Zircon U-Pb ages and Hf isotope data from the Kukuluma Terrain of the Geita Greenstone Belt, Tanzania Craton: Implications for stratigraphy, crustal growth and timing of gold mineralization

Kwelwa, Shimba; Sanislav, Ioan V.; Dirks, Paul H.G.M.; Blenkinsop, Thomas G.; Kolling, Sergio L.

doi:10.1016/j.jafrearsci.2017.11.027

Cited by 17 publications

(28 citation statements)

References 31 publications

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“…A generalized stratigraphic column for the Kukuluma terrain is presented in Figure 4. This column has been reconstructed from mapping and drilling around the Kukuluma and Matandani pits, as presented in this study, combined with age constraints from intercalated volcaniclastics and cross-cutting porphyry dykes [28]. The Kukuluma terrain is bounded to the west by a major northwest-trending shear zone, which juxtaposes lower greenschist facies meta-sediments of the Central terrain, and lower amphibolite facies mafic to ultramafic meta-basalts at the stratigraphic base of the Kukuluma terrain ( Figure 2; [37]).…”

Section: Stratigraphy Of the Kukuluma Terrainmentioning

confidence: 99%

“…In this paper, a deformation model for the area around the Matandani and Kukuluma pits will be presented, based on detailed mapping and core logs from the pits and surrounding areas. The deformation model will be linked to the relative timing of intrusive units and gold mineralization, and forms the basis for geochemical and geochronological studies in the area [26,28]. [27]: DBST-Dodoma Basement; ELVST-East Lake Victoria; LNST-Lake Nyanza; MAST-Mbulu-Masai; MLEST-Mwanza Lake Eyasi; MMST-Moyowosi-Manyoni; NBT-Nyakahura-Burigi.…”

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confidence: 99%

“…The deformation model will be linked to the relative timing of intrusive units and gold mineralization, and forms the basis for geochemical and geochronological studies in the area [26,28]. [25,28,29]). The insert shows the study area in Figure 3.…”

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confidence: 99%

“…These units were intruded by syn-tectonic igneous complexes of dioritic to tonalitic composition [24][25][26]. The diorite intrusive complex around Nyankanga and Geita Hill were dated at 2686 ± 13 Ma and 2699 ± 9 Ma (U-Pb zircon, [35]), and the intrusive complex around Kukuluma at between 2717 ± 12 Ma and 2667 ± 17 Ma (Figures 2 and 3, [26,28]).…”

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confidence: 99%

“…Detailed structural work in these deposits [24,25] has shown that the mineralization is centered on northwest dipping reverse faults (referred to in Geita Hill as D 6 ) that overprint a complexly folded (referred to in Geita Hill as D [1][2][3][4][5] ) stack of meta-ironstone and chert, and were reactivated as later normal faults at the time of mineralization (called D 8 at Geita Hill). Gold-deposition preferentially occurred along diorite-meta-ironstone contacts exploited by the fracture systems [24,25] after emplacement of a lamprophyre dyke at 2644 ± 3 Ma [35], i.e., [20][21][22][23][24][25][26][27][28][29][30] Ma later than the formation of reverse faults [24].…”

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confidence: 99%

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Archaean Gold Mineralization in an Extensional Setting: The Structural History of the Kukuluma and Matandani Deposits, Geita Greenstone Belt, Tanzania

Kwelwa¹,

Dirks

Sanislav

et al. 2018

Minerals

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Three major gold deposits, Matandani, Kukuluma, and Area 3, host several million ouncez (Moz) of gold, along a~5 km long, WNW trend in the E part of the Geita Greenstone Belt, NW Tanzania. The deposits are hosted in Archaean volcanoclastic sediment and intrusive diorite. The geological evolution of the deposits involved three separate stages: (1) an early stage of syn-sedimentary extensional deformation (D 1 ) around 2715 Ma; (2) a second stage involving overprinting ductile folding (D 2-4 ) and shearing (D 5-6 ) events during N-S compression between 2700 and 2665 Ma, coeval with the emplacement of the Kukuluma Intrusive Complex; and (3) a final stage of extensional deformation (D 7 ) accommodated by minor, broadly east-trending normal faults, preceded by the intrusion of felsic porphyritic dykes at~2650 Ma. The geometry of the ore bodies at Kukuluma and Matandani is controlled by the distribution of magnetite-rich meta-ironstone, near the margins of monzonite-diorite bodies of the Kukuluma Intrusive Complex. The lithological contacts acted as redox boundaries, where high-grade mineralization was enhanced in damage zones with higher permeability, including syn-D 3 hydrothermal breccia, D 2 -D 3 fold hinges, and D 6 shears. The actual mineralizing event was syn-D 7 , and occurred in an extensional setting that facilitated the infiltration of mineralizing fluids. Thus, whilst gold mineralization is late-tectonic, ore zone geometries are linked to older structures and lithological boundaries that formed before gold was introduced. The deformation-intrusive history of the Kukuluma and Matandani deposits is near identical to the geological history of the world-class Nyankanga and Geita Hill deposits in the central part of the Geita Greenstone Belt. This similarity suggests that the geological history of much of the greenstone belt is similar. All major gold deposits in the Geita Greenstone Belt lack close proximity to crustal-scale shear zones; they are associated with intrusive complexes and volcanics that formed in an oceanic plateau rather than subduction setting, and formed late-tectonically during an extensional phase. They are not characteristic of typical orogenic gold deposits.

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Section: Stratigraphy Of the Kukuluma Terrainmentioning

confidence: 99%

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