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Title: Pb isotopic constraints on the formation of the Dikulushi Cu-Pb-Zn-Ag mineralisation, Kundelungu Plateau (Democratic Republic of Congo)
Authors: Haest, Maarten ×
Schneider, Jens
Cloquet, Christophe
Latruwe, Kris
Vanhaecke, Frank
Muchez, Philippe #
Issue Date: Apr-2010
Publisher: Springer-Verlag
Series Title: Mineralium Deposita vol:45 issue:4 pages:393-410
Abstract: Base metal-Ag mineralisation at Dikulushi and in other deposits on the Kundelungu Plateau (Democratic Republic of Congo) developed during two episodes. Subeconomic Cu-Pb-Zn-Fe polysulphide ores were generated during the Lufilian Orogeny (c. 520 Ma ago) in a set of E-W- and NE-SW-oriented faults. Their lead has a relatively unradiogenic and internally inhomogeneous isotopic composition (Pb-206/Pb-204 = 18.07-18.49), most likely generated by mixing of Pb from isotopically heterogeneous clastic sources. These sulphides were remobilised and enriched after the Lufilian Orogeny, along reactivated and newly formed NE-SW-oriented faults into a chalcocite-dominated Cu-Ag mineralisation of high economic interest. The chalcocite samples contain only trace amounts of lead and show mostly radiogenic Pb isotope signatures that fall along a linear trend in the Pb-207/Pb-204 vs. Pb-206/Pb-204 diagram (Pb-206/Pb-204 = 18.66-23.65; Pb-207/Pb-204 = 15.72-16.02). These anomalous characteristics reflect a two-stage evolution involving admixture of both radiogenic lead and uranium during a young fluid event possibly c. 100 Ma ago. The Pb isotope systematics of local host rocks to mineralisation also indicate some comparable young disturbance of their U-Th-Pb systems, related to the same event. They could have provided Pb with sufficiently radiogenic compositions that was added to less radiogenic Pb remobilised from precursor Cu-Pb-Zn-Fe polysulphides, whereas the U most likely originated from external sources. Local metal sources are also suggested by the Pb-208/Pb-204-Pb-206/Pb-204 systematics of combined ore and rock lead, which indicate a pronounced and diversified lithological control of the immediate host rocks on the chalcocite-dominated Cu-Ag ores. The Pb isotope systematics of polysulphide mineralisation on the Kundelungu Plateau clearly record a diachronous evolution.
ISSN: 0026-4598
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Geology
× corresponding author
# (joint) last author

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