9

6

7

8

5

4

3 2

1

UTAH

ARIZONA

Cortez

Durango

MONTEZUMA CO. LA PLATA CO.

Pagosa Springs

ARCHULETA CO.

RIO ARRIBA CO.

CIBOLA CO.

SANDOVAL CO.

BERNALILLO CO.

SAN JUAN CO.

MCKINLEY CO.

Farmington

Cuba

Grants

Gallup

Albuquerque

Transverse Mercator Projection

HINSDALE CO.

MINERAL CO.

RIO

GRANDE

CO.

SAN JUAN CO.

APACHE CO.

CONEJOS

CO.

30'

109o

30' 108o

30' 107o 30'

30'

37o

30'

36o

30'

35o

30'

109o 30'

108o

30' 107o 30'

35o

30'

36o

30'

37o

30'

HOGBACK FAULT

SYSTEM

FOUR CORNERS 

PLATFORM AREA

U.S. GEOLOGICAL SURVEY 

GEOLOGIC INVESTIGATIONS SERIES

Dulce

Chama

U

D

U

U

D

D

D

D

D

D

U

U U

U

U D

D

D

U

U

U

D

D

U

U

U

U

U U

U

U U D

D

D

D D

D

D

D

D

D

U

U

COLORADO

NEW MEXICO

20 W 19

18 17 16 15 14 13 12

11

10 9 8 7 6

5 43

2 1/2

2 1 W 1 E 2

3

4

32 S

33

33 1/2

34

35

36

37

37

35

34

33

32 S

25 26 E

22 23 24

43 S

42

41

40

39

38

27 E 28 29 30

29 30

27 E 28 29 30 31

19 N

20

21

22

23

24

25

26

39

38

37

41

7

6

4

3

2

1 N

9 8 7 6 5

21 20 W 19 18 17 16 15 14

13

12 11 10 9 8

7

6

5

4 3 2 1 W 1 E

2 34

32 N

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32 N

APPROXIMATE LOCATION

OF THE DAKOTA FORMATION

OUTCROP

Nacimiento Fault

( Baltz, 1967 )

MAP SHOWING INFERRED AND MAPPED BASEMENT FAULTS, SAN JUAN BASIN AND VICINITY, NEW MEXICO AND COLORADO

David J. Taylor and A. Curtis Huffman, Jr.

1998

By

U.S. DEPARTMENT OF THE INTERIOR

Scale 1:500,000

10 0 10 20 30 Miles

10 0 10 20 30 40 Kilometers

APPROXIMATE LOCATION

OF THE DAKOTA FORMATION

OUTCROP

APPROXIMATE LOCATION

OF THE DAKOTA FORMATION

OUTCROP

Outline of the Dakota Formation from Huffman (1987).

Manuscript approved for publication April 9, 1998

Any use of trade names in this publication is for

descriptive purposes only and does not imply

endorsement by the U.S. Geological Survey

For sale by U.S. Geological Survey Information Services

Box 25286, Federal Center, Denver, CO 80225

Fault — Approximately located

Fault — Inferred

Thrust fault — Approximately located;

D, downthrown side; U, upthrown side

Thrust fault — Mapped;

D, downthrown side; U, upthrown side

Seismic line

Referenced deep well

State boundary

County boundary

EXPLANATION

9

U

D

D

U

36

GEOLOGIC SUMMARY

INTRODUCTION

Interpretation of more than 1,100 mi (1,750 km) of seismic reflection data in the San 

Juan Basin and vicinity allowed us to map a large number of faults that have 

measurable offset at the top of the Proterozoic crystalline basement. Predominant fault 

trends are N. 60o–70o W. and N. 30o–40o E. with a typical spacing of 4–10 mi (6–16 

km). The orthogonal pattern was established in the Precambrian, but episodic 

movements in the late Paleozoic, Mesozoic, and Cenozoic have been measured by the 

authors on a number of the faults. Periods of significant movement correspond to 

recognized orogenic events, particularly the Pennsylvanian to Permian Ancestral Rocky 

Mountain orogeny and the early Tertiary Laramide orogeny.

The seismic data set available to the authors is composed of long regional lines and 

shorter lines used for oil and gas prospect evaluation. All lines of the data were shot 

conventionally as two-dimensional surveys between 1969 and 1983, most utilizing 

dynamite as the source. Data were purchased from Bass Enterprises Production Co., 

Dome Petroleum Co., El Paso Natural Gas Co., Northwest Exploration Co., and 

Tenneco Oil Co. and were borrowed from Amoco Production Co., Maxus Exploration 

Co., Meridian Oil Co., and the Ute Mountain Ute Tribe (Wintershall Oil Co.). In 

addition, two small seismic surveys were shot by the U.S. Geological Survey over 

uranium deposits in the southwestern part of the study area. With the exception of the 

USGS data, all lines and shot points are proprietary.

METHODS

Generally, data quality was adequate to resolve subsurface structure on a coarse 

regional scale but not on a smaller detailed exploration-oriented scale. Digital field data 

were obtained for a limited number of lines, allowing for some reprocessing using 

newer and more advanced techniques. This resulted in better definition of the faults 

with more detail, but little or no change in the overall pattern or interpretation. The 

basement reflector was identified by generating synthetic seismograms from a number 

of key wells (located on the map and described below) that penetrated basement rocks. 

Where available, sonic and formation density logs were used, but because these logs 

were not run on many of the wells, some of the synthetic seismograms were generated 

from pseudo sonic logs derived from resistivity logs. For a description of this technique 

see Peterson and others (1955).

In order to construct the map, fault intercepts at the basement reflector were plotted on 

a basin shot-point map. Each of the faults was annotated as to style and direction of 

motion as observed at the basement level. Only those faults having observable seismic 

time offset are shown on the map, and all faults were plotted as straight line segments. 

These ground rules were adopted in order to provide a manageable framework for the 

almost limitless number of possible interpretations

Geologic mapping around the basin margins (for example, Goddard, 1966; Baltz, 

1967; Santos, 1970; Thaden and Zech, 1984; Condon, 1990; Thaden, 1990) indicates 

that the predominant fault directions throughout the section are northeast and northwest 

with some north-south and east-west. We began our interpretation and correlations in 

the areas of greatest data density with this general pattern in mind but also tried a 

number of other orientations. The data fit the northwest-southeast and northeastsouthwest pattern better than any other. The blocks defined by the orthorhombic fault 

pattern are similar in size and orientation to those mapped on the Four Corners platform 

by Stevenson and Baars (1986), and the density of faulting is comparable to that around 

the margins of the basin compiled by Thaden and Zech (1984).

DISCUSSION

Several aspects of the fault pattern and density should be noted: (1) there is an 

apparent clockwise rotation of fault trends from east to west across the basin (for 

example from about N. 28o E. near Cuba to about N. 38o E. west of Farmington), which 

continues beyond the hogback fault into the Paradox Basin to the west and may be 

partly explained by Laramide rotation of the Colorado Plateau (Hamilton, 1988); (2) in 

the southeast part of the basin more of the predominant through-going faults appear to 

be northwest-trending whereas in the northwest the northeast-trending set appears to be 

more common; and (3) there is an apparent increase in the density of faulting west of 

the Hogback fault system. None of these observations is unambiguous, since the quality 

and density of data vary significantly across the area, but taken together they suggest 

that the Precambrian basement of the San Juan Basin might be divided into several 

structural domains.

Proterozoic reconstructions of southwestern North America indicate that the boundary 

between the Yavapai (1.75–1.70 Ga) and Mazatsal (1.66–1.60 Ga) Provinces trends 

northeastward across the San Juan Basin (Bowring and Karlstrom, 1990; Condie, 1992; 

Karlstrom and Daniel, 1993). Baars and Stevenson (1982) proposed a north-south 

principle stress, dated at 1.60 Ga by Baars and Ellingson (1984), to produce the 

observed fault pattern of the San Juan Basin. This would correspond generally with the 

Mazatsal orogeny (Karlstrom and Daniel, 1993). Northwest of the boundary 

(northwestern San Juan Basin and Paradox Basin) the fracture pattern would probably 

have originated in the Yavapai orogeny (1.74–1.69 Ga) under a slightly different stress 

regime.

During the Phanerozoic the large number of blocks in the San Juan Basin may have 

moved individually relative to each other, as discussed by Stevenson and Baars (1977) 

and Baars and Stevenson (1982); together as larger blocks as documented by Baltz 

(1967); or as some combination of the two as suggested by Huffman and Condon 

(1993). Fault activity related primarily to either uplift or extension would result in 

mostly normal faulting and vertical movement of the blocks, with or without tilting, 

relative to each other. Compression would likely produce mostly reverse faulting and 

some amount of rotation of the blocks, particularly if the compressive stress was oblique 

to the bounding faults. Any shear stress associated with extension or compression 

would increase the likelihood of block rotation. Because the basin has been subjected to 

a wide variety of stress fields since the Precambrian, it is likely that the blocks would 

have moved a number of times in a variety of directions relative to each other. The 

movement on any one fault at a particular time is determined by its orientation in the 

stress field of the time so that the present pattern is a result of many periods of 

movement and care must be taken in interpreting it.

DEEP WELLS USED

The following deep wells were used to generate synthetic seismograms. The numbers 

on the map correspond to the numbered wells listed.

1. Stanolind Oil Co. 6. Tidewater

Hover No. 1 Mariano Dome

Total Depth 10,800 ft Total Depth 4,708 ft

Sec. 23, T. 30 N., R. 16 W. Sec. 8, T. 15 N., R. 13 W.

2. Stanolind Oil Co. 7. Great Western Drilling

USG No. 13 No. 1 Hospah

Total Depth 7,440 ft Total Depth 7,852 ft

Sec. 19, T. 29 N., R. 16 W. Sec. 1, T. 17 N., R. 9 W.

3. Pure Oil Co. 8. Sun Oil Co.

Navajo No. 1 New Mexico State No. 1

Total Depth 11,148 ft Total Depth 10,572 ft

Sec. 18, T. 29 N., R. 15 W. Sec. 16, T. 20 N., R. 6 W.

4. Pan American Oil Co. 9. Pan American Oil Co.

No. 1 Gulf Navajo “C” USA No. 1

Total Depth 10,108 ft Total Depth 10,428 ft

Sec. 4, T. 25 N., R. 16 W. Sec. 17, T. 20 N., R. 3 W.

5. Shell Oil Co.

No. 113-17 “Carson Unit”

Total Depth 11,445 ft

 Sec. 17, T. 25 N., R. 11 W.

REFERENCES CITED

Baars, D.L., and Ellingson, G.M., 1984, Geology of the Western San Juan Mountains, 

in Brew, D.C., ed., Rocky Mountain Section, 37th annual meeting, Durango,

Colorado, Guidebook for field trips: Geological Society of America, p. 1–45.

Baars, D.L., and Stevenson, G.M., 1982, Subtle stratigraphic traps in Paleozoic rocks of

 Paradox Basin, in Halbouty, M., ed., Deliberate search for the subtle trap: American

 Association of Petroleum Geologists Memoir 32, p. 131–158.

Baltz, E.H., 1967, Stratigraphic and regional tectonic implications of part of Upper 

Cretaceous and Tertiary rocks, east-central San Juan Basin, New Mexico: U.S. 

Geological Survey Professional Paper 552, 101 p.

Bowring, S.A., and Karlstrom, K.E., 1990, Growth stabilization and reactivation of 

Proterozoic lithosphere in the southwestern United States: Geology, v. 18, no. 12, p. 

1203–1206.

Condie, K.C., 1992, Proterozoic terranes and continental accretion in southwestern 

North America, in Condie, K.C., ed., Proterozoic crustal evolution: Amsterdam, 

Elsevier Science Publishers, p. 447–480.

Condon, S.M., 1990, Geologic and structure contour map of the Southern Ute Indian 

Reservation and adjacent areas, southwest Colorado and northwest New Mexico: 

U.S. Geological Survey Miscellaneous Investigations Series Map I–1958, scale 

1:100,000.

Goddard, E.N., 1966, Geologic map and sections of the Zuni Mountains fluorspar 

district, Valencia County, New Mexico: U.S. Geological Survey Miscellaneous 

Geologic Investigations Map I–454, scale 1:31,680.

Hamilton, W.B., 1988, Laramide crustal shortening, in Perry, W.J., and Schmidt, C.J., 

eds., Interaction of the Rocky Mountain foreland and Cordilleran thrust belt: 

Geological Society of America Memoir 171, p. 27–39.

Huffman, A.C., Jr., 1987, Petroleum geology and hydrocarbon plays of the San Juan 

Basin petroleum province: U.S. Geological Survey Open-File Report 87–450–B, 67 

p. 

Huffman, A.C., Jr., and Condon, S.M., 1993, Stratigraphic, structure, and 

paleogeography of Pennsylvanian and Permian rocks, San Juan Basin and adjacent 

areas, Arizona, Colorado, New Mexico, and Utah: U.S. Geological Survey Bulletin 

1808–O, 44 p.

Karlstrom, K.E., and Daniel, C.G., 1993, Restoration of Laramide right-lateral strike 

slip in northern New Mexico by using Proterozoic piercing points—Tectonic 

implications from the Proterozoic to the Cenozoic: Geology, v. 21, no. 12, p. 1139– 

1142.

Peterson, R.A., Fillipone, W.R., and Coker, F.B., 1955, The synthesis of seismograms 

from well log data: Geophysics, v. 20, no. 4, p. 516–638.

Santos, E.S., 1970, Stratigraphy of the Morrison Formation and structure of Ambrosia 

Lake district, New Mexico: U.S. Geological Survey Bulletin 1271–E, 30 p.

Stevenson, G.M., and Baars, D.L., 1977, Pre-Carboniferous paleotectonics of the San 

Juan Basin, in Fassett, J.E., ed., San Juan Basin III, northwestern New Mexico: 

New Mexico Geological Society 28th Field Conference Guidebook, p. 99–110.

Stevenson, G.M., and Baars, D.L., 1986, Paradox—A pull apart basin of Pennsylvanian 

age, in Peterson, J.A., ed., Paleotectonics and sedimentation: American Association 

of Petroleum Geologists Memoir 41, p. 513–539.

Thaden, R.E., 1990, Geologic map of the Window Rock quadrangle, Apache County, 

Arizona, and McKinley County, New Mexico: U.S. Geological Survey Geologic 

Quadrangle Map GQ–1647, scale 1:24,000.

Thaden, R.E., and Zech, R.S., 1984, Preliminary structure contour map on the base of 

Cretaceous Dakota Sandstone in the San Juan Basin and vicinity, New Mexico: 

U.S. Geological Survey Miscellaneous Field Studies Map MF–1673, scale 

1:500,000.

Base compiled from U.S. Geological Survey 1:250,000

Albuquerque (1963), Aztec (1961), Cortez (1969), 

Durango (1945), Gallup (1970), Shiprock (1969) 

Land grid compiled from U.S. Geological Survey State

Maps at 1:1,000,000 scale for Arizona (1974), Colorado

(1969), New Mexico (1985), Utah (1976). 

I–2641