor interruption. At least some of the coals in the Moreno Hill Formation indicate this type of peat accumulation. Tschudy (1969a, p. 81) has suggested that plants forming the vegetation of a peat bog contribute the major amount of pollen and spores to the organic accumulation that may eventually become coal, overwhelming any representation by non-bog plants. Studies on modern peat producing swamps and marshes, such as those 69

by Cohen and Spackman (1972) and Cohen (1973) agree, although they found little relationship between the relative proportions of pollen and spores to the actual proportions of plants in the source communities. For example, there is an overrepresentation of anemophilous trees such as pine and oak. A change in water level may either drain the peat swamp exposing the peat to oxidation and fire or drown the vegetation. In both cases, the habitat favoring the peat producing community is altered and peat accumulation stops.

In the case of a lowering of the water table, a new bottomland plant community may become established on tap of the exposed peat. In the case of a raised water table, lake or pond sediments may accumulate on the peat or other substrate. These sediments may have their origin outside the site of deposition but more commonly they reflect organic detritus derived as sedimentary particles, including pollen and spores, which represent surrounding indigenous vegetation. Lateral migration of distributaries may cut channels across the peat build-ups which may later fill with inorganics or in some cases, with peat. The topping or breaching of a natural levee may leave splay deposits of sand, silt or clay temporarily choking out the existing vegetation or burying it completely.

Regardless of the particular series of depositional events during the growth of a delta plain, a number of ecologically diverse sites are available for plant growth.

The plants, occupying both sites on the delta and in the 70 headwater areas of the streams, will contribute pollen, spores, and various other microscOpic plant detritus to the deltaic sediments and peat. This organic detritus, and the entombing rock provide the material used for paleoecologic reconstruction. A number of considerations need examina-

tion. Good discussions on the limitations and problems of paleoecological reconstruction with palynologic data can be

found in "Palynology in Oil Exploration" (Cross, ed., 1964) and also in papers by, Dick (1964), Leopold (1964), Potter

(1964) and Tschudy (1969). Just a few of the considerations are: Types of plants represented by the microfossils; rates of production and transportability of pollen and spores; differential preservation and the environment of deposition as indicated by lithology.

Very little is known about mid-Cretaceous plants and

their ecological preferences (Penny, 1969). This problem is compounded by the large span of time separating Moreno Hill

time (Turonian) from recent plants. In many cases, very little information can be drawn by direct comparisons and perhaps a great deal of misinformation could result

(Tschudy, 1969b, p. 118-123). Cross (1964), however, points out that, even as far back as the Upper Cretaceous, some pollen and spores are directly comparable to modern families or genera.

Working within this framework, a search was made to,

correlate fossil pollen and spore data in the Moreno Hill

rocks to the various lithologies. 71

Pollen-Spore Assemblages:

Five pollen-spore assemblages are recognized, in the sections studied, on the basis of the occurrence and relative abundances of palynomorph groups or taxa.

Assemblages 1 and 2 were found in sediments deposited in marine or partial marine environments while Assemblages 3, 4 and 5 were found in the coal-bearing, freshwater strata of the Moreno Hill Formation.

Assemblage 1. Off-shore marine shale and siltstone

(Figure 20): This assemblage is distinguished by gymnosperm pollen dominance. Classopollis is the single most abundant

pollen form. This generally increases in relative abundance off-shore. A similar distribution of mangrove pollen was reported in the offshore region from the Orinoco Delta by

Muller (1964) and also of pine pollen in bottom sediments in the Gulf of California by Cross and others (1966).

Angiosperm pollen is common, though not diverse, and ferns are generally uncommon. Members of the BryOphyta and

Lchpsida are very rare to absent. Marine microplankton are also rare but fossil mollusks (ammonites and bivalves) are present in outcrOp exposures and have been used for zonation by Cobban and Book (1983).

Assemblage 1 is found in samples from the Rio Salado

Tongue of the Mancos Shale and in one of the thick shale 72

SAMPLE NUMBER151: - P513587. PB13592. P313591. P313590. P313569. P213589. Relative Frequency avg. min. max. Angiosperms A I 27.6 18.6 37.6

L9. ret. C3 ‘ 1.0 0.3 2.0 Ferns. 2. 3 1.0 ' 3.6 Cuathidites - 8.7 3.0 1.5 BPHOPhuta .' 6.0 e.o 6.0 Lycophuta V 8.1 0.0 0.5

Gwmnoeperms ] 63.6 36.6 55.0 Taxod. ' ' 1.6 3.0 2.5

Othlrv 26.7 23.3 36.7 5 I: ' ' r :‘n i A . 1 total loll-n and worn

PB 13116 .Relative Frenuencu Angiosperms 22

L9. ret. C3 . £3

Ferns - 0'

Cuathidites G!

Brwophwta I!

Lwcophuta 61

Gymnosperms 1'

Taxod.

Other 1 ...

5" 1 v 1 AT ﬁn I u B ‘. :::al all" m we!

SAHPLE NUHEER1S): P3131951 Relative Frequency

Angiosperms 11.6 L9. ref. C3 6.3

Ferns 17.1

Cyathidites 10.6

lruanhuta 2.5 Lwcophyta 1.5

Gumnosperms 36.7 Iaxod. 7.3

Other 32.7

5 1| ' ' ' in ' c 1 16m Min and in"!

FIGURE 20 - Pollen-spore Assemblage 1 of off-shore marine shale and siltstone. A) Rio Salado Tongue of Mancos Shale from the Moreno Hill section, B) sample Pb 13116 from the Antelope Coal Zone at the Moreno Hill section, and C) lowest sample in the Rio Salado Tongue from well 519-21-1. Lg. Ret. C3 = large reticulate tricolpate angiosperm pollen. Taxod. = Taxodiaceaepollenites. Other = unidentified and inaperturate grains of uncertain affinity. 73

SAMPLE NUHPER'S)‘ #513195. P513193. P313197. P813198. P213202. P213206. P313170. PB13175. P813180. Relative Frequency avq. min. max.

Ana 1 0' PQPMI _I . 34.9 27.3 1.3.2 L9. ret. CJ 2.3 0.0 6.6 Ferns ‘ 15.2 7.9 27.0

Cwathndxtes h: 8.0 3.9 13.0 Brvopnuta 1.1 0.0 2.1 Lyconhuta 1.0 0.0 2.0 Gumnosperms , 13.7 7.2 25.2 Tnmm Marine microfossils 9.2 3., “.7 0mg.- 1 31.: 19.1 «3.9

1 total pollon and cadres A

SAMPLE NUHPEP1S): P81349~. P213693. Relative Frequency avg. mxn. max.

Ang1osperms 6.5 0.0 9.0 ' L9. ret. c3 11.5 11.6 1.- Ferns ' 1.7 0.11 3.3 Cyathidxtes , 1.5 0.0 3.0

l'myophgta 0.0 0.0 0.3

Lucophwta 0.0 0.0 0.0

Gumnospermc , 5.3 0.0 11.7 lanod. % Marine microlouils 9.7 0.0 1.3 Other WWW ] 911.6 76.0 1113.0

1 1. ' ' ' 1.. ' 1 total sullen and tastes

FIGURE 21 - Pollen-spore Assemblage 2 of near-shore or . brackish shale and siltstone. A) upper Rio Salado Tongue of Mancos Shale, Atarque Fm. and marine zone from base of Moreno Hill Formation in well 519-21-1, and B) Atarque Fm. from the Moreno Hill section. Lg Ret. C3 = large reticulate tricolpate angiosperm pollen. Taxod. = Taxodiaceaepollenites. Other = unidentified and inaperturate grains of uncertain affinity. 74

SIMPLE NUMBER 1 5) a - P313132. P313123. P013112. Relative Frequency avg. min. max. Angiosperms 11.0 1.7 21.6

L9. ret. C3 0.0 0.0 0.0

Ferns ] 51.5 26.0 93.2

§wathiditea 17.7 9.8 27.1

Brgoshwta 0.0 0.0 0.0 Lwcophwta 0.9 0.0 2.5

Gymnospcrma 7.5 2.5 17.5 Taxod. 1.6 0.0 2.6 Other 28.2 0.3 66.1

ﬁt 1 16111 sullen and 500!!!

FIGURE 22 - Pollen-spore Assemblage 3 of fern-dominated shale in the Lower Member,of the Moreno Hill Fm. from the Moreno Hill section. Lg. Ret. C3 = large reticulate tricolpate angiosperm pollen. Taxod. = Taxodiaceaepollenites. Other = unidentified and_inaperturate grains of uncertain affinity.

SAHPLE HUMP-EMS) 1 \ P613620. P013626. P313627. P813628. P013631. 9213632. P213633. P213635. P013636. ' Relative Frequency avg. min. max.

An9:osqerms —I 54.7 33.5 72.0 L9. ret. c3 ' 2.0 0.0 3.5 Ferns 10.7 1.9 17.3 Cuatnldxtea 1.7 0.0 3.1 lrwophwta 1. N 0.0 4.0 Lycorhuta 1. m 0.0 7.3 Gymnce per-ma ' 15. u- 7.2 36.6 Tamed.

L t 2. 6.2 Other ' 16.1 8.0 26.4

3 h 1 1 I 1 j ' A 1 10:01 0011.. 111: spam

SsnPLE NUHFER1S): F31J141. P313139. P213137. P313135. P313127. Relatxve Frequency avg. m1n. max. Anqxosnerma 4‘_] 71.0 68.6 81.4

La. ret. ca ' 1.. 0.5 2.7 Ferns

'0 .‘ 6 1.0 18.0 (gathiditel

U .1 0.5 9.9 Brgoohyta . (a G 0.0 0.0 Lucophuta

B . F 0.0 0.7 Gumnoaperma

O . N 1.5 10.3 Taxcd.

0.) . C 0.0 5.5 Other . . N . a: 6.1 21.2 5 10 ' I I B 1 10101 001100 and 000m

FIGURE 23 - Pollen-spore Assemblage 4 of angiosperm. dominated shale in the Lower Member of the Moreno H111 Fm.. A) well Sl7-25-1, and B) the Moreno Hill section. Lg. Ret. C3 8 large reticulate tricolpate angiosperm pollen. Taxod. = Taxodiaceaepollenites. Other = unidentified and inaperturate grains of uncertain affinity. ‘76

SAHPLE NUHBEH1518 F213621. P013622. P013623. P013626. P013630. Relative Frequency avg. o1n. max.

Angiosperms I __l ‘ 50.9 53.5 60.2 L9. ret. (:3 : 6.9 3.5 6.5 Ferns' 13.2 12.0 16.0 Cyathxditee 3.0 0.3 5.0 Bruophuta 0.5 6.2 17.1 Lucaphuta “.1 0.7 6.7 Gumnosperme 3 9 1.0 0.1 faxed 0.6 0.0 1.2 'JtHer 13.6 9.9 17.9

7 I I I I an A 1 1:111 0011.0 and 100m

SAFPLE NUHPER(S): 0013190. P313191. P513192. P013193. P313196. Relative Frequency avg. min. aaxn

Anoxoeperms 60.7 39.1 57.2

Lg. ret. c3 } 3.3 1.0 5.9

Ferns 20.1 13.0 27.1 Cyathicites .. 4 0.0 3.1 13.5 Bryoehuta 6.3 2.5 5.0 Lucopnuta 5.6 0.6 0.7 Gumnoeoerms 6.7 2.7 10.1 Taxod. 6.1 2.6 6.2 Other 16.0 0.6 17.2 I 1 *{‘*ﬁ B 1 10101 001100 000 We!

FIGURE 24 - Pollen-spore Assemblage 5 of interbedded coal and shale in the Lower Member of the Moreno Hill Fm.. A) .well 517-25-1, and 8) well $19-21-1. Lg. Ret. C3 = large reticulate tricolpate angiosperm pollen. Taxod. f Taxodiaceaepollenites. Other = unidentified and inaperturate grains of uncertain affinity.

77 units from Coal Zone A (AntelOpe) of the Moreno Hill outcrop section. With the exception of sample Pb 13116 which contains no marine microfossils, this appears to be a near offshore or unprotected nearshore depositional environment in which spores and pollen were transported with other sediments by marine currents in front of a prograding delta.

Assemblage 2. Near-shore or brackish sediments, shale and siltstone (Figure 21): Assemblage 2 is clearly distinguished by the common occurrence of marine microfossils. This assemblage is found here in shale and siltstone partings between sandstone beds of the Atarque

Formation and in the five closely spaced samples at the base of the Moreno Hill Formation in well 519-21-1. The sediments appear to represent a protected bay depositional environment. The high relative frequency of marine dinoflagellates may be due to warmer nearshore waters and/or fluvially derived higher nutrient levels which may supply a large papulation of marine organisms. Selective winnowing by local marine currents must also be considered as an explanation of abundance of microplancton cysts.

Assemblage 3. Fern-dominated shale (Figure 22): This fern-dominated assemblage is found in some gray shale and carbonaceous shale units in the Moreno Hill Formation at the principal outcrop locality on Moreno Hill. The genus

Cyathidites is common in all of these samples, comprising 30

to 402 of the fern population. In sample Pb13112, where

fern spores comprise 932 of the total assemblage, the

relative abundance of Gleicheniidites is slightly higher

than Cyathidites. In the remaining two samples representing

Assemblage 3 the abundance of fern spores other than

Cyathidites is variable. Angiosperms and gymnosperms are

common to uncommon in abundance. No members of the

Bryophyta were identified and lycopodiaceous spores are either absent or uncommon.

This assemblage suggests that cyatheoid ferns were very common on some areas of the delta and that there may have been local sites with large pepulations of gleicheniaceous ferns.

Assemblage 4. Angiosperm-dominated shale (Figure 23):

Assemblage 4 is dominated by angiosperms of varying diversity and abundance. Ferns and gymnosperms are generally common and diverse. Spores of the BryOphyta and

Lycophyta are uncommon or absent.

This assemblage is found in the majority of gray shales and carbonaceous shale units of the Moreno Hill sequence.

These shales represent deposition of fresh-water overbank muds and flooded marshes. The assemblage reflects the vegetation of a large area which contributed pollen and spores to the sediment accumulation mainly by water and, to a limited extent, by wind. 79

Assemblage 5. Interbedded coal and shale (Figure 24):

Assemblage 5 is found in samples of rock cuttings containing

varying amounts of coal mixed with other rock types, most

commonly shale. The volume percentage of coal in the mixed

samples which contained this assemblage ranges from 10 to

352. Such mixing is a result of drilling through successive

interbeds of elastic sediments which are present as partings

in the coal seams. Such clastic interbeds are usually the

result of successive inundations of the peat swamps by overbank muds or splay deposits during floods which spread over the coal forming peat swamps.

Like Assemblage 4, Assemblage 5 is also dominated by angiosperms, but there is a greater abundance of large, reticulate, tricolpate pollen, in particular Tricolpites sp.

K, than is the case in Assemblage 4. Assemblage S is also distinguished by the common occurrence of bryophytic spores, mostly Stereisporites, and an increased number of 1yc0pod

spores although such spores are not common. Fern spores are common, with Cyathidites making up a slightly greater part

of the fern population than in Assemblage 4. Gymnosperms are generally less common.

Other Dispersed MicroscOpic-Sized Plant Detritus:

During the counting of pollen and spores in each sample, notes were also made on the presence and general abundance of other plant tissue fragments such as preserved woody 80

tissue, charcoal, leaf cuticle fragments and individual cells and cell fillings. Such notes were also made for samples which were either barren or in which, for various reasons, the pollen and spores could not be counted.

In general, the coals and carbonaceous shales contain the greatest abundance of recognizable plant tissues. Gray shale residues are characterized by fine charcoal and finely fragmented cuticle, although good leaf cuticles are occasionally found. Carbonaceous shales usually contain excellent leaf and stem cuticles. Tissues found in the coals are varied. A few coal samples contained cuticle and little else. Most of the coals here also contain tracheidal tissue either in the form of vitrain or fusain without recognizable wall structure and/or thick-walled, scalariform tracheids. Occasionally vessel elements and tracheids with circular bordered pits are also found, though these are not common. Resinous cell fillings are also commonly found. 81

Paleoecological Reconstruction:

In preparing this paleoecological reconstruction in the

study area, for Moreno Hill time, I have relied to varying

degrees on plant affinities suggested by previous authors.

Angiosperms appear to be fairly diverse, judging from the

pollen data. There are 43 species listed. A few of these

may actually represent morphological or preservational

variations of the same species. Liliacidites species are

found only rarely. Of the tricolpate forms only

Cupuliferoideapollenites sp. A and 9. sp. B, and Tricolpites

sp. A and 1. sp. B are generally abundant. These four

species are distinguished from each other on the basis of an

arbitrarily chosen size range and on exine sculpturing. The

Cupuliferoideapollenites species have a psilate exine

surface and the Tricolpites species have a very fine

reticulate pattern. Otherwise the shapes and size ranges

are nearly identical and, because they occur in nearly the

same relative proportions to one another in every sample, may represent co-occurring species or they may represent morphological variation between members of the same genetic

population. Their small size (8-18 microns), thin walls,

and abundance in most samples may indicate that these

represent wind-pollinated angiosperms (Tschudy, 1969b). The

other species of tricolpate pollen grains are generally larger with distinctive exine sculpturing and/or

thickenings. The affinities of these are not known other

than their angiosperm origin. The two fossil leaf beds 82 discovered in the Moreno Hill outcrop section (Figure 4) contain several different species of detached angiosperm leaves. The lower leaf bed is a light brown, slightly carbonaceous shale and the upper leaf bed is a fine light gray shale which appears to represent lake sediments.

Fern spores appear to be much more diverse than the angiosperms. Those assigned here to the modern families,

Cyatheaceae (some may also represent the Dicksoniaceae,

Hughes, 1969) and Gleicheniaceae, are less diverse but generally more abundant than those assigned to Schizaeaceae.

Other fern spores are infrequent. Habitats of modern ferns in the Schizaeaceae and Gleicheniaceae range from marshes or bogs to open, well-drained sites (Tryon and Tryon, 1982).

Modern members of the Dicksoniaceae and Cyatheaceae are generally found in high-elevation, wet forests, though some members of the Cyatheaceae are known from low-elevation swamp forests.

Spores assigned to the Bryophyta, in particular

Stereisporites, though generally uncommon, can be locally

abundant as can those assigned to the Lyc0phyta. The genus

Stereisporites is believed to represent the Sphagnales

(Hughes, 1969). It has a higher abundance in the samples containing coal. It is interesting to compare this with the modern Nyssa swamps in the Okefenokee swamp-marsh complex where, in some areas, Sphagnum and Woodwardia cover the peat

surface beneath the trees. In those areas, the peat contains a high percentage of Sphagnum spores (Cohen, 1973). 83

The division CycadOphyta is represented in this study by the monosulcate pollen CycadoPites. It is generally present but it is common in only a few samples. It may be important to note that, due to either the lack of distinct morphological features of this grain or to inexperience of the author, this pollen may be difficult to distiguish from some monosulcate angiosperm grains at the resolution provided by the light microsc0pe.

The fossil pollen ClassoPOllis is generally believed to

represent the extinct gymnospermous family Cheirolepidiaceae

(Stewart, 1983). The habitat of the plant producing

C1a880pollis has been the subject of a good deal of

speculation (Parker, 1976; Pocock and Jansonius, 1961;

Thompson, 1969; Srivastiva, 1976). In this study the relative abundance of Classopollis pollen generally

increases offshore. A similar phenomenon with modern pine pollen was described for samples from bottom sediments in the Gulf of California (Cross et a1, 1966) and with mangrove pollen in samples offshore from the prograding margin of the

Orinoco delta (Muller, 1959) and discussed with reference to

Classopollis pollen by Thompson (1969). Plants producing

Classopollis are, on one hand, believed to have occupied

well-drained upland slopes and/or coastal areas and may have formed essentially pure stands at times (Pocock & Jansonius,

1961; Srivastiva, 1976). In contrast to this, Parker (1976) has suggested, based on the occurrence of plant macrofossils in particular lithotypes, that at least one of the 84

Cla380pollis producing plants occupied swampy environments

on the fluvial floodplain some distance inland from the coast.

Taxodiaceaepollenites, representing the Taxodiaceae,

occurs in varying but generally low abundance in most samples. Samples from well 519-21-1, the section furthest west in this study, has a consistently higher percentage of this pollen. Its abundance does not appear to vary significantly in different lithologies.

Bisaccate pollen is notably rare in the Moreno Hill

Formation sediments.

The primary source of information on the vegetation which contributed to peat accumulation is the coal or altered peat itself. Although it is not possible to determine the precise components of Assemblage 5 which accumulated in the peat-forming coal swamps, a reasonable approximation of a pure coal-swamp assemblage can be synthesized by comparing the mixed coal and shale samples of Assemblage S to the shale samples of Assemblage 4. Assuming the difference between these two assemblages is due primarily to the proximity and abundance of the plants of the coal-forming peat swamps, the palynomorph assemblage in the coal is probably dominated by large, reticulate, tricolpate angiosperm pollen and bryophyte spores with lesser amounts of ferns, lycopods and very few gymnosperms.

These coals represent wet, boggy, lowland depositional environments with little or no mineral accumulation. Such 85

an accumulation, relatively free of extraneous clastic

sediment, could be due, at least in part, to the baffling

effect of the dense peat-forming community at the margins of

the peat swamps or other restriction to flowing water in

which peat accumulation kept up with or exceeded local

subsidence or compaction, raised bogs, or to the protection

of the marginal lowlands by natural levees. A pollen-spore

assembage of the coal is likely to indicate the presence of

the plants which constituted the peat-forming community

itself with some lesser influence expected by wind transport of pollen and spores from sources outside the peat swamp.

Reconstructing the flora which formed the peat-forming community is extremely speculative. As discussed earlier, while the pollen-spore data may accurately represent the plants growing in and around the peat-forming community, the relative prOportions of palynomorphs is not likely to reflect the actual prOportions of plants. Furthermore, palynologic studies on modern peat-forming communities indicate that migrating peat vegetation zones are detected only as gradual shifts (Cohen & Spackman, 1972). The lack of fine sampling resolution of the coal seams in this study makes it virtually impossible to differentiate these types of zones. The lack of knowledge concerning the morphology and habitat requirements of the plants during this period makes speculation all the more difficult. The abundance of cuticlar debris in some coal samples may indicate a more significant role for herbaceous plants in some peat-forming 86

communities. Perhaps bryOphytes and ferns made up the

dominant flora in these areas. The abundance of certain

fossil angiosperm pollen, the notable rarity of gymnosperm

pollen and the presence of varying amounts of secondary wood

tissue indicate that some woody angiosperms also grew in and

around the peat-forming swamps.

Pollen-spore assemblages 3 and 4 are found in shale

samples representing sediment deposition in a relatively

low-energy, fresh-water environment. The pollen-spore assemblages represent plants growing not only in and around

the site of deposition but also the sediment source areas and includes some airborn pollen and spores from outside areas. As such, these assemblages may not be indicative of the floral composition of specific communities but do indicate, to some extent, the diversity of plants in Moreno

Hill time.

Assemblage 4, in particular, combined with plant megafossil information, gives some indication of a well- estabished angiosperm community. The two previously mentioned fossil leaf beds indicate a riparian, or bottomland-floodplain community comprised, at least in part, of angiosperms. Variously preserved fossil logs have been reported to occur in some of the channel sandstones

(Campbell, 1984). These may indicate the presence of arborescent plants along upstream river floodplains or banks or levees. The affinities of these logs are not known.

The abundance of the fossil fern spore genus Cyathidites 87 in Assemblage 3 indicates a common presence of ferns, having affinities with either or both the Cyatheaceae and/or the

Dicksoniaceae, in and around the prograding lower delta plain. The remarkably high abundance of gleicheniaceous fern spores in sample Pb 13112 may indicate the near proximity of a dense stand of gleicheniaceous ferns. Modern ferns in the family Gleicheniaceae often form dense thickets

(Tryon and Tryon, 1982). Also dense stands of Woodwardia occur in clearings and at the edge of swamps where they merge with open marshes in parts of the Okefenokee swamp- marsh complex (Cohen, 1973). In these areas the percentage of Woodwardia spores was also found to be higher.

I have interpreted well 519-21-1 to have been located in a position marginal to the prograding delta during lower

Moreno Hill time. The Lower Member of the Moreno Hill

Formation in this well is only about 50 ft. thick and lacks the good coal seams which are present in the other sections.

The generally higher abundance of Taxodiaceaepollenites in this well may indicate the presence of taxodiaceous vegetation on bottomlands outside of the actively prograding delta. 88

CONCLUSIONS:

Figure 19 outlines the palynological zonation of the four principal sections in this study. This zonation is based on local pollen-spore occurrence and range, clustering analysis, and relative abundance peaks of selected pollen- spore groups.

The Rio Salado zone is characterized by low pollen diversity, a low frequency of marine algal grains and a very high frequency of ClassOpollis. The indications here are of

an offshore, low energy environment.

The Atarque zone is characterized by a higher frequency of marine algal grains, a higher diversity of terrestrially derived pollen and spores and a much lower relative abundance of Classopollis. The stratigraphic sequence of

lithologic units in the Atarque at the Moreno Hill outcrOp locality is indicative of the coastal sedimentary buildup expected with a prograding barrier bar system.

Coal Zone A (Antelope) is non-marine in the Moreno Hill outcrOp section but contains marine microfossils in well

519-21-1. It also appears to be present in coal test well

Sl7-34-l to the northeast (Figure 5). This zone is identified by a high frequency of ferns and relatively low frequency of angiosperms. The gymnospermous population alternates between Taxodiaceaepollenites and Classopollis dominance. Classopollis may reach highs of 50 percent of

the total palynoflora. The pattern of shifts in the relative frequency of the various terrestrially derived palynomorphs and groups used for identification of this zone in the Moreno Hill section is nearly duplicated at the base of the Moreno Hill Formation in well 519-21-1 to the northwest. This strongly indicates that a marine, nearshore environment existed at the location of well 519-21-1 at the same time that a swamp vegetation was present at the the

Moreno Hill outcrOp location.

Coal zone B (Cerro Prieto) is present in well 517-25-1 and may include the lower coal in USGS well #1. This zone is characterized by a very high relative abundance of angiosperms and a very high frequency of cycad-like pollen in the gymnospermous papulation. In addition, PhimOpollen-

1333 pollen is common through most of this zone. Though the

B coal zone was not identified in the Moreno Hill outcrop section it may be indicated by the thin coal which is bracketed by sandstones between the A and C coal zones. No pollen or spores were retrieved from the two samples taken in this section of the outcrOp probably due to deep weathering, and the palynological correlation was not possible.

Coal Zone C (Lower Rabbit) has been identified in all four of the primary sections in this study. Though this zone is similar to the B coal zone (Cerro Prieto) in pollen- spore relative abundances it can be distinguished by the occurrence of stratigraphically restricted palynomorphs 90

(Figure 7) and on the slightly higher frequency of

Taxodiaceaepollenites in the gymnosperm papulation.

Coal zone D has been identified in well 519-21-1, the

Moreno Hill outcrop section, well 517-25-1 and its presence is indicated in the outcrOp section 7/27/82 11 several miles to the south. In three of these sections (Moreno Hill outcrOp, well 517-25-1 and outcrOp 7/27/82/11) abundant specimens of what appears to be an algal cyst were found in the lower part of this zone. Marine acritarchs and/or dinoflagellates were also found associated with these grains in samples from both well $17-25-1 and at the southern outcrOp exposure (7/27/82/ 11). The presence of these algal-like cysts may be of value in correlating the D coal zone.

Coal zone D may further be identified by the frequent shifts of dominance in the gymnospermous papulation between cycads or cycadeoids, Taxodiaceaepollenites and Classopollis

and by the characteristic pattern of relative abundance changes for the angiosperms. The top of this zone is marked by the introduction of marine algal grains in all sections except well 519-25-1.

The recurrence of a marine flora below the Moreno Hill

Middle Sandstone Member is strong evidence of a Marine transgression into or near the study area. Possible equivalence with the Pescado Tongue of the Mancos Shale, identified to the north and east, should be considered. An alternative explanation is that this marine zone apparently 91

associated with the Middle Sandstone is equivalent, in part,

to the Torrivio Member of the Gallup sandstone. This was

suggested as a possible correlation by Hook, Molenaar and

Cobban (1983), and Molenaar (1983).

The Lower Moreno Hill Formation appears to represent the

sedimentary buildup of a prograding deltaic system.

Analysis of five recuring pollen-spore assemblages and other micro- and macroscopic-sized plant detritus suggests that there was a diverse land flora occupying the shifting habitats of this system. BIBLIOGRAPHY

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101

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102

APPENDIX I

List of Samples Used and Abbreviated Lithologic Description.

MRs- Rio Salado Tongue of Mancos Shale; A- Atarque Formation; LMH- Lower Moreno Hill Formation; MMH- Moreno Hill Formation Middle Member; UMH- Upper Moreno Hill Formation.

MORENO HILL OUTCROP SECTION: Sec. 7, T4N, R18W

Sample number Preparation number Lithology

7/25/81 11 9 Pb 13141 sh., rooted LMH 7/25/81 11 7 Pb 13139 carb. sh., 1f LMH 7/25/81 11 5 Pb 13137 sh., rooted LMH 7/25/81 II 4 Pb 13136 carb. sh. LMH 7/25/81 11 3 Pb 13135 dk. sh. LMH 7/25/81 I 11 Pb 13132 sh. & clayst. LMH 7/25/81 I 10 Pb 13131 coaly sh. LMH 7/25/81 I 7 Pb 13128 lignitic sh. LMH 7/25/81 I 6 Pb 13127 coal 6 carb sh. LMH 7/24/81 I 14 Pb 13121 clayst. LMH 7/24/81 I 13 Pb 13120 carb. sh. LMH 7/24/81 I 9 Pb 13116 sh. 6 clayst. LMH 7/24/81 I 5 Pb 13112 sh. 6 clayst. LMH 7/24/81 I 4 Pb 13111 coaly sh. LMH 8/17/79 III 2 Pb 13494 sh. & ss. A 8/17/79 111 1 Pb 13493 sh. & ss. A 7/29/82 11 6 Pb 13587 sh., siltst. 6 ss. MRS 7/29/82 11 5 Pb 13592 sh., dk. MRS 7/29/82 11 4 Pb 13591 sh. MRS 7/29/82 11 3 Pb 13590 sh. MRS 7/29/82 11 2 Pb 13589 sh. w/concretions MRS 7/29/82 II 1 Pb 13588 sh. MRS

WELL SECTION 519-21-1: Sec. 21, R19W

Depth Preparation number Lithology

260-265' Pb 13400 sh. 6 siltst. UMH 290-295' Pb 13406 siltst. LMH 300-305' Pb 13190 carb. sh. LMH 305-310' Pb 13191 carb. sh. 6 coal LMH 310-315' Pb 13192 carb. sh. 6 ss. LMH 315-320' Pb 13193 siltst., as, coal LMH 320-325' Pb 13194 siltst., some coal LMH

103

325-330' Pb 13195 sh., carb. sh. LMH 330-335' Pb 13196 sh. LMH 335-340' Pb 13197 sh., ss. LMH 345-350' Pb 13198 clayst. LMH 365-370' Pb 13202 sh. 6 carb. sh. A 385-390' Pb 13206 sh. 6 carb. sh. A 400-405' Pb 13170 sh. MRS 425-430' Pb 13175 sh. 6 carb. sh. MRS 450-455' Pb 13180 sh. MRS 475-480' Pb 13185 sh. MRS

WELL SECTION 517-25-1: Sec. 25, TSN, R17W

Depth Preparation number Lithology

5-10' Pb 13619 silty sh. 6 siltst. LMH 40-45' Pb 13620 silty sh. 6 sh. LMH 45-50' Pb 13621 sh. 6 carb. sh. LMH 50-55' Pb 13622 sh. 6 some coal LMH 65-70' Pb 13951 sh. 6 carb. sh. LMH 80-85' Pb 13623 sh. 6 coal LMH 110-115' Pb 13624 sh. 6 carb. sh. LMH 120-125' Pb 13625 sh. 6 some coal LMH 125-130' Pb 13626 sh. 6 coal LMH 130-135' Pb 13627 sh. LMH 175-180' Pb 13628 sh. 6 some coal LMH 185-190' Pb 13629 ab. 6 coal LMH 190-195' Pb 13630 sh. 6 coal LMH 195-200' Pb 13631 sh. 6 some coal LMH ZOO-205' Pb 13632 sh. LMH 205-210' Pb 13633 sh. LMH 215-220' Pb 13634 sh. LMH 270-280' Pb 13636 sh. LMH

WELL SECTION 517-34-1: Sec. 34, TSN, R17W depth Preparation number Lithology

180-185' Pb 13992 sh. 6 coal LMH 185-190' Pb 13993 sh. 6 coal LMH

TEJANA OUTCROP SAMPLES: Sec. 14 6 23, T2N, R16W

Sample number Preparation number Lithology

7/30/82 I 2 Pb 13699 sh. 6 siltst. UMH 7/30/82 I 1 Pb 13698 shaley siltst. UMH

104

LAKE ARMIJO OUTCROP SECTIONS:

Sample number Preparation number Lithology Sec. 8, T2N, R17W 7/30/82 II 3 Pb 13702 sh., siltst. & ss. UMH 7/30/82 II 2 Pb 13701 sh. & siltst. UMH Sec. 6, T2N, R17W 7/27/82 I 3 Pb 13440 sh. & carb. sh. MMH Sec. 33, T3N, R18W 7/27/82 II 8 Pb 13448 sh. LMH 7/27/82 II 5 Pb 13445 sh. LMH

FENCE LAKE SW: USGS WELL #1: Sec. 4, T4n, R17W

Depth Preparation number Lithology

49'6"-55' Pb 12716 sh. 6 carb. sh. LMH 70-75' Pb 12729 sh. LMH 75-79' Pb 12726 sh. 6 carb. sh. LMH

105

APPENDIX II

Species List:

(ref.no.) Plate-fig. Division Chlorophchphyta Ovoidites sp. (178) 1-1,2

Division PyrrhOphycophyta Division Dinophyceae Dinoflagellates Deflandrea accumata (229) type 1 (222) 1-7 type 2 (223) type 3 (224) type 4 (225) type 5 (226) type 6 (227) type 7 (228) Hystrichospheres type 1 (241) type 2 (242) type 3 (243) type 4 (244) type 5 (245) type 6 (246) type 7 (247)

Algae (Incertae Sedis) Acritarchs type 1 (231) type 2 (232) type 3 (233) type 4 (234) type 5 (235) type 6 (236) Unknown sp. 248 (248) 8p. 249 (249)

Division Bryophyta Class Musci Order Sphagnales Distverrusporites antiquasporites (130) Cingutriletes clavus (133) C. sp. A (132) Sterisporites sp. A (126)

S. sp. B (127) _ So 8pc C (128) S. sp. D (129)

106

Class Hepaticae Aequitriradites ornatus Upshaw (147) Triporoletes reticulatus (148) 2-10 1. sp. A (147) 2-11

Division Lycophyta Camarozonosporites sp. A (134) 9. sp. B (135) 2 7 9. sp. C (136) 2-6 Echinatisporites sp. A (139). 2 8 8p. B (140) sp. C (141) sp. D (142) sp. E (143) sp. F (144) Neoraistrickia INHWFHNH“ truncata (145) 2-9 Perotriletes sp. A (137) 2-1 2. sp. B (138)

Division PteridOphyta Shizaeaceae Appendicisporites dentimarginatus (202) 2-16 5. sp. (72) 2-14 sp. (73) 18> sp. (74) 2-15 Sp. (75) SP. (76) 8p. (198) 8p. (217) SP. (218) SP. (151) 3-1

SP. (209) 2-13 N‘uhiﬂ'ﬂFIUC5ul> omotriletes sp. A (85) catricosisporites venustus (77) 3-4 sp. (78) 3 2 sp. (79) 8p. (80) 8p. (81) SP. (82) 3-3 sp. (83) sp. (84) 8p. (150) sp. (201) 3-5

_. sp. (210) NHHED'ﬁMCOU

ounuwruonnuncnouaEzgy>u>wﬂ>4>u>WH>4 Gleic eniaceae Deltoidospora hallii (95)

2. sp. A (93) Gleicheniidites senonicus (90) 3-7 G. sp. A (91) E . sp. B (92) E . sp. C (149) E . sp. D (203) 3-6 o rnamentifera tuberculata (96)

107

Matoniaceae Biretisporites sp. A (97) 2. sp. B (98) B. sp. C (99) B. sp. D (100) Matonisporites sp. A (104) M. sp. B (105) M. sp. C (106) Cheiropleuriaceae DictyoPhyllidites sp. A (125) Polypodiaceae Laegigatosporites sp. A (63) L. sp. B (64) L. sp. C (65) L. sp. D (66) Cyatheaceae Cyathidites minor (89)

2. sp. A (86) 9. sp. B (87)

Division Pteridophyta Incerae Sedis Ariadnaesporites sp (123) Concavisporites sp (107) Nevesisporites simiscalaris (124) Toroisporis delicatus (108) Triletes sp. A (113) 1. sp. B (114) 1. sp. C (115) 1. sp. D (116) 3. sp. E (117) 1. sp. F (118) 3. sp. G (152) 1. sp. H (199) 1. sp. I (200) 3. sp. J (207) 2. sp. K (208) 1. sp. L (211) 1. sp. M (214) 1. sp. N (215) 1. sp. 0 (219) 3. sp. P (204) Trilobosporites sp. A (119)

3. sp. B (120) 2. sp. C (121) 1. sp. D (122) Undulatisporites sp. A (109) E. sp. B (110) Verrucosisporites sp. A (111) 1. 8p. B (112)

108

Division Cycadophyta Cycadopites sp. A (54) 5-4 G. sp. B (56) 5-5 2. sp. C (57) Exesipollenites tumulus (182) 5-8

Division Coniferophyta Cheirolepidiaceae ClassoPOllis sp. A (159) Classopollis sp. B (160) 5-6,7 Taxodiaceae Inapertur0pollenites sp. A (154) 5-10 1. 8p. B (155) ' Taxodiaceaepollenites sp. (156) 5-9 Araucariaceae Araucariacidites sp. (157) Pinaceae Alisporites sp. (173) 5-11

Division GnetOphyta Ephedripites sp. (181)

Division MagnoliOphyta Class LiliOpsida Liliacidites sp. A (44) L. sp. B (45) E. sp. 0 (46) 6-14 2. sp. D (47)

Monocolpopollenites sp. A (49)

Class MagnoliOpsida Tricolpate pollen grains Cupuliferoidaepollenites sp. A (1) 5-12,13 9. sp. B (2) 5-14 9. sp. C (185) 5-1,2,3 PhimOpollenites sp. A (18) 6-12 3. sp. B (19) 6-13 3. sp. C (20) P. 8p. D (21) Rousea gggrgensis (15) 6-4 5. sp. A (16) 6-5 R. sp. B (17) Tricolpites minutus (14) 6-1 1. angloluminosus (10) 6-2 1. sp. A (3) 5-15,16 1. sp. B (4) 5-17 1. sp. C (5) 5-18 1. sp. D (6) 5-20 3. sp. E (7) 5-21 1. sp. F (8) 3. sp. G (9)

108

Division CycadOphyta CycadoPites sp. A (54) 5-4 2. sp. B (56) 5-5 2. sp. C (57) Exesipollenites tumulus (182) 5-8

Division Coniferophyta Cheirolepidiaceae Classopollis sp. A (159) Classopollis sp. B (160) 5-6,7 Taxodiaceae InaperturOpollenites sp. A (154) 5-10 1. 8p. B (155) ' Taxodiaceaepollenites sp. (156) 5-9 Araucariaceae Araucariacidites sp. (157) Pinaceae Alisporites sp. (173) 5-11

Division GnetOphyta Ephedripites Sp. (181)

Division Magnoliophyta Class LiliOpsida Liliacidites sp. A (44) L. sp. B (45) g. Sp. c (46) 6-14 L. sp. D (47) L. sp. E (48) 6-15 Monocolpopollenites sp. A (49)

Class Magnoliopsida Tricolpate pollen grains Cupuliferoidaepollenites sp. A (1) 5-12,13 9. sp. B (2) 5-14 9. sp. C (185) 5-1,2,3 Phimopollenites sp. A (18) 6-12 P. sp. B (19) 6-13 3. sp. C (20) P. sp. D (21) Rousea georgensis (15) 6-4 5. sp. A (16) 6-5 5. sp. B (17) Tricolpites minutus (14) 6-1 I. aggloluminosus (10) 6-2 1. sp. A (3) 5-15,16 2. sp. B (4) 5-17 1. sp. C (5) 5-18 1. sp. D (6) 5-20 3. sp. E (7) 5-21 3. 8p. F (8) T. sp. G (9)

109

1. sp. I (11) 3. sp. J (12) Tricolporate pollen grains Margocolporites sp. (37) Nyssapollenites nigricolpus (27) N. triangulus (29) sp. A (26) sp. B (32) sp. C (28) sp. D (33) sp. E (30)

e sp. F (31)

H icolporites sp. A (34)

O sp. B (35)

e SP. C (36)

Iahewﬂznzmnzumzt

Incertae Sedis Inaperturate grains of uncertain affinity type (161) type (162) type (163) type (164) type (165) 1 bu.) type (166) HH type (167) type (168) type (169)

WQNO‘UIL‘WNH type 10 (170) Unknown palynomorphs type (197) type (186) type (187) type (188) type (190) type (191) type (195) type

mﬂOu-§UNH (196)

PLATES

110

PLATE 1

Magnification X1000 unless otherwise stated

1,2. Ovoidites sp. 1. slide Pb 13622-1, co-ord. 112.0/42.3, 18 x 23 um. 2. slide Pb 13622-1, co-ord. 126.8/34.2, 19 x 27 um.

3,4. Inaperturate grains of uncertain affinity.

4. slide Pb 13112-1, co-ord. 126.1/43.2, 25 um.

5. Unidentified sp. 248. slide Pb 13951-1, co-ord. 122.7/32.5, 49 um.

6. Unidentified sp. 249, X900. slide Pb 13951-1, 123.1/35.0, 90um.

7. Dinoflagellate type 1. slide Pb 13493-3, co-ord. 123.1/43.0, 38 x 42 um.

8. Dinoflagellate type 4. slide Pb 13493-3, co-ord. 114.0/32.1, 45 x 63 um.

9. Dinoflagellate type 5. slide Pb 13493-3, co-ord. 121.5/46.9, 43 x 62 um.

10. Acritarch type 1. slide Pb 13493-1, co-ord. 119.3/39.5, 38 um.

11. Acritarch type 4. slide Pb 13493-3, co-ord. 112.2/41.6, 25 um.

12. Acritarch type 5. slide Pb 13493-3, co-ord. 126.8/43.1, 34 um.

Plaie

111

PLATE 2

Magnification X1000 unless otherwise stated

1. Stereisporites sp. A. slide Pb 13622-1, co-ord. 124.6/46.9, 20 um.

2. S. sp. B. slide Pb 13622-1, co-ord. 128.2/40.9, 25 um.

3. Distverrusporites antiquasporites. slide Pb 13128-1, co-ord. 118.7/40.5, 23 um.

4. Cingutriletes sp. A. slide Pb 13198-1, co-ord. 120.1/27.2, 27 um.

5. 9' clavus. slide Pb 13633-1, co-ord. 116.0/39.6, 27 um.

6. Camarozonotriletes sp. C. slide Pb 13128-1, co-ord. 123.6/26.1, 24 um.

7. 2. sp. B. slide Pb 13633-1, co-ord. 114.1/45.1, 27 um.

8. Echinatisporites sp. A. slide Pb 13112-1, co-ord. 112.6/4l.9, 17 um.

9. Neoraistrickia truncata. slide Pb 13128-1, co-ord. 117.0/41.7, 20 um.

10. Triporoletes reticulatus. slide Pb 13633-1, co-ord. 121.6/36.2, 50 um.

11. 1. sp. A. slide Pb 13625-11, co-ord. 112.2/30.7, 52 um.

12. Perotriletes sp. A. slide Pb 13622-1, co-ord. 120.2/46.5, 49 um.

13. Appendicisporites sp. K. slide Pb 13625-11, co-ord. 118.9/33.6, 55 um.

14. A. sp. A.

15. A. sp. C. slide Pb 13112-1, co-ord. 121.6/32.6, 45 um.

16. A. dentimarginatus. slide Pb 13625-12, co-ord. 118.4/47.7, 38 um. ore-7‘4 112

PLATE 3

Magnification X1000 unless otherwise stated

1. Appendicisporites sp. J. slide Pb 13625-10, co-ord. 109.6/45.3, 52 um.

2. Cicatricosisporites sp. B. slide Pb 13622-1, co-ord. 110.8/30.1, 31 um.

3. 2. sp. F. slide Pb 13112-2, co-ord. 119.9/31.0, 25 um.

4. C. venustus Slide Pb 13112-1, co-ord. 123.6/34.1, 23 x 27 um.

50 2. sp. J. slide Pb 13625-11, co-ord. 105.0/29.8, 50 um.

6. Gleicheniidites sp. D. slide Pb 13625-11, co-ord. 128.7/31.l, 35 um.

7. E. senonicus. slide Pb 13112-1, co-ord. 117.3/45.9, 32 um.

8, 9. Cyathidites minor.

...- 8. slide Pb 13112-2, co-ord. 128.3/31.9, 29 um.

r‘)' 9. slide Pb 13128-1, co-ord. 111.0/41.1, 31 um.

10. Matonisporites sp. B. slide Pb 13198-1, co-ord. 117.5/48.2, 64 um.

11. Triletes sp. G. slide Pb 13625-11, co-ord. 109.3/28.7, 56 um.

n 0w0-L 113

PLATE 4

Magnification X1000 unless otherwise stated

1. Undulatisporites sp. A. slide Pb 13626-1, co-ord. 111.5/47.7, 17 um.

2. Ho 3pc Bo slide Pb 13112-1, co-ord. 111.6/37.4,

3. Triletes sp. E. slide Pb 13634-4, co-ord. 123.7/25.8, 27 um.

4. 1. sp. D. slide Pb 13112-1, co-ord. 112.5/41.5, um.

5. Nevesisporites simiscalaris. slide Pb 13633-1, co-ord. 112.3/42.3, 31 um.

Verrucosisporites sp. A. slide Pb 13128-1, co-ord. 115.5/39.6, 32 um.

Ariadnaesporites sp.

slide Pb 13626-1, co-ord. 119.3/47.5, 34 x 36 um.

Biretisporites sp. D. slide Pb 13633-1, co-ord. 118.0/46.2, 46 um.

Triletes sp. P. slide Pb 13625-11, co-ord. 109.1/39.9, 46 um.

10. T. sp. 1. inde Pb 13625-11, co-ord. 122.4/33.6, 67 um.

11. Trilobosporites sp. C. slide Pb 13112-1, co-ord. 117.1/3o.o, 64 um.

Plaie 4

114

PLATE 5

Magnification X1000 unless otherwise stated

1-3. Cupuliferoidaepollenites sp. C. I. slide Pb 13633-1, co-ord. 128.4/43.8, 10 um. 2. slide Pb 13633-1, co-ord. 127.2/43.7, 10 um. 3. slide Pb 13633-1, co-ord. 122.9/43.9, 12 um.

4. CycadOpites sp. A. slide Pb 13633-1, co-ord. 123.4/43.7, 8 x 13 um.

5. 2. sp. B. slide Pb 13633-1, co-ord. 125.0/43.7, 11 x 17 um.

6, 7. Cla330pollis sp. B. 6. slide Pb 13493-3, co-ord. 123.1/35.2, 25 um. 7. tetrad, slide Pb 13633-1, co-ord. 119.4/28.0, 27 um.

8. Exesispollenites tumulus.

9. Taxodiaceaepollenites sp. slide Pb 13493-3, co-ord. 122.4/43.5, 25 x 32 um.

10. Inaperturapollenites sp. A. slide Pb 13493-3, co-ord. 114.3/46.7, 28 um.

11. Alisporites sp. A. slide Pb 13493-3, co-ord. 126.4/35.8, 50 x 70 um.

12, 13. Cupuliferoidaepollenites sp. A. 12. slide Pb 13633-1, co-ord. 124.8/44.0, 9 x 17 um. 13. slide Pb 13128-1, co-ord. 115.4/43.2, 12 x 18 um.

14. 9 sp. B. slide 13622-1, co-ord. 108.4/44.4, 19 um.

15, 16. Tricolpites sp. A. 15. slide Pb 13622-1, co-ord. 120.4/47.6, 10 x 14 um. 16. slide Pb 13622-1, co-ord. 118.1/46.2, 13 um.

17. 1. sp. B. slide Pb 13622-1, co-ord. 127.3/46.8, 17 um.

18. I. 8p. C. Slide Pb 13626-1, co-ord. 109.7/27.3, 21 um.

190 10 8p- I. slide Pb 13629-2, co-ord. 116.7/42.9, 16 x 17 um. 115

20. :0 8p. D. slide Pb 13493-4, co-ord. 122.5/38.3, 17 um.

21. 1. 8p. E. slide Pb 13626-1, co-ord. 118.8/37.6, 22 x 36 um. Plaie 5

116

PLATE 6

Magnification X1000 unless otherwise stated

1. Tricolpites minutus.

slide Pb 13493-4, co-ord. 127.9/37.2, 13 um.

2. T. angloluminosus slide Pb 13493-1, co-ord. 123.1/46.0, 18 um.

3. 3. sp. J. slide Pb 13493-3, co-ord. 114.3/34.2, 3O um.

4. Rousea georgensis.

23 um.

5. 3. sp. A. slide Pb 13128-1, co-ord. 110.0/45.8, 34 um.

6. Nyssapollenites sp. A.

slide Pb 13128-1, co-ord. 118.6/40.2, 16 um.

7. N. nigricolpus. slide Pb 13196-1, co-ord. 113.5/46.8, 18 1.1111.

8. N. triangulus.

slide Pb 13622-1, co-ord. 127.2/39.5, 19 um.

9, 10. Tricolporites sp. A.

13 x 15 um. 10 slide Pb 13198-1, co-ord. 108.6/26.8, 11 x 19 um.

11. 1. sp. B. slide Pb 13622-1, co-ord. 113.3/42.3, 13 x 21 um.

12. Phimopollenites sp. A.

slide Pb 13629-2, co-ord. 113.5/34.7, 19 1.1111.

13. P. sp. B. slide Pb 13629-2, co-ord. 125.7/42.9, 19 1.1111.

14. Liliacidites sp. C. slide Pb 13112-1, co-ord. 119.7/40.6, 10 x 19 um.

15. £0 8pc E0 slide Pb 13112-2, co-ord. 115.3/29.7, 25 x 46 um. Plate 6

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII ux\I“mum“;u)1111111))“1mmu 780