The Mesoproterozoic Karagwe-Ankole Belt (formerly the NE Kibara Belt): The result of prolonged extensional intracratonic basin development punctuated by two short-lived far-field compressional events

Fernández‐Alonso, M. Carmen; Cutten, H.; Waele, Bert De; Tack, L.; Tahon, A.; Baudet, Daniël; Barritt, S.D.

doi:10.1016/j.precamres.2012.06.007

Cited by 150 publications

(118 citation statements)

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“…Some of them, including the Kisenge deposit, are located along the margins of the proto-Congo Craton, which included the Gabon and São Francisco blocks (Fernandez-Alonso et al, 2012).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The age of supergene manganese deposits in Katanga and its implications for the Neogene evolution of the African Great Lakes Region

Putter

Ruffet

Yans

et al. 2015

Ore Geology Reviews

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International audienceSupergene manganese deposits commonly contain K-rich Mn oxides with tunnel structure, such ascryptomelane, which are suitable for radiometric dating using the 39Ar–40Ar method. In Africa, Mn depositshave been dated by this method for localities in western and southern parts of the continent, whereas onlysome preliminary data are available for Central Africa. Herewe present new39Ar–40Ar ages for Mnoxide samplesof the Kisenge deposit, in southwestern Katanga, Democratic Republic of the Congo. The samples represent supergeneMn oxide deposits that formed at the expense of primary Paleoproterozoic rhodochrosite-dominatedcarbonate ores. Main phases of Mn oxide formation are dated at c. 10.5 Ma, 3.6 Ma and 2.6 Ma for a core thatcrosses a mineralized interval. The latter shows a decrease in age with increasing depth, recording downwardpenetration of a weathering front. Surface samples of the Kisenge deposits also record a ≥c.19.2 Ma phase, aswell as c. 15.7 Ma, 14.2 Ma and 13.6 Ma phases. The obtained ages correspond to distinct periods of paleosurfacedevelopment and stability during the Mio-Pliocene in Katanga. Because Katanga is a key area bordered to theNorth by the Congo Basin and to the East by the East African Rift System, these ages also provide constraintsfor the geodynamic evolution of the entire region. For the Mio-Pliocene, the Kisenge deposits record ages thatare not systematically found elsewhere in Africa, although the 10.5–11 Ma event corresponds to a roughly simultaneousevent in the Kalahari Manganese Field, South Africa. The rest of the Katanga paleosurface record differssomewhat fromrecords for other parts of Africa, forwhich older, Eocene ages have been obtained. This differenceis most probably related to the specific regional geodynamic context: uplift of the East African Plateau, with associatederosion, and the opening of the East African Rift System at c. 25 Ma are events whose effects, in thestudy area, interfere with those of processes responsible for the development of continent-wide paleosurfaces

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“…Some of them, including the Kisenge deposit, are located along the margins of the proto-Congo Craton, which included the Gabon and São Francisco blocks (Fernandez-Alonso et al, 2012).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The age of supergene manganese deposits in Katanga and its implications for the Neogene evolution of the African Great Lakes Region

Putter

Ruffet

Yans

et al. 2015

Ore Geology Reviews

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“…The lithostratigraphy of the Akanyaru supergroup in central Rwanda is subdivided into four successive units: from bottom to top, the Gikoro, Pindura, Cyohoha and Rugezi groups ( Figure 1; [10,21,22]). The rocks of the KAB were intruded by several generations of S-type granites (e.g., [17]).…”

Section: Geologic Setting Of Tungsten Mineralizationmentioning

confidence: 99%

“…This anticline is composed of Mesoproterozoic rocks, which belong to the Gikoro and Pindura groups of the Akanyaru supergroup ( Figure 1; [21,22]). The core of the anticline has been intruded by granites.…”

Section: Geologic Setting Of Tungsten Mineralizationmentioning

confidence: 99%

“…The thick W-mineralized bedding-parallel quartz veins are also typically hosted by the carbonaceous shales, where they formed along bedding-parallel parting planes. These veins are interpreted to be related to the intrusion of the G4-granites, which were emplaced in the context of post-collisional relaxation [5,22,23]. Both types of bedding-parallel veins are often crosscut by subvertical veins, which are at a high angle to bedding.…”

Section: Geologic Setting Of Tungsten Mineralizationmentioning

confidence: 99%

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Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

et al. 2013

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Tungsten mineralization in hydrothermal quartz veins from the Nyakabingo, Gifurwe and Bugarama deposits in central Rwanda occurs as the iron-rich endmember of the wolframite solid solution series (ferberite) and in the particular form of reinite, which represents a pseudomorph of ferberite after scheelite. Primary ferberite, reinite and late secondary ferberite are characterized by their trace element chemistry and rare earth element patterns. The replacement of scheelite by ferberite is also documented in the trace element composition. Primary ferberite shows high Mg, Zn, Sc, V, Nb, In and Sn concentrations, but very low Ca, Pb, Sr and Ba contents. Reinite and late secondary ferberite display an uncommon trace element composition containing high concentrations of Ca, Pb, Sr, Ba, As and Ga, but very low levels in Sn, Zr, Hf, In, Ti, Sc, Nb, Ta, Mg and Zn. Late secondary ferberite replacing primary ferberite is characterized by additional enrichments in Bi, Pb, As and Sb. The rare earth element patterns of reinite and secondary ferberite are also similar to hydrothermal scheelite. The formation of the tungsten deposits in central Rwanda is interpreted to be epigenetic in origin, and the hydrothermal mineralizing fluids are related to the intrusion of the G4-granites.

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“…They intruded the Mesoproterozoic rocks of the KaragweAnkole belt around 1375 Ma and form a SW-NE alignment of nine intrusions in Burundi, with further continuation towards Tanzania (Fig. 1;Fernandez-Alonso et al, 2012). Several drilling campaigns have been executed between 1970 and 1990 to explore the nickel and PGE potential of these intrusions (PNUD-UNDP, 1977;Exploration und Bergbau Gmbh, 1985;Deblond, 1994;Deblond & Tack, 1999).…”

Section: Introductionmentioning

confidence: 99%

Platinum group element mineralization at Musongati (Burundi): concentration and Pd-Rh distribution in pentlandite

Paredis¹,

Muchez²,

Dewaele³

2017

Geol. Belg.

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ABSTRACT. The mafic-ultramafic intrusions of the Karagwe-Ankole belt in Burundi are considered as a new potential source for platinum group elements (PGE). The intrusions have mainly been studied for their PGE potential with regard to PGE concentration, but the mineralogical distribution of PGE has not been examined to the same level. This study focuses on the Pd and Rh distribution in pentlandite of ultramafic rocks of the Musongati layered intrusion. The results are based on whole rock and pentlandite analyses which were incorporated into a mass balance. Palladium proportions in pentlandite vary between 4 and 69%. Rhodium is present in proportions ranging from 1-39% in pentlandite. Other PGE distributions could not be determined in pentlandite due to concentrations below detection limits. The results from this study demonstrate that Pd and Rh are hosted by sulfides since sulfur saturation of the magma occurred early on, perhaps before or simultaneously with the precipitation of silicate minerals. Based on these findings, a preliminary model for the mineralization of PGE in the Musongati intrusion is proposed.KEYWORDS: mafic-ultramafic, layered intrusion, Karagwe-Ankole belt, LA-ICP-MS, NiS FA, pentlandite, mass balance, sulfur saturation.(see further; e.g. Robb, 2005;Kennedy et al., 2013;Kennedy, 2014). A second model is the sulfide fractionation model, which is based on physical and chemical processes where an immiscible sulfide liquid incorporates the major part of PGE (see further; e.g. Dare et al., 2010;Chen et al., 2015). A third, relatively newer model, proposed by e.g. Mungall et al. (2015) is that of flotation of sulfide melt on vapor bubbles, in which the PGE are incorporated during their way up. Knowledge about where and in which phase(s) the PGE occur is, therefore, essential to obtain an insight in the ore-forming processes and hence to assess their recovery from raw materials.In this paper, the results of the investigations for the concentration of PGE in mafic-ultramafic rocks and the Pd and Rh distribution in pentlandite from the Musongati intrusion in Burundi will be discussed. The results are based on whole rock and sulfide phase analyses that were incorporated into a mass balance to calculate the Pd and Rh distribution. Based on these data a preliminary model for the PGE mineralization of the Musongati intrusion is proposed.

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The Mesoproterozoic Karagwe-Ankole Belt (formerly the NE Kibara Belt): The result of prolonged extensional intracratonic basin development punctuated by two short-lived far-field compressional events

Cited by 150 publications

References 45 publications

The age of supergene manganese deposits in Katanga and its implications for the Neogene evolution of the African Great Lakes Region

The age of supergene manganese deposits in Katanga and its implications for the Neogene evolution of the African Great Lakes Region

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

Platinum group element mineralization at Musongati (Burundi): concentration and Pd-Rh distribution in pentlandite

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