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Proceedings, 8th African Rift Geothermal Conference Nairobi, Kenya: 2 – 8 November 2020

Identification of Thermal Springs in Eastern DRC, Case Study of Katanga, Kivu and Ituri Provinces

Deogratias A. Odhipio0, Pacifique S. Mukandala0, Grace N. Kawa0, Georges M. Kasay0,0, Vikandy S.H. Mambo00 1Department of Geology, Université Officielle de Ruwenzori, DRC 2Department of Geoscience, Pan African University of Life and Earth Science, University of Ibadan, Nigeria 3Department of Chemistry, Université de Kinshasa, DRC. Emails:[email protected], [email protected], [email protected], [email protected]

Keywords: Thermal spring, Power potential, Geologic formation, Eastern DRC.

ABSTRACT

The Democratic Republic of Congo (DRC) has a huge and varied renewable and non- renewable energy potential. It consists of hydroelectricity, timber, oil, coal, gas, solar energy, biomass and geothermal energy. Among others, geothermal potential is very common in the Eastern part of the DRC. The substratum of the Eastern DRC consists of a basement complex with an age varying between Archean and middle Proterozoic. It is covered by upper Proterozoic sedimentary rocks in several areas. These geologic formations are folded in a general northeast direction which, from Kiambi, bends to take a north-south direction. Besides these orogenic movements caused by tangential pressures, the East of the DRC is a beautiful illustration of relatively recent vertical movements, giving raise to the rift valley which is filled up by Phanerozoic sediments. The fractures are often lined by surface and subsurface geothermal manifestations. Hot springs are the most common surface manifestations. They are located in many places of the western branch of the rift in the DRC. Some of them are relatively very hot for the most part and their chemical composition is dominated by the abundant presence of sulphide and salt minerals. They are located in the valley of , , in the basin, in the Lowa, Ulindi, Ruzizi, Elila, Lualaba, Luama, Luika, Lukuga, Luvua, Lufira, between the Lomami and Luembe stream, in the western part of the South of and finally in the volcanic region around .

1. Introduction The DRC has a huge and varied energy potential which can be exploited from hydroelectricity, wood, proven oil reserves, proven coal reserves, methane gas in the Odhipio et al. lake Kivu, solar energy, agricultural biomass, wind, nuclear and geothermal energy (Makuku, 2019). Energy potential is very high but still underexploited. With the growing number of the population and eager need of development of many aspects of life, the energy demand is also increasing. This has to be addressed by exploiting the potential which is already known and explore the unknown. The DRC is one of the first African countries to learn about geothermal energy. Indeed the first geothermal installation in Africa was born in the country in 1952 and had a production of 0.2 MW at the geothermal site of Kiabukwa with a temperature of 91°C in the province of Katanga. This production did not last long after independence perhaps because of Belgian colonial paternalism, or because of the bankruptcy of the second republic. (Mambo and Mahinda, 2012). However, there is much work to be done before exploitation. All starts from a good and correct assessment of the energy potential of the country. The influence of geothermal energy in the DRC tends to be positive mainly due to the prevention and protection of environmental pollution impacts related to the use of fossil fuels and woodfire. Preservation of dense forest is a key to the climate change and global warming disasters. Another aspect is that the DRC is a vast country and energy supplies are always far from remote villages and towns. Considering the cost of energy transportation from the supply center to the consumption area, it is always good to think of local energy supply for small communities in villages or towns. Some of the potential energy sources which can fit this demand are most of them renewable such as wind, solar and geothermal energy. The last one is mostly concentrated in the East part of the country which is located within the western branch of the African Rift System. The presence of geothermal energy potential is evidenced by the presence of surface manifestations with the most common being hot springs. Several hot springs are located in the East of the DRC within the rift. Some of them have been well studied and others are still unknown to the scientific community (Makuku et al., 2019; Mambo et al., 2008; Mukandala et al., 2018; Luse and Makonga, 2019). A recent study was done by Makuku (2019) and gave an inventory of thermal springs in the DRC and their development plans for the electrification of rural areas. It focused on the important contribution of hydroelectricity in the electrification of urban and rural agglomerations of the DRC in general and of geothermal energy to cover up the lack of energy remote areas of the eastern DRC. Another study did a regional detailed review of hot springs in the East of the DRC (Mambo et al., 2008). Nevertheless, since then, some other hot springs have been identified and the list needs to be updated with some new discoveries. This work aims to identify thermal springs in the East of the DRC and to describe the geology of this part of the country, by including new findings from the recent implemented researches and new discoveries of unreported hot springs. It will constitute a useful new database both for the scientific community and for the government, to make a wise choice on the source of a useful, clean and affordable energy for the Congolese people.

2. Literature review Geothermal manifestations are known in a great part of the System and a part of southern Africa (Figure 1). They are located along the rift where they Odhipio et al. have various temperatures depending on their geographic locations. In some places within the rift do not show any surface geothermal manifestations but have huge geothermal potentials which is related to subsurface or deep manifestations. The entire eastern borders of the DRC extend along the western branch of the East African Rift region (Delvaux et al., 2006). In the eastern branch of the rift, in Kenya and Ethiopia, the geothermal power has already been developed (Varet, 2014). In the western branch of the East African rift system, is at an advanced stage of geothermal energy production (Kato and Kraml, 2000). The East of the DR Congo is dominated by volcanic provinces with two known active volcanoes, Nyiragongo and Nyamulagira (Scoon, 2020). This part of the country has also got several geothermal surface manifestations which are mainly represented by hot springs (Figure 1). They are situated in different locations and provinces and are of various temperatures (Makuku, 2019; Mambo et al, 2008; Mambo et al, 2012). Prospecting and identifying these hot springs could lead to the research of clean and affordable sources of energy. This would allow the government to select the best available energy resources, taking into account not only the cost but also other benefits, including long-term environmental benefits. In this logic, preliminary reconnaissance studies were already carried out in the past, by Belgian researchers on the distribution of thermal springs in Katanga (Cornet, 1906), on the thermal springs of Bas-Katanga (Mathieu, 1913) in the region of Katanga and also the thermo-mineral sources of Kivu. Another research focused later on the relations between hot springs with the great radial fractures and their use from a tectonic point of view (Boutakoff, 1933), and then on the thermal sources of the Orientale Province (Passau, 1933). These studies most likely facilitated the installation of Africa’s first geothermal power plant at the Kiabukwa geothermal site in 1952, with a capacity of 0.2 MW (Mambo et al., 2012). Odhipio et al.

Figure 1: Index map of thermal springs in Central, Eastern and Southern Africa (after Gerald et al., 1965).

3. Regional Geology of the East of the DRC The geology of the DRC is characterized by two large structural groups separated by a discrepancy (an important gap):

• The metamorphic and basement formations (Precambrian terrains) forming an uninterrupted ring around the ; • Non-metamorphosed cover formations (Phanerozoic terrain), generally fossiliferous and of age between the Upper Carboniferous and the Holocene. 3.1.The basement grounds The basement is subdivided into tectonostratigraphic units (Figure 2) which are:

a) Archean shields are greater than or equal to 2500 Ma outcropping in northern Congo and Kasai. The northern part includes, in addition to and Ruwenzori, the region which extends from the Congo- watershed ridge in the East to the Ubangui watershed in the West. The geologic formations here are crystallophyllian series formed mainly of mica schist, quartzites, graphitic schists and gneiss; b) The lower and middle Precambrian belt (2500 to 1300 Ma) represent the sediments which are deposited in mobile meridian zones located on the eastern and western Odhipio et al.

borders of the craton and in transverse intracratonic ditches. Its southern part is the largest part of the province of Katanga as well as a portion of Kasai Oriental; c) The cover of the Upper Precambrian called the Katangian whose sediments are deposited on the epicontinental platforms and in the subsistence areas of the Congo craton (pleated and tabular Katanga).

Figure 2: Geological map of the eastern part of the DRC (after Delvaux et al., 2016).

This substratum brings together all of the magmatic and metamorphic formations (Figure 2) set up during the period between the Archean and the Neoproterozoic (3.3 and 0.57 Ga):

• Cratonic zones : Kasai, W. Nilian, Bilatian (3.3 - 2.5 Ga); • Mobile chains : Ubendian, Lukoshian, Kibalian and Zadinian (Paleoproterozoic: 2.5 - 1.4 Ga); • Kibarian, Burundian, Moyombian (Mesoproterozoic: 1.4 - 0.9 Ga); • Pan-African: Katanguian, Lindian, Bushimay, West Congolian (Neoproterozoic: 0.9 - 0.57 Ga). 3.2.Cover formations We group, in this set, all the resting deposits in discrepancy on the grounds of the base. The cover consists mainly of Paleozoic to Tertiary and even quaternary age terrains (Figure 3). Odhipio et al.

The Paleozoic outcrops in the Orientale Province, North Kivu, , Maniema and northern Katanga. The Mesozoic is represented by the Kwango series (upper Cretaceous); the Lualaba series (lower Cretaceous); the floor of Kisangani (Jurassic). They are exposed in four zones. The first zone is a coastal area, between the Atlantic Ocean and the Mayumbe mountains (Crystal Mountains) where marine formations of tertiary and Cretaceous age are found. The second is the central basin where deposits of Mesozoic age spread; vast grounds are exposed on the perimeter of the Cuvette. The third zone is the border of old lands subdivided into six non-connectable regions. And the last zone is the tectonic ditches of eastern Congo occupied by particular Cenozoic formations and recent volcanism. Tertiary volcanism manifests in four isolated geological provinces along the western branch of the East African rift (the provinces of Toro-Ankole, Virunga, Kivu and Rungwe). These provinces coincide with areas of depression showing an intimate relationship between volcanism and faults during the initial stages of the development of the continental rift.

Figure 3: Homogeneous cross-border synthetic geological map of the East of DR Congo with overprinted neotectonic features, neotectonic faults, late Quaternary volcanic (Delvaux et al., 2016).

4. Thermal Springs of the East of the DRC The several hot springs in Eastern DR Congo are described in Error! Reference source not found., together with their respective locations and references.

Odhipio et al.

Table1: Description of thermal springs in the eastern part of DRC (Name of springs in bold) N° Name or location Remarks and additional references

1 Vicinity of Lake Albert: In general, these waters are hot (ranging from 50°C to 85°C), with sulfur deposits. TDS: Kaswa and Lilida 427ppm, Alkalinity: 152.5ppm, Principal chemical constituents: SO 2- : 62ppm, HCO - Vicinity of Lake Albert-Con. 4 3 : 152.5ppm, Na+ : 75.6ppm, K+ : 6.8ppm, Mount Laba, Goda and Pandju Ca2+: 38.4ppm, Mg2+ : 14.6ppm, Cl- : 18ppm. (Luse and Makonga, 2019) In the vicinity of Albert-Con, petroleum is also found. (Demissie, G. 2010; Gerald et al., 1965)

2 Semliki River valley: With temperatures varying between 37°C to 52°C, These thermal waters are discharged Zumbia (Kwaniwa), Eastside from the depth through cracks of rocks and of the valley near the base of they release steam. Principal chemical Mount Ruwenzori: constituents: Na+ : 750ppm, K+ : 113ppm, Molinglingo, Katuka, Mg2+ : 727ppm, Ca2+ : 558ppm, Cl- : 140ppm 2- Vyatungo, Mutsora, and SO4 :286ppm. (Mukandala et al., 2018 ; Masambo, Kambo, Kikura, Mambo et al., 2008) Kyavitumbi

3 Vicinity of Lake Edward The pH ranges from 7.99 - 8.94, the lower (Rutshuru): range of temperature is between 45°C and 90°C. Principal chemical constituents : Na+ : - Bitagoha, Mayi ya Moto (in 2,170ppm - 2,745ppm, HCO3 : 3,400ppm - - 2- ), 5,096ppm, Cl : 1,070-1,140ppm, SO4 : 400- Kalieri/Katale, Nyabugezi 590ppm, Mg2+ : 0.9 - 2.0ppm, Ca2+ : 1 - 9.6ppm. (Mambo et al., 2008 ; Gerald et al., 1965; Makuku, L. 2019)

4 Lowa River basin More than 14 springs. Kolokolo, one of these springs with H2S containing water. Their temperature varies between 56°C - 68°C.(Mathieu, 1913; Makuku, L. 2019)

5 Lake Kivu volcanic area: Water, 60°C in general, rises in the bathing pool. Much free C02. A large deposit of tufa Sake (Masisi), Tingi/Sake, and travertine. (Boutakoff, 1933; Mambo et Kisuma, Bukomo, Katana al., 2008) (Kakondo), on border of lake. Luiro (near Kahusi volcano), pH : 7.3 (neutral), TDS concentration : less Nyangezi (Walungu), Uvira, than 1,500ppm. Dominant ions : Na+ - Mahyuza (Kabare), Kankule, =200ppm, HCO3 = 800ppm. (Demissie, G. Maziba, Muganzo. 2010).

Odhipio et al.

Table 1: Description of thermal springs in the eastern part of DRC (Cont'd) N° Name or location Remarks and additional references

6 Ulindi (Ilindi) River Water is sulfurous and their temperature varies basin: between 40°C - 50°C. (Gerald et al., 1965; Demissie, G. 2010; Makuku, L. 2019) Nyaluindja, Lualatshi, Lubuka and Eight other springs

7 valley: No available data. Luwangi, , Mokindwa and Minyove

8 Elila River basin: Most of waters are saline, with the deposits of sulfur. Temperature is between 55°C - 95°C. Mount Kasongo, Pene (Demissie, G. 2010; Makuku, L. 2019) Kabonde and Tchavula Kitutu and 19 other springs

9 valley Water issues from schist and is saline. near Kibombo: TDS = 33,360 ppm. Principal chemical Kihimbi and Lufubu, constituents: CaS04 (1,791 ppm); CaCl (3,747 Piani Mimba (Pene ppm); NaCl (18,494 ppm). (Passau, 1923; Gerald et Sipo) group, 12 km al., 1965; Mathieu, 1913) west of Lufubu spring.

10 Luama River basin: Clear water with temperature varying between 45°C and 84°C. Deposits of sulfur. (Demissie, G. 2010; Basikabusi, Makuku, L. 2019) Basimakule and 15 other springs

11 Luika River basin: These springs are not very hot, their temperature is Muesse and Kilenga about 35°C. (Demissie, G. 2010; Makuku, L. 2019)

12 Westside of the The temperature of water ranges from 96 - 103°C, northern part of Lake pH : 6.5 and SiO2 concentration of about 210ppm. Tanganyika: Water is sulfurous. (Demissie, G. 2010; Gerald et al., 1965; Makuku, L. 2019) Uvira, Cap Banza, pemba brine and Mutarnbula Odhipio et al.

13 Pakundi, in Lukuga The thermal water is bubbling up in a marshy River basin. region, the temperature of the stream (a little upstream) is 46°C. According to Stanley, this water must hold a lot of iron in solution, as an evidence of the ocher color with which plants and herbs are dyed. (Mathieu, 1913)

Table 1: Description of thermal springs in the eastern part of DRC (Cont'd) N° Name or location Remarks and additional references

14 Kiabukwa and This hot spring has a very marked saline flavor and Tshapona, between is exploited by the natives to extract salt. Cornet, Lomami and Luembe 1906; Mathieu, 1913) Rivers

15 basin : The thermal springs of Kalonga near Kisabi, have a saline composition and a temperature of 60°C, their Kisabi, Luona Mbalai, waters ooze from the joints of stratification of the Sanga and Luiboso rocks. (Gerald et al., 1965; Mathieu, 1913)

16 Westside of the Sulphated waters with sodium chlorides and southern part of Lake sodium carbonates. Their emergence temperature is Tanganyika: average, varying between 40 and 70°C, they sometimes release a few odorless gas bubbles and Rutuku, Kayungwa, have a saline taste. (Cornet, 1906; Mathieu, 1913; Kakonta, Kianza, near Makuku, L. 2019) Tampa and N'Ganza

17 Vicinity of Lake Clear water, emergence temperature close to Upemba: boiling (> 70°C), sensitive odor of hydrogen sulphide, white calcareous deposit, spongy, deposit Kafungwe, Katapena, of sulfur caused by algae. (Cornet, 1906; Mathieu, Konkula and 10 other 1913; Gerald et al., 1965) springs

18 basin: Sulphated and chlorinated waters, sometimes strongly calcareous, bubbling out at low Moashia, Tanda temperature (between 30 and 35°C) through the Mukola, Kashiba, stratification joints of the upright primary layers of Basumba and the Moachia system. (Mathieu, 1913; Cornet, 1906; Manjakito fault Demissie, G. 2010)

In total, 18 different regions have been identified (Table 1) from the North to the South of the Eastern part of the DR Congo. These regions have hot springs of different temperature, different chemical composition (Mambo et al., 2008) and are hosted in various country rocks. They are all along the western branch of the East African Rift system as shown in Figure 4. Odhipio et al.

Figure 4: Location of thermal springs in eastern DRC (Makuku, 2019).

5. Discussion & Conclusion The East of the DRC is full of enormous geothermal potential, with numerous surface manifestations along the western branch of the rift (Gerald et al., 1965). Surface geothermal manifestations are dominated by hot springs which are directly related to the presence of fractures and cracks in these geological formations. These thermo- mineral springs are found in different hydrographic basins of rivers and lakes in the Katanga region (Makuku, 2019; Mathieu, 1913; Cornet, 1906), in the Kivu region where they seem to be bordered by fractures (Mukandala et al., 2018; Mambo et al., 2008; Boutakoff, 1933) and in the various depressions in Ituri (Luse and Makonga, 2019, Passau, 1933). Most of these springs are relatively hot (Gerald et al., 1965). Their various positions in space coincide with the fracture networks of the Kibarian belt formations and with those of the Karagwe - Ankole series (Figure 3). These formations are folded in a general northeast direction which, from Kiambi, bends to take a north-south direction (Mathieu, 1913) The chemical composition of these thermal waters is dominated by the abundant presence of sulphide and salt minerals for certain sources in the Elila river basin, Lualaba (Passau, 1923), Luvua and the western part of the south of Lake Tanganyika (Cornet, 1906). They are also highly enriched in hydrogeno-carbonate minerals Odhipio et al.

(Mambo et al., 2008). Furthermore, there are tuff deposits and significant emission of CO2 in those which are located in the volcanic region around Lake Kivu (Passau, 1933). Apart from orogenic movements due to tangential pressures, there are examples of relatively recent vertical movements in eastern DRC, giving rise to sagging regions or Graben. These movements are of particular interest to us, as the traces of the fractures are often punctuated by geothermal manifestations (Figure 3).

REFERENCES

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