Structural Control on the Dikulushi Cu-Ag Deposit, Katanga, Democratic Republic of Congo

Abstract

The Dikulushi Cu-Ag deposit is located in the Kundelungu Plateau region in the southeast Katanga province of the Democratic Republic of Congo. The Kundelungu Plateau is a triangular-shaped area to the north of the Lufilian arc, which contains part of the Central African copperbelt, the largest known sediment-hosted copper province in the world. The Lufilian arc and the Kundelungu Plateau comprise Neoproterozoic sedimentary rocks of the Katanga Supergroup that attain an overall thickness of more than 7,000 m. The Lufilian orogeny imposed a northeast-directed shortening on the Kundelungu Plateau region, forming several gentle, northwest-oriented anticlines above subparallel detachment surfaces at depth. A north-northwest-oriented thrust is exposed in the western part of the Dikulushi mine, marked by ductile deformed shale that was transported upward and is in faulted contact with an overlying dolomite-sandstone sequence. This upward emplacement of the shale caused brecciation and the local development of kink folds in the dolomite-sandstone sequence. The brecciated layers in the west and nonbrecciated sandstone layers in the central part of the mine are crosscut by several east-west-and northeast-oriented faults. This complex set of faults produced a damage zone that was a favorable site for the migration of mineralizing fluids. The faults and brecciated layers contain Cu-Pb-Zn-Fe mineralization consisting of chalcopyrite, bornite, and chalcocite, with minor pyrite, arsenopyrite, sphalerite, and galena, with dolomite, calcite, and quartz as gangue minerals.The northeast-oriented fault direction was reactivated several times, with dextral strike-and oblique-slip fault movement. These fault zones were sites of remobilization and enrichment of the previously deposited Cu-Pb-Zn-Fe mineralization. The remobilized sulfides consist of Ag-rich chalcocite, with barite, calcite, and quartz as gangue minerals. The study has shown that the deposit of Dikulushi is structurally controlled by a crosscutting set of east-west-and northeast-oriented faults. Similar structural settings in the mine and in the Dikulushi region represent important future exploration targets.the Dikulushi mine a Cu-Ag ore is mined, with total past production and current reserves estimated at 1.94 Mt, having an average grade of 8.5 percent Cu and 226 g/t of silver (Tassel, 2003). These grades make the Dikulushi orebody one of the richest Cu-Ag deposits in the world, providing an incentive for further exploration on the Kundelungu Plateau.This study attempts to unravel the relationship between deformation and mineralization observed in the Dikulushi mine and to place the structural control of the deposit in a broader context relevant to regional exploration. Geologic SettingThe Dikulushi deposit is located near the northeastern edge of the triangular Kundelungu Plateau, bordered to the west by the Mesoproterozoic Kibaran belt, to the east by the Paleoproterozoic Bangweulu block in Zambia, and to the south by the Lufilian arc (Fig. 1). The sediments in the ...

Numerical modelling of structural controls on fluid flow and mineralization

“…Taylor, 1984;De Roo, 1988;Baudemont and Fedorowich, 1996;Broadbent et al, 1998;Yigit et al, 2003;Jolley et al, 2004;Haest et al, 2007), and shown by the examples of vein-type mineralization in this paper. At camp and deposit scales, such structural controls are represented by strain localization (shear strain and dilation), the formation of linear structures (faults, shear zones and fractures) and the reactivation of pre-existing structures, which in turn influence fluid flow and mineral precipitation.…”

“…fault, thrust-fracture or folds) include: (1) the Silvermines PbeZn deposit in Ireland (Taylor, 1984); (2) Mount Carbine WeSn deposit, Queensland, Australia (De Roo, 1988); (3) Dominique-Peter U deposit, Saskatchewan, Canada (Baudemont and Fedorowich, 1996); (4) Century Zn deposit, Northwest Queensland, Australia (Broadbent et al, 1998); (5) Carlin-type Au deposit in the Gold Bar District, Nevada (Yigit et al, 2003). (6) Au deposits in the Witwatersrand basin (Jolley et al, 2004) and Bendigo, Australia (Schaubs and Wilson, 2002); (7) the CueAg deposits of D. R. Congo (Haest et al, 2007). Studying and understanding of key structural factors controlling mineralization in an area can lead to the determination of exploration targets and the discovery of ore bodies (e.g.…”

Structure and geological history of the Congo Basin: an integrated interpretation of gravity, magnetic and reflection seismic data

“…1000 m thick tabular fluvio‐deltaic red arkoses (Redbeds) can be found, defined as the Inkisi Subgroup in West Congo (Alvarez et al , 1995), the Aruwimi Group in the Lindi–Ubangi region (Verbeek, 1970) and the Upper Kundelungu (Ku3) in the foreland of the Katanga belt. For the latter, it has been described as ‘Plateaux’ Subgroup (Lepersonne, 1974a, 1974b; Dumont et al , 1997; Dumont & Hanon, 2000; Cailteux et al , 2005; Batumike et al , 2006) and recently renamed ‘Biano’ Subgroup by Batumike et al (2007) and Haest et al (2007). Ar‐Ar dating of detritical muscovites form this unit by Master et al (2005) gave a maximum age of 573 Ma (terminal Edicarian), supporting the idea that it has been deposited in the foreland of the Lufilian orogen.…”

Rare earth element fractionation in heterogenite (CoOOH): implication for cobalt oxidized ore in the Katanga Copperbelt (Democratic Republic of Congo)

“…The primary stratiform Cu-Co sulfide mineralization is early syn-diagenetic (Dewaele et al, 2006;El Desouky et al, 2010;Muchez et al, 2008) and occurred around 820 Ma (Selley et al, 2005) and/or after ~750 Ma (Hitzman et al, 2005). Later mineralization events took place before or during the pan-African Lufilian folding (Cailteux et al, 2005;Decrée et al, 2011;Decrée et al, 2014;Dewaele et al, 2006;El Desouky et al, 2009;Haest and Muchez, 2011;Haest et al, 2007;Haest et al, 2009;Kampunzu et al, 2009). In these primary deposits, carrollite (CuCo 2 S 4 ), siegenite ((Ni,Co) 3 S 4 ) and linnaeite (Co 2+ Co 3+ 2 S 4 ) are the most abundant primary cobalt ore minerals.…”