Lithology of Evaporite Cycles and 

Cycle Boundaries in the Upper Part of the 

Paradox Formation of the Hermosa Group of 

Pennsylvanian Age in the Paradox Basin, 

Utah and Colorado

U.S. GEOLOGICAL SURVEY BULLETIN 2000-B

-3

I
On the Front Cover: View south toward LaSal Mountains along Colorado River between Cisco and Moab, Utah. Fisher Towers in center 

are composed of Permian Cutler Formation and capped by Triassic Moenkopi Formation. 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 ChinleMoenkopi contact is marked by a thin white ledge-forming gritstone. Valley between Fisher Towers and Fisher Mesa in background is part 

of Richardson Amphitheater part of Professor Valley. Photograph by Omer B. Raup, U.S. Geological Survey.
Lithology of Evaporite Cycles and 

Cycle Boundaries in the Upper Part of the 

Paradox Formation of the Hermosa Group of 

Pennsylvanian Age in the Paradox Basin, 

Utah and Colorado

By OMER B. RAUP and ROBERT J. KITE

EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN 

A.C. HUFFMAN, JR., Project Coordinator

U.S. GEOLOGICAL SURVEY BULLETIN 2000-B

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 : 1992
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

For sale by the Books and Open-File Reports Section

U.S. Geological Survey

Federal Center, Box 25286

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

Evolution of sedimentary basins Paradox Basin.

p. cm. (U.S. Geological Survey bulletin ; 2000)

Includes bibliographical references.

Contents: ch. B. Lithology of evaporite cycles and cycle boundaries in the upper part of the Paradox Formation of the Hermosa 

Group of Pennsylvanian age in the Paradox Basin, Utah and Colorado / by Omer B. Raup and Robert J. Kite.

Supt. of Docs. no.: I 19.3:2000 (v. 2)

1. Geology Paradox Basin. I. Raup, Omer B. (Omer Beaver), 1930-. II. Kite, R. J. (Robert J.) m. Series. 

QE75.B9 no. 2000, etc. 

[QE79] 

552'.5 dc20 92-15577

cn»
CONTENTS

Abstract................................................................................................................................. Bl

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

Geologic Setting................................................................................................................... 1

Core Description................................................................................................................... 3

Delhi-Taylor Oil Company Cane Creek No. 1........................................................... 3

Delhi-Taylor Oil Company Shafer No. 1 ................................................................... 4

Evaporite Cycles................................................................................................................... 5

Lithologic Characteristics of Cycles 2 and 3 of the Paradox Formation.............................. 6

Interbeds..................................................................................................................... 6

Anhydrite (transgressive)...................................................................................... 6

Silty Dolomite (transgressive).............................................................................. 13

Black Shale........................................................................................................... 14

Dolomite (regressive)........................................................................................... 15

Anhydrite (regressive).......................................................................................... 16

Halite Beds.................................................................................................................. 18

Anhydrite Laminations......................................................................................... 21

Bromine Distribution............................................................................................ 26

Potash Deposits..................................................................................................... 29

Interbed Contact Relationships............................................................................................. 30

Detailed Correlation of Cycle 3 Interbeds Between Cane Creek No. 1 and Shafer No. 1

Core Holes ................................................................................................................... 31

Sea-Level Control During Evaporite Deposition ................................................................. 33

Summary of Evidence for Environments of Deposition of Evaporites in the Paradox

Basin............................................................................................................................. 35

References Cited................................................................................................................... 36

FIGURES

1. Map of Paradox Basin, southwestern Colorado and southeastern Utah, showing limits of evaporite facies in

the Paradox Formation........................................................................................................................................... B2

2-4. Schematic stratigraphic columns of:

2. Cane Creek No. 1 core hole........................................................................................................................... 4

3. Shafer No. 1 core hole................................................................................................................................... 5

4. Cycle 2 facies in Cane Creek No. 1 core....................................................................................................... 6

5. Diagram showing correlation of lithologic units in Shafer No. 1 and Cane Creek No. 1 core.............................. 7

6. Charts showing mineral composition of penesaline and clastic intervals in Cane Creek No. 1 core as

determined by X-ray diffraction............................................................................................................................. 8

7-12. Photographs of polished surface of core:

7. Cane Creek No. 1, depth 2,460.5 ft............................................................................................................... 10

8. Shafer No. 1, depth 2,588 ft........................................................................................................................... 10

9. Cane Creek No. 1, depth 2,456.5 ft............................................................................................................... 11

10. Cane Creek No. 1, depth 2,455.3 ft............................................................................................................... 11

11. Shafer No. 1, depth 2,583.5 ft........................................................................................................................ 12

12. Shafer No. 1, depth 2,581.5 ft........................................................................................................................ 12

13. Photograph of segment of Cane Creek No. 1 core, depth 2,438 ft......................................................................... 14

14. Photograph of polished surface of core from Shafer No. 1 core, depth 2,569 ft.................................................... 14

15. Photomicrograph of transgressive dolomite from Cane Creek No. 1 core, depth 2,433.5 ft................................. 15

16. Photograph of polished surface of core from Shafer No. 1 core, depth 2,542 ft.................................................... 15

m
IV CONTENTS

17. Photomicrograph of black shale from Cane Creek No. 1 core, depth 2,410.5 ft................................................... 16

18-24. Photographs of polished surface of cores from:

18. Shafer No. 1, depth 2,523.5 ft........................................................................................................................ 16

19. Cane Creek No. 1, depth 2,372 ft ................................................................................................................. 17

20. Shafer No. 1, depth 2,517.5 ft........................................................................................................................ 17

21. Cane Creek No. 1, depth 2,366 ft.................................................................................................................. 18

22. Cane Creek No. 1, depth 2,364.2 ft............................................................................................................... 18

23. Cane Creek No. 1, depth 2,356.7 ft .............................................................................................................. 19

24. Cane Creek No. 1, depth 2,353.7 ft............................................................................................................... 19

25. Photographs of polished surface of core from Shafer No. 1 at consecutive depths, 2,500-2,505 ft...................... 20

26-35. Photographs of segment of:

26. Cane Creek No. 1 core, depth 2,336.5 ft....................................................................................................... 22

27. Cane Creek No. 1 core, depth 2,265 ft.......................................................................................................... 23

28. Shafer No. 1 core, depth 2,860 ft................................................................................................................... 24

29. Shafer No. 1 core, depth 3,673 ft................................................................................................................... 25

30. Cane Creek No. 1 core, depth 2,623.5 ft....................................................................................................... 25

31. Cane Creek No. 1 core, depth 2,616.5 ft....................................................................................................... 26

32. Shafer No. 1 core, depth 2,610.5 ft................................................................................................................ 26

33. Shafer No. 1 core, depth 2,491 ft................................................................................................................... 27

34. Cane Creek No. 1 core, depth 2,340.4 ft....................................................................................................... 27

35. Cane Creek No. 1 core, depth 2,218.5 ft ...................................................................................................... 28

36-37. Profiles of bromine distribution in halite bed of:

36. Cycle 2, Cane Creek No. 1 core .................................................................................................................... 29

37. Cycle 3, Cane Creek No. 1 core .................................................................................................................... 30

38-40. Photographs of polished surface of core from Shafer No. 1:

38. Depth 2,655 ft................................................................................................................................................ 31

39. Depth 3,303 ft ............................................._ 31

40. Depth 3,528.5 ft......................................................................_ 32

41, 42. Photographs of segment of:

41. Shafer No. 1 core, depth 3,892 ft................................................................................................................... 32

42. Cane Creek No. 1 core, depth 2,640.5 ft....................................................................................................... 33

43-45. Photographs of polished surface of core from Shafer No. 1:

43. Depth 2,869.5 ft........................................._ 34

44. Depth 3,919.5 ft........................................................................................................................ 34

45. Depth 4,149.5 ft............................................................................................................................................ 35
LITHOLOGY OF EVAPORITE CYCLES AND 

CYCLE BOUNDARIES IN THE UPPER PART OF

THE PARADOX FORMATION OF THE

HERMOSA GROUP OF PENNSYLVANIAN AGE IN THE

PARADOX BASIN, UTAH AND COLORADO

By OMER B. RAUP and ROBERT J. HTTE

ABSTRACT

Evaporites of the Paradox Formation of the Hermosa 

Group of Pennsylvania!! age in the Paradox Basin of southeastern Utah and southwestern Colorado are direct precipitates from marine brines and have been changed only 

slightly by subsequent events. Geophysical logs of deep 

wells indicate that the Paradox Formation is composed of 29 

halite-bearing evaporite cycles. Rock types that make up the 

cycles, in order of increasing salinity, are organic-carbonrich carbonate shale (black shale), dolomite, anhydrite, and 

halite (with or without potash). Studies of core from two core 

holes in the central part of the basin show that some of the 

cycles in the upper part of the Paradox Formation are 

remarkably complete, indicating regular changes in salinity. 

Newly recognized lithologic textures and cycle boundaries 

in 11 evaporite cycles indicate very regular cyclicity of subaqueous sedimentation in a basin in which salinity was probably controlled by Gondwana glaciation.

INTRODUCTION

The Paradox Basin of southeastern Utah and southwestern Colorado contains a thick section of evaporites in the 

Paradox Formation of the Hermosa Group of Pennsylvania 

age. This section contains 29 well-defined cycles composed 

of halite beds and associated penesaline and siliciclastic 

rocks (interbeds) (Hite, 1960).

Dissolution disconformities that separate each of the 

evaporite cycles in the Paradox Formation were recognized 

by Hite (1970). Since then, much detailed work has been 

done to characterize the sedimentological sequence within 

the cycles. The present study was done using cores from two 

core holes drilled during potash exploration in two areas 

southwest of Moab, Utah. These cores were taken from the

upper part of the Paradox Formation in cycles 2-11 and part 

of cycle 13. In this paper we describe some of the important 

features of these evaporite cycles that serve as the basis for 

interpretations of the mode of deposition of these rocks.

Acknowledgments. We thank James Hodgkinson and 

David Hogle for preparing the polished core samples, Samuel J. Dennis, Robert H. Weir, and H. Leon Groves, Jr., for 

photographic processing, and Lisa Ramirez Bader for computer graphics. We appreciate the helpful reviews of the 

manuscript by Sherilyn Williams-Stroud and Joseph P. 

Smoot.

GEOLOGIC SETTING

The Paradox Basin in southeastern Utah and southwestern Colorado in the eastern part of the Colorado Plateau (fig. 

1) is a structural and depositional basin that trends northwest-southeast adjacent to the southwest flank of the 

Uncompahgre Uplift. The depositional basin was asymmetrical in a northeast-southwest direction; it was deepest adjacent to the Uncompahgre Uplift and shallowed toward the 

shelf areas, which were toward the west, southwest, and 

south. The present sedimentary basin covers an area of 

approximately 11,000 mi2 (28,500 km2), and its boundaries 

are defined by the limit of the halite deposits in the Paradox 

Formation of the Hermosa Group of Pennsylvania age. The 

original maximum depositional thickness of the Paradox 

Formation was 5,000-6,000 ft (1,500-1,800 m) in the deepest part of the basin. The halite-bearing interval has been 

locally thickened to as much as 14,000 ft (4,300 m) in diapiric anticlines (Hite, 1968, p. 321).

Saline rocks of the Paradox Formation consist of 29 

known halite-bearing evaporite cycles. Each cycle contains 

penesaline and siliciclastic rocks (interbeds) at the base and 

a halite bed, with or without potash, at the top. Individual 

halite beds are now 20-790 ft (6-240 m) thick near the basin
B2 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

39°

38° -

37°

pproximate limit of the halite facies in the 

Paradox Formation of the Hermosa Group 

(Pennsylvanian)

Approximate limit of major potash zones in 

the halite facies of the Paradox Formation 

of the Hermosa Group (Pennsylvanian)

40 50 60 KILOMETERS

Figure 1. Limits of evaporite facies in the Paradox Formation of the Hermosa Group in the Paradox Basin, southwestern Colorado and 

southeastern Utah. Locations of Delhi-Taylor Oil Company Cane Creek No. 1 (CC-1) and Shafer No. 1 (S-1) core holes are also shown.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B3

center (Hite 1983). Hite (1960) numbered the halite beds 

from 1 to 29 from top to bottom. Recent drilling, however, 

has shown that there are two younger, thin halite beds near 

the depocenter of the basin. These have not as yet been incorporated into the present numbering system.

The areal distribution of the evaporite facies reflects the 

asymmetry of the basin (fig. 1). The potash facies is best 

developed in areas that were the deepest parts of the basin 

adjacent to the Uncompahgre Uplift (unpub. data). The halite 

facies has a wider distribution and extends farther to the 

northwest, southwest, and southeast. The anhydrite facies 

extends beyond the halite facies, and the carbonate facies, 

both limestone and dolomite, extends onto the shelf areas 

beyond the edges of the basin (Hite and Buckner, 1981).

Rocks of the northeastern part of the Paradox Basin are 

folded into parallel anticlines and synclines that trend northwest-southeast. In the area of the thickest evaporites, the 

halite facies has flowed into the cores of the anticlines from 

the adjacent synclines. Anticlines closest to the Uncompahgre Uplift are diapiric, and large volumes of halite in the 

upper parts of their cores have been removed by dissolution. 

In anticlines farther from the uplift, the halite facies is conformable with overlying sedimentary rocks. This is the case 

for both the Cane Creek Anticline and Shafer Dome, from 

which the cores of this study were taken.

The Paradox Basin was formed in Pennsylvanian time 

in response to plate collisions that produced the OuachitaMarathon orogeny (Kluth and Coney, 1981). The South 

American-African plate encountered the North American 

plate from the southeast starting in Late Mississippian to 

Early Pennsylvanian time. Major structural displacement 

occurred from Middle Pennsylvanian to Early Permian time. 

The major stresses of impact progressed from east to west, 

first in the Ouachita area, then in the Marathon Basin area 

(Ross, 1979). Structural deformation in the ancestral Rocky 

Mountains responded to the same east to west sequence. 

Coarse arkose flanking the ancestral Front Range is Early 

Pennsylvanian to Early Permian in age (Mallory, 1975), 

whereas arkose flanking the Uncompahgre Uplift is Late 

Pennsylvanian and Permian in age (Peterson and Hite, 

1969).

Tectonism in and around the Paradox Basin reached a 

climax with major downwarping of the basin in Desmoinesian time. The major positive elements were the ancestral 

Front Range, the Uncompahgre Uplift, the Emery Uplift, the 

Piute positive element (Mallory, 1975), and the ancestral 

Kaibab and Zuni-Defiance Uplifts (Peterson and Hite, 

1969). Except for the deeper water parts of the Paradox 

Basin, the surrounding areas were covered by shallow seas.

CORE DESCRIPTION

This study of evaporite cycles in the Paradox Basin is 

based on two cores: the Delhi-Taylor Oil Company Cane

Creek No. 1 and the Delhi-Taylor Oil Company Shafer 

No. 1. In these holes, which were drilled for potash, 

much of the upper part of the Paradox Formation was 

cored. These two core holes are located on nondiapiric salt 

anticlines where the stratigraphic sequence of the Paradox 

Formation is still well preserved. The two cores are 

described in Raup and Hite (199la, b).

Hite (1960) and Hite and Buckner (1981) established 

stratigraphic correlation of the evaporite cycles in the Paradox Formation throughout the Paradox Basin. The correlations were based on distinctive geophysical log signatures of 

many of the penesaline and siliciclastic intervals (interbeds) 

within the evaporite sequence; these log signatures can be 

traced from one end of the basin to the other and from the 

evaporite facies in the center of the basin into the carbonate 

rocks on the shelf of the basin.

DELHI-TAYLOR OIL COMPANY 

CANE CREEK NO. 1

The Delhi-Taylor Oil Company Cane Creek No. 1 well 

was drilled near the crest of the Cane Creek Anticline, Grand 

County, Utah, in section 25, T. 26 S., R. 20 E. (fig. 1). The 

total depth of the hole was 2,805 ft (855 m), and the cored 

interval included four of the upper five evaporite cycles of 

the Paradox Formation (fig. 2). Coring started at a depth of 

1,840 ft (561 m) in limestone of the Honaker Trail Formation, which overlies the Paradox Formation and is the upper 

formation of the Hermosa Group.

The rocks of cycle 1 are represented in this core hole by 

anhydrite, silty dolomite, black shale, and some limestone 

that overlie the halite bed of cycle 2. The halite bed of cycle 

1 is present in the northeast part of the basin (depocenter) but 

is absent at this location.

The upper part of cycle 2 contains a bed of halite that is 

171.3 ft (52.2 m) thick and is underlain by interbed units that 

are 110.2 ft (33.6 m) thick. The vertical distribution of the 

rock types in the interbeds is remarkably symmetrical and 

complete. The major rock types of this interval are anhydrite, 

silty dolomite, and black shale (Raup and Hite, 199 la). The 

basal anhydrite contains a thin unit of black shale.

The upper part of cycle 3 contains a bed of halite that is 

133.8 ft (40.8 m) thick and is underlain by interbeds that are 

106 ft (32.3 m) thick. Like cycle 2, these interbeds are vertically symmetrical with respect to lithology. The base of this 

interval is anhydrite, overlain successively by silty dolomite, 

black shale, silty dolomite, and anhydrite. A detailed log of 

these interbeds is illustrated in figure 5, and a detailed 

description is given later.

The halite bed at the top of cycle 4 is 179.5 ft (54.7 m) 

thick. It overlies interbeds that are only 37 ft (11.3 m) thick. 

In addition to being thin, this interval does not have the regular vertical symmetry of cycles 2 and 3. The lithologic units 

of these interbeds are thin and repetitious.
B4 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

DEPTH 

METERS FEET

550 - 1 '8°°

600 

2,000 -

650 

2,200 -

700 

Fig. 34

2,400 

750 

800 

2,600 

850 2,800 

1

Cycle 

1

Cycle 

2

Fig. 35

Fig. 27

Fig. 26

See fig. 5

Cycle 

3

Figs. 30, 31

Fig. 42

Cycle 

4

Cycle 

5

Figure 2. Schematic stratigraphy of Cane Creek No. I core hole. 

Penesaline and siliciclastic intervals (interbeds) between halite 

beds (nonpatterned) are indicated by a diagonal pattern. Locations 

of photographic figures are indicated by arrows; location of core 

hole shown in figure 1.

The halite bed of cycle 5 and only 1 m of anhydrite 

in the underlying interbed were drilled in this core hole. 

The halite bed is 127.3 ft (38.8 m) thick. A bed of sylvinite (crystalline intergrowth of sylvite and halite), approximately 11.8 ft (3.6 m) thick, is near the top of this halite 

bed. The Texasgulf Corporation has been mining this potash deposit near Moab, Utah, since 1964.

DELHI-TAYLOR OIL COMPANY 

SHAFER NO. 1

The Delhi-Taylor Oil Company Shafer No. 1 well was 

drilled on the crest of Shafer Dome 14 mi (22.5 km) 

southwest of Moab, Utah, in section 15, T. 27 S., R. 20 E.,

San Juan County, Utah. It was drilled to a depth of 4,155.8 ft 

(1,266.7 m) through 11 of the 29 numbered evaporite cycles 

in the Paradox Basin (figs. 1, 3). Coring started at 2,160.1 ft 

(658.4 m) just above the halite bed of cycle 2. The halite bed 

of cycle 1 halite is absent in this part of the basin. No core 

was taken from just below the top of the halite bed of cycle 

2 to about 30 ft (6.7 m) above the base of the halite bed in 

cycle 3 (fig. 3) (Raup and Kite, 1991b).

The interbeds of cycle 3 have the same very regular vertical symmetry as the same interval in the Cane Creek No. 1 

core. A detailed correlation and comparison of this interval 

in both wells is presented later (fig. 5).

Both the halite bed and the interbeds in cycle 4 are thin, 

29.8 ft (9.1 m) and 37 ft (11.3 m), respectively. The interbeds 

of cycle 4 are mostly silty dolomite; thin beds of anhydrite 

are at the top and bottom of the interbeds and a very thin 

black shale is in the middle.

The halite bed of cycle 5 is 213.9 ft (65.2 m) thick and 

contains widely disseminated crystals of sylvite. Although 

there is no economic concentration of sylvite in cycle 5 at 

this locality as there is at Cane Creek No. 1, the total interval 

of sylvite-mineralized rock is thicker.

The halite bed of cycle 6, one of the thickest halite beds 

in the upper part of the Paradox Formation, is 312 ft (95.1 m) 

thick. The underlying interbeds, on the other hand, are only 

23 ft (7 m) thick and contain only anhydrite and dolomite. A 

zone of sylvinite near the top of the halite bed is approximately 20 ft (6 m) thick.

Cycle 7 contains a halite bed that is 99.1 ft (30.2 m) 

thick. The interbeds at the base of the cycle are only 9.8 ft (3 

m) thick and are mostly anhydrite with a thin dolomite in the 

middle.

Cycle 8 is similar to cycle 7 in that the interbeds are 

composed only of anhydrite and dolomite. The halite bed is 

69.9 ft (21.3 m) thick, and the interbeds are 46.9 ft (14.3 m) 

thick.

The halite bed of cycle 9 contains a zone of sylvinite 

near its top that is approximately 19.7 ft (6 m) thick. The 

halite bed is 157.8 ft (48.1 m) thick, and the underlying interbeds are 35.1 ft (10.7 m) thick. The bottom two-thirds of the 

interbeds is dolomite, and the upper third is anhydrite. A thin 

bed of black shale is in the upper part of the dolomite.

The halite bed of cycle 10 is very coarsely crystalline in 

its upper part, and it contains several thin zones of anhydritehalite pseudomorphs after gypsum. This halite bed is 134.8 

ft (41.1 m) thick, and the underlying interbeds are 36 ft (11 

m) thick. The interbeds consist mainly of anhydrite and dolomite and contain three thin zones of black shale near the top.

The halite bed of cycle 11 is only 25.9 ft (7.9 m) thick. 

It is underlain, however, by thick interbeds that contain two 

relatively thick black shale beds and some relatively thin 

black shale beds. Because the halite of cycle 12 is not present 

in this core, it is probable that part of these interbeds 

represents cycle 12.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B5

DEPTH 

METERS FEET

2,100 |

650 

700 - 2,300 -I

750 

2,500 

800

2,700 

850 

Fig. 28,

2,900 

900

3,100 

Cycle 

2

F '9- 32 Cycle 

Fig. 38 4

Cycle

Cycle 6 

(part)

DEPTH 

METERS FEET

3,100 | 

950 

1,000 

3,300 

1,050 

3,500 

1,100 

3,700 

1,150 

3,900 

1,200 

1,250 _ 4,100 

Cycle 6 

(part)

Fia39

Cycle

7

Cycle

Fig. 29

Cycle 

9

Cycle 

10

Fig. 41

Cycle / Cycle 

11 / 12 halite

missing

Fig. 45

Figure 3. Schematic stratigraphy of Shafer No. 1 core hole. Penesaline and siliciclastic intervals (interbeds) between halite beds (nonpatterned) are indicated by diagonal pattern. Locations of photographic figures are indicated by arrows; location of core hole shown in figure 1.

The halite bed of cycle 13 and a few feet of underlying 

anhydrite constitute the base of this core hole. This halite 

bed, which is 169.9 ft (51.8 m) thick, contains thin beds and 

disseminated crystals of sylvite scattered throughout, except 

for a few meters at the base. Small nodules of kieserite 

(MgSO4-H2O) are in a 16.4-ft (5 m) -thick zone near the 

middle of the halite bed.

EVAPORITE CYCLES

Each of the evaporite cycles in the upper part of the Paradox Formation of the Hermosa Group in both the Cane 

Creek and Shafer cores contains a halite bed and an underlying sequence of penesaline and siliciclastic rocks that we

collectively refer to as interbeds (figs. 2-4). The cycles are 

separated by erosional or dissolution unconformities that are 

characterized by sharp knife-edge contacts (Kite, 1970; Kite 

and Buckner, 1981; Raup and Kite, 199la, b).

Most of the interbeds are made up of anhydrite, dolomite, and organic-carbon-rich carbonate shale (black shale). 

Some interbeds contain primarily anhydrite and dolomite 

and little or no black shale. Each of the interbeds has anhydrite at the top and bottom, and most contacts within the 

interbeds are gradational.

Of the 11 cycles available for study in the Cane Creek 

and Shafer cores, the most perfectly developed, in terms of 

lithologic representation and distribution, are cycles 2 and 3. 

The interbeds of these two cycles are vertically symmetrical 

and comprise a sequence of anhydrite, silty dolomite, black
B6 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

shale, dolomite, and anhydrite. Figure 4 illustrates the stratigraphic sequence in cycle 2.

A typical cycle starts at the base of the lower anhydrite 

at a disconformity at the top of the underlying halite bed. As 

we discuss later, we believe that the cycle is initiated by an 

abrupt rise in sea level and an influx of sea water into the 

basin (letter X, fig. 4). The lower part of the interbeds, therefore, is termed the transgress! ve phase because of rising sea 

level. We believe that sea level reached a maximum during 

deposition of the middle of the black shale (letter Y) and then 

began to drop. Thus, we consider the rock types in the upper 

part of the cycle (Y to Z) to be regressive.

It is probable that the cycles in the lower part of the Paradox Formation were deposited in relatively deep water in a 

basin that had subsided before evaporite deposition started. 

The rapid rate of evaporite deposition, however, quickly 

overtook basin subsidence, and the basin rapidly filled with 

evaporites in a manner described for other evaporite basins 

(Borchert and Muir, 1964; Wardlaw and Schwerdtner, 1966; 

Schmalz, 1969).

LITHOLOGIC CHARACTERISTICS OF 

CYCLES 2 AND 3 OF THE 

PARADOX FORMATION

The lithology described for cycle 2 (fig. 4) (Hite and 

Buckner, 1981) and cycle 3 (fig. 5) is very regular with 

respect to vertical distribution and representation of the 

evaporite rock types. Each of the cycles is bounded top and 

bottom by a solution disconformity, and each has a 

sequence, from base upward, of anhydrite, silty dolomite, 

organic-carbon-rich carbonate shale (black shale), dolomite, 

anhydrite, and halite. All of the contacts within the interbeds 

between these rock types are conformable, and most are gradational.

The lithologic sequences of cycles 2 and 3 (figs. 4 and 

5, respectively) are almost identical. Hite and Buckner 

(1981) described and interpreted the depositional history of 

cycle 2. Most of the lithologic detail presented herein is from 

cycle 3, but lithologic features of both cycles are presented 

and interpreted. Some general characteristics of the major 

rock types are included from descriptions of other cycles 

(Raup and Hite, 1991a,b).

Semiquantitative mineralogy of the various rock types 

in the interbeds of cycles 2 and 3 in the Cane Creek No. 1 

core, as determined by X-ray diffraction, is illustrated by histograms for the minerals halite, anhydrite, calcite, dolomite, 

quartz, plagioclase, orthoclase, and clay and mica (fig. 6) 

(Raup and Hite, 1991a). The quantities of the minerals were 

determined by comparing major peak heights of minerals in 

the samples with peak heights of prepared standards.

CM

o 

O

vwwwn

Halite

Anhydrite

Dolomite

Black 

shale

Silty 

dolomite

Anhydrite

.A/WWW

SALINITY

INCREASE

Z

O) Q. 

0) 

DC

V) <D 

0) V)

HCO

UP

SEA LEVEL

DOWN

Figure 4. Stratigraphy of cycle 2 facies in Cane Creek No. 1 core. 

Curve shows relative sea level and salinity during deposition of 

each facies. Points X, Y, and Z (referred to in text) are important positions in the salinity cycle. Location of core hole shown in figure 

1. Modified from Hite and Buckner (1981).

INTERBEDS 

ANHYDRITE (TRANSGRESSIVE)

The lower anhydrite unit in cycle 3 overlies the halite 

bed of cycle 4 with a very sharp, knife-edge contact (solution 

disconformity) in both the Cane Creek and Shafer cores 

(figs. 7, 8). The anhydrite rock is composed primarily of the 

mineral anhydrite and locally minor amounts of interspersed 

dolomite. Other minor constituents include quartz, mica, 

clay minerals, and pyrite. The basal part of this anhydrite 

unit is very fine grained and laminated. The laminae average 

1-3 mm thick and consist of light-gray to dark-gray or tan 

layers. The darker layers are colored by accumulations of 

organic matter. The laminated interval in the Cane Creek 

core is about 4.4 ft (1.3 m) thick. The laminated interval is 

overlain by nodular anhydrite (figs. 9-12). This nodular 

interval in the Cane Creek core is 8.6 ft (2.6 m) thick.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO

Shafer No. 1 Cane Creek No. 1

B7

DEPTH 

METERS FEET

760 

Fig. 33

785

Fig. 8

790 

Fig. 34

Halite (cycle 3)

Coarse pseudomorphs 

Q) after gypsum

Possible stromatolite laminations

Fine, parallel laminations

Anhydrite and dolomite interlaminated.

small pseudomorphs

CD

CD

D) 

CD 

DC

Halite (cycle 4)

I/VN

Figure 5. Correlation of lithologic units in Shafer No. 1 and Cane Creek No. 1 cores in penesaline and siliciclastic rocks (interbeds) and 

lower part of halite bed near base of cycle 3 (see figs. 2, 3). Base of transgressive anhydrite at bottom of interbeds is in knife-edge contact 

with underlying halite bed (cycle 4). Top of regressive anhydrite, at top of interbeds, contains coarse pseudomorphs of anhydrite and halite 

after gypsum; pseudomorphs are gradational with overlying halite bed. Locations of photographic figures are indicated by arrows; locations of core holes are shown in figure 1.
DEPTH Lithol 

METERS FEET Y

- 640 2,100 -

- 645

- 650

- 655

- 660

- 665

- 670

- 675

Halite Anhydrite Calcite Dolomite Quartz Plagioclase Orthoclase : mic
DEPTH 

METERS FEET Cycle

Lithology Halite Anhydrite Calcite Dolomite Quartz Plagioclase Orthoclase Clay and mica

-715-720

2,350 - -755 en3en3GonSm *o >£Os§25in§

2,480

Figure 6 (above and facing page). Mineral composition of penesaline and siliciclastic intervals in Cane Creek No. 1 core as determined by X-ray 

diffraction. Quantities of minerals were determined semiquantitatively by comparing major peak heights of minerals in samples with peak heights of 

prepared standards. Lengths of histogram bars represent ranges in amounts of mineral components (Raup and Hite, 1991a). Location of core hole shown 

in figure 1.

W
BIO EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 7. Photograph of polished surface of core from 

Cane Creek No. 1 core, depth 2,460.5 ft (750 m), illustrating sharp contact (arrow) between overlying laminated anhydrite at base of interbeds at base of cycle 3 and halite bed 

at top of cycle 4. This part of halite bed 4 contains small 

pseudomorphs of halite and anhydrite after gypsum. Location of core shown in figure 5.

Figure 8. Photograph of polished surface of core from Shafer 

No. 1 core, depth 2,588 ft (788.8 m), illustrating sharp contact 

(arrow) between overlying, finely laminated anhydrite at base of 

interbeds at base of cycle 3 and halite bed at top of cycle 4. 

Location of core shown in figure 5.
EV APORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO Bll

Figure 9. Photograph of polished surface of 

core from Cane Creek No. 1 core, depth 

2,456.5 ft (748.7 m), illustrating laminated 

transgressive anhydrite grading upward into 

nodular anhydrite near base of cycle 3. Location of core shown in figure 5.

Figure 10. Photograph of polished surface of core 

from Cane Creek No. 1 core, depth 2,455.3 ft (748.4 

m), illustrating nodular transgressive anhydrite in 

lower part of cycle 3. This is classic chicken-wire texture of nodular anhydrite. A faint remnant layering is 

visible through nodules. Location of core shown in 

figure 5.
B12 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 11. Photograph of polished surface of core 

from Shafer No. 1 core, depth 2,583.5 ft (787.4 m), illustrating nodular transgressive anhydrite in lower pan of 

cycle 3. Remnant horizontal layering is visible through 

nodules. Location of core shown in figure 5.

Figure 12. Photograph of polished surface of core from 

Shafer No. 1 core, depth 2,581.5 ft (786.8 m), illustrating 

nodular transgressive anhydrite in lower part of cycle 3. 

Location of core shown in figure 5.

The disconformities at the base of cycles 2 and 3, as 

well as those of all of the other cycles in the upper part of the 

Paradox Formation, are thought to result from an abrupt rise 

in sea level as indicated by the sea-level curve in the center 

of the diagram (fig. 4). This rise in sea level resulted in an 

inflow of sea water that caused an overall lowering of brine 

salinities in the basin and dissolution of the upper part of the 

halite bed of the preceding cycle. The character of the dissolution surfaces could be observed in the underground
EV APORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B13

workings of the Texasgulf potash mine near Moab, Utah. 

Two photographs of these underground exposures are illustrated in a paper by Kite (1970, p. 56, 57).The transgressive 

phase of deposition, from point X to point Y in figure 4, is 

considered to have occurred during a rise in sea level. The 

anhydrite of this phase, which is laminated in the lower part 

of cycle 3 and nodular in the upper part (fig. 5), was probably 

deposited as a result of a new influx of calcium and sulfate 

into the basin from the open ocean. The laminated anhydrite 

(possibly originally gypsum) would have been deposited 

during the early stages of influx when the salinity of the 

brines in the basin was still very high, and it may have precipitated from the incoming brine as that brine mixed with 

brines of higher salinity that were already in the basin (Raup, 

1982).

The upward progression of laminated anhydrite to nodular anhydrite may be related to the reduction in brine salinity as conditions approached those for the deposition of the 

dolomite. The nodular anhydrite is probably a diagenetic 

texture that resulted from recrystallization of laminated 

anhydrite in the bottom muds in the presence of brines of 

lower salinity. Traces of laminations through the nodules 

indicate that the nodular anhydrite (fig. 11) was originally 

laminated and that the nodular texture is a secondary feature. 

The transgressive anhydrite in the interbeds of cycles 4,5,6, 

8, and 10 also exhibits laminated textures grading to nodular 

textures as it approaches rock types that were deposited 

under less saline conditions. These examples also indicate 

that the changes in texture from laminated to nodular anhydrite are probably related to changes from higher to lower 

salinity.

Since the discovery of anhydrite nodules in the modern 

sediments along the Trucial Coast of the Arabian Gulf in 

what is considered a classic example of the sabkha depositional environment (Kinsman, 1966; Butler, 1969), researchers have been quick to interpret any nodular anhydrite as 

having formed in a sabkha setting. Dean and others (1975), 

in their paper on the sedimentological significance of nodular and laminated anhydrite in the Delaware Basin, made a 

good case for the diagenetic origin of nodular anhydrite 

regardless of original depositional setting. Dean and others 

(1975) and Dean and Anderson (1978, 1982) described 

cycles in the Permian Castile Formation of Texas and New 

Mexico in which laminated anhydrite grades upward into 

nodular anhydrite that is overlain by halite. In this sequence, 

the nodular anhydrite probably formed in an environment of 

increasing salinity rather than the decreasing salinity 

sequence of the Paradox cycles. Like the evaporite cycles of 

the Castile Formation, the Paradox cycles probably were 

deposited by subaqueous processes, and the nodular anhydrite in the middle of this sequence is part of these processes. 

The nodular anhydrite in the Paradox Basin evaporites most 

likely formed as the result of diagenesis that occurred early 

in the depositional process or at some later time. The original 

calcium sulfate precipitation may have been gypsum, and the

nodules may have formed when the gypsum was converted 

to anhydrite.

SILTY DOLOMITE (TRANSGRESSIVE)

The anhydrite is overlain by silty dolomite above a contact that in both cores is abrupt. In general the dolomitic 

rocks are composed of mainly dolomite, varying significant 

amounts of quartz, calcite, anhydrite, clay, and mica, and 

minor amounts of orthoclase, plagioclase, and some halite. 

All of the constituents of the dolomitic rocks are fine to very 

fine grained. The rocks have a sugary to earthy texture and 

are medium to light tannish gray. The transgressive dolomite 

in cycle 3 has a fine-grained sugary texture (figs. 13,14) that 

is due in part to silt-sized sucrosic dolomite crystals and in 

part to very well sorted quartz grains of about the same size. 

These rocks have indistinct and occasional disrupted bedding. Some irregularities in the bedding may be due to bioturbation. This dolomite in cycle 3 in the Cane Creek core is 

14.4 ft (4.4 m) thick. The lower half of this dolomite, in both 

cores, contains a thin interval of black shale (see fig. 5).

The transgressive dolomite precipitated as an influx of 

sea water continued to cause a further drop in basin salinities 

and the basin brines were enriched in the HCO3 ion. The 

fine-grained sucrosic texture of the dolomite in the Paradox 

interbeds probably is the result of early diagenetic dolomitization or of primary precipitation. Reduced dissolved sulfate 

in the basin brines, caused by bacterial reduction (Baker and 

Kastner, 1981) and (or) precipitation of reaction calcium sulfate as a result of dolomitization (Kite, 1985), could have 

contributed to conditions necessary for the precipitation of 

primary dolomite. Subtle textural and physical properties of 

chemical sediments, however, are subject to alteration 

through geologic time (Hardie, 1987).

This transgressive dolomite contains a high percentage 

(as much as 40 percent) of detrital quartz and some feldspar, 

and the grain size of this material is about the same as that of 

the sucrosic dolomite (figs. 6, 15). Much of the quartz and 

feldspar and possibly much of the dolomite may have been 

transported to the site of deposition by density currents similar to the mechanism proposed by Harms (1974) for parts of 

the Permian Brushy Canyon Formation in the Delaware 

Basin. The currents may have acquired clastic material as the 

shoreline advanced through the arkosic fan deltas adjacent to 

the Uncompahgre Uplift during rising sea level. The high 

degree of sorting of the quartz may be the result of winnowing of the material during current transport. Kite and Buckner (1981) believed that the remarkably well sorted material 

indicates that deposition may have been from turbidity currents that flowed across the basin on dense bottom-basin 

brines. The high degree of sorting of the quartz also suggests 

the possibility of an eolian origin. Further petrographic study 

on a regional scale would improve our understanding of the 

origin of these rocks.
B14 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 13. Photograph of segment of Cane 

Creek No. 1 core, depth 2,438 ft (743.1 m), illustrating typical transgressive silty dolomite in 

lower part of cycle 3. This quartz-rich carbonate 

may have been deposited by a combination of 

density currents and chemical precipitation. Location of core shown in figure 5.

Figure 14. Photograph of polished surface of core from 

Shafer No. 1 core, depth 2,569 ft (783.0 m), illustrating 

typical transgressive silty dolomite in lower part of cycle 3. 

Faint laminations are marked by concentrations of organic 

matter. Black spots are very small nodules of organic matter and pyrite. Location of core shown in figure 5.

BLACK SHALE

The transgressive dolomite is overlain by organiccarbon-rich carbonate shale (black shale) (figs. 5, 16) that 

comprises the middle lithologic unit in these sets of interbeds. The black shale of the Paradox Formation consists 

mainly of dolomite, calcite, quartz, clay minerals, and mica 

and minor amounts of pyrite and some sphalerite (fig. 6). 

Samples taken from different cycles in both cores have 

almost identical mineral compositions. In cycle 3 of the Cane 

Creek core the contact between the underlying dolomite and 

the black shale is gradational, but in the Shafer core it is 

abrupt. This shale interval, referred to as the "Gothic shale" 

by industry, is 36.5 ft (11.1 m) thick in the Cane Creek core
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B15

Figure 15. Photomicrograph of transgressive dolomite from 

Cane Creek No. 1 core, depth 2,433.5 ft (741.7 m); crossed nicols. 

Most of white, clear grains are quartz; cloudy gray grains are dolomite. Sample contains about 40 percent quartz. Location of core 

shown in figure 5.

and is dark gray to jet black. Its mineral components are finesilt to clay sized and include dolomite, calcite, and quartz 

and minor amounts of feldspar, illite, and other clay minerals 

(fig. 6). Fine silt-sized quartz is abundant in some intervals 

in amounts of as much as 40 percent (fig. 17). The carbonate 

content is 20-30 percent (Kite, 1970). The total organic 

carbon content in the black shale of cycle 3 is 2-3 percent in 

the Shafer core (Kite and others, 1984, p. 264). Black shale 

in the interbeds of other cycles in the Paradox Basin contains 

organic matter in amounts from 0.5 to 13 weight percent 

(Kite and others, 1984). A few broken shell fragments, some 

small intact shells, and occasional conodonts indicate some 

biological activity.

The black shale was probably deposited during the time 

of highest sea level within each cycle when the salinity of the 

brines in the basin was lowest. The organic matter was probably derived from both marine and continental sources, as 

well as from algae and bacteria that flourished within the 

basin, and was preserved by residual, dense, relatively high 

salinity, anoxic brines that covered the basin floor. The 

siliciclastic components may have been deposited by density 

currents similar to those during deposition of the silty dolomite interval described earlier, but it is possible that a significant amount may have an eolian origin. An extensive 

discussion concerning the composition and origin of these 

unusual rocks is given in a paper by Kite and others (1984).

The upper part of the cycle 3 interbeds is interpreted as 

having been deposited during a lowering of sea level and is 

thus considered to be the regressive phase. The lowering of

Figure 16. Photograph of polished surface of core from Shafer No. 1 core, depth 2,542 ft (774.8 m), illustrating typical interval of organic-carbon-rich carbonate shale (black shale) 

near middle of interbeds in cycle 3. Location of core shown in 

figure 5.

sea level and the accompanying rise in salinity in the basin 

started sometime during deposition of the black shale as 

indicated at point Y on figure 4.

DOLOMITE (REGRESSIVE)

The black shale is overlain by a dolomite (fig. 18) that, 

like the transgressive dolomite, has a sugary texture. The 

contact between these rock types is gradational in the Cane 

Creek core and abrupt in the Shafer core. In the Cane Creek 

core this dolomite unit is 21 ft (6.4 m) thick. This regressive 

dolomite has a blotchy texture as a result of included organic 

matter and small clots of pyrite. Occasional zones of disrupted bedding may be the result of bioturbation.

The regressive dolomite was deposited at a time when 

basin salinities were rising. It contains somewhat less siliciclastic material than the transgressive dolomite, especially in 

cycle 2 (fig. 6), possibly because less clastic material may
B16 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 17. Photomicrograph of black shale from Cane Creek No. 

1 core, depth 2,410.5 ft (734.7 m); crossed nicols. Sample contains 

about 15 percent very fine grained, silt-sized quartz. Location of 

core shown in figure 5.

have been available near the basin edges during the 

regressive phase of the cycle and because much of the 

available material would have been mobilized during the 

transgressive phase. Rainfall over the highland areas may 

also have been lower during this phase in the cycle, and 

therefore flooding from the land was less.

The transgressive dolomite, the black shale, and the 

regressive dolomite in cycles 2 and 3 contain abundant siltsized siliciclastic material, mostly quartz. The other rock 

types of the cycles, anhydrite and halite, contain very little 

quartz. Rates of sedimentation of the different rock types 

may account, in large part, for these differences. If siliciclastic material entered the basin at an almost constant but slow 

rate, either by density currents from the shoreline or by wind, 

it would accumulate in greater amounts within the chemical 

sediments that precipitated the slowest. Kite and Buckner 

(1981, p. 157) showed that the dolomite and black shale were 

deposited, in general, at rates lower than the anhydrite and 

halite. This difference in deposition rates may account, at 

least in part, for the distribution of the siliciclastic material 

in these rocks.

Between the regressive dolomite and the overlying 

anhydrite is a transition zone of interbedded dolomite and 

anhydrite (fig. 5) that contains numerous thin layers of small 

pseudomorphs of anhydrite after gypsum (figs. 19, 20). In 

the Cane Creek core this transitional interval is 8.8 ft (2.7 m) 

thick. The increase in amount of anhydrite (gypsum) and the 

presence of bottom-growth crystals are indicative of rising 

salinity of the brines in the basin.

Figure 18. Photograph of polished surface of core from Shafer No. 1 core, depth 2,523.5 ft (769.2 m), illustrating an interval 

of regressive dolomite in upper part of interbeds in cycle 3. 

Blotches are composed of organic matter, pyrite, quartz, and minor halite. Location of core shown in figure 5.

ANHYDRITE (REGRESSIVE)

Anhydrite having a variety of textures overlies the dolomite-anhydrite transition zone. Laminated texture in the 

lower part of this anhydrite unit probably resulted from primary precipitation from the brine column as may also have 

occurred in the transgressive anhydrite (fig. 5). Extremely 

fine and wavy laminations in part of the unit may be the 

result of anhydrite replacement of carbonate algal mats (fig. 

21). This interval in the Cane Creek core is 2 ft (0.6 m) thick. 

Above the finely laminated anhydrite is a 3-ft (1m) -thick 

zone of anhydrite that contains clasts of extremely finely 

laminated anhydrite. This zone, too, could possibly be a 

replacement of algal mat structures (fig. 22). If this finely 

laminated anhydrite was originally produced by algal 

deposition, the zone of deposition must have been within the 

photic zone (water depth less than 80 m). Cycle 3 is in the 

upper part of the Paradox Formation and thus was probably 

deposited in relatively shallow water during the later stages
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B17

Figure 19. Photograph of polished surface of core 

from Cane Creek No. 1 core, depth 2,372 ft (722.0 

m), illustrating an interval of interbedded dolomite 

(D) and anhydrite (A) that contains pseudomorphs 

(P) after bottom-growth gypsum in regressive phase 

in upper part of interbeds in cycle 3. Location of 

core shown in figure 5.

Figure 20. Photograph of polished surface of core from 

Shafer No. 1 core, depth 2,517.5 ft (767.3 m), illustrating 

an interval of interbedded dolomite (D) and anhydrite (A) 

that contains small pseudomorphs (P) after bottomgrowth gypsum in regressive phase in upper part of interbeds in cycle 3. Location of core shown in figure 5.

of basin filling. This depositional sequence fits the model for 

deep-water evaporites described by Schmalz (1969).

The upper part of the regressive anhydrite unit contains 

a zone of coarse pseudomorphs of anhydrite and halite after 

gypsum (fig. 5). This pseudomorphic texture in cycle 3 is 

illustrated from both cores in figures 23-25. In the Cane 

Creek core this zone is 8.2 ft (2.5 m) thick. The top of this 

zone of pseudomorphs is conformably overlain by bedded 

halite.

The pseudomorphic zone, which is common to all 

cycles in the upper part of the Paradox Formation, must 

somehow be related to conditions of rising salinity in the 

basin because the anhydrite lithology grades upward into the 

overlying halite bed. Whatever the conditions were that fostered development of large gypsum crystals at the top of the 

interbeds, these conditions were repeated during each cycle.
B18 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 21. Photograph of polished surface of core 

from Cane Creek No. 1 core, depth 2,366 ft (721.2 m), 

illustrating fine, wavy laminations in regressive anhydrite in upper part of interbeds in cycle 3. Location of 

core shown in figure 5.

Figure 22. Photograph of polished surface of core 

from Cane Creek No. 1 core, depth 2,364.2 ft (720.6 

m), illustrating a zone of faint pseudomorphic structures and patches of extremely finely laminated anhydrite that may be pseudomorphs after stromatolitic 

limestone in upper part of interbeds in cycle 3. Location of core shown in figure 5.

Each of the interbeds in all of the cycles observed in the 

Cane Creek and Shafer cores exhibits the same kinds of contacts as those in cycles 2 and 3. In each there is a sharp contact between the anhydrite at the base of the interbeds and the 

underlying halite beds, and each of the interbeds has an 

anhydrite interval at the top that grades into the overlying 

halite bed through a zone of pseudomorphs. Not all of the 

interbeds contain black shale, but all contain dolomite and 

anhydrite.

HALITE BEDS

The halite bed of cycle 3 in the Cane Creek core is 134 

ft (40.8 m) thick and is in gradational contact with the interbeds of cycle 3 below and in sharp contact with the overlying 

interbeds of cycle 2 (fig. 2). The halite crystals are clear to 

slightly cloudy; some are smoky gray to light tan. The cloudiness is due to minute inclusions of brine or very small crystals of anhydrite. The tan coloration is due in some halite to 

inclusions of organic matter and in some halite to inclusions 

of fluid hydrocarbons. The halite crystals normally range in 

size from 2 to 5 mm. The halite bed contains thin laminae of 

anhydrite that are spaced about 6 in. (15 cm) apart near the 

top of the halite bed. Downward the anhydrite laminae are 

closer spaced, and spacing near the base is about 1-2 in. 

(2.5-5.0 cm). For the most part the anhydrite is in distinct, 

dense laminae (figs. 26-28). Some laminae, however, have a 

distinctive texture that we have called "snow-on-the-roof."
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B19

Figure 23. Photograph of polished surface of core 

from Cane Creek No. 1 core, depth 2,356.7 ft (718.3 

m), illustrating coarse pseudomorphic texture of anhydrite and halite after gypsum at top interbeds in cycle 3. Location of core shown in figure 5.

Figure 24. Photograph of polished surface of 

core from Cane Creek No. 1 core, depth 2,353.7 ft 

(717.4 m), illustrating coarse pseudomorphic texture of anhydrite and halite after gypsum at top of 

interbeds in cycle 3. Location of core shown in 

figure 5.
B20 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 25 (above and facing page). Photographs of polished surfaces of core from Shafer No. 1 core at consecutive depths illustrating coarse pseudomorphic texture of anhydrite and halite after gypsum at top of interbeds in cycle 3. Some especially good examples of swallow-tail morphology of the pseudomorphs are shown in B. Location 

of core shown in figure 5. A, 2,500 ft (762.0 m). B, 2,502 ft (762.6 m). C, 2,505 ft (763.5 m).

Examples of this texture are illustrated in figures 29-32. The 

origin of the anhydrite laminae and the snow-on-the-roof 

texture is discussed later.

Two of the anhydrite laminae near the base of the halite 

bed of cycle 3 contain an array of crystals that are pseudomorphs of halite and anhydrite after gypsum (figs. 33, 34). 

The two layers in the Shafer core are within 3 ft (1 m) of each 

other (fig. 5), and the lower of the two is illustrated in figure

33. The two pseudomorphous layers in the Cane Creek core 

are separated more widely than those in the Shafer core (fig. 

5). The upper layer is illustrated in figure 34. These two 

pseudomorphous layers, near the base of the halite bed in 

each core, are probably correlative. The top of the halite bed 

of cycle 3 is truncated by the disconformity that separates 

this halite bed from the interbeds of the overlying cycle 2 

(fig. 35).
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B21

ANHYDRITE LAMINATIONS

The halite beds of the Paradox Basin contain laminations of anhydrite in intervals that are more widely spaced at 

the top than at the base. These laminations are 0.03-0.09 in. 

(0.5-2 mm) thick, and the intervening halite layers are 

0.75-6.0 in. (2-15 cm) thick. Typical anhydrite-halite 

couplets were described by Holser (1979, p. 283) as 

alternations of clear to translucent halite and dark to black 

halite. The dark color is caused by a dispersion of anhydrite 

crystals that diffuse the light. In the halite rocks of the Paradox Basin, the darker layers contain a discrete layer of gray 

anhydrite. Excellent examples of anhydrite laminations in

halite rocks of the Paradox Basin are illustrated in figures 

26-28.

The rhythmic occurrence of anhydrite laminations in 

halite rocks has been described in rocks attributed to be of 

marine origin from many deposits of many ages from around 

the world (Lotze, 1957; Borchert and Muir, 1964; Borchert, 

1969; Braitsch, 1971). Anhydrite laminations in halite, other 

than those in the Paradox Basin, are found in the Permian 

Castile and Salado Formations of Texas and New Mexico 

(Dean and Anderson, 1978; Holser, 1979); the Permian 

Zechstein of Germany (Richter-Bernburg, 1955; Lotze, 

1957; Borchert, 1969); the Upper Permian Zechstein of 

Poland (Czapowski and others, 1990); the Permian Upper 

Kama deposits of the former U.S.S.R. (Fiveg, 1948; Vakhramayeva, 1956); the Devonian Prairie Evaporite in 

Saskatchewan, Canada (Wardlaw and Schwerdtner, 1966); 

and Upper Silurian evaporites of the Michigan Basin (Dellwig, 1955; Dellwig and Evans, 1969; Kunasz, 1970).

Evidence for the origin of anhydrite laminations in the 

halite rocks of the Paradox Basin may be provided by the 

occasional anhydrite layers that have a texture that we have 

called snow-on-the-roof. This texture, described by Kite 

(1985, p. 225), is composed of the draping of a layer of anhydrite on the uneven top surface of coarse (as much as 0.39 in. 

(1 cm)), angular, bottom-growth crystals of halite (figs. 

29-32) and gives the impression of snow that has fallen on 

angular roof tops. The occurrence of anhydrite only on the 

tops of these crystals is interpreted to mean that the halite 

bottom-growth crystals were in place at the time of calcium 

sulfate deposition and that the calcium sulfate rained down 

from the overlying column of brine. There is no evidence to 

indicate whether the anhydrite was primary or whether the 

original precipitate was gypsum. In any event, the present 

anhydrite is very fine grained, and there is no evidence of 

preexisting gypsum. We conclude that the snow-on-the-roof 

texture indicates that both the halite and associated anhydrite 

were the result of subaqueous crystallization.

Stewart (1963, p. 5) suggested that the periodicity of the 

anhydrite laminations could be explained by periodic (probably annual) climatic temperature changes that would have 

controlled the temperature of the brine body, or at least the 

upper layers of the brine body. The solubility of calcium sulfate is dependent on temperature, calcium sulfate being more 

soluble in cold solutions than in warm. Cyclic temperature 

fluctuations, therefore, could have precipitated calcium sulfate (probably gypsum) during the summer months and not 

during the winter months. Periodic, rapid precipitation 

would have caused a rain of gypsum (anhydrite) crystals 

onto bottom-growth crystals of halite. An example of this 

mechanism for the formation of anhydrite laminations in 

halite in the Permian Zechstein of Poland was described by 

Czapowski and others (1990).

Anhydrite laminations could also have resulted from 

periodic influx of meteoric waters that carried calcium bicarbonate into the basin (Kite, 1985; Magaritz, 1987). The
B22 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 26. Photographs of segment of Cane Creek No. 1 core, depth 

2,336.5 ft (712.2 m). Location of core shown in figure 2. A, Reflected light 

Anhydrite laminae appear as light-colored layers within the gray halite of 

the halite bed in cycle 3. B, Transmitted light. Optical density results from 

significant amount of anhydrite disseminated in halite between discrete 

laminae.
EV APORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B23

Figure 27. Photographs of segment of Cane Creek No. 1 core, depth 

2,265 ft (690.4 m). Location of core shown in figure 2. A, Reflected light. 

Anhydrite laminae appear as light-colored layers within the gray halite of 

the halite bed in cycle 3. B, Transmitted light. Similar to figure 26B, the 

large dark area near the top of the core shows the optical density caused 

by significant amounts of anhydrite disseminated in the halite between the 

discrete laminae.
B24 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 28. Photographs of segment of Shafer No. 1 core, depth 2,860 ft 

(871.7 m), illustrating an unusually clear example of halite-anhydrite couplets 

in halite bed 5. Location of core shown in figure 3. A, Reflected light. B, Transmitted light.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B25

Figure 29. Photograph of segment of 

Shafer No. 1 core, depth 3,673 ft (1,119.5 

m), illustrating snow-on-the-roof texture in 

halite bed of cycle 9. Location of core 

shown in figure 3.

calcium would react with sulfate in the basin brines to precipitate gypsum or anhydrite. If such influxes were the result 

of seasonal (annual) storm cycles, then the resultant periodic 

precipitation of calcium sulfate would have had the same 

effect as annual temperature fluctuations.

In the Paradox Formation, the thickness of the halite 

part of the halite/anhydrite couplets generally increases from 

the bottom to the top of the halite beds. This is especially 

obvious in the halite beds of cycles 2-5 in the Cane Creek 

core and in the halite beds of cycles 4-8, 10, and 11 in the 

Shafer core (Raup and Hite, 199la, b). In addition to the 

upward thickening of the halite part of the couplets, the 

halite layers in the upper parts of the halite beds contain less 

disseminated anhydrite and organic matter.

The upward thickening of the halite in the couplets 

would indicate an increased rate of halite precipitation

Figure 30. Photograph of segment of 

Cane Creek No. 1 core, depth 2,623.5 ft 

(799.6 m), illustrating snow-on-the-roof 

texture in halite bed of cycle 4. Location of 

core shown in figure 2.

throughout the deposition of the halite bed if the anhydrite 

laminations were deposited annually or at some other regular 

interval. Halite would have been deposited relatively faster 

through time if the brines in the basin were becoming more 

concentrated in the more soluble constituents in the sea 

water, such as the potassium and magnesium chlorides, 

through a salting-out mechanism that was operating along
B26 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 31. Photograph of segment of Cane 

Creek No. 1 core, depth 2,616.5 ft (797.5 m), 

illustrating snow-on-the-roof texture in halite 

bed of cycle 4. Location of core shown in 

figure 2.

with normal evaporative concentration (Raup, 1970; 

Braitsch, 1971). The precipitated halite would also be 

cleaner upward in the halite bed because coprecipitated 

anhydrite and organic constituents in the brine would have 

been diluted by the increased halite precipitation.

Figure 32. Photograph of segment of 

Shafer No. 1 core, depth 2,610.5 ft (795.7 

m), illustrating snow-on-the-roof texture 

in halite bed of cycle 4. Location of core 

shown in figure 3.

BROMINE DISTRIBUTION

Bromine accumulates in sea-water brines when the 

brines are concentrated through evaporation. Because a constant, small part of this bromine is incorporated in halite 

(substituting for chlorine) as it is precipitated, the bromine 

content in halite reflects the amount of bromine in the brine 

and serves as an index of the concentration (salinity) of the 

brine (Raup, 1966; Raup and Kite, 1978). Bromine 

distribution profiles for the halite beds of cycles 2 and 3 

(figs. 36, 37) are very regular; bromine generally increases
EV APORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B27

Figure 33. Photograph of segment of Shafer 

No. 1 core, depth 2,491 ft (759.3 m), illustrating layer of pseudomorphic crystals of anhydrite and halite after gypsum on top of thin 

lamina of anhydrite. This layer is one of only 

two such layers in lower part of halite bed in 

cycle 3. Location of core shown in figures 3 

and 5.

from bottom to top, typical of the thick halite beds of the Paradox Basin evaporites (Raup, 1966; Raup and Kite, 1978; 

Hite, 1983) and in general accordance with theoretical considerations (Holser, 1966, 1979; Borchert, 1969).

There are three dominant trends in the profile of the 

bromine content for the halite bed of cycle 2. Starting at the 

bottom of the halite bed bromine content is 180 ppm, it 

decreases upward to 70 ppm, then increases to 160 ppm, and 

finally decreases in the upper part of the halite bed (Raup, 

1966). The last two trends probably correspond to changes in 

basin salinity during the deposition of this halite bed. The 

initially high and then decreasing bromine content in the 

basal 24 ft of halite could also reflect changes in basin salinity; however, it is more likely that this high bromine content

Figure 34. Photograph of segment of Cane 

Creek No. 1 core, depth 2,340.4 ft (713.3 m), illustrating layer of pseudomorphic crystals of anhydrite and halite after gypsum on top of thin 

lamina of anhydrite. This layer is one of only two 

such layers in lower part of halite bed in cycle 3. 

Location of core shown in figures 2 and 5.

at the base is due to expulsion of residual, bromine-rich 

brines from the underlying sediments during lithification 

(Raup and Hite, 1978). From 2,088 to 1,950 ft (636.4-594.4 

m), the salinity of the brine generally increased, yet the frequent changes in the slope of the profile, which indicate a 

rhythmic increase and decrease of bromine in the halite, indicate that the increase in salinity of the brine was interrupted 

four times by brine dilution that probably resulted from 

influx of sea water into the basin. Subsequently, during deposition of the upper 14 ft (4.3 m) of the halite bed, the salinity 

of brine decreased rapidly, probably as the result of 

increased circulation into the basin. Rocks not far above the
B28 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 35. Photograph of segment of Cane Creek 

No. 1 core, depth 2,218.5 ft (676.2 m), illustrating 

sharp contact (arrow) between top of the halite bed of 

cycle 3 and overlying laminated anhydrite at base of 

cycle 2 interbeds Location of core shown in figure 2.

halite bed of cycle 2 are predominantly normal marine 

limestone of the Honaker Trail Formation of the Hermosa 

Group (Raup and Kite, 199la, b).

The bromine content of the cycle 3 halite bed similarly 

generally increases from bottom to top. At the base of the 

halite bed of cycle 3 the bromine content is 90 ppm. The 

slightly higher bromine content at the base of this halite bed 

was probably derived from residual, bromine-rich brines that 

were expelled from the underlying rocks during lithification 

similar to the halite bed in cycle 2. Above the basal part of 

the profile, bromine content decreases to 72 ppm at 2,328 ft 

(709.6 m). From 2,328 to 2,230 ft (709.6-679.7 m), it 

increases to 130 ppm but with enough irregularities to suggest the existence of minor salinity variations, similar to 

those in the halite bed of cycle 2. The bromine content of the 

upper 10 ft (3 m) of the halite bed of cycle 3 very greatly 

increases, so much so, in fact, that at the top of the bed the 

salinity is just short of that necessary for the precipitation of 

potash minerals (Raup, 1966).

The bromine profiles of the halite beds of cycles 2 and 

3 are typical of bromine profiles measured in halite beds of 

several other cycles in the Paradox Formation (Raup, 1966; 

Raup and others, 1970; Raup and Kite, 1978; Kite, 1983). 

The generally regular nature of the profiles indicates that the 

bromine content of the brines from which the halite precipitated changed gradually during deposition of the halite beds; 

this gradual change would have required a relatively large 

volume of brine in the basin. These regular profiles are in 

contrast to irregular, erratic profiles typical of halite beds 

deposited from shallow, transitory brines and in geologic 

settings where the salts were susceptible to episodes of frequent recrystallization (Raup and Kite, 1978).

Bromine profiles for halite beds of the Paradox Formation (Raup, 1966; Raup and Kite, 1978; Kite, 1983) indicate 

essentially continuous, uninterrupted deposition. The rapidity of salt deposition would require sufficient basin depth to 

accommodate the entire thickness of at least a single halite 

bed. The thickest halite bed in the upper part of the Paradox 

Basin evaporites is the halite bed of cycle 6, which is about 

330 ft (100 m) thick. Other halite beds, lower in the stratigraphic section, are several hundred feet thick (Kite, 1960). 

Wardlaw and Schwerdtner (1966) analyzed the deposition 

rate of the halite in the Prairie Evaporite of Saskatchewan 

and concluded that, if the annual sedimentation rate was 5 

cm per year, then the 600-ft-thick chloride section in the center of the basin would have formed in less than 4,000 years. 

Because this sedimentation rate far exceeds any known tectonic subsidence rate, it is assumed that the basin would have 

been at least that deep prior to halite deposition. Borchert 

(1969) followed a similar line of reasoning for the depositional rates and tectonic setting of evaporites in the Permian 

Zechstein Basin of Germany. Following the same reasoning 

for evaporites of the Paradox Basin, which had an original 

deposition thickness in excess of 5,000 ft (1,500 m), the 

lower part of the evaporites must have been deposited in 

fairly deep water. As the evaporites accumulated, the depth 

of the water in the basin would have decreased (Schmalz, 

1969).
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B29

1,935

LU

Q

1,945 - 

1,955 

1,965 - 

1,975 - 

1,985 - 

1,995 

2,005 

2,015 

2,025 

2,035 

2,045 

2,055 

2,065 

2,075 

2,085 

2,095 - 

2,105 

2,115

50

B

590

600

610

w 

cc.

620

-630

-640

100 150 200 50 100 150 200

BROMINE, IN PARTS PER MILLION BROMINE, IN PARTS PER MILLION

Figure 36. Bromine distribution in halite bed of cycle 2, Cane Creek No. 1 core. A, Analytical results. B, Smoothed profile using a moving average of five points.

POTASH DEPOSITS

Potash, generally in the form of sylvinite, is in 17 of the 

29 evaporite cycles in the Paradox Basin (Kite, 1960). Concentration of the potash at or near the tops of the halite beds, 

for the most part, indicates the salinity asymmetry of the 

evaporite cycles. Bromine distribution studies of the halite 

beds of the Paradox Basin (Raup, 1966; Kite, 1983) show

that salinity of the basin brines increased during deposition 

of most of the halite beds. The salinity curve for cycle 2 (fig. 

4) shows an increase of salinity from the middle of the black 

shale upward through the interbeds and through the halite 

bed, in the part of the curve Y through Z. This interval is in 

the regressive phase of the cycle when the sea level dropped 

to its low stand, circulation of sea water into the basin was 

restricted, and salinities within the basin were steadily
B30 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

2,210

LLJ

Q

2,220 ' 

2,230 ' 

2,240 ' 

2,250 

2,260 

2,270 

2,280 

2,290 

2,300 

2,310 

2,320 

2,330 - 

2,340 - 

2,350 -

2,360

680

690

I 

D700 g

710

50 100 150 200 250 50 100 150 200 250

BROMINE, IN PARTS PER MILLION BROMINE, IN PARTS PER MILLION

Figure 37. Bromine distribution in halite bed of cycle 3, Cane Creek No. 1 core. A, Analytical results. B, Smoothed profile using a moving 

average of five points.

increasing. Potash mineralization is indicative of extreme 

brine salinities that resulted from extreme aridity during the 

final stages of those particular cycles.

INTERBED CONTACT 

RELATIONSHIPS

All of the interbeds in each of the cycles observed in the 

Cane Creek and Shafer cores are identical with respect to

their upper and lower contacts. These contact relationships 

are well illustrated in cycle 3 (fig. 5). In cycle 3 the base of 

the interbeds is in sharp contact with the underlying halite 

bed of cycle 4 (figs. 7, 8), and the upper contact is 

gradational with the halite bed of cycle 3 through a zone of 

coarse pseudomorphs of anhydrite and halite after gypsum 

(figs. 23-25). Photographs of these contact relationships in 

cycles other than 3 are illustrated in figures 38-45.

The sharp, disconformable basal contacts of interbeds 

in cycles 2, 4, 6, 8, and 10 are illustrated in figures 38-41.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B31

Figure 38. Photograph of polished surface of 

core from Shafer No. 1 core, depth 2,655 ft (809.2 

m), illustrating sharp contact (arrow) between finely laminated anhydrite at base of interbeds at base 

of cycle 4 and underlying halite bed at top of cycle 

5. Location of core shown in figure 3.

The locations of the photographic figures in the Cane Creek 

core are indicated by arrows in figure 2, those in the Shafer 

core in figure 3.

Figure 39. Photograph of polished surface of core from 

Shafer No. 1 core, depth 3,303 ft (1,006.7 m), illustrating sharp 

contact (arrow) between finely laminated anhydrite at base of 

interbeds at base of cycle 6 and underlying halite bed at top of 

cycle 7. Black areas within the halite are organic matter. Location of core shown in figure 3.

The gradational pseudomorphic zones of the upper contacts of interbeds in cycles 4, 5, 11, and 13 are illustrated in 

figures 42-45. In these upper contact zones, which are 1-3 ft 

(0.30-1 m) thick, anhydrite grades upward to halite with no 

sharply defined contact.

DETAILED CORRELATION OF CYCLE

3INTERBEDS BETWEEN CANE

CREEK NO. 1 AND SHAFER NO. 1

CORE HOLES

The degree to which correlations of lithologic units can 

be made between core holes is indicative of uniformity of 

deposition in a sedimentary basin. The lithology and texture 

of interbeds at the base of cycle 3 in both the Cane Creek and 

Shafer core holes are sufficiently distinct to make detailed 

correlation possible (fig. 5). These two core holes are about 

5 mi (8 km) apart. Although this is not a great distance in a
B32 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 40. Photograph of polished surface of core 

from Shafer No. 1 core, depth 3,528.5 ft (1,075.5 m), illustrating sharp contact (arrow) between layered anhydrite at base of interbeds at base of cycle 8 and 

underlying glassy halite in halite bed at top of cycle 9. 

Location of core shown in figure 3.

Figure 41. Photograph of segment of Shafer No. 1 core, depth 3,892 ft (1,186.3 m), illustrating sharp contact (arrow) between 

layered anhydrite at base of interbeds at base 

of cycle 10 and underlying halite bed at top of 

cycle 11. Location of core shown in figure 3.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B33

basin the size of the Paradox Basin, it is sufficient distance 

to require conditions of uniform deposition in this part of the 

basin through the time required for the accumulation of these 

interbeds. Thus, correlation of thin units over this distance 

indicates water that was deep enough that the bottom was not 

disturbed by waves and currents. Dense bottom brines would 

have also inhibited activity of burrowing organisms.

The base of the interbeds in both the Cane Creek and 

Shafer core holes is composed of finely laminated anhydrite 

(figs. 7 and 9 in the Cane Creek core and fig. 8 in the Shafer 

core). The laminated anhydrite grades upward into nodular 

anhydrite (figs. 9 and 10 in the Cane Creek core and figs. 11 

and 12 in the Shafer core). The nodular interval is thicker in 

the Cane Creek core than in the Shafer core. The overlying 

silty dolomite is about the same thickness in both holes. A 

very distinct thin black shale interval near the middle of the 

dolomite is somewhat thicker in the Cane Creek core than in 

the Shafer core. There are, however, no distinct correlatable 

units in the black shale. The silty dolomite above the black 

shale is about the same thickness in both core holes, but here 

too, there are no correlatable units.

The upper anhydrite has several distinctive lithologic 

units. The lowest unit in this regressive anhydrite is laminated but has small pseudomorphs after gypsum. This unit in 

the Cane Creek core is illustrated in figure 19 and in the Shafer core in figure 20. In both cores this unit is overlain by a 

thin interval that has thin, parallel laminations (fig. 21). 

Above the thin parallel laminations is a zone of very thin 

laminations that may be replacements of algal (stromatolitic) 

limestone (fig. 22). Overlying this unit is the zone of coarse 

pseudomorphs after gypsum that grades upward into the 

overlying halite bed. The coarse pseudomorphs are illustrated in figures 23 and 24 for the Cane Creek core and in figure 25 for the Schafer core.

Because of the similarity between interbeds of cycle 3 

and interbeds of the other cycles, it is not unreasonable to 

assume that conditions were similar during deposition of all 

of the cycles of the upper part of the Paradox Formation.

SEA-LEVEL CONTROL DURING 

EVAPORITE DEPOSITION

^ >, v

- TV

Peterson and Ohlen (1963) and Hite and Buckner 

(1981) attributed the cyclicity of the Paradox Basin 

evaporites to periodic changes in sea level in response to 

advance and retreat of glaciers in Gondwanaland during 

Pennsylvanian time. Interglacial melting would cause a rise 

in sea level that would increase water depths in the shelf

Figure 42 (facing column). Photograph of segment of Cane 

Creek No. 1 core, depth 2,640.5 ft (804.8 m), illustrating coarse 

pseudomorphic texture of anhydrite and halite after gypsum at top 

of interbeds in cycle 4. Location of core shown in figure 2.
B34 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

Figure 43. Photograph of polished surface of core from 

Shafer No. 1 core, depth 2,869.5 ft (874.6 m), illustrating 

coarse pseudomorphic texture of anhydrite and halite after 

gypsum at top of interbeds in cycle 5. Location of core 

shown in figure 3.

'if

sir

,/

areas of the Paradox Basin resulting in an increase in circulation and a lowering of salinity of the basin waters. This 

freshening of the basin brines would cause dissolution of the 

upper layers of previously deposited halite and produce a 

disconformity onto which the overlying anhydrite of succeeding cycles was deposited. The buildup of Gondwanaland glaciers would have caused a lowering of sea level that

Figure 44. Photograph of polished 

surface of core from Shafer No. 1 core, 

depth 3,919.5 ft (1,194.7 m), illustrating coarse pseudomorphic texture of 

anhydrite and halite after gypsum at 

top of interbeds in cycle 11. Location 

of core shown in figure 3.
EVAPORITE CYCLES IN THE PARADOX FORMATION, UTAH AND COLORADO B35

Figure 45. Photograph of polished surface of core from Shafer 

No. 1 core, depth 4,149.5 ft (1,264.8 m), illustrating coarse pseudomorphic texture of anhydrite and halite after gypsum at top of interbeds in cycle 13. Location of core shown in figure 3.

would restrict circulation in the Paradox Basin, causing a rise 

in salinity of the basin brines and the deposition of a 

sequence of precipitates of increasing salinity. It is possible 

that the evaporite cycles of the Paradox Basin, which probably formed in response to the Gondwanaland glacial cycles, 

could be correlated with the numerous Pennsylvania 

cyclothems of the Midcontinent region of the United States.

SUMMARY OF EVIDENCE FOR

ENVIRONMENTS OF DEPOSITION OF

EVAPORITES IN THE

PARADOX BASIN

In the foregoing discussion several lines of evidence 

indicate (1) that evaporites of the Paradox Basin were deposited in a silled basin in which the sill was a broad, shallow 

shelf along the northwest, west, south, and southeast sides of 

the basin and (2) that the northeast side of the basin was 

bounded by the Uncompahgre Uplift, which was probably a 

prominent range of mountains during Desmoinesian time. 

The basin had probably become quite deep prior the deposition of the first evaporites. Further work is needed to determine the rates of tectonic subsidence of the basin, the depth 

of the basin at the time of first evaporite deposition, and the 

rates of evaporite deposition as compared with the rates of 

basin subsidence.

The following criteria indicate that the evaporites of the 

Paradox Basin were deposited subaqueously in a brine-filled 

basin.

1. Concentric distribution of rock types indicates a normal basin configuration for the Paradox Basin. Rock types 

having the highest solubility are concentrated in the deepest 

and most restricted part of the basin, whereas those having 

the lowest solubility are most widespread (fig. 1) (unpublished data). This lithologic distribution, along with characteristics listed below, indicates a regular distribution of 

brines of differing salinity within the basin (Kite and Buckner, 1981) that would require a dynamic evaporation and circulation system in a basin containing a large volume of 

brine.

2. Halite crystals in snow-on-the-roof textures are 

interpreted to be the result of basin bottom growth; anhydrite 

(gypsum) precipitated in the overlying brine and then rained 

down onto the halite. Both aspects of this interpretation 

require a standing body of brine.

3. The progressive increase in thickness of halite in the 

halite-anhydrite couplets of many of the halite beds is best 

explained by a progressive change in the chemistry of the 

brines in the basin that resulted in an increasing precipitation 

rate of the halite. For such a mechanism, the basin had to 

contain a relatively large volume of brine.

4. Progressively cleaner halite from bottom to top of a 

halite bed probably resulted from the dilution effect of
B36 EVOLUTION OF SEDIMENTARY BASINS PARADOX BASIN

progressively more rapid precipitation of halite from bottom 

to top that would have incorporated less anhydrite and 

organic matter during deposition.

5. Bromine profiles for halite beds of the Paradox Formation (Raup, 1966; Raup and Hite, 1978; Hite, 1983) indicate essentially continuous deposition. Because of the 

inferred rapid rates of halite precipitation, each of the halite 

beds, or perhaps a series of halite beds, must have been 

deposited in a deep basin from a relatively large volume of 

brine (Borchert and Muir, 1964; Wardlaw and Schwerdtner, 

1966).

6. Correlatability of thin stratigraphic units over large 

distances has been accepted in other areas as good evidence 

for relatively deep basin deposition. The two core holes presented in this study are 5 mi (8 km) apart, and they have several small units that can be correlated with confidence. 

Although this distance is not as great as some of the distances over which correlations have been made in the Zechstein Basin of Germany or in the Delaware Basin of Texas 

and New Mexico, it is, nevertheless, a greater distance than 

correlations could be expected in shallow-water or sabkha 

environments.

7. The consistent presence of pseudomorphs of halite 

and anhydrite after gypsum at the top of each of the interbeds 

indicates the regular cyclic recurrence of some mechanism 

that would most likely occur in a basin with a large volume 

of brine.

8. Generally gradational contacts between all rock 

types within each cycle and unconformities between cycles 

indicate a recurring sequence of sedimentation that is probably controlled by dynamics within the basin brines.

9. On the negative side, the lack of mudcracks, ripple 

marks, or other indicators of desiccation in the Paradox 

evaporites within the basin indicates a lack of shallow-water 

or subaerial conditions within the basin margins.

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Borchert, Hermann, and Muir, R.O., 1964, Salt deposits: New York, D. Van 

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Published in the Central Region, Denver, Colorado 

Manuscript approved for publication March 6, 1992.

ir U.S. GOVERNMENT PRINTING OFFICE: 1992-673-049/66005