23

CANDOR

CHASMA

Candor Colles

C e t i

L a b e s

Fault Zone III

Fault Zone III

Fault Zone II

Fault Zone I

2

9

7

7

6

4

1

9

7

3

7

8

7

7

3

9 9

7

7

3

4 5

5 7

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9

7

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6

9

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8

8

6

5 3

7

8

3

6

9

8

9

3

3

8

3 5

3

5

7

5

5

9

7

7

5

3

9

5

7 9

8 6

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6

9

3

8

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5

3

3

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3

8

5

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5

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5

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9 6

4

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5

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5

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3

6 4

5

9 6

5

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9

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6

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9

3

7

6

8

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8

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5

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4

7

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5

5

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8

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7

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8

6

6

4

6

3

7

5

9

2

5

5 2

9

5

8

4

4

4

7 5

9

3 8

2

5

3

2

6

2

5

9

8

7

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8

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7

8

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5 8

7

9

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5

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3

9

8

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3 8 7

8

9

7

8

8

8 9 9 8

8

9

8

7

7

8

7

20

18

12

19

19

28

21

15

11 24

16

16

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10

24

21

13

16

14

17

14

25

23

26

11

10

29

16

19

21

27

13

17

22

24

13

12

12

21

28

36

28

18

20

23

15

20

11

13

12

16

11

18

23

10

37

11 14

36

32

28 21 54

10

18

31 34

14

11

20

34

10

16 25 23

43

15

35

31

20

38

21

14

25

13

22

20

38

11

18 51

49 12

17

17

22

34

33

22

11

16

31

25

19

18

28

16

13

13

63

20

13

12 13

31

25

14

21

17

12

38 12

36

32

29 11

19

14

16

12

13 18

15

15

24

20

15

16

13

11

21

11

18

18

12

17

14

14

19

21

10

12

10

15 20

10 18

10

12

11

11

11

10

10

10

11

15

19

16

22 13

10

12

20

23

24

13

19

22

18

12

10

12

10

11

13

11

10

11

15

21

35

21

11 10

12

12

15

16

12 12

10

12

11

11

10

15

11

12

13

13

12

11

13

13

44

16

22

12

14

16

22

11

11

12

14

15

12

12

20

10

13

11 14

23

24 13

12 13 15

11

12

21

16

19 21

26

14

18

22

11

11

17

11

20

19

21

12

20 22

15

12

16

18

23

14

13

24

10

18

20

24

11

13

28

23

23

11

16

14 15

15

14

25

11

16

11

10

14

25

12

24

16

22

15

11

10

12

23

22

13 18

24 16

21

11

10

17 10 15

15

15

13

12

16

22

29 11 12

15

17 11

11

22

18

48

37

17

22 21 54

65 40

20

22

76

41

12

31

31

12

16

19

32

37 7

14

56

17

68

35

31

26

20 24

27

23

25 29

14

16

17

18

16

14

28

23 23

14

53

35 14 36 38

42

45

59

41

29

38

23

33

53 44

40

39

58

42

43

37

29

41

32

27

48

48

40

45

32 14

14 32

47

55

45

82

32

49

50

40

36

51

21 34

27

15

10

70

22

17 51 36

25

57

38

45

61

18

22

42

52

18

52

40

52

32

29

31

42

30

37

32

39

40

29

26 27

18

51

31

35

35 31

36

40

62

43 28

27

35

58

66

73

38

18

33

33

40

33

25

17

40

43

23

19

33

18

30

57

46

47

62

26

21

19

27

54

26

29

49

42

23

42

31

25

53

44

33

45

49

64 24

34

31 12

74

63

11

32

19

12

16

34

20

19

13

29

24

10

40

25

19

54

45

27

62

27 50

60

57

26

27

75

60

36

21 46

72

64

73

15

24 14

59 65 73 71

77

76

13

15

23

33

35

9

9

8

9

6

8

4

7

59

12

17

14

35

30

25

37

18

19

19

11

19

17 23

39

13

19

15

16

31

CaC

CaC

CaC

CaC

CaC

CeMk

CeMk

CeL

CeL

CeL

ld

ld

CeL

CeL

cf

CeMk

CeMk

cf

A'

A

284.24°E

284.22°E

284.20°E

284.18°E

284.26°E

284.28°E

284.24°E

284.22°E

6.56°S

6.58°S

6.52°S

6.54°S

6.60°S

6.62°S

6.64°S

6.66°S

6.68°S

6.70°S

6.72°S

6.74°S

6.76°S

6.78°S

6.80°S

6.82°S

6.84°S

6.52°S

6.54°S

6.56°S

6.58°S

6.50°S

6.60°S

6.62°S

6.64°S

6.66°S

6.68°S

6.70°S

6.72°S

6.74°S

6.76°S

6.78°S

6.80°S

6.82°S

6.84°S

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

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3309/

Suggested citation: Okubo, C.H., 2014, Bedrock geologic and structural map through the 

western Candor Colles region of Mars: U.S. Geological Survey Scientific Investigations 

Map 3309, pamphlet 8 p., scale 1:18,000, http://dx.doi.org/10.3133/sim3309. Printed on recycled paper

Bedrock Geologic and Structural Map Through the 

Western Candor Colles Region of Mars

By

Chris H. Okubo

2014

Prepared for the

National Aeronautics and Space Administration

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3309

Pamphlet accompanies map

ISSN 2329-1311 (print)

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3309

SCALE 1:18 000

TRANSVERSE MERCATOR PROJECTION

Planetocentric latitude and east longitude coordinate system

1000 500 0 1000 METERS

Prepared on behalf of the Planetary Geology and Geophysics 

Program, Solar System Exploration Division, Office of Space 

Science, National Aeronautics and Space Administration

Edited by Kate Jacques; digital cartography by Kathryn Nimz

Manuscript approved for publication September 2, 2014

Descriptions of nomenclature used on map are listed at 

http://planetarynames.wr.usgs.gov/

MC–19

MC–3

MC–4 MC–5

MC–6

MC–10 MC–11 MC–12 MC–13

MC–1

MC–18 MC–20 MC–21

MC–25

MC–26 MC–27

MC–28

MC–30

MAP LOCATION

Photomosaic showing location of map area 

(in red). An outline of 1:5,000,000-scale 

quadrangles is provided for reference.

300°

300°

60°

60°

0°

30°

65°

270° 315° 0° 45° 90°

–30°

–65°

0°

30°

65°

–30°

–65°

Contact—Unconformity that bounds an allostratigraphic unit. 

Dashed where approximately located; dotted where concealed

Internal unconformable contact—Disconformity, paraconformity 

or angular unconformity located within an allostratigraphic unit. 

Long-dashed where approximately located; short-dashed where 

inferred; dotted where concealed

Faults

Normal fault—Showing dip. Ball and bar on downthrown block

Thrust fault—Showing dip. Sawteeth on upper (tectonically 

higher) plate

Fault—Breccia zone or zone of broken rock around fault

Fracture—Showing dip. Long-dashed where approximately located; 

short-dashed where inferred; dotted where concealed. Queried 

where identity or existence questionable

Unmapped fracture dip —Fractures too dense to show at map 

scale 

Folds—Dashed where approximately located

Anticline—Identity and existence certain

Doubly plunging anticline

Syncline

Plunging syncline—Showing direction of plunge

Small, minor dome

Landslide Features

Head or main scarp—Inactive, subdued, indistinct, and (or) 

approximately located. Hachures point downscarp

Internal or minor scarp (distinct)—Showing dip. Inactive, 

sharp, and accurately located. Hachures point down scarp

Internal or minor scarp (indistinct)—Showing dip. Inactive, 

subdued, and approximately located. Hachures point down 

scarp

Main toe—Inactive, subdued, indistinct, and (or) approximately 

located. Sawteeth on overiding block

Tension crack or fracture

Direction of downslope movement

Inclined bedding—Showing strike and dip

Unconformity orientations—Showing strike and dip

75

25

40

36

49

18

18

39

Ceti Mensa knobby unit—Forms irregularly shaped knobs. 

Layer surfaces appear even to curved and parallel; numerous 

unconformities. Occurs at elevations above approximately 

-100 m. Buries units CaC and CeL. Unit has moderate albedo

Candor Colles unit—Forms stair-stepped morphology where 

layers exist in upper section of unit; forms broad slopes in 

lower sections. Consists of low, conical hills and semicircular mesas of Candor Colles. Layer surfaces appear even 

to curved and parallel; numerous unconformities in lower 

sections. Occurs at elevations between ~720 m and –300 m. 

Buries unit CeL. Unit has moderate albedo

Unit traceable westward toward summit of Ceti Mensa. Entire 

thickness of unit not exposed within map area; only lowermost ~1 km section of unit exposed. Layers discontinuous 

owing to numerous unconformities. Unit drapes underlying 

topography and, where thin, may mimic meter-scale patterns, 

or ghost patterns, of underlying topography. Equivalent to 

youngest layers in structural maps of Okubo and others 

(2008) and Okubo (2010). Composed of hydrated sulfates 

(Murchie and others, 2009a).

Top and bottom of unit defined by prominent unconformities. 

Unit ~1 km thick within map area. Uppermost ~650 m of unit 

has continuous layers traceable over multiple kilometers; 

stratigraphically lower layers discontinuous owing to numerous unconformities. Contains numerous fault and fracture 

traces, and linear ridges >1 km in length; ridges unconformably overlain by unit CeMk outside of map area (observed in 

adjacent HiRISE data). Local contorted bedding present 

throughout. Most hills of Candor Colles cored by massive 

material. Unit drapes underlying topography and, where thin, 

may mimic meter-scale patterns of underlying topography. 

Equivalent to oldest layers in structural maps of Okubo and 

others (2008) and Okubo (2010). Composed of hydrated 

sulfates (Murchie and others, 2009a).

Layered sediments formed through regional deposition and 

mantling of pre-existing topography, accompanied by 

episodic erosion and renewed deposition. Early deposition 

preserved primary landslide textures of underlying unit CeL, 

implying low energy environment.

Layered sediments formed through regional deposition and 

mantling of pre-existing topography, accompanied by 

episodic erosion and renewed deposition. Erosion negligible 

during formation of youngest layers. Early deposition 

preserved primary landslide textures of underlying unit CeL, 

implying low energy environment. Kilometer-scale ridges 

consist of fault-related damage zones. Candor Colles reflect 

erosional remnants of injectite megapipes; together with 

contorted bedding indicates soft-sediment deformation 

induced by seismicity; indicates water saturated and nonindurated state of sediments during seismicity. Numerous 

faults within unit represent potential seismic sources

Unit Name and Definition

Chasma foothill unit—Forms smooth-lying material with 

occasional meter-scale boulders. Unit has low albedo

Lobate deposit unit—Forms small deposit with lobate 

margins. Contains ridged material with occasional 

meter-scale boulders. Buries unit CeL, coeval with unit cf. 

Unit has low albedo

Ceti Labes unit—Forms low, broad hills covered by parallel 

ridges and grooves; includes hummocky terrain adjacent to 

south wall of west Candor Chasma. Makes up Ceti Labes. 

Layering not apparent. Oldest unit in map area. Unit has low 

albedo

Additional Characteristics

Covers lower slopes of south wall of west Candor Chasma

Occurs in single deposit in southwest part of map area. Entire 

deposit sinuous in map view in CTX data

Top of unit defined by prominent unconformity in some 

places; unconformity buried or partially obscured elsewhere; 

entire thickness of unit not exposed within map area. 

Scattered ~10- to 100-m-diameter mounds of moderate 

albedo material on surface

Interpretation

Colluvium and other sediments derived from 

southern wall of west Candor Chasma

Debris flow deposit originating from south wall of Candor 

Chasma. Age unconstrained other than being younger than 

Candor Colles unit (CaC)

One or more landslides from southern wall of west Candor 

Chasma; hummocky terrain in southern part of unit represents 

landslide head region. Low, broad hills in northern part of 

unit reflects landslide toes; indicates that local floor of 

chasma at time of landsliding at similar elevation as 

present-day

DESCRIPTION OF MAP UNITS

WALL MATERIAL

EXPLANATION OF MAP SYMBOLS

Unit

Label

LAYERED MATERIAL

cf

ld

CeL

CeMk

CaC

CORRELATION OF MAP UNITS AND

NON-DEPOSITIONAL EVENTS

CaC

CeMk

LAYERED

MATERIAL

Erosion into unit CeMk and exposure of underlying units 

CaC and CeL

Episodic erosion contemporaneous with deposition of unit 

CeMk

Episodic erosion contemporaneous with deposition of the 

oldest layers of unit CaC

Formation of west Candor Chasma

Erosion into unit CaC and exposure of underlying unit CeL

Contemporaneous formation of Fault Zones I through IV 

and Candor Colles

NON-DEPOSITIONAL EVENTS

ld

post-CaC

cf

CeL

WALL

MATERIAL

episodic

deposits

0 100 METERS

Massive core

Massive

core

A B

0 100 METERS

6.64°S

6.65°S

284.29°E 284.30°E

6.64°S

6.65°S

284.29°E 284.30°E

Figure 7. Image data (A) and annotated features (B) of a group of colles along Fault Zone I. While most colles exhibit a core of massive rock, some appear as domes of contorted layers, as shown by the collis in 

the lower left corner of this image. See Explanation of Map Symbols for feature descriptions. 

Injectite

megapipes

(Candor Colles)

Landslide

(Ceti Labes)

Translational slide

CaC

cf

CeL CaC

Wallrock

(not mapped)

CeMk

CeMk CeMk

Contorted

bedding

A A′

?

?

?

0

1

2

0

1

2

0 5 10

KILOMETERS

15 20 

KILOMETERS KILOMETERS

Figure 6. Cross section A–A′ showing the interpreted subsurface structure based on measured orientations of bedding, unit contacts, and faults. The wall rock composing the south wall of west Candor 

Chasma crops out just outside of the map area and was not mapped. The wall rock is included here to show its location relative to cross section A–A′. No vertical exaggeration.

284.11°E 284.12°E 284.13°E 284.14°E 284.15°E

6.59°S

6.56°S

6.57°S

6.58°S

CeMk

CaC FAULT ZONE IV

0 500 METERS

Figure 5. Contact between units CeMk, CaC, and Fault Zone IV. Locale is 

outside of the map area (see fig. 1) but provides a key constraint on the relative 

timing between these three mapped features. From HiRISE observation 

ESP_022699_1735. See Explanation of Map Symbols for feature descriptions.

5

7 9

8 6

7

9

8

7

5

3

3

7

3

8

5

4

5

6

5

5

9

10

15

20

10

18

10

12

49

57

Massive

core 6.66°S

6.67°S

284.21°E 284.22°E 284.23°E

6.66°S

6.67°S

284.21°E 284.22°E 284.23°E

A B

0 100 METERS 0 100 METERS

Figure 4. Image data (A) and mapped structure and topographic contours (B) of an isolated collis within the map area. The core of this colles is indicated in tan. The cores of many colles exhibit no clear 

bedding, breccia or other structure. Many of the surface textures of these core rocks appear to be erosional features in the full-resolution HiRISE data. See Explanation of Map Symbols for feature descriptions.

CaC

Contours—Layer orientations,

 2 percent intervals (n=297)

Unconformities (n=6) A B C

Unit CaC inner fault (n=26)

Unit CaC bounding fault (n=22)

Fault Zone III

Unit CaC layer orientation (n=18)

CeMk

Contours—Layer orientations,

 2 percent intervals (n=262)

Unconformities (n=22)

0 10 20 30 40 50

Percentage of data per

 1 percent plot area

Figure 3. Stereonet plots showing layer and fault orientations within map area. All stereonets are in identical lower hemisphere, equal area projections. A, Poles to faults within fault 

zone III, as well as poles to bedding in surrounding unit CaC as much as 0.5 km from the fault zone. B, Contours of poles to layer orientations from unit CaC overlaid with poles to 

unconformities from the same unit. C, Contours of poles to layer orientations from unit CeMk overlaid with poles to individual unconformities with measurable orientations from the 

same unit.

AREA OF MAP

FAULT ZONE I

FAULT ZONE I

FAULT ZONE II

FAULT ZONE II

FAULT ZONE III

FAULT ZONE III

FAULT ZONE IV

Candor Colles

6.7°S

6.6°S

284.1°E 284.2°E 284.3°E

C e t i L a b e s

Figure 5

Figure 4

Figure 7

0 1 KILOMETER

Figure 2. Overview of the western Candor Colles region. The most prominent colles are labeled as domes, with elongation directions indicated as appropriate. The extent of 

the map area in this region is shaded in pink – the map extends to the north and south of this figure. The location of fault zone IV and figure 5 relative to the map area is 

shown, as are the locations of figures 4 and 7. See Explanation of Map Symbols for feature descriptions.

ELEVATION

(km)

4 

2 

0

-2 

-4 

Ceti

Mensa

Ophir Chasma

Candor

Mensa

West Candor Chasma

282°E 283°E 284°E 285°E 286°E 287°E

7°S

4°S

5°S

6°S

X1

H6 H7

H5

H4

H3 H2

X4

X3

X2

Fig. 5

Candor Colles

-05077 -05072

H1

(AREA OF MAP)

Figure 1. Location of the map area and other geographic features in west Candor Chasma. Thumbnails of HiRISE images 

and footprints of CTX data used during mapping also shown. All HiRISE and CTX data are stereopairs, designated H1–H7 

and X1–X4, respectively. Observation IDs for these stereopairs are listed in tables 1 and 2 (in pamphlet). The map area of 

this publication corresponds to stereopair H1 and lies within the MTM–05072 quadrangle. The Candor Colles are located 

within the shaded area as indicated. Base map is colorized Mars Orbiter Laser Altimeter elevation data overlaid with 

THEMIS daytime visible imagery.