Petrographic and Kinematic Analysis of the Itombwe Synclinorium Formations Exposed at Tshondo and Bugoy (South-Kivu region, Democratic Republic of the Congo)

Petrographic and Kinematic Analysis of the Itombwe Synclinorium Formations Exposed at Tshondo and Bugoy (South-Kivu region, Democratic Republic of the Congo)

Aganze B. Gloire* Masirika M. Lucien Ganza B. Gloire Nandezo W. Robert

Department of Geology, Université Officielle de Bukavu, Bukavu, P.O. Box 570, DRC

Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen, P.O. Box 28759, Germany

Corresponding Author Email: 
a.baciyunjuze@jacobs-university.de
Page: 
104-113
|
DOI: 
https://doi.org/10.18280/eesrj.090304
Received: 
2 July 2022
|
Accepted: 
1 August 2022
|
Published: 
28 September 2022
| Citation

OPEN ACCESS

Abstract: 

The purpose of this study is to investigate the Itombwe synclinorium formations that were affected by the late Pan-African orogenesis in the nordeastern Congo. A variety of controversies surround Tshondo and Bugoy's tectonic evolution and associated metasedimentary formations. A field-based approach combined with paleostress inversion techniques and petrographic analyses were conducted on 190 structural measurements and 6 rock samples used in this study. The results reveal the presence of four major petrographic facies: conglomeratic facies (conglomerate and diamictite), carbonate facies (travertine), greenschist facies (graphitic black shale and pelite), as well as quatzitic facies (quartzite and sandstone). The mineral assemblages consisting of high contents (>70%) of muscovite/sericite and biotite albite, plagioclase, quartz, and some opaque minerals. With the assistance of Win-Tensor software, the kinematic analysis reveals two major deformation phases, (1) a ductile deformation phase (D1-2), which is associated with isoclinal folds and strike-slip faults, and (2) a submeridian brittle deformation phase (D2), which generated extensive faults trending NNW-SSE to NE-SW directions, while reactivating bedding surfaces (NE-SW) in a series of secondary faults. The findings of this research may assist geologists in conducting core logging operations and provide a baseline for understanding the relationship between rock, minerlization, and tectonics in mineral-rich areas.

Keywords: 

Pan-African orogeny, metasedimentary rocks, mineral paragenesis, deformation phases, paleostress, DRC

1. Introduction

The Itombwe synclinorium, often referred to as the Neoproterozoic belt, is one of the geological units in Kivu region [1]. This elongated folded structure lies within the range of Lake Kivu between its northern shore and the nord-western shore of Lake Tanganyika [2]. In the upper Kibaran, it consists of two lithological units: lower and upper Kadubu, which are separated by faults [3, 4]. The rock formations outcropping in these two units have been mapped in differnt places, including Tshondo, Bugoy, Nya-Kaziba, Kigogo, Kalama, and Madubwe. Tshondo and Bugoy belong to the upper Kadubu unit, which contains rocks of varying sizes including sandstone, conglomerates, granites, gneisses and schists [5]. These conglomerates, reminiscent of glacial deposits, are called mixitites or diamicites [6, 7].

The Itombwe synclinorium, dated between 1020 ± 50 and 575 ± 83 Ma abounds with a plethora of mineralization, the most important of which is gold and some rare metals (Figure 2). They derivve from an albitite dyke (970 Ma) in the Kasika granite [8, 9].

Recent Pan-African tectonic events have severely strained this belt [3, 10]. However, other deformation phases are still debated today. Additionally, the growing interest in Tshondo and Bugoy's economic potential also calls for a more detailed petrographic study, which is a source to a wealth of information during core logging in mineral exploration.

The interpretations of kinematic indicators within a paraconglomerate by Walemba et al. [6, 8], revealed a jusxtaposition of two crustal blocks associated with E-W compressive stresses,as well as large-scale dextral/sinistral shearing but, the exact kinematic reationship between these faulting system at tshondo and bugoy is still unclear.

Similary, Lefevère [4] used remote sensing data and image interpretations to understand the deformation in the two areas inverstigated. He noted the presence of concemtric lineaments that he interpreted as resulting from 2 compression systems, associated with lithology such as shales, sandstones, quartizites and conglomerates. However, a detailed in-situ survey is always crucial to confirm what may at times not be captured remotely. In recent years, not much has been updated in terms of knowledge. Among the reasons are the difficulty of field access, active rugged terrains, and the risk of slope failure, among others.

Thus, the results highlighted in this paper provide an update and complete the general petrographic and structural knowledge available in the Neoproterozoic belt of South-Kivu, while shedding new light the stress regimes and petrographic types in these areas using modern techniques.

The study areas are located the eastern part of the Democratic Republic of the Congo and cover a total area of ca. 4 km2. They are respectively bounded by longitudes 28.60°E and 28.75°E and latitudes -2.86°S and -2.92°S (Figure 1).

Figure 1. Location of the study areas and geology of the Itombwe synclinorium with its associated lithological units (modified from Villeneuve 1987)

Figure 2. The origin of mineral deposits in the Itombwe Synclinorium [2]

2. Methods

Over the course of one month, the two areas were mapped. Outcrop profiles were described on a macroscale. For each sampling station, the geographical coordinates were recorded. Fresh rock samples were collected, packed, and labelled for ex-situ analyses. A "Breithaupt-Kassel" compass was used to map linear and planar structures in the field. To make the interpretation of the data easier, the orientations were recorded in Dip/Dip direction format, then converted to Strike/Dip format. Thin-section microscopy was performed on 6 rock samples at the Geological Museum of Bukavu and optical observations were conducted at the Official University of Bukavu's mineralogical laboratory in plane-polarized and crossed-polarized light. FIJI (ImageJ) point counting software was used to calculate the mineral content of samples.

Structural measurements were computed using paleo stress inversion techniques in Win-tensor software 5.9.3, developed by Delvaux and Sperner [11], of which two methods are recognized: the classical R-Dihedron methods and the modern iterative Rotational Optimization Method [12, 13].

3. Results and Discussion

3.1 Petrographic analysis

Rock samples were described macroscopically based on factors such as mineralogical composition, color, structure, weathering rate, and behavior after being exposed to hydrochloric acid. In contrast, microscopic descriptions of minerals were based on characteristics like color, pleochroism, habit, cleavage, relief, and twining [14].

Figure 3. Conglomerate outcrop (a) and associated pebbles (b), used as retaining walls in the Rugenge mining quarry. Diamictite outcrop, also known as " paraconglomerate" (c). They are mostly found on the western slope of the Irongero River at Bugoy (d) and are believed to have been deposited during the latest Cryogenian glaciation (720-635 Ma)

Figure 4. Microphotographs of conglomerate and diamictite: microscopic observations in plane polarized light (a, c) and crossed polarized light (b, d). Both rocks show large content in quartz crystals and opaque minerals

3.1.1 Rocks with conglomerate facies

Conglomerate and diamictite. Both sides of the Kadubu and Kashwa rivers are covered in Congolomerates. It consists of colorless mono-crystalline quartz grains (50-60%) along with medium relief chlorite (Figure 4a), which polarizes into yellowish gray and bluish green (Figure 4b) in a brown--reddish to yellowish ferruginous, clayey matrix Also present in the rock are fragments of polygenic and heterometric rocks consisting of black-blueish graphitic shales, rounded pebbles, sandstones, quartzites, and pelites measured in centimeters (Figure 3a), rounded pebbles, sandstones, quartzites, and pelites mostly in the order of centimeters (Figure 3b).

On the western slope of the Irongero River, a few miles north of Bugoy, diamictite outcrops were found (Figure 3c, d). A gray or black color characterizes them, and they are compact in nature. Quartz veins, granite, sandstone, gneiss, and quartzite clasts range in size from 1 to 15 cm long. They are strongly foliated in N-S directions and embedded in a chloritic clay matrix (Figure 4c, d).

3.1.2 Rocks with carbonate facies

Travertine. This rock was sampled from the Karhendezi-Bugoy geothermal field. In essence, it is a calcareous concretion with a rough surface (massive structure). The soil is predominantly clayey-graphite with veins of quartz (1 cm thick), rich in red iron oxides and calcite. A dozen hot springs are located on either side of the Karhendezi-Cidubwe river (Figure 5a, b). Several dissolved minerals, including sulfur, contribute to a rotten egg-like smell in the water, which is between 65℃ and 73℃.

Figure 5. A travertine deposit surrounded by green algae at the emergence of a geothermal spring(a). Sample of travertine (b)

3.1.3 Rocks with greenschist facies

Pelite and graphitic black shale These are clayey rocks that have been indurated and stratified by compaction. Throughout the study area, they are found in black-grayish and yellowish colors. (Figure 6a, b) shows pelite cleavages that are slightly fresh on matte surfaces. A microscopic examination of the rock shows quartz (20-40%), sericite (15-20%), and chlorite (10-15%); there is a second order birefringence and the rock is polarizing into a greenish color with a right extinction angle (Figure 7a, b). Graphitic black shale, like pelite, exhibits a flaky texture due to foliation (Figure 6c, d) containing quartz crystals (15%), recrystallized pyrite (50%), carbon (10%), and muscovite (5%) (Figure 7c, d).

Figure 6. A pelite outcrop from Bugoy area (a) and a corresponding sample (b). Outcrop of graphitic schists from Tshondo (c) and eroded sample (d) collected along Musheke river valley

Figure 7. Microphotographs of pelite and graphitic schist (shale): microscopic observations in plane polarized light (a, c) and crossed polarized light (b, d)

3.1.4 Rocks with quartzitic facies

Quartzites. Their mineral composition consists of quartz minerals along with hematite, muscovite, biotite, and K-feldspar. Those found at Tshondo exhibit a superficial alteration of the type "cargneule-type" which is characterized by decayed and vacuolar habits (Figure 8). Quartz crystals appear as transparent patches under a microscope, whereas metallic minerals appear opaque. There are irregular shapes and xenomorphic properties to these minerals. Small elongated prisms of alkaline feldspar are also colorless. With relatively high relief and dark brown to greenish pleochroism, the yellow-browned absorption minerals represent biotite. Cross-polarized light shows bright polarization colors ranging from gray to white with an undulatory extinction, indicating a positive deformation, but difficult to detect. An elongated and attenuated polarization tint is present in biotite. Due to the mass of opaque minerals, orthoclase shows an oblique extinction and Carlsbad twinning associated with two crystals (Figure 9a, b).

Auriferous quartzite, which is composed primarily of metallic minerals (here Au), is also analyzed. Gaseous inclusions appear as small bubbles. The colorlessness of mucovite can be attributed to its pleochroism, ranging from yellow to pale yellow (Figure 9c, d).

Figure 8. Sample of a Cargneule Quartzite from Tshondo

Figure 9. Microphotograph of ferriferous quartzite and gold-bearing quartz: in plane polarized light (a, c) and crossed polarized light (b, d)

3.2 Kinematic analysis

A total of 190 linear and planer features were analyzed. Subset indexes were used for conjugates shear fractures, fracture planes, extensive fractures, joints as well as foliation and bedding surfaces (Appendix Table 1, Table 2, and Table 3). In both areas, these measurements were used to quantify deformation.

Only a few faults with sense of movement were recorded due to the physical properties of the rock formations at Tshondo and Bugoy (friable, unconsolidated graphitic schists). It was not possible to collect a lot of data since fault planes are sparsely carved with tectoglyphs (Figure 10). In our opinion, erosion or other exogenous factors could have crumbled and erased most of the markers. A total of thirteen striae were correctly identified. As a result of their poor pronunciation, others were considered "Probable" and overlooked during the analysis process. The Striae have a preferential trend towards the NE-SW and NNE-SSW directions. There are two structural preferential trends for he fractures, bedding planes, and foliation: NE-SW and NNE-SSW (Figure 11a, b).

Figure 10. Striae appearing on a fault mirror and fault breccia made up with a mixture of clays and pellitic rocks

Figure 11. Rose diagram showing average statistical orientations for linear (a) and planar (b) measurements

Figure 12. Stereoplots after optimization and separation: from PBT axes, R.Dihedron and R.Optim Methods(a, b, c) and final results for stress parameters (Reduced stress tensor, orientation of the horizontal principal stress axes and the stress regime

In accordance with Anderson's theory (Figure 14), kinematic analysis using Win-tensor software indicates two phases of deformation, highlighted by a strike-slip stress regime such that $\sigma_1: \mathrm{N} 118^{\circ} / 03^{\circ} \mathrm{SE}, \sigma_2: \mathrm{N} 358^{\circ} / 85^{\circ} \mathrm{SE}, \sigma_3: \mathrm{N}$ $208^{\circ} / 04^{\circ} \mathrm{SW}\left(\sigma_2 \geq \sigma_3 \geq \sigma_1\right)$ and an average stress ratio index $\mathrm{R}^{\prime}=1.53$ (Figure 12a, b, c), as well as a an pure extensive regime with stress ratio $\mathrm{R}=0.46$ (Figure 13). The principal $\sigma_3: \mathrm{N} 250^{\circ} / 9^{\circ} \mathrm{SW}\left(\sigma_1 \geq \sigma_2 \geq \sigma_3\right)$. The values were obtained following subsequent tensor optimization and data separation based on Dihedron methods, which requires the background minimum counting deviation value (C.V) representing $\sigma_1$ in the counting grid to be equal to 0 and the maximum counting deviation value representing $\sigma_3$ to be equal to 100 [11].

As shown by Villeneuve et al. [3, 6, 8, 15] and other reseachers who have investigated the Itombwe Synclinorium, Tshondo and Bugoy, as we have also just seen, have undergone a small-scale regional metamorphism, evolving towards greenschist facies and an important granitization highlighted by the Kasika granitic intrusion, but geochronological studies are needed.

Figure 13. Stereoplots after optimization and separation for conjugated fractures and faults without senses of movement: R.Dihedron and R.Optim Methods (a, b)

Figure 14. Stress regime and stress tensor types according to Anderson deformation theory [11]

Microscopic analyses of thin sections of rocks as well as different macroscopic observations have shown a mineral paragenesis mainly made of chlorites, muscovites / sericites and biotites, and metallic minerals. Observations also revealed large ranges of quartz which recrystallized under mono and polycrystalline crystals presenting undulatory to right extinctions.

Admittedly, traces of deformation were not detectable. It is believed that long after their formation, these lithological units underwent an orogeny marked by strong fracturing and a slightly to more pronounced crushing following N-S directions. Foliation is the most dominant structural feature and the most penetrating at the scale of the outcrops. This foliation probably corresponds to the major deformation phase in the Itombwe. It is associated with local folds testified by the Kinematic analysis performed on faults with movement. However, a second deformation is evidenced.

4. Conclusion

Investigations at Tshondo and Bugoy reveals four petrography facies mainly made of rocks such as graphitic schist, pelite, conglomerate, paraconglomerate, travertines, quartzites, and sandstone.They have undergone a strong to weak metamorphism that has evolved in the facies of green schists with quartz, chlorite, muscovite, biotite, and opaque minerals as dominant mineral assemblages.

The estimation of stress tensors using inversion techniques by Anderson [16] reveals pure strike-slip and extensive deformation phases. This is tangible proof that at least two phases of deformation have occurred in the geological formations outcropping at Tshondo and Bugoy. First, a ductile deformation phase D1-2 which generated isoclinal folds and then a submeridian brittle deformation which generated thrusting faults of Tshondo and Bugoy while reactivating stratification surfaces in a series of secondary faults trending NE-SW.

In order to complete this study, the following must be done in the future:

- Conduct a non-hasty lithostratigraphic study at Tshondo and Bugoy by drilling deep to determine the thickness of related formations.

- Polish sections of rocks in order to combine the mineral parageneses of greenschist facies with the parageneses of metallic minerals (opaque minerals).

- Analyze and characterize the faults affecting the formations in both areas, relying not on structural markers, but instead on morphological markers in direct field observation.

- Date both areas’ geological formations geochronologically and compare their ages with the ages established in the itombwe.

Acknowledgment

The authors acknowledge the help and support provided by the Department of Geology of the Official University of Bukavu. The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Nomenclature

Cm

Centimetres

C.V

Counting deviation value

D1

Deformation 1

D2

Deformation 2

DRC

Democratic Republic of the Congo

km

Kilometres

Ma

Million years

PBT

Pressure tension and null axis

PPL

Plane Polarized Light

XPL

Crossed-Polarized Light

$\sigma_1$

Principal stress axis sigma 1

Celcius degree

Appendices

Table 1. Structural measurements for striation and analytical results

Striae

ID

Lat

(degree)

Long X

(degree)

Alt Z

(m)

Plane

Line

Sense

1

-2,87464

28,65513

1310

62/052

33/342

NS

2

-2,87731

28,65761

1311

79/029

26/305

NS

3

-2,87731

28,65761

1310

79/029

43/310

NS

4

-2,87731

28,65761

1454

44/026

44/028

IS

5

-2,87731

28,65761

1454

40/034

38/057

IS

6

-2,87731

28,65761

1454

40/027

38/050

IS

7

-2,8746

28,65511

1314

81/231

59/156

NS

8

-2,8746

28.65511

1314

30/305

05/223

NS

9

-2,87435

28,65801

1373

64/045

62/068

IS

10

-2,87435

28,65801

1373

64/045

63/057

IS

11

-2,87435

28,65801

1373

64/045

53/095

IS

12

-2,87435

28,65801

1373

40/088

39/071

NS

13

-2,87435

28,65801

1373

64/045

64/049

IS

Table 1. Continued

Kinematic Axes

Stress Parameters

PIncl

P Azim

B Incl

B Azim

T Incl

T Azim

Shmax

Shmin

R'

46

285

44

111

3

18

107

17

1

26

254

61

98

10

349

77

167

1.5

38

249

45

108

20

356

79

169

1

1

207

1

297

89

72

27

117

2.5

6

227

11

318

77

109

46

136

2.5

6

220

11

311

77

102

39

129

2.5

46

81

29

316

30

207

104

14

1

42

195

30

316

34

68

174

84

1

18

53

9

320

69

204

57

147

2.5

19

49

5

317

71

213

51

141

2.5

15

65

24

328

61

183

70

160

2.5

81

22

8

168

6

259

170

80

0.5

46

2

316

71

221

47

137

2.5

2

Table 2. Structural measurements for conjugated fractures and analytical results

Conjugated Fractures

ID

Lat

(degree)

Long

(degree)

Alt

(m)

Fracture 1(degree)

Fracture 2(degree)

1

-2.87731

28.65761

1365

85/330

14/059

2

-2.87541

28.65461

1340

75/265

02/355

3

-2.87464

28.65514

1310

89/302

26/032

4

-2.87464

28.65514

1310

78/150

23/065

5

-2.87474

28.6551

1314

70/080

16/164

6

-2.79596

28.68737

1520

84/320

25/233

7

-2.79829

28.68514

1521

85/082

06/171

8

-2.79829

28.68514

1521

86/330

07/240

9

-2.79829

28.68514

1521

75/135

18/220

10

-2.79829

28.68514

1521

86/164

23/252

Table 2. Continued

Kinematic Axes

Stress Parameters

PIncl

P Azim

B Incl

B Azim

T Incl

T Azim

Shmax

Shmin

R'

26

9

75

259

12

118

27

117

1.5

26

9

75

259

12

118

27

117

1.5

49

25

64

214

6

316

47

137

1.5

49

25

64

214

6

316

47

137

1.5

197

25

64

38

8

291

19

109

1.5

197

25

64

38

8

291

19

109

1.5

206

8

82

30

1

296

26

116

1.5

206

8

82

30

1

296

26

116

1.5

236

21

67

83

10

330

58

148

1.5

236

21

67

83

10

330

58

148

1.5

Table 3. Structural measurements for bedding planes, fractures plane, joints, and foliation

Bedding planes, fracture planes, joints, foliation

ID

Lat Y

(degree)

Long X (degree)

Alt Z

(m)

Dip-angle/Dip-direction (degree)

Type

1

-2.87464

28.65514

1522

85/320

Fracture plane

2

-2.87464

28.65514

1522

85/305

Fracture plane

3

-2.87474

28.6551

1522

85/150

Fracture plane

4

-2.87474

28.6551

1522

63/104

Fracture plane

5

-2.87515

28.65637

1705

80/175

Fracture plane

6

-2.87515

28.65637

1705

37/350

Fracture plane

7

-2.87562

28.65441

1721

75/300

Fracture plane

8

-2.87515

28.65637

1721

72/175

Fracture plane

9

-2.87515

28.65637

1721

37/175

Fracture plane

10

-2.87731

28.65761

1721

80/122

Fracture plane

11

-2.87731

28.65761

1721

80/122

Fracture plane

12

-2.87731

28.65761

1721

85/076

Fracture plane

13

-2.87688

28.65811

1721

79/042

Fracture plane

14

-2.87688

28.65811

1688

75/043

Fracture plane

15

-2.87688

28.65811

1688

76/040

Fracture plane

16

-2.87688

28.65811

1688

70/042

Fracture plane

17

-2.87688

28.65811

1688

75/040

Fracture plane

18

-2.87818

28.65897

1688

75/044

Fracture plane

19

-2.87691

28.65874

1672

76/045

Fracture plane

20

-2.87688

28.65811

1672

89/052

Fracture plane

21

-2.87688

28.65811

1672

87/055

Fracture plane

22

-2.87923

28.66048

1672

74/110

Fracture plane

23

-2.87691

28.65874

1672

66/091

Fracture plane

24

-2.87691

28.65874

1654

86/336

Fracture plane

25

-2.87691

28.65874

1654

88/352

Fracture plane

26

-2.87691

28.65874

1654

65/263

Fracture plane

27

-2.87691

28.65874

1654

49/037

Fracture plane

28

-2,87562

28,65441

1355

20/099

Bedding plane

29

-2,87491

28,65592

1348

61/255

Bedding plane

30

-2,87491

28,65592

1348

61/262

Bedding plane

31

-2,87515

28,65637

1365

86/262

Bedding plane

32

-2,87515

28,65637

1365

85/092

Bedding plane

33

-2,87515

28,65637

1365

85/272

Bedding plane

34

-2,87515

28,65637

1365

80/264

Bedding plane

35

-2,87515

28,65637

1365

80/272

Bedding plane

36

-2,87731

28,65761

1454

84/272

Bedding plane

37

-2,87731

28,65761

1454

85/122

Bedding plane

38

-2,87731

28,65761

1454

71/122

Bedding plane

39

-2,87731

28,65761

1454

76/142

Bedding plane

40

-2,87731

28,65761

1454

80/150

Bedding plane

41

-2,87688

28,65811

1416

85/110

Bedding plane

41

-2,87688

28,65811

1416

85/010

Bedding plane

42

-2,87688

28,65811

1416

16/185

Bedding plane

43

-2,87688

28,65811

1416

42/089

Bedding plane

44

-2,87818

28,65897

1409

75/022

Bedding plane

45

-2,87818

28,65897

1409

10/002

Bedding plane

46

-2,87691

28,65874

1356

65/008

Bedding plane

47

-2,87691

28,65874

1356

40/290

Bedding plane

48

-2,87691

28,65874

1356

60/282

Bedding plane

49

-2,87691

28,65874

1356

50/280

Bedding plane

50

-2,87691

28,65874

1356

70/120

Bedding plane

51

-2,87691

28,65874

1356

80/274

Bedding plane

52

-2,87691

28,65874

1356

79/007

Bedding plane

53

-2,87691

28,65874

1356

20/228

Bedding plane

54

-2,87691

28,65874

1356

71/112

Bedding plane

55

-2,85733

28,65827

1345

74/110

Bedding plane

56

-2,85733

28,65827

1345

66/091

Bedding plane

57

-2,85733

28,65827

1345

86/336

Bedding plane

58

-2,85733

28,65827

1345

88/352

Bedding plane

59

-2,85733

28,65827

1345

65/263

Bedding plane

60

-2,87568

28,65882

1380

49/037

Bedding plane

61

-2,87568

28,65882

1380

20/099

Bedding plane

62

-2,87584

28,65888

1363

85/350

Bedding plane

63

-2,87584

28,65888

1363

81/002

Bedding plane

64

-2,87584

28,65888

1363

81/012

Bedding plane

65

-2,8741

28,65462

1319

85/144

Bedding plane

66

-2,8741

28,65462

1319

87/030

Bedding plane

67

-2,87397

28,65886

1318

87/184

Bedding plane

68

-2,87458

28,65505

1315

75/218

Bedding plane

69

-2,8746

28,65511

1314

85/023

Bedding plane

70

-2,85509

28,656

1352

75/046

Bedding plane

71

-2,85509

28,656

1352

87/200

Bedding plane

72

-2,87542

28,67637

1381

80/198

Bedding plane

73

-2,87542

28,67637

1381

89/024

Bedding plane

74

-2,87841

28,65871

1456

71/210

Bedding plane

75

- 2,87904

28,66027

1511

88/190

Bedding plane

76

-2,87812

28,659

1420

80/190

Bedding plane

77

-2,87812

28,659

1420

80/144

Bedding plane

78

-2,87549

28,65672

1392

81/200

Bedding plane

79

-2,87549

28,65672

1392

76/200

Bedding plane

80

-2,87472

28,65511

1318

84/032

Bedding plane

81

-2,87476

28,65503

1317

89/032

Bedding plane

82

-2,87435

28,65801

1373

85/222

Bedding plane

83

-2,87167

28,6783

1398

80/010

Bedding plane

84

-2,87167

28,6783

1398

82/200

Bedding plane

85

-2,87167

28,6783

1398

89/190

Bedding plane

86

-2,87546

28,65895

1330

85/182

Bedding plane

87

-2,87564

28,65927

1346

89/006

Bedding plane

88

-2,87482

28,65847

1316

75/042

Bedding plane

89

-2.87443

28.65554

1311

85/045

Foliation

90

-2.87208

28.67290

1409

71/042

Foliation

91

-2.87208

28.67290

1409

70/044

Foliation

92

-2.87208

28.67290

1409

88/034

Foliation

93

-2.87208

28.67290

1409

85/032

Foliation

94

-2.87443

28.65554

1311

74/035

Foliation

95

-2.782

28.68537

1512

71/032

Foliation

96

-2.782

28.68537

1512

85/044

Foliation

97

-2.782

28.68537

1512

75/052

Foliation

98

-2.782

28.68537

1512

52/032

Foliation

99

-2.782

28.68537

1512

67/054

Foliation

100

-2.782

28.68537

1512

66/050

Foliation

101

-2.79817

28.68407

1522

45/044

Foliation

102

-2.79817

28.68407

1522

70/060

Foliation

103

-2.79817

28.68407

1522

49/022

Foliation

104

-2.87464

28.65514

1310

53/034

Fracture plane

105

-2.87464

28.65514

1310

65/052

Fracture plane

106

-2.87474

28.6551

1314

61/055

Fracture plane

107

-2.87474

28.6551

1314

39/032

Fracture plane

108

-2.87515

28.65637

1365

75/063

Fracture plane

109

-2.87515

28.65637

1365

45/042

Fracture plane

110

-2.87562

28.65441

1355

45/052

Fracture plane

111

-2.87515

28.65637

1365

41/044

Fracture plane

112

-2.87515

28.65637

1365

40/041

Fracture plane

113

-2.87731

28.65761

1454

39/032

Fracture plane

114

-2.87731

28.65761

1454

42/024

Fracture plane

115

-2.87731

28.65761

1454

44/058

Fracture plane

116

-2.87688

28.65811

1416

44/043

Fracture plane

117

-2.87688

28.65811

1416

53/030

Fracture plane

118

-2.87688

28.65811

1416

37/016

Fracture plane

119

-2.87688

28.65811

1416

44/044

Fracture plane

120

-2.87688

28.65811

1416

40/042

Fracture plane

121

-2.87818

28.65897

1409

42/045

Fracture plane

122

-2.87691

28.65874

1356

35/032

Fracture plane

123

-2.87688

28.65811

1416

39/034

Fracture plane

124

-2.87688

28.65811

1416

39/030

Fracture plane

125

-2.87923

28.66048

1551

64/069

Fracture plane

126

-2.87691

28.65874

1356

65/069

Fracture plane

127

-2.87691

28.65874

1356

49/026

Fracture plane

128

-2.87691

28.65874

1356

50/028

Fracture plane

129

-2.87691

28.65874

1356

41/022

Fracture plane

130

-2.87691

28.65874

1356

38/010

Fracture plane

131

-2.87691

28.65874

1356

44/140

Fracture plane

132

-2.87691

28.65874

1356

85/052

Fracture plane

133

-2.87691

28.65874

1356

72/042

Fracture plane

134

-2.87691

28.65874

1356

60/035

Fracture plane

135

-2.87568

28.65882

1380

59/020

Fracture plane

136

-2.87584

28.65888

1363

70/038

Fracture plane

137

-2.87584

28.65888

1363

64/044

Fracture plane

138

-2.87464

28.65514

1310

61/018

Fracture plane

139

-2.87585

28.65409

1368

54/038

Joint

140

-2.87620

28.67660

1440

68/035

Joint

141

-2.87701

28.65816

1414

70/028

Joint

142

-2.87868

28.66009

1492

66/048

Joint

143

-2.87496

28.65596

1349

67/052

Joint

144

-2.87196

28.673

1416

49/028

Joint

145

-2.87516

28.65844

1325

53/032

Joint

146

-2.79596

28.68737

1520

40/056

Joint

147

-2.79829

28.68514

1521

60/082

Joint

148

-2.79829

28.68514

1521

55/050

Joint

149

-2.79829

28.68514

1521

60/064

Joint

150

-2.79829

28.68514

1521

46/036

Joint

151

-2.79829

28.68514

1521

46/014

Joint

152

-2.79817

28.68407

1522

81/040

Joint

153

-2.79817

28.68407

1522

75/030

Joint

154

-2.79817

28.68407

1522

70/050

Joint

155

-2.79817

28.68407

1522

57/010

Joint

156

-2.8225

28.68217

1705

56/010

Joint

157

-2.82297

28.68180

1721

50/070

Joint

158

-2.82297

28.68180

1721

72/023

Joint

159

-2.82297

28.68180

1721

65/034

Joint

160

-2.82297

28.68180

1721

59/045

Joint

161

-2.82126

28.68261

1672

75/132

Joint

162

-2.83088

28.69354

1702

85/118

Joint

163

-2.83088

28.69354

1702

81/112

Joint

164

-2.83010

28.69312

1704

65/124

Joint

165

-2.83010

28.69312

1704

88/288

Joint

166

-2.79596

28.68737

1520

84/300

Joint

  References

[1] Lepersonne, J. (1971). Les formations du soubassement au Maniema et au Kivu. Belgium, Tervuren.

[2] Villeneuve, M. (1978). Etude Photogéologique du Secteur Precambrien de Luemba (Sud-Kivu-Zaire) la partie Meridionale du “Synclinal de L’itombwe” et son Substratum. Annales de La Société Géologique de Belgique, 101: 47-52. https://popups.uliege.be/0037-9395/index.php?id=4379.

[3] Villeneuve, M. (1987). Géologie du Synclinal de l’Itombwe (Zaire Oriental) et le Problème de l’existence d’un Sillon Plissé Pan-Africain. Journal of African Earth Sciences, 9(6): 869-880. https://doi.org/10.1016/0899-5362(87)90046-7 

[4] Lefevère, J. (2003). Analyse et interprétation des canevas lithostratigraphiques et tectoniques du Synclinal de l’Itombwe (Sud-Kivu République Démocratique du Congo) à l’aide des données satellitaires et radar. Université Libre de Buxelles.

[5] Lhoest, A. (1946). Une coupe remarquable des couches de base de l’Urundi, dans l’Itombwe (Congo belge). Annales de La Société Géologique de Belgique., 69(B): 250-256. 

[6] Walemba, K.M. (2001). Geology, geochemistry, and tectono-metallogenic evolution of Neoproterozoic gold deposits in the Kadubu area, University of the Witwatersrand. http://hdl.handle.net/10539/15209, accessed on June 17, 2022.

[7] Peeters, L. (1952). Observations géomorphologiques et géologiques au Sud-Ouest de Costermansville (Kivu). Annales Du Musée Du Congo Belge, 8(10): 9-62. http://bibliotheque.donboscordc.org/index.php?lvl=notice_display&id=1331.

[8] Walemba, K.M.A., Master, S. (2005). Neoproterozoic diamictites from the Itombwe Synclinorium, Kivu Province, Democratic Republic of Congo: Palaeoclimatic significance and regional correlations. Journal of African Earth Sciences, 42(1-5): 200-210. https://doi.org/10.1016/j.jafrearsci.2005.08.009

[9] Villeneuve, M., Chorowicz, J. (2004). Les sillons plissés du Burundien supérieur dans la chaine Kibarienne d’Afrique centrale. Geosciences, 336(9): 807-814. https://doi.org/10.1016/j.crte.2004.01.006

[10] Villeneuve, M. (1977). Précambrien du Sud du lac Kivu. Etude stratigraphique, pétrographique et tectonique, Fac. Sci et Techn. St Jérôme, 1977. https://doi.org/10.2113/gssgfbull.S7-XX.6.915 

[11] Delvaux, D., Sperner, B. (2003). New aspects of tectonic stress inversion with reference to the TENSOR program. The Geological Society of London, 212: 75-100. http://dx.doi.org/10.1144/GSL.SP.2003.212.01.06 

[12] Angelier, J. (1994). Fault slip analysis and paleostress reconstruction. Continental Deformation, 4: 101-120. 

[13] Angelier, J., Tarantola, A., Manoussis, S. (1982). Inversion of field data in fault tectonics to obtain the regional stress — I. Single phase fault populations: A new method of computing the stress tensor. Geophysical Journal of the Royal Astronomical Society, 69(3): 607-621. https://doi.org/10.1111/j.1365-246X.1982.tb02766.x

[14] Hutchinson, C. (1974). Laboratoty Handbook of Petrographic Techniques. Wiley, New York. https://doi.org/10.1017/S001675680004574X 

[15] Rumvegeri, B. (1987). Le Précambrien de l’Ouest du lac Kivu et sa place dans l’évolution géodynamique de l’Afrique centrale et oriental: pétrologie et Tectonique, St Jérôme.

[16] Anderson, E.M. (1905). The dynamics of faulting. Transactions of the Edinburgh Geological Society, 8(3): 387-402. https://doi.org/10.1144/transed.8.3.387