Palynology and Its Relationship to 

Climatically Induced Depositional Cycles 

in the Middle Pennsylvanian (Desmoinesian) 

Paradox Formation of Southeastern Utah

U.S. GEOLOGICAL SURVEY BULLETIN 2000-K
Cover. View south toward the La Sal Mountains along the Colorado River between 

Cisco and Moab, Utah. Fisher Towers in center is composed of Permian Cutler Formation 

and capped by Triassic Moenkopi Formation. The prominent mesa at left center is capped 

by Jurassic Kayenta Formation and Wingate Sandstone and underlain by slope-forming 

Triassic Chinle and Moenkopi Formations. The Chinle-Moenkopi contact is marked by a 

thin white ledge-forming gritstone. The valley between Fisher Towers and Fisher Mesa in 

the background is part of Richardson Amphitheater, part of Professor Valley. Photograph 

by Omer B. Raup, U.S. Geological Survey.
Palynology and Its Relationship to 

Climatically Induced Depositional Cycles 

in the Middle Pennsylvanian (Desmoinesian) 

Paradox Formation of Southeastern Utah

By Bruce F. Rueger

EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN 

A.C. Huffman, Jr., Project Coordinator

U.S. GEOLOGICAL SURVEY BULLETIN 2000-K

A multidisciplinary approach to research studies of 

sedimentary rocks and their constituents and the 

evolution of sedimentary basins, both ancient and modern

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1996
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

For sale by U.S. Geological Survey, Information Services

Box 25286, Federal Center

Denver, CO 80225

Any use of trade, product, or firm names in this publication is for descriptive purposes only and 

does not imply endorsement by the U.S. Government

Library of Congress Cataloging-in-Publication Data

Rueger, Bruce F.

Palynology and its relationship to climatically induced depositional cycles in the 

Middle Pennsylvanian (Desmoinesian) Paradox Formation of southeastern Utah/by Bruce 

F. Rueger.

p. cm. (Evolution of sedimentary basins Paradox Basin ; ch. K) 

(U.S. Geological Survey bulletin ; 2000)

Includes bibliographical references.

Supt. of Docs, no.: I 19.3:2000-K

1. Palynology Utah. 2. Paleobotany Pennsylvanian. 3. Paleoclimatology 

Utah. 4. Sedimentation and deposition Utah. 5. Paradox Formation. I. Title. 

II. Series. III. Series: U.S. Geological Survey bulletin ; 2000 

QE75.B9 no. 2000-K 

[QE993] 

557.3 s dc20

[561'.13'09792] 95-24457

CIP
CONTENTS

Abstract........................................................................................................................... Kl

Introduction..................................................................................................................... 1

Regional Geology and Stratigraphic Setting................................................................... 2

Location and Configuration of the Paradox Basin.................................................. 2

Late Paleozoic Tectonics and Stratigraphy............................................................. 2

Previous Investigations Concerning Palynology of Salt Deposits.................................. 5

Evaporite Cycles of the Paradox Formation ................................................................... 6

Idealized Evaporite Cycle ....................................................................................... 6

Evaporite Cycle 7.................................................................................................... 8

Interbed 8-9 ............................................................................................................ 8

Comparison with Idealized Cycle of Hite............................................................... 10

Climatic Factors Influencing Cyclic Sedimentation ....................................................... 11

Palynology of the Paradox Formation ............................................................................ 13

Samples and Location ............................................................................................. 13

Sample Preparation................................................................................................. 13

Preservation of Palynomorphs ................................................................................ 13

Lithologic Occurrence of Palynomorphs ................................................................ 15

Stratigraphic Occurrence of Palynomorphs .................................................................... 15

Stratigraphic Distribution of Palynomorph Genera in the Paradox Formation....... 15

Distribution of Palynomorph Genera in a Single Salt Cycle .................................. 18

Conclusions..................................................................................................................... 18

References Cited............................................................................................................. 20

PLATES

1-4. Selected palynomorphs from the Middle Pennsylvanian (Desmoinesian) Paradox Formation, 

Gibson Dome No. 1 borehole, southeastern Utah.

FIGURES

1. Map of Paradox Basin showing approximate limits of halite in Middle Pennsylvanian Paradox Formation....... K3

2. Chart showing generalized Late Paleozoic stratigraphy for Paradox Basin.......................................................... 4

3. Diagrammatic north-south Stratigraphic section showing nomenclature of Middle and Upper Pennsylvanian

Hermosa Group ..................................................................................................................................................... 5

4. Diagram showing idealized evaporite cycle of Middle Pennsylvanian Paradox Formation ................................ 7

5. Generalized lithologic section of interbed 8-9 of Middle Pennsylvanian Paradox Formation............................. 9

6. Graph showing bromine distribution in evaporite cycle 7 of Middle Pennsylvanian Paradox Formation,

Gibson Dome No. 1 borehole................................................................................................................................ 11

7. Diagram showing Stratigraphic distribution of palynomorph genera recovered from Middle Pennsylvanian

Paradox Formation, Gibson Dome No. 1 borehole ............................................................................................... 16

8. Chart showing biostratigraphic zonation of palynomorph genera recovered from Middle Pennsylvanian

Paradox Formation, Gibson Dome No. 1 borehole ............................................................................................... 17

9. Diagram showing Stratigraphic distribution of palynomorph genera recovered from interbed 8-9 of Middle

Pennsylvanian Paradox Formation, Gibson Dome No. 1 borehole ....................................................................... 19

III
IV CONTENTS

TABLE

1. Lithology and location of palynological samples collected from the Gibson Dome No. 1 borehole,

San Juan County, Utah.......................................................................................................................................... K14
Palynology and Its Relationship to

Climatically Induced Depositional Cycles in the

Middle Pennsylvanian (Desmoinesian)

Paradox Formation of Southeastern Utah

By Bruce F. Rueger 1

ABSTRACT

The Middle Pennsylvanian (Desmoinesian) Paradox 

Formation of the Hermosa Group consists of a thick sedimentary wedge of strongly cyclical predominantly evaporitic rocks and minor siliciclastic units that define the areal 

extent of the Paradox Basin. Palynomorphs are abundant 

throughout the formation and provide a tool to aid in the 

evaluation of the climatic factors influencing cyclicity. 

Analysis of the palynomorph assemblage of the Paradox 

Formation allows construction of four distinct biofacies, 

from base to top, zones of Vesicaspora, Striatites, Potonieisporites, and Striatites-Potonieisporites. Analysis of a 

single evaporite cycle provides data significant to understanding the mechanisms influencing cyclicity. Rocks of 

the carbonate-siliciclastic interbeds between halite units 

contain palynomorphs typically associated with Desmoinesian coal beds and indicate relatively moist conditions. No 

palynomorphs of this type were collected from the halites 

of the Paradox Formation, but those collected from the 

interbeds indicate conditions more xeric in nature. These 

changes in palynomorph assemblage composition reflect 

an oscillation between warm, wet and cool, dry conditions. 

This climatic oscillation corresponds with the rock types 

within each cycle. Sedimentation rates for the rock types 

in each cycle provide a periodicity of approximately 

100,000 years, which is attributable to perturbations in the 

eccentricity of the Earth's orbit. Palynomorph assemblages in the Paradox Formation reflect this periodicity and 

indicate expansion and contraction of equatorial desert or 

arid regions caused by the impact of continental glaciation 

on the global climatic regime. As Gondwanan glaciers

Department of Geology, Colby College, Waterville, Maine 04901, 

and Department of Geological Sciences, Campus Box 250, University of 

Colorado, Boulder, Colorado 80309.

built up, cool and dry climatic conditions developed in 

equatorial regions, initiating evaporite deposition. When 

glacial conditions relaxed, the climate became warmer and 

wetter and carbonate-siliciclastic strata were deposited. 

Vegetation in the Paradox Basin region may have 

responded to this climatic variability by becoming specialized, and by evolving rapidly, and may represent a source 

area for plants of gymnospermous and pteridospermous 

affinity and a plant province distinct from the 

Midcontinent region of the United States.

INTRODUCTION

The Paradox Formation of the Hermosa Group consists 

of a thick sedimentary wedge of primarily marine rocks 

dominated by evaporites in the Paradox Basin, a major structural and depositional basin in southeastern Utah and southwestern Colorado. It was deposited during the Middle 

Pennsylvanian (Desmoinesian) and has been related to a 

period of major worldwide eustatic sea-level rise and epicontinental transgression. The rocks of the formation are 

strongly cyclical in nature and are characterized by the classic vertical and lateral succession of facies associated with 

evaporite deposits. Each cycle is composed of chemical and 

clastic rocks deposited in the sequence anhydrite, silty dolomite, black shale, silty dolomite, anhydrite, and halite and 

terminates with an unconformity. Many theories have been 

advanced that address possible mechanisms controlling such 

cyclicity, including changes in sedimentation rate, tectonic 

pulses, climate fluctuations, and eustatic rise and fall of sea 

level, but none except those having climatic influences adequately explain the characteristics of the cycles.

A paucity of invertebrate fossils is in the evaporite 

facies of Paradox Formation. The high salinity of the brines 

that formed the Paradox Formation probably was very 

inhospitable to most organisms that would have existed

Kl
K2 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

under normal marine conditions and is the most probable 

explanation for the noticeable lack of fossils. Because of 

high salinities, the brines were anoxic. This lack of oxygen 

was, however, favorable for the preservation of organic matter, and palynomorph fossils are well preserved in sediments 

of the Paradox Formation. These palynomorphs allow definitive dating for the Rocky Mountain region, biozonation, and 

regional biostratigraphic correlation and can aid in ascertaining the mechanisms inducing cyclicity.

During an investigation of water-insoluble residues 

collected from halite samples of the Paradox Formation, 

abundant diverse and exquisitely preserved palynomorphs 

were encountered in the organic fraction. The samples 

were obtained from complete, unaltered core recovered 

from the U.S. Department of Energy Gibson Dome No. 1 

borehole, sec. 21, T. 30 S., R. 21 E., San Juan County, 

southeastern Utah (fig. 1). This fortuitous discovery led to 

further investigation, and palynomorphs were subsequently 

recovered in varying amounts from every halite sample, as 

well as from rocks of most of the other chemical and clastic 

facies, throughout the Paradox Formation in the borehole. 

These palynomorphs were the first widespread fossils to be 

discovered in the evaporite facies of the Paradox Formation, and they have considerable potential for biostratigraphic zonation and regional biostratigraphic correlation. 

Because the lithofacies and palynomorph record of the Paradox Formation is so complete and well preserved in the 

borehole, possibilities are afforded for biostratigraphic and 

paleoenvironmental studies that hopefully will add significantly to the interpretation of these evaporite deposits.

In this report I evaluate the use of the Paradox palynomorphs for precise dating, biostratigraphic zonation, and 

regional to intercontinental correlation at a level previously 

not possible from sparse foraminifera (fusilinid) data. I 

also analyze the palynomorph biofacies and biostratigraphic zones within the context of large- and small-scale 

depositional cycles of the Paradox Formation and present 

interpretations of environmental, climatic, and other factors 

that may have produced these cycles.

Acknowledgments. I am indebted to the support and 

friendship offered by Robert J. Hite and Dr. Robert M. 

Kosanke, without whose help this project would not have 

reached fruition. I am also grateful for their careful and 

critical review of this manuscript, which has greatly 

improved its quality. I also acknowledge the support of Dr. 

Erie G. Kauffman,'chairman of my M.S. thesis committee 

at the University of Colorado, Boulder, whose faith in me 

has made me a much better geologist. I am also grateful to 

Dr. Susan K. Short, who with Dr. Kosanke, served on my 

M.S. thesis committee. My wife Donna provided moral 

support throughout this endeavor. Alice Ridky typed the 

original draft of this manuscript and assisted in the development of the figures. The majority of the research

presented in this investigation was completed while I held a 

Student Appointment with the U.S. Geological Survey.

REGIONAL GEOLOGY AND 

STRATIGRAPHIC SETTING

LOCATION AND CONFIGURATION OF THE 

PARADOX BASIN

The Paradox Basin in the east-central part of the Colorado Plateaus province extends from southeastern Utah 

into the Four Corners area (fig. 1). It is both a structural 

and sedimentary basin, the boundaries of which are delineated by the areal extent of salt deposits in the Middle 

Pennsylvanian (Desmoinesian) Paradox Formation of the 

Hermosa Group. The Paradox Basin is bounded at its 

northeastern margin by the Uncompahgre uplift, along its 

southern margin by the Defiance uplift, and along its western margin by the Monument uplift and the San Rafael 

Swell (fig. 1). The northeastern half of the basin is characterized by a deep trough, designated the Uncompahgre 

trough by Hite (1968), that contains very thick accumulations of salt (>450 m) and a series of northwest-trending 

salt anticlines. The southwestern half of the basin was 

the site of a shallow shelf and is characterized by relatively undeformed and considerably thinner salt deposits 

(<450 m).

LATE PALEOZOIC TECTONICS AND 

STRATIGRAPHY

Tectonic activity associated with elevation of the 

Uncompahgre uplift began to break up the stable Cordilleran shelf in the Early Pennsylvanian (Ohlen and Mclntyre, 

1965). This tectonic activity was accompanied by regional 

sagging, especially in southeastern Utah, that initiated 

development of the Paradox Basin. Associated with this 

subsidence, areas of relatively low relief evolved that surrounded the subsiding basin and delineated the areal extent 

of the Paradox Basin (Kelley, 1958). During the early 

periods of subsidence in the Middle Pennsylvanian (Atokan), marine waters invaded the area from accessways on 

the southeastern and western margins of the basin (Peterson and Hite, 1969). This invasion of marine waters is 

associated with a major rise in sea level that continued 

throughout the Pennsylvanian (Vail and others, 1978). As 

relative sea level rose, filling the newly formed basin, the 

soil and regolith overlying the Mississippian Leadville 

Limestone was reworked and redeposited as red shale of 

the lower part of the Molas Formation (fig. 2). This
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K3

Approximate

extent of 

Paradox Basin

38° -

37°

20 40 60 KILOMETERS

0 10 20 MILES

Figure 1. Map of Paradox Basin showing approximate limits of halite in the Middle Pennsylvanian Paradox Formation 

(heavy line) and location of Uncompahgre trough (shaded area) and uplift and Gibson Dome No. 1 borehole. Modified 

from Friedman and others (1994).

transgression began in the late Morrowan (Early Pennsylvanian), and by the end of Atokan time marine waters covered all but the northwestern part of the basin (Herman 

and Sharps, 1956). Stabilization of the basin during this 

time allowed deposition of shallow-water marine limestone 

that forms the Upper part of the Molas Formation.

During Desmoinesian time, the Uncompahgre uplift 

once again became active, rising slowly and gently to 

become a dominant structure in the Paradox Basin

region. Coincident with this renewed uplift, basinal 

sagging west of the rising Uncompahgre rapidly accelerated, especially in a major foredeep area, the Uncompahgre trough, that developed along the southwestern flank of 

the Uncompahgre uplift. This tectonic activity, coupled 

with the development of broad shelf areas and low-lying 

land masses on the western and southern basin margins, 

acted to significantly restrict marine circulation with the 

developing Paradox Basin (Peterson and Hite, 1969). Also
K4 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

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Figure 2. Generalized Late Paleozoic stratigraphy for the Paradox Basin, southeastern Utah.

during the Early Pennsylvanian, the climate changed from 

the warm humid environment of the Late Mississippian to 

a much more arid environment (Herman and Barkell, 

1957).

As the Uncompahgre uplift rose, fine-grained continental sediments were shed into the Paradox Basin along 

its northeastern margin, and conditions suitable for carbonate deposition continued at the basin's center and 

along its western and southwestern margins. In the central 

and western part of the basin, the underlying Molas Formation grades upward into marine carbonate rocks of the 

Pinkerton Trail Formation of the Hermosa Group. The 

Pinkerton Trail Formation represents the transition from 

open-marine conditions of the Molas Formation to the 

hypersaline environment of the Paradox Formation 

(Bodine and Rueger, 1984).

As a result of restriction of circulation caused by continued uplift along the basin margins, and under the arid 

conditions prevalent during Desmoinesian time, deposition of the cyclic evaporite sequences that characterize 

the Paradox Formation of the Hermosa Group began. 

The cyclicity of the Paradox Formation is attributed to 

the fact that the Paradox Basin was never completely isolated tectonically; thus, evaporite deposition was controlled by small-scale sea-level oscillation related to 

fluctuations in continental ice volume in the Southern 

Hemisphere (Wanless and Shepard, 1936). As sea level 

fell during regressive phases and the quantity of seawater 

available to replace losses by evaporation was diminished, prime conditions for deposition of anhydrite, halite, 

and occasionally potash salts developed. Each transgressive phase began when a fresh influx of seawater lowered 

salinity to near-normal conditions and carbonate rocks 

and shale were deposited. In the Paradox Formation penetrated by the Gibson Dome No. 1 borehole, 33 of these 

transgressive-regressive sequences have been reported, and 

results from this and other boreholes show that each cycle 

has its own areal extent (R.J. Hite, oral commun., 1992). 

Deposition of these cycles initially was restricted to the 

foredeep area of the Uncompahgre trough and includes 

cycles 20-29 (fig. 3); as this foredeep area was filled, 

evaporite deposition began to take place across the broad 

southwestern shelf area continuing through cycles 1-19 

(fig. 3), reaching maximum areal extent in cycles 6 and 9 

(Hite, 1970).

The development of shoaling in the Late Pennsylvanian eliminated any barriers to circulation that previously 

had existed. Shoaling, caused by the infilling of the basin 

with evaporites, prevented the trapping of evaporite brines 

and caused reflux. Near-normal marine conditions 

resulted, and marine carbonate deposition resumed 

throughout the Paradox Basin. This carbonate facies constitutes the Honaker Trail Formation of the Hermosa Group 

(fig. 2) and represents the transition from hypersaline to 

normal marine conditions (Bodine and Rueger, 1984).

During deposition of the Hermosa Group, the 

Uncompahgre uplift was also shedding fine-grained clastic 

sediments into the basin along its northeastern margin. 

Deposition of these fine-grained sediments was generally 

confined to the northeastern side of the basin because sediment-carrying currents were unable to mix with the higher 

density brines of the basin (Hite, 1970). As salinity 

decreased during deposition of the Honaker Trail Formation of the Hermosa Group and a major tectonic pulse 

exposed the granitic core of the Uncompahgre uplift at the 

close of the Pennsylvanian Period, coarse arkosic marginal-marine and continental clastic sediments, which constitute the Lower Permian Cutler Group (fig. 2), filled the
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K5

South North

175 km (105 mi}

EXPLANATION 

Halite facies 

Carbonate rocks facies

Figure 3. Diagrammatic north-south stratigraphic section showing the stratigraphic nomenclature of the Middle and Upper 

Pennsylvanian Hermosa Group. This relationship is similar to that toward the basin margins in all other directions. Numbered 

units are evaporite cycles of the Paradox Formation, which are predominantly halite. Maximum extent of evaporite deposition 

was during cycles 6, 9, 13, and 18. Modified from Hite and Buckner (1981).

basin. The Cutler Group represents the final episode of 

Paleozoic deposition in the Paradox Basin.

PREVIOUS INVESTIGATIONS

CONCERNING PALYNOLOGY

OF SALT DEPOSITS

Although salt deposits are present on every continent 

(Zharkov, 1981), only in Europe and North America has 

the palynology of salts of any age been investigated to any 

large degree. Studies in Europe are directly attributed to 

the pioneering work of Dr. Wilhelm Klaus, whose palynological research on the Permian Zechstein salts in the German and Austrian Alps (1953a, b, 1955, 1963, 1964, 1965, 

1970, 1972, 1974) set the precedent for future study. Subsequently, Potonie and Klaus (1954), Leschik (1956),

Grebe (1957), and Grebe and Schweitzer (1962) added 

much to the knowledge of the palynology of German 

Zechstein salts. Palynomorphs from Zechstein equivalents 

have been reported in Hungary by Deak (1959) and Stuhl 

(1962) and in Poland by Orlowska-Zwolinska (1962) and 

Dybova-Jachowicz(1974, 1978).

Since the discovery of palynomorphs in the salts of the 

Zechstein, other salt deposits have come under scrutiny. 

Palynomorphs have been reported in Mississippian deposits 

in the former Soviet Union by Varencov and others (1964), 

in Permian and Triassic deposits of the Hengelo salts of the 

Netherlands by Freudenthal (1964) and Visscher (1966), in 

Triassic salts of France by Geisler and others (1978), and in 

the Tertiary salt deposits of Romania by Costea and Baltes 

(1962) and Baltes (1967).

Palynological investigations of salt deposits in North 

America have been primarily directed toward the Mesozoic
K6 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

salt in the domes developed in the Gulf Coast region. Jux 

(1961), in an effort to date the formation of these salt 

domes, recovered Triassic and Jurassic palynomorphs from 

subsurface deposits in Louisiana. Later, as part of the Deep 

Sea Drilling Project, Kirkland (1969) recovered and 

described Jurassic palynomorphs from core material taken 

from the Challenger Knoll salt dome in the Gulf of Mexico. 

In a followup to this investigation, Kirkland and Gerhard 

(1971) also reported the occurrence of palynomorphs collected from a single sample taken from the salts of the Paradox Basin. Cousminer (1978) collected and described 

Jurassic palynomorphs from salt cores from the Isthmus of 

Tehuantepec of Mexico. Shaffer (1964), however, provided the most extensive data concerning the palynology of 

salt deposits of North America in his investigation of the 

salts within the Lower Permian Wellington Formation of 

Kansas. He collected samples at 1-foot intervals from two 

salt beds and attempted correlation between the two mines 

from which he obtained samples; he also determined relative abundances of important and diagnostic palynomorph 

genera.

My investigation adds a new dimension to the study of 

the palynology of salt deposits in several ways. First, it 

offers a technique that allows the extraction of 

palynomorphs from evaporite rocks in quantity and without 

any apparent damage to the palynomorphs. Prior to this 

investigation, no successful mechanism for the digestion of 

bulk evaporite samples had been developed. Second, core 

samples obtained from the Gibson Dome No. 1 borehole in 

the Paradox Basin yielded abundant palynomorphs 

throughout and thus provide the first opportunity to evaluate Carboniferous palynomorphs preserved in salt in North 

America. Finally, this research provides the first refined 

biostratigraphy for use within the Paradox Basin and for 

regional biostratigraphic correlation of the Paradox Formation with rocks of similar age in other basins. With the discovery of abundant palynomorphs in the salts of the 

Paradox Formation it was hoped that the Desmoinesian age 

based on fusilinids could be substantiated; however, the 

composition of the palynomorph assemblages extracted 

from the Paradox Formation presents a further problem of 

correlation because these palynomorphs represent a complex and unusual palynoflora that is not typically associated 

with the Middle Pennsylvanian but rather is associated with 

the Upper Pennsylvanian (Virgilian) and the Lower Permian (Wolfcampian) in the Midcontinent of the United 

States (Jizba, 1962; Peppers, 1964; Tschudy and Kosanke, 

1966), Europe (Leschik, 1956; Klaus, 1963), and Asia 

(Bharadwaj and Sulujha, 1963; Bharadwaj, 1966). The relative abundance of Striatites, Vesicaspom, and Potonieisporites within the overall assemblage is atypical of floras 

obtained from Pennsylvanian coals of the world, which 

have been extensively studied.

EVAPORITE CYCLES OF THE 

PARADOX FORMATION

The evaporite cycles preserved within the Paradox Formation of the Hermosa Group are unique in that they provide 

a record of sedimentation that is unequaled by other known 

evaporite sequences, both in number and completeness. 

Superimposed upon a major worldwide eustatic event (Sloss, 

1963; Vail and others, 1978) that reached a maximum during 

the Atokan and Desmoinesian Series, the 33 cycles of the 

Paradox Formation, because of their predominantly chemical nature, preserve a sensitive record of salinity fluctuation. 

As extensive coal swamps of the eastern United States developed in the more humid climate of what were then slightly 

northerly paleolatitudes during the Middle Pennsylvanian, 

evaporites of the Paradox Basin accumulated in the arid climate of the equatorial regions (Wray, 1983).

IDEALIZED EVAPORITE CYCLE

Hite (1960) observed that the depositional pattern of 

chemical and clastic constituents of the cycles in the Paradox 

Formation is very similar to the sequence of salt precipitation from seawater defined by Usiglio (1849). In Usiglio's 

model, as salinity is increased due to continued evaporation, 

more and more soluble salts are precipitated. Recognizing 

the similarities between Usiglio's model and the evaporites 

of the Paradox Formation, Hite (1970) hypothesized that the 

depositional cycles preserved were induced by variations in 

relative sea level that caused major changes in salinity. 

Applying the barred basin model of Ochsenius (1877), 

which implies restricted circulation within a basin by topographic barriers, Hite (1970) also concluded that changes in 

relative sea level caused a significant variation in the influx 

and reflux of dissolved salt into and out of the basin. When 

sea level is at its highest, or maximum transgressive stage, 

waters of a basin freely reflux with influxing waters of the 

open ocean. If sea level is high enough, salt load reflux 

equals salt load influx, and salinity increase is prohibited and 

normal marine sedimentation occurs. As sea level falls with 

regression, the barrier restricts circulation and salt load 

influx remains constant at the expense of reflux. As sea level 

continues to fall, reflux is inhibited causing a surplus of salts, 

and evaporites are precipitated. On the basis of this scenario, 

the evaporite-clastic cycles of the Paradox Formation were 

defined in terms of a chemical sequence that reflects a rapid 

decrease, followed by a gradual increase, in salinity (Hite, 

1970).

The model of Hite (1970) explains the sedimentary 

sequence preserved in the Paradox salt cycles as follows. As 

marine waters of the Paradox Basin attained a point of maximum sea-level highstand, normal marine sedimentation 

resulted in deposition of silty, calcareous, dolomitic, 

organic-rich black shale (fig. 4). As sea level began to fall
DISCONFORMITY

DEPOSITIONAL CYCLES OF THE PARADOX FORMATION 

 > SALINITY INCREASE

K7

HALITE

ANHYDRITE

SILTY DOLOMITE

BLACK SHALE

SILTY DOLOMITE

ANHYDRITE 

DISCONFORMITY

HALITE

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I.ii

II I I

55 £

to <g

LU <

CC. I

UP«

SEA LEVEL

-> DOWN WARM, WET<-

CLIMATE CYCLE

-> COOL, DRY

Figure 4. Idealized evaporite cycle of the Middle Pennsylvanian Paradox Formation. Relative sea-level, salinity, and climatic 

conditions during deposition of each facies are also shown. Rock types are shown in figure 2. Modified from Hite (1970).

and reflux was limited, evaporation exceeded mixing of normal seawater causing an increase in salinity and precipitation 

of silty dolomite (fig. 4). In this facies, most of the clastic 

material was derived from terrestrial sources (Hite and others, 1984). Continued salinity increase, sea level lowering, 

and less frequent mixing led to the deposition of more soluble nodular and laminar anhydrite (fig. 4), which overlies the 

silty dolomite facies of the cycle. When conditions of maximum salinity were attained during peak sea-level lowstand,

halite, with or without potash salts, was deposited (fig. 4). 

Halite deposition was continuous except for occasional seasonal spurts of thin, single or multiple laminations of anhydrite or shale. These laminations are thought to represent 

seasonal or annual fluctuations in salinity, temperature, and 

clastic supply caused by variations in runoff (Hite, 1970). 

Halite deposition ceased when relative sea level once again 

began to rise and increased inflow of normal marine waters 

during the transgression increased reflux; salinity began to
K8 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

drop, initiating first deposition of anhydrite as in the regressive phase and subsequently very silty dolomite followed by 

black shale, as before (fig. 4).

Although this discussion suggests that the transgressive and regressive phases of the Paradox evaporite 

cycles are symmetrical, strong asymmetry is present. In 

the regressive marine phase, each of the units, black 

shale, silty dolomite, anhydrite, and halite, was deposited 

in response to gradually increasing salinity, and there is a 

gradual transition from one rock type to the next. Ideally, 

the point of maximum regression should occur at the midpoint of the halite unit; however, it can be shown, based 

on bromine content, that salinity continued to increase to 

near the top of most halite units and that there is- no gradual transition with the overlying anhydrite (Kite, 1970). 

Potash salts, which, when present, represent conditions of 

highest salinity, are near the top rather than in the middle 

of the halite unit. The contact between the halite and the 

overlying anhydrite represents a sharp break in the record 

of sedimentation caused by rapid incursion of marine 

waters that redissolved some of the halite at the sediment-water interface, producing a disconformity (fig. 4). 

Asymmetry of the cycle is primarily the result of abrupt 

cessation of halite deposition, but asymmetry is also 

observed in the thicknesses of the transgressive and 

regressive hemicyclothems (fig. 4). The transgressive 

phase is very similar to the regressive phase in terms of 

lithology but represents a much more condensed section.

In developing an idealized model for the cycles in the 

Paradox Formation, Kite (1970) and Kite and Buckner 

(1981) suggested the use of the prominent disconformities 

at the top of each halite unit as a much more workable 

system of cycle boundaries than individual rock units (fig. 

4). Therefore, when using the disconformities, the 

sequence of lithologic units in the idealized model is 

anhydrite, silty dolomite, black shale, silty dolomite, anhydrite, and finally halite, and the entire sequence is 

bounded above and below by a disconformity (fig. 4). 

The change from transgressive to regressive conditions 

occurs at the midpoint of the black shale and therefore 

represents the change from decreasing to increasing salinity (fig. 4).

The cycles of the Paradox Formation, because of their 

relative completeness, afford an excellent opportunity to 

evaluate the effects of climate, both direct local influences 

and indirect global factors, on the oscillating salinity conditions in the waters of the Paradox Basin and on the vegetation of the region. In analyzing the variations in 

palynomorph flora throughout the various lithologies of the 

cycles, the numerous theories, such as tectonism, changes in 

sedimentation rate and climate, proposed as possible mechanisms causing cyclicity can be evaluated. To accomplish 

this, palynomorph assemblages were analyzed in two ways, 

first by looking at changes throughout the entire Paradox 

Formation and then by studying a single evaporite-clastic

cycle. It was hoped that a complete cycle within the Paradox 

Formation could be analyzed as a continuous sequence, but 

restrictions on sampling and previous bulk sampling precluded this opportunity, leaving the halites of salt cycle 7 and 

the transitional interbeds between the halites of cycles 8 and 

9 as the only alternatives (fig. 3).

EVAPORITE CYCLE 7

The halite facies of evaporite cycle 7 (fig. 3) represents 

microvariations of hypersalinity during deposition. This 

facies is composed of numerous anhydrite-halite couplets in 

which halite is the dominant lithology and anhydrite is 

present as thin bands separating the halite units. Precipitation of the evaporites in cycle 7 was induced by a continued 

increase in salinity. As salinity continued to rise, minor episodes of potash salt deposition occurred as the result of saturation of the brines of the basin with respect to potash 

minerals. Sylvite is present in cycle 7 only as small isolated 

crystals in the upper part of the salt unit. Precipitation of 

halite and sylvite in cycle 7 and in all halite beds of the Gibson Dome No. 1 core was also contemporaneous with precipitation of thin sulfate laminae, each averaging 0.80 mm in 

thickness, that are thought to represent periods of annual 

replenishing of 804 ions in the basin by marine influx (Kite, 

1983a). It is not known whether these laminae were anhydrite or gypsum when precipitated.

The halite facies of cycle 7 is 20.4 m thick, and the base 

of this deposit is transitional with the anhydrite below. 

Above the transitional contact, the halite facies of cycle 7 is 

a massive halite deposit containing regularly spaced (4.0-cm 

intervals) bands of anhydrite. Near the top of cycle 7, halite 

is intercalated with scattered crystals of potash salts. Precipitation of halite was dominant within cycle 7 until its deposition was terminated by a rapid influx of much lower salinity 

waters that dissolved the upper part of the halite of cycle 7 

and produced a disconformity between cycle 7 and the carbonate-siliciclastic facies of cycle 6.

INTERRED 8-9

The carbonate-siliciclastic facies that separates the 

halite facies of cycles 8 and 9, herein designated interbed 

8-9, represents deposition under conditions of changing 

salinity and sea level. In interbed 8-9 anhydrite was deposited first, followed by silty dolomite and black shale. At the 

end of black shale deposition the sequence was reversed, and 

silty dolomite followed by anhydrite were deposited. Interbed 8-9 represents an imperfect Kite cycle because minor 

salinity fluctuations are apparent. These minor salinity fluctuations are preserved as duplication of black shale and
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K9

DEPTH IN FEET 

(METERS)

3,510 

(1,063.6)

3,515 

(1,065.2)

->SALINITY INCREASE

3,520 

(1,066.7)

3,525 

(1,068.2)

3,530 

(1,071.2)

-y-.-y / 

 y--y 

3,535 

(1.071.2)

3,540 

(1,072.7)

3,545 

(1,074.2)

3,550 

(1,075.8)

 v / / / 

7 T7 -/ -fl

/ / /-

 /- 

ROCK HALITE

ANHYDRITE

SILTY DOLOMITE

ANHYDRITE

SILTY DOLOMITE

ANHYDRITE

SILTY DOLOMITE

BLACK SHALE

SILTY DOLOMITE 

BLACK SHALE

SILTY DOLOMITE 

BLACK SHALE

SILTY DOLOMITE

ANHYDRITE

UNCONFORMITY

ROCK HALITE

UP<-

SEA LEVEL

 DOWN

Figure 5. Generalized lithologic section of interbed 8-9 of the Middle Pennsylvanian Paradox Formation 

showing relative sea-level and salinity conditions during deposition of each facies. Modified from Hite (1970).
K10 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

anhydrite units within the carbonate-siliciclastic facies 

designated interbed 8-9 (fig. 5). Deposition of interbed 8-9 

was initiated by a rapid decrease in salinity associated with a 

sudden influx of normal marine water during transgression. 

These conditions produced the bedding sequence of anhydrite through black shale (fig. 5). They were followed by a 

gradual increase in salinity and a corresponding drop in sea 

level and associated marine regression. As salinity increased 

after the clastic sedimentation of black shale, the lithologies 

of silty dolomite and anhydrite in interbed 8-9 (fig. 5) reflect 

the succession of salt precipitation described by Usiglio 

(1849).

The deposits of interbed 8-9 are 11.1 m thick, and the 

base of these carbonate-siliciclastic facies is marked by a 

disconformity that has been used to designate the boundary 

with cycle 9 (Kite, 1970) and also represents initiation of 

the transgressive phase of deposition (fig. 5). The decrease 

in salinity as a result of this transgression resulted in deposition of 1.9 m of sulfate mineral, preserved as nodular and 

laminar anhydrite. This period of sulfate precipitation was 

followed by the deposition of 3.6 m of very silty dolomite 

in response to a further decrease in salinity (fig. 5). Many 

of the beds in this silty dolomite unit were disturbed by 

fluid-release phenomena that are preserved as sedimentary 

structures. The high silt content of the silty dolomite 

reflects significant terrigenous clastic influx attributed to 

runoff (R.J. Kite, written commun., 1994). Deposition of 

this very silty dolomite unit was interrupted twice by deposition of black, carbonaceous shale beds, each approximately 0.1 m thick, that represent minor sea-level 

oscillations during transgression (fig. 5). A 0.3-m-thick 

bed of black carbonaceous shale caps this sequence (fig. 5); 

this bed is the thickest accumulation of shale in this cycle 

and represents the point of maximum transgression, free 

mixing of normal marine waters, and the period of 

minimum salinity.

As conditions of salinity began to reverse and increase 

with the onset of regression, black shale deposition continued but gradually changed to deposition of a very thin (0.33 

m) bed of silty dolomite that has a significantly lower silt 

content than the silty dolomite deposited during the transgressive phase (fig. 5) (Hite, 1970). This thin silty dolomite 

grades into a much thicker (3.1 m) anhydrite unit reflecting 

further increase in salinity (fig. 5). The anhydrite unit is predominantly nodular at its base and laminar and massive 

toward its top. Precipitation of the anhydrite unit was also 

interrupted by two major periods of silty dolomite deposition deposition of a lower bed 1.2 m thick and deposition 

of a bed 1.5 m thick that again represents sea-level oscillation (fig. 5). The uppermost part of the anhydrite unit is 

transitional into the overlying halite of cycle 8, and many 

halite laminae and inclusions are present within the upper 

1.0 m of anhydrite.

COMPARISON WITH IDEALIZED CYCLE 

OF HITE

In comparing the observed depositional sequence of 

evaporites in cycle 7 with that described in the model proposed by Hite (1970), the similarities are striking. At the 

base, both salt units are transitional with the underlying 

anhydrite and both rapidly become massive halite deposits. 

Each salt unit is characterized by anhydrite laminae of varying thickness. As in the model, potash salts, which are 

present in cycle 7 as minor constituents, are near the top of 

the salt unit. Due to their stratigraphic position, the potash 

salts give the cycle a lithologic asymmetry that is also consistent with the model.

Complementing the lithologic asymmetry of the potash 

salts, a profile of bromine distribution in cycle 7 derived by 

X-ray fluorescence (fig. 6) reflects changes in salinity based 

on changes in bromine concentration in the salts precipitated 

from the basin brines and documents the chemical asymmetry that is called for by the model. The bromine profile indicates a period of relatively stable salinity during early 

deposition of halite near the base of cycle 7. The sudden 

increase in bromine concentration indicates an increase in 

salinity, which resulted in potash precipitation further into 

the basin. This increase in salinity continued until salt precipitation ended, marked by a disconformity.

Sediments of the transitional rocks of interbed 8-9 

reflect, on the other hand, several minor deviations from the 

model of Hite, although, in general, deposition occurred as 

described. Deposition was initiated by an abrupt decrease in 

salinity associated with the rapid influx of normal marine 

waters into the basin. This event is preserved as a sharp contact between the salt of cycle 9 and the lowermost anhydrite 

of interbed 8-9 (fig. 5). This anhydrite grades into a silty 

dolomite, thought to correspond with a rise in sea level and 

decreasing salinity (Hite, 1970) (fig. 5).

It is at this point that the depositional sequence of interbed 8-9 begins to deviate from that of the model. Silty dolomite is overlain by a thin black shale bed that immediately 

grades back into silty dolomite reflecting a minor oscillation 

of salinity and, possibly, sea level. A second oscillation 

caused repetition of the sedimentary sequence before conditions of minimum salinity were achieved, and conditions 

ultimately reversed, initiating regression (fig. 5).

Black shale deposition ended suddenly, and precipitation of silty dolomite was initiated with continued regression 

(fig. 5). Adhering to the model of Usiglio (1849), silty dolomite deposition should have been followed by precipitation 

of anhydrite. Again, the depositional model does not precisely match the sequence of facies in this example: anhydrite, which should be overlain by halite, actually grades into 

silty dolomite, indicating a brief reversal in environmental 

conditions that control the cycles (fig. 5). This type of reversal is present twice before the uppermost anhydrite grades
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION Kll

3.380 

(1.024.2)

fc 3,400 

5 (1,030.3)

3,420 

(1,036.4)

3,440 

(1.042.4)

40 60 100 120 140 

BROMINE, IN PARTS PER MILLION

160 180 200

Figure 6. Bromine distribution in evaporite cycle 7 of the Middle Pennsylvanian Paradox Formation, Gibson Dome No. 1 borehole. Analysis by X-ray fluorescence (Hite, 1983b, fig. 7). Location of borehole is shown in figure 1.

into halite, indicating development of maximum salinity in 

the basin (fig. 5).

Although the deposits of interbed 8-9 may vary in 

regards to the model, all the elements defined by Hite (1970) 

are evident. Only minor fluctuations of sea level, climate, or 

subsidence history are required to explain the repetition of 

some of the units within the cycle. The observed differences 

in the depositional sequences do not surpass the expected 

limitations inherent in a generalized model such as this, and 

hence the model of Hite (1970) is used in subsequent discussions of the cycles within the Paradox Formation.

CLIMATIC FACTORS INFLUENCING 

CYCLIC SEDIMENTATION

As a result of the definition of numerous cyclothems in 

the Middle Pennsylvanian sequence of the Eastern Interior 

Basin of the United States by Weller (1930, 1931), Pennsylvanian cyclicity has attracted considerable interest due to 

recognition of its correlative worldwide scale. Since the 

time of the recognition of Pennsylvanian cyclothems, considerable debate has developed, however, regarding possible mechanisms controlling the cyclic sedimentation 

inherent to those deposits. Fortuitously, the Paradox Formation of southeastern Utah, with the unusual preservation 

of 33 halite-bearing evaporite-clastic cycles and the presence of abundant, well-preserved palynomorphs, provides

an excellent opportunity to investigate the driving mechanisms controlling cyclicity in such deposits and, especially, 

to test the role of climatic variability.

Shortly after Weller (1930) defined the Pennsylvanian 

cyclothems of the Eastern Interior Basin and proposed tectonism as the dominant control influencing cyclicity, Wanless and Shepard (1936) presented a convincing argument 

documenting the existence of Gondwanan continental glaciation throughout much of the late Paleozoic. Using this evidence, they offered a hypothesis that sea-level fluctuation, 

strongly influenced by glacial accumulation and ablation, 

provided a mechanism for cyclic deposition of epeiric facies 

during the Pennsylvanian Period. In their hypothesis, 

decrease and increase of ice mass volume were associated 

with cyclic changes in the worldwide climate system and, in 

addition, caused alternate episodes of transgression and 

regression in the Eastern Interior Basin. This mechanism 

was considered to be responsible for the lithologic variations 

noted within each of these cyclothems. Accumulation of 

large continental ice masses would have caused dramatic 

changes in relative humidity on a worldwide basis, which in 

turn would strongly influence amounts of precipitation, even 

in regions far removed from glaciated areas. As the volume 

of glacial ice grew, humidity would drop in equatorial 

regions and sea level would fall, restricting marine connections with inland seas. These conditions would allow the precipitation of evaporites such as those in the Paradox Basin, 

and ablation of glacial ice would cause a reverse situation to
K12 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

occur. Wanless and Shepard (1936) cited the combined 

effects of periodic perturbations of the Earth's eccentricity, 

inclination of the Earth's axis, and the migration of perihelion all related to the 100,000-, 42,000-, and 21,000-year 

cycles defined by Milankovitch as the regulating mechanism for climatic changes that may have controlled glacial 

cycles and induced the development of the Pennsylvanian 

cyclothems of the United States and elsewhere. In a subsequent investigation, Wanless and Patterson (1951) extended 

this study of cyclic sedimentation in the Eastern Interior 

Basin (Wanless and Shepard, 1936) to Pennsylvanian rocks 

of the southwestern United States. They attributed the cyclic 

deposition of evaporites in the Paradox Basin to an increase 

in aridity caused by the same global climatic fluctuations 

described earlier.

In a more recent investigation, Hite and Buckner (1981) 

applied relative sedimentation rates for halite (4.0 cm/year), 

anhydrite (0.08 cm/year), dolomite (0.017 cm/year), and 

shale (0.21 cm/year) to these rock types within the cycles of 

the Paradox Formation and documented the approximate 

100,000-year nature of these cycles. In an attempt to determine a possible mechanism for the Paradox cycles, Hite and 

Buckner (1981) also relied on global climatic factors 

induced by changes in ice volume that directly influenced 

eustatic changes in sea level and indirectly modified regional 

climatic regimes. Together these factors caused the development of cyclicity observed in the Paradox Formation. The 

glacio-eustatic hypothesis of Hite and Buckner (1981) proposes that changes in water volume in the Paradox Basin 

during the Pennsylvanian Period were directly related to 

changes in ice volume in the Southern Hemisphere.

In the Milankovitch theory, three types of orbital perturbations act to influence the Earth's climate on a global 

scale (Covey, 1984). The dominant influence on the global 

climate regime is attributed to fluctuations in the Earth's 

eccentricity as it travels about the Sun. These fluctuations 

occur in cycles of approximately 100,000 years. Perturbation of 42,000 years, due to changes in the tilt of the Earth's 

axis (obliquity), and 21,000 years, caused by variations in 

precession of the North Pole, also act to influence the Earth's 

global climate system. It should be noted, however, that, 

although the shorter cycles should potentially have a much 

greater influence on the amount of solar insolation received 

by the Earth and hence a greater effect on the Earth's climate, it is the perturbations of the eccentricity with a periodicity of 100,000 years that appear to dominate global climate 

regimes, at least during the Pennsylvanian. The influence of 

changes in orbital eccentricity may have a much greater 

effect on world climate because these perturbations occur at 

a frequency near the natural frequency of the world's climate 

system and thereby force the effects of the 100,000-year 

periodicity over those of the 42,000- and 21,000-year cycles 

(Covey, 1984).

Because of the location of the Paradox Basin at 10° N. 

paleolatitude (Wray, 1983), there are two potential ways in

which the climate could have been modified in response to 

the orbital perturbations described by the Milankovitch theory and subsequently could have acted to influence the 

cyclicity observed in the Paradox Formation (EJ. Barron, 

oralcommun., 1984). Of these factors, the most obvious climatic influence on the deposits of the Paradox Formation is 

the changes in orbital variation that modify the climate by 

altering the amounts of solar insolation received by the Earth 

at different latitudes and seasons. Effects of varying 

amounts of solar insolation are greatest in the northern latitudes and influence the development of polar ice masses. 

These ice masses increase and decrease in response to 

changes in the eccentricity of the Earth's orbit around the 

Sun. Accumulation and melting of ice masses would have a 

major influence on the water volume of inland seas such as 

the Paradox Basin. Changes in ice volume would have global implications on climate.

Due to the equatorial location of the Paradox Basin, the 

Milankovitch periodicity could have modified the climate of 

the region on a 100,000-year basis. The first of these 

modifiers is very appealing to the understanding of cyclic 

sedimentation of the Paradox Formation in that it documents 

the development of desert areas in equatorial regions of the 

world during Pleistocene glacial periods (Sarnthein, 1978). 

Development of extensive sand dunes during Pleistocene 

glaciation indicated an arid climatic optimum during the glacial maximum. This arid situation was enhanced because, 

even though temperatures were lower due to accumulation of 

ice masses, decreases in precipitation and increased wind 

intensity increased total evaporation (Sarnthein, 1978). Similar conditions of high aridity have been observed in the tropical regions during Gondwanan glaciation during the late 

Paleozoic (Wanless and Patterson, 1951), and this mechanism could have greatly influenced the climate of the Paradox Basin.

The second of the two regional climatic factors that 

potentially could have developed in response to Milankovitch periodicity, and could have influenced the deposition 

of the Paradox Formation, involves the circulation of air 

masses in the tropics and the relationship of land masses to 

ocean basins (Manabe and Hahn, 1977). The climate 

model of Manabe and Hahn illustrates a situation in which 

the climate of the tropics during maximum glaciation is 

considerably drier than during periods of glacial minimum. 

This tropical aridity can be ascribed to air circulation phenomenon whereby surface outflow from the continents is 

greater than surface inflow from the oceans and thus precludes precipitation (Manabe and Hahn, 1977). Stronger 

outflow enhances sinking and reduces precipitation over 

tropical continents. This effect could have possible implications in the Paradox Basin region, but, because of the 

proximity of the continents, separated only by a narrow 

oceanic belt at the equator (Fairish, 1982), the surface 

inflow-outflow circulation pattern would be weak, at least 

during the Pennsylvanian.
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K13

It is hypothesized that changes in climate should influence the distribution of vegetation in the Paradox Basin and 

that these changes should be reflected in the abundant 

palynomorph assemblages discovered in the Paradox Formation. If changes in the palynoflora indeed are observed, a 

major question is which of two climatic factors both attributable to Milankovitch periodicity was dominant in the 

Paradox Basin.

PALYNOLOGY OF THE PARADOX 

FORMATION

SAMPLES AND LOCATION

As part of an investigation to evaluate the suitability of 

salt in the Paradox Formation of the Hermosa Group for 

underground disposal of nuclear waste, the U.S. Department 

of Energy contracted Woodward-Clyde Consultants to drill 

and core the Gibson Dome No. 1 borehole in sec. 21, T. 30 

S., R. 21 E., San Juan County, Utah (fig. 1). This borehole, 

on .the southeast-plunging nose of Gibson Dome, a small salt 

anticline in the Paradox Basin, was drilled to a depth of 

1,946.4 m with the coring beginning 127 m below Kelly 

bushing. This yielded 1,819 m of 4-inch-diameter core 

(Bodine and Rueger, 1984). Drilling began in the Lower 

Permian Cutler Group, with coring starting at a depth of 127 

m, and passed through the Pennsylvanian Hermosa Group 

and the Molas Formation as well as the Mississippian Leadville Limestone and was completed 9.8 m below the Mississippian-Devonian contact in the Upper Devonian Ouray 

Limestone (fig. 2).

All samples used in this investigation were collected 

from the Paradox Formation penetrated by the borehole and 

are listed in table 1. The intervals given in table 1 represent 

the depth of the sample below Kelly bushing, which was 5.2 

m above ground surface.

SAMPLE PREPARATION

Because many of the samples used in this investigation 

were collected from an evaporite sequence, modifications of 

standard palynomorph extraction techniques were necessary. Samples collected from halite and anhydrite were first 

washed in distilled water to remove any readily water soluble minerals, namely halite, sylvite, and carnallite. Most of 

the palynomorphs were still held within the resulting 

water-insoluble residue composed primarily of sulfate, carbonate, and silicate minerals. These residues presented a 

major problem in preparation. Although carbonate and silicate minerals can be easily removed by conventional techniques utilizing hydrochloric and hydrofluoric acids.

respectively, sulfate minerals are generally unaffected by 

these acids.

In an attempt to alleviate this problem, many alternative 

techniques were considered and tried, including modifications of the standard acid technique for evaporite rocks by 

Sittler (1955), Freudenthal (1964), and Visscher (1966) and 

the use of potassium hydroxide as suggested by Deak (1959), 

but none of these methods proved satisfactory. However, 

while working on an investigation of the clay mineralogy of 

the Paradox evaporites, I made use of a very simple, yet 

highly effective technique that was developed by Bodine and 

Fernalld (1973) for the separation of clay minerals from 

evaporite host rocks. This same technique was modified 

slightly for the extraction of palynomorphs from evaporite 

rocks (Rueger, 1986) and allows the complete removal of 

both sulfate and carbonate minerals from the water-insoluble 

residue by the use of an EDTA (ethylenedinitrilotetraacetic 

acid) solution.

After removal of the evaporite minerals, the remaining 

silicate-dominated residue was removed by treatment with 

hydrofluoric acid, and the palynomorphs were concentrated 

using heavy liquid separation as described by Doher (1980).

Samples collected in shale, dolomitic siltstone, and silty 

dolostone were processed using standard palynomorph 

extraction techniques also described by Doher (1980).

Slides were prepared from the organic residue using 

canada balsam as a mounting medium. Slides were labeled 

giving sample designation and slide number for future reference. A complete set of slides including type and all illustrated specimens will be deposited in the type collections of 

the Department of Paleobiology, U.S. National Museum, 

Washington, D.C.

PRESERVATION OF PALYNOMORPHS

Typically, preservation of palynomorphs in evaporite 

deposits is extraordinary and is directly influenced by the 

geochemical nature of the evaporite environment. Because 

most evaporites are precipitated directly from seawater, 

palynomorphs suspended in the water column are readily 

incorporated into the evaporite rock as it forms, and little or 

no abrasive or corrosive damage is done to the palynomorph 

once it reaches the depositional surface of the evaporite 

basin (Klaus, 1970). The degree of preservation observed in 

the palynomorphs recovered from the evaporite-clastic rocks 

of the Paradox Formation is extremely variable, ranging 

from exquisite to very poor.

A substantial number of the samples collected from the 

Paradox evaporites yielded palynomorphs in an extraordinary state of preservation. These well-preserved specimens, 

which were collected from the halites, are unbroken and 

undeformed and show little or no evidence of corrosion or 

abrasion. However, these exceptional palynomorphs were 

also found in association with a much larger number of
K14 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Table 1. Lithology and location of palynological samples collected from the Gibson Dome No. 1 borehole, San Juan County, Utah, 

sec. 21, T. 30S.,R. 21 E. 

[Salt cycles are from Hite (I960)]

Sample 

No.

GDI-472

GDI-237

GDI-239

GDI-240

GDI-325

GDI-326

GDI-327

GDI-328

HR-3

HR-4

HR-5

HR-6

HR-7

GDI-319

GDI-596

GDI-624

GDI-625

GDI-626

GDI-597

GDI-627

GDI-628

GDI-629

GDI-598

GDI-630

GDI-631

GDI-632

GDI-599

Salt 

cycle

5

6

6

6

7

7

7

7

8

8

8

8

8

13

15

18

19

19

21

21

21

24

24

24

25

25

26

Depth below Kellv bushing

(feet)

2,981.8-2,983.7

3,242.9-3,243.3

3,312.2-3,312.6

3,324.1-3,324.5

3,377.5-3,377.9

3,399.7-3,400.1

3,421.3-3,421.7

3,435.2-3,435.6

3,515.4-3,515.6

3,518.8-3,519.0

3,525.0-3,525.1

3,530.5-3,530.8

3,545.4-3,545.5

3,924.5-3,925.0

4,147.8^,149.7

4,716.3-4,716.7

4,856.3-4,856.7

4,954.2-4,954.6

5,113.8-5,116.1

5,138.3-5,138.7

5,211.3-5,211.7

5,313.3-5,313.7

5,314.2-5,316.0

5,380.3-5,380.7

5,462.3-5,462.7

5,485.3-5,485.7

5,503.2-5,504.5

(meters)

903.6-904.2

982.7-982.8

1,003.7-1,003.8

1,007.3-1,007.4

1,023.5-1,023.6

1,030.2-1,030.3

1,036.8-1,036.9

1,041.0-1,041.1

1,065.27-1,065.33

1,066.3-1,066.4

1,068.18-1,068.21

1,069.8-1,069.9

1,074.36-1,074.39

1,189.2-1,189.4

1,256.9-1, 257.5

1,429.2-1,429.3

1,471.6-1,471.7

1,501.3-1,501.4

1,549.6-1,550.3

1,557.1-1,557.2

1,579.2-1,579.3

1,610.1-1,610.2

1,610.4-1,610.9

1,630.4-1,630.5

1,655.2-1,655.4

1,662.2-1,662.3

1,667.6-1,668.0

Lithology

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Anhydrite with silt stringers and halite inclusions.

Dark-gray dolomitic siltstone.

Gray dolomitic siltstone.

Black carbonaceous shale.

Black silty dolostone.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

Rock halite with anhydrite laminae.

grains that are crumpled, folded, corroded, and abraded and 

have been rendered unidentifiable. This high degree of variance in preservation can be attributed to the processes by 

which the palynomorphs were transported into the basin. It 

is highly likely that those grains exhibiting the best preservation were carried into the basin by wind, a mechanism to 

which many of the bisaccate and monosaccate 

palynomorphs are extremely well adapted. The poor preservation of the remaining palynomorphs can be attributed to 

transport into the Paradox Basin by streams or by marine 

reflux during transgression. These grains were probably 

subjected to much more abrasion, and possibly corrosion, 

than those carried by wind. The presence of many 

well-preserved grains probably introduces a degree of bias in 

terms of evaluating the degree of preservation of the 

palynomorphs recovered from the Paradox Formation.

Preservation of specimens extracted from the interbed 

deposits of the Paradox Formation is generally of lesser 

overall quality than that of those recovered from halites.

The interbed samples yielded a much greater quantity of 

broken, abraded, and corroded palynomorphs than the halite 

samples, and identification was difficult. No palynomorphs 

were recovered from sample HR-3 (table 1), which was 

collected from anhydrite, probably because the anhydrite of 

the interbeds was likely precipitated as gypsum that was 

subsequently dehydrated to form anhydrite. Most likely 

any palynomorphs in the gypsum were destroyed in the process of dehydration. Samples HR-4, HR-5, and HR-6 

(table 1), collected from dolomitic siltstone and black shale, 

yielded a large quantity of palynomorphs and organic matter, but, because of the geochemical nature of these rocks, 

most grains were highly corroded, and identification was 

difficult if not impossible in some cases. One unusual sample, HR-7 (table 1), collected from dolomitic siltstone, 

yielded extremely well preserved palynomorphs on a par 

with those obtained from the halite samples. This occurrence of well-preserved palynomorphs may indicate the 

development in the water column of primary dolomite that
DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K15

was later precipitated as sedimentary particles along with 

the palynomorphs rather than by recrystallization of calcium carbonate.

Another peculiar aspect of the palynomorphs extracted 

from the rocks of the Paradox Formation is the inability of 

the palynomorphs to take and hold an organic stain, even 

after the palynomorphs were subjected to stain over a long 

period of time (as long as 1 hour). This characteristic may 

be attributed to the modification of organic compounds by 

the evaporite brines and has been noted by other palynologists studying specimens collected from salts (Klaus, 1955; 

Baltes, 1967; Kirkland and Gerhard, 1971).

LITHOLOGIC OCCURRENCE OF 

PALYNOMORPHS

Palynomorph distribution was generally widespread 

and abundant, regardless of host lithology. Palynomorphs 

were recovered from all rock types sampled in the Gibson 

Dome No. 1 drillhole (table 1) except those taken from the 

anhydrite of interbed 8-9. Although barren in terms of identifiable palynomorphs, very minute organic particles were 

abundant in this anhydrite sample and tiny fragments of 

palynomorphs were recovered. The fragmented state of 

these palynomorphs is attributed to dehydration of gypsum 

to form anhydrite, as described earlier. Samples collected 

from halite containing numerous anhydrite laminae invariably yielded more palynomorphs than any other rock type 

analyzed. Samples of halite having a greater spacing of 

anhydrite laminae also yielded palynomorphs but in fewer 

numbers. This observation can be directly related to sedimentation rate in that halite is precipitated much more rapidly than anhydrite so there is greater rock volume per unit 

time accumulated and hence palynomorph concentration is 

not as great as it is in the anhydrite laminae. It has also 

affected the number of countable grains per sample, and 

consequently some samples did not have an adequate number of grains (minimum 300) for statistical analysis. Samples collected from the interbed material, excluding 

anhydrite, also yielded palynomorphs in significant numbers, but many were poorly preserved. Sample HR-7 (table 

1) had the greatest abundance of palynomorphs of all the 

interbed samples.

STRATIGRAPHIC OCCURRENCE OF 

PALYNOMORPHS

The stratigraphic distribution of palynomorphs 

obtained from samples collected in the Paradox Formation 

was evaluated at three levels. First, the palynoflora of the 

Paradox Formation is dominated by monosaccate and 

bisaccate palynomorphs, and the initial level of evaluation

determined the relative abundance of monosaccate, bisaccate, and cryptogamic and other palynomorphs.

A second and higher level of evaluation involved determination of the relative abundances of striated monosaccate 

and bisaccate palynomorphs versus nonstriated monosaccates and bisaccates. Striated palynomorphs include those 

forms that have few to many well-defined grooves on the 

surface of the body (see, for example, figs. 5-7 of plate 1 and 

figs. 1-4 of plate 2). An increase in abundance of striated 

palynomorphs in the late Paleozoic may indicate a separate 

line of development for the plants that produced the palynomorphs recovered from the Paradox Formation. These first 

two levels of analysis were discussed in detail in a previous 

publication (Rueger, 1984), and the results are reflected in 

the third level of analysis.

The third and most advanced level of analysis determined the stratigraphic distribution of palynomorph genera. 

This determination was done to evaluate changes in generic 

abundance throughout the formation and to provide the finest detail possible in terms of palynofloral changes that may 

reflect climatic fluctuation. The generic analysis of palynomorphs within the Paradox Formation also provides an 

excellent opportunity for the development of a useful 

biostratigraphic zonation.

All of the analyses described above were performed at 

two scales to provide the optimal amount of data in terms of 

palynoflora variation. Initially, these analyses were performed on the entire Paradox Formation to evaluate any 

large-scale changes in the palynoflora. Subsequently, these 

analyses were done on samples collected from cycle 7 and 

interbed 8-9 to evaluate changes in the palynoflora during 

the deposition of a complete cycle. These data were then 

used to evaluate the minor changes in the palynoflora and to 

determine the possible mechanism that may have influenced 

cyclic sedimentation in the Paradox Basin.

STRATIGRAPHIC DISTRIBUTION OF

PALYNOMORPH GENERA IN THE

PARADOX FORMATION

The third and most detailed phase of the investigation 

was earned out at the generic level due to the complexity of 

the palynomorph suite obtained from the Paradox Formation 

and the number of species that presently remain undescribed. 

At this level it was still possible, however, to detect small 

changes in the palynoflora that may have been induced by 

variations in climatic regime. This phase of investigation 

was also undertaken to provide a detailed biostratigraphy 

available for use within the Paradox Formation. Samples 

illustrated in figure 7 comprise those samples containing a 

minimum of 300 identifiable palynomorphs, which afforded 

statistical credibility to the samples. Continued taxonomic 

differentiation of the palynomorph specimens recovered
K16 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

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DEPOSITIONAL CYCLES OF THE PARADOX FORMATION K17

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BIOSTRATIGRAPHIC

ZONE

ZoneofStriatifesPoton ie ispo rites

Zone of Potonieisporites

Zone of Striatites

Zone of Vesicaspora

Figure 8. Biostratigraphic zonation of 

palynomorph genera recovered from the 

Middle Pennsylvania!! Paradox Formation 

penetrated by the Gibson Dome No. 1 

borehole. Numbers indicate cycles. Location of borehole is shown in figure 1.

Figure 7 (facing page). Stratigraphic distribution of palynomorph genera recovered from the Middle Pennsylvanian Paradox 

Formation penetrated by the Gibson Dome No. 1 borehole. Numbers refer to biostratigraphic zones: 1, Striatites-Potonieispontes; 2, 

Potonieisporites; 3, Vesicaspora. Location of borehole is shown in 

figure 1.

from the Paradox Formation, as well as the addition of larger 

samples at closer spacing, should ultimately produce a 

refinement of the biostratigraphic zonation developed in this 

investigation.

In analyzing the Stratigraphic distribution of palynomorph genera, only dominant genera were considered and 

illustrated in the accompanying plates. Dominant genera 

include those genera that were present in the samples with a 

relative abundance of at least 5 percent.

Three distinct biostratigraphic zones became apparent 

during evaluation of the Stratigraphic distribution of palynomorph genera (fig. 7). A fourth but less obvious zone was 

also noted. The basal zone is dominated by Vesicaspora spp. 

(plate 1, figs. 1-4), which is a nonstriated, monosaccate 

palynomorph, and the zone ranges from the bottom of the 

Paradox Formation to sample GDI-625 (fig. 7). Vesicaspora spp. (36-46 percent) by far outranks the other genera of this zone, which include Striatites spp. (plate 1, figs. 

5-7), Potonieisporites spp. (plate 2, fig. 7; plate 3, figs. 1^), 

Monosaccate sp. A (plate 1, fig. 8), Punctatisporites spp., 

and Monosaccate sp. B (plate 2, figs. 1-3) in terms of relative abundance. Stratigraphic ally, cycles 19-26 in the Gibson Dome No. 1 borehole are included in the zone of 

Vesicaspora (fig. 8).

Stratigraphically above the zone of Vesicaspora is the 

zone of Striatites (fig. 7), a striated bisaccate palynomorph. 

The zone of Striatites extends from sample GDI-319 to 

sample GDI-625 and includes sample GDI-596 (fig. 7). 

This zone is dominated by species of Striatites (52-61 percent) but also includes species of Potonieisporites, Punctatisporites, Monosaccate sp. B, Limitisporites (plate 4, fig. 

2), and Complexisporites (plate 4, figs. 3, 4) as other 

important components of this assemblage in terms of relative 

abundance. The zone of Striatites Stratigraphically includes 

cycles 13-18 in the Gibson Dome No. 1 borehole (fig. 8).

Continuing upward, the third zone in the Gibson Dome 

No. 1 borehole is the zone of Potonieisporites spp., which is 

also a nonstriated monosaccate palynomorph but is distinct 

from Vesicaspora. This zone extends from sample 

GDI-325 to sample GDI-319 and includes samples 

GDI-327 and GDI-328 (fig. 7). Other significant taxa 

within the zone of Potonieisporites are Striatites, Monosaccate sp. B, Limitisporites, and Punctatisporites. Cycles 7-10 

penetrated by the Gibson Dome No. 1 borehole are Stratigraphically within the zone of Potonieisporites (fig. 8).

The fourth and uppermost palynomorph zone of the 

Paradox Formation was not easily recognized until this particular phase of the investigation, during which genera were 

considered. In this zone Striatites spp. are co-dominant with 

Potonieisporites spp. The zone of Striatites-Potonieisporites begins at sample GDI-325 and continues upward 

to the top of the Paradox Formation (fig. 7). Other genera 

significant to this zone are Limitisporites, Monosaccate sp. 

B, Complexisporites, Punctatisporites, and Ricaspora (plate 

4, fig. 1). Another significant taxon that is present within the
K18 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

zone of Striatites-Potonieisporites is Costapollenites ellipticus (plate 4, figs. 5, 6). The stratigraphic range of this species therefore is extended into much older rocks because it 

previously was not reported in strata older than the Wolfcampian (Tschudy and Kosanke, 1966). The zone of Striatites-Potonieisporites stratigraphically encompasses cycles 

4-6 (fig. 8).

DISTRIBUTION OF PALYNOMORPH GENERA 

IN A SINGLE SALT CYCLE

Parts of two adjacent cycles were used for cycle analysis because samples were unavailable from a complete cycle 

in the Paradox Formation. The closest available sampling to 

illustrate the distribution of palynomorph genera in a single 

cycle was from the halite facies of cycle 7 and the carbonate-siliciclastic facies of cycle 8 (interbed 8-9).

Both the halite of cycle 7 and interbed 8-9 are completely included within the zone of Potonieisporites and contain the same dominant genera (figs. 7, 8). The stratigraphic 

distribution of palynomorph genera within interbed 8-9 is of 

extreme importance in the understanding of the climatic 

influence on the Paradox Formation. Within the rocks of 

interbed 8-9 is the unprecedented occurrence of Middle 

Pennsylvanian palynomorphs that are commonly extracted 

from coals of the Midcontinent region. Although the abundances of these palynomorphs, which include Calamospora, 

Densosporites, Lycospom (plate 2, figs. 5, 6), Acanthotriletes, Convolutispora, Cyclogranisporites, Knoxisporites, 

Dictyotriletes, Leiotriletes, and Triquitrites, are low in terms 

of relative abundance and they are not all included within the 

genera illustrated in figure 9, they are extremely important 

because they indicate that changes in climate took place during the deposition of a single Paradox cycle.

CONCLUSIONS

As a result of evaluating palynomorph taxa and their 

abundances in the Paradox Formation penetrated by the 

coring of the Gibson Dome No. 1 borehole, significant 

interpretations regarding climatic variations were made. 

Although the palynomorph suite recovered from the entire 

Paradox Formation tends to represent, to a large degree, the 

regional composition of the vegetation surrounding the Paradox Basin (fig. 7), very subtle changes were detected during the analysis of the palynoflora of a single salt cycle 

that, although masked by regional components of the 

palynoflora, are of major significance. The presence of 

palynomorphs typically associated with Middle Pennsylvanian coal deposits, including such genera as Densosporites, 

Acanthotriletes, Convolutispora, Cyclogranisporites,

Dictyotriletes, Leiotriletes, Triquitrites, and Lycospora, 

indicates that when sea level was at maximum highstand 

the environment of the Uncompahgre highlands bordering 

the Paradox Basin on the east had been modified sufficiently to support large, arborescent plants normally associated with a coal-swamp environment. In support of this 

conclusion, the occurrence of Lepidodendron johnsonii 

from central Colorado may represent the remains of an in 

situ forest (Arnold, 1940). These data do not imply development of extensive coal swamps during sea-level highstand, but they indicate that moisture availability was 

sufficiently high in the region to support some of the plants 

commonly associated with the coal-swamp environment. 

These plants could also have existed throughout deposition 

of the Paradox Formation, but, because sea level was at a 

highstand, their palynomorphs were more readily transported into the basin simply because transport distance was 

shortened. In support of the preceding it should be noted 

that, although these plants did exist, conditions were never 

optimum for the development of coal swamps, as indicated 

by the absence of Middle Pennsylvanian coals in the Rocky 

Mountain region. The occurrence of these palynomorph 

genera does, however, have implications in terms of climatic variability during each of the cycles within the Paradox Formation and tends to support the hypothesis of 

expanding and contracting equatorial desert regions proposed by Sarnthein (1978). Applying this hypothesis to the 

Pennsylvanian Period the following scenario is suggested. 

As continental glaciation increased in the Southern Hemisphere, deserts or at least very arid conditions developed in 

the equatorial regions, which then included the Paradox 

Basin. The climate of the Paradox Basin during the glacial 

periods was cool and dry, and sea level was at a minimum, 

allowing the development of restricted inland seas and 

inducing the precipitation of evaporites. At the opposite 

extreme of the cycle, when glacial melting was greater than 

accumulation, large amounts of water were free to once 

again become part of the hydrologic cycle during the interglacial period. This event influenced the volume of water 

in the ocean basins on a worldwide scale, causing a rise in 

sea level and associated changes in the global climate 

regime. In the Paradox Basin the climate became warmer 

and wetter. Terrestrial runoff was at a maximum during the 

interglacial periods, as documented by the increased 

amounts of terrestrial organic matter incorporated within 

the rocks of the interbeds (Kite and others, 1984). In this 

manner, the cyclic nature of the Paradox Formation can be 

attributed to the 100,000-year perturbations of the Earth's 

eccentricity defined in the Milankovitch theory that control 

the development of continental glaciation.

By adding this climatic information to the idealized 

Paradox evaporite cycle of Kite (1970), an interesting relationship between climate and cyclic sedimentation is
DEPTH IN

(METERS) LITHOLOGIC SAMPLE 

COLUMN INTERVAL

(1,063.6)

HR-3

3,520 

(1,0667)

3,530 

(1,0697)

3,540 

(1,0727)

3,550 

1,075.8)

- 

HR-4

HR-5

HR-6

HR-7

50 25 25 25 0 25 0 25 0 25 

RELATIVE ABUNDANCE, IN PERCENT

25 

Figure 9. Stratigraphic distribution of palynomorph genera recovered from interbed 8-9 of the Middle Pennsylvanian Paradox Formation penetrat

hole. Conodonts also were collected from sample locations HR-4 and HR-6. Relative sea-level and salinity conditions during deposition of each fa

shown in figure 2; location of borehole is shown in figure 1.
K20 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

apparent (fig. 4). The climatic-cycle and sea-level curves 

are identical in nature. Deposition of black shale corresponds with the warm, wet (humid) climatic phase and precipitation of halite with the cooler, drier phase of the climate 

cycle. In this climatic model, the interglacial period corresponds with the transgressive phase of Hite (1970), and the 

glacial period is equivalent to the regressive phase of Hite 

(fig. 4). During the cool, dry glacial period the drop in temperature was not great enough to compensate the decreased 

precipitation and increased wind that allowed precipitation 

of evaporites. The dominance of saccate palynomorphs in 

the salts indicates that the source of these palynomorphs was 

nearby, and the anemophilous nature of the saccate palynomorphs allowed easy transport by winds that were active 

during the glacial periods. The increased abundance of nonsaccate palynomorphs in the interbeds is favored by the 

increase in runoff associated with the interglacial periods, 

and these palynomorphs are preserved because they are 

small enough to withstand the effects of abrasion.

The dominance of saccate palynomorphs has long been 

accepted as a sudden event associated with the advent of 

Permian time (Wilson, 1962), and this is the nature of the 

assemblage recovered from the Paradox Formation. 

Although common components of the Middle Pennsylvanian Desmoinesian Series of the Midcontinent and eastern 

United States, such as Schopfites, Laevigatosporites, 

Thymospora, or Alatisporites (Kosanke, 1969), are not 

present in any of the samples examined from the Paradox 

Formation, neither are any true Permian guide fossils such 

as Nuskoisporites (Hart, 1969). Also, the distribution of 

palynomorph genera in the Paradox Formation is quite different from the genera collected by Shaffer (1964) in Permian salts of Kansas, from which a much more typical 

Permian assemblage was recovered. In very small amounts, 

however, specimens of Calamospora, Densosporites, 

Acanthotriletes, Convolutisporites, Cyclogranisporites, 

Leiotriletes, Triquitrites, Knoxisporites, Dictyotriletes, and 

particularly Lycospora, where it is present with its highest 

abundance, have been recovered from the Paradox Formation. The presence of Lycospora, although low in abundance in the Paradox Formation, is significant because it is 

not known to be present naturally above the Desmoinesian 

coals of the Midcontinent region, and where it is present it is 

only in non-coals in very small amounts, probably as 

reworked grains (Peppers, 1964).

It can be stated that the dominance of saccate palynomorphs is attributable to climate, particularly the aridity 

associated with the Paradox Basin region and the central 

Rocky Mountains during the Middle Pennsylvanian. In 

addition, the high abundances of saccate grains may indicate 

that the Paradox Basin region represents the area in which 

the gymnosperms and pteridosperms underwent evolution 

and radiation. Fossil evidence from central Colorado 

(Arnold, 1941) substantiates this conclusion. The presence

of abundant saccate grains in the palynoflora of the Paradox 

Formation also indicates the development of a separate and 

distinct Lower-Middle Pennsylvanian palynomorph province previously unrecognized in North America. The climate of the Paradox Basin provided an environment to 

which the vegetation of the region was forced to adapt or perish, resulting in the rapid evolution of these plants, while at 

the same time this stress had little effect on organisms of the 

marine realm.

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Published in the Central Region, Denver, Colorado 

Manuscript approved for publication June 9, 1995 

Edited by Judith Stoeser 

Graphics by Norma J. Macs 

Photocomposition by Norma J. Maes
PLATES

Contact prints of the plates in this report are available, at cost,

from U.S. Geological Survey Photograph Library.

Federal Center, Denver. Colorado 80225
PLATE 1

[All photographs were taken using ordinary light microscopy. Slide coordinates established using 

Leitz Ortholux microscope 569349]

Figure 1. Vesicaspora sp. A. Distal view, sample GDI-597, slide 2, negative number 4365; 

location 104.6 x 13.4, length 63 microns, width 49 microns, USNM 382729.

2. Vesicaspora sp. A. Proximal view, sample GDI-625, slide 2, negative number 4704; 

location 99.3 x 6.4, length 60 microns, width 46 microns, USNM 382730.

3. Vesicaspora wilsonii (Schemel) Wilson and Venkatachala, 1963. Proximal view, 

sample GDI-597, slide 1, negative number 4190; location 116.2x17.8, length 

53 microns, width 33 microns, USNM 382731.

4. Vesicaspora vw'foomV (Schemel) Wilson and Venkatachala, 1963. Proximal view, 

sample GDI-597, slide 2, negative number 4242; location 109.3x18.1, length 

53 microns, width 34 microns, USNM 382732.

5. Striatites splendens (Jizba) Tschudy and Kosanke, 1966. Proximal view, sample 

GDI-319, slide 3, negative number 3920; location 98.3x3.9, length 84 microns, 

width 50 microns, USNM 382733.

6. Striatites splendens (Jizba) Tschudy and Kosanke, 1966. Proximal view, sample 

GDI-237, slide 5, negative number 3903; location 117.1 x 8.9, length 80 microns, 

width 42 microns, USNM 382734.

7. Striatites splendens (Jizba) Tschudy and Kosanke, 1966. Equatorial view, sample 

GDI-319, slide 3, negative number 3952; location 107.3x15.1, length 78 microns, 

USNM 382735.

8. Monosaccate sp. A. Proximal view, sample GDI-237, slide 1, negative number 4834; 

location 123.6 x 6.6, length 58 microns, USNM 382736.

9. Monosaccate sp. Proximal view, sample GDI-319, slide 2, negative number 4701; 

location 114.9 x 23.1, slide label at right side of stage, length 102 microns, width 

55 microns, USNM 382737.
U.S. GEOLOGICAL SURVEY BULLETIN 2000-K PLATE 1

SELECTED PALYNOMORPHS FROM THE 

MIDDLE PENNSYLVANIAN PARADOX FORMATION
PLATE 2

[All photographs were taken using ordinary light microscopy. Slide coordinates established using 

Leitz Ortholux microscope 569349]

Figure 1. Monosaccate sp. B. Proximal view, sample GDI-237, slide 1, negative number 4657; 

location 120.5 x 13.2, length 100 microns, width 66 microns, USNM 382738.

2. Monosaccate sp. B. Proximal view, sample GDI-319, slide 3, negative number 3956; 

location 118.4 x 17.1, length 84 microns, width 60 microns, USNM 382739.

3. Monosaccate sp. B. Proximal view, sample CD 1-597, slide 1, negative number 4478; 

location 105.0 x21.1, length 87 microns, width 44 microns, USNM 382740.

4. Monosaccate sp. C. Proximal view, sample GDI-328, slide 3, negative number 4675; 

location 107.0 x!3.4, length 102 microns, width 55 microns, USNM 382741.

5. Lycospora pellucida (Wicker) Schopf, Wilson, and Bentall, 1944. Proximal view, 

sample GDI-597, slide 2, negative number 4483, location 108.9x21.9, length 33 

microns, USNM 382742.

6. Lycospora sp. Proximal view, sample GDI-237, slide 5, negative number 3904; 

location 103.7 x 11.6, length 34 microns, USNM 382743.

7. Potonieisporites simplexVJilson, 1962. Proximal view, sample GDI-325, slide 1, 

negative number 4665, location 114.8 x 3.4, length 126 microns, width 94 microns, 

USNM 382744.
U.S. GEOLOGICAL SURVEY BULLETIN 2000-K PLATE 2

SELECTED PALYNOMORPHS FROM THE 

MIDDLE PENNSYLVANIAN PARADOX FORMATION
PLATE 3

[All photographs were taken using ordinary light microscopy. Slide coordinates established using 

Leitz Ortholux microscope 569349]

Figure 1. Potonieisporites simplexWihon, 1962. Proximal view, sample GDI-237, slide 5,

negative number 3900; location 113.8 x 8.1, length 131 microns, width 105 microns, 

USNM 382745.

2. Potonieisporites grarafo Tschudy and Kosanke, 1966. Proximal view, sample

GDI-237, slide 6, negative number 4728; location 123.4x 13.8, length 109 microns, 

width 59 microns, USNM 382746.

3. Potonieisporites cf. P. novicus Bharadwaj, 1954. Proximal view, sample GDI-328, 

slide 3, negative number 4672, location 117.4x4.1, length 113 microns, width 

81 microns, USNM 382747.

4. Potonieisporites (?) sp. Proximal view, sample GDI-237, slide 6, negative number 

4726; location 107.0 x 3.2, length 99 microns, width 58 microns, USNM 382748.
U.S GEOLOGICAL SURVEY BULLETIN 2000-K PLATE 3

»"

SELECTED PALYNOMORPHS FROM THE 

MIDDLE PENNSYLVANIAN PARADOX FORMATION
PLATE 4

[All photographs were taken using ordinary light microscopy. Slide coordinates established using 

Leitz Ortholux microscope 569349]

Figure 1. Ricaspora grandis Bharadwaj and Salujha, 1963. Proximal view, sample GDI-325, 

slide 2, negative number 4839; location 107.6x21.3, length 84 microns, USNM 

382749.

2. Limitisporites cf. L. rectus Leschik, 1956. Proximal view, sample GDI-327, slide 1, 

negative number 4706; location 111.9 x 18.3, length 68 microns, width 51 microns, 

USNM 382750.

3. Complexisporitespolymorphus Jizba, 1962. Proximal view, sample GDI-319, slide

2. negative number 4844; location 118.4 x 8.4, length 87 microns, width 57 microns, 

USNM 382751.

4. Complexisporites polymorphus Jizba, 1962. Proximal view, sample GDI-319, slide

3. negative number 3958; location 100.1 x 18.7, length 92 microns, width 49 microns, 

USNM 382752.

5. Costapollenites ellipticus Tschudy and Kosanke, 1966. Proximal view, sample 

GDI-237, slide 3, negative number 4723; location 111.4x 11.6, length 63 microns, 

width 30 microns, USNM 382753.

6. Costapollenites ellipticus Tschudy and Kosanke, 1966. Proximal view of incomplete 

specimen, sample GDI-240, slide 1, negative number 3948; location 97.7x 12.6, 

length 66 microns, width 34 microns, USNM 382754.
U.S. GEOLOGICAL SURVEY BULLETIN 2000-K PLATE 4

SELECTED PALYNOMORPHS FROM THE 

MIDDLE PENNSYLVANIAN PARADOX FORMATION

 ft U.S. GOVERNMENT PRINTING OFFICE: 1996 - 774-045 / 20035 REGION NO.