TY - JOUR
T1 - Alteration and ore distribution in the Proterozoic Mines Series, Tenke-Fungurume Cu-Co district, Democratic Republic of Congo
AU - Fay, I.
AU - Barton, M. D.
N1 - Funding Information:
Acknowledgments This research, which comprised the first author’s MS thesis, has been supported by Freeport-McMoRan Copper & Gold and its Congolese subsidiary, Tenke-Fungurume Mine. Particular thanks are due to Rich Leveille and Ralph Stegen for providing the research opportunity and to Wolf Schuh, Bob North, Joseph Nzita, Sergio Castro-Reino, Linda Dufek, and Pascal Mambwe for their scientific assistance during the project. Further financial support was provided by a grant to HIF from the Society of Economic Geologists and by Science Foundation Arizona through the University of Arizona Institute for Mineral Resources. Thesis committee members Eric Seedorff and Jon Patchett provided helpful guidance and comments. Another committee member, Frank Mazdab, deserves special thanks for helping with the petrographic work and designing the titration experiments. We also thank Bob Downs and Dave Bish for help with mineral characterization, and the reviewers for their helpful comments and suggestions.
PY - 2012/6
Y1 - 2012/6
N2 - Two sediment-hosted stratiform Cu-Co deposits in the Tenke-Fungurume district of the Central African Copperbelt were examined to evaluate the alteration history of the ore-hosting Mines Series and its implications for ore distribution and processing. Core logging and petrography, focused on lithology and timing relationships, outlined a complex alteration sequence whose earliest features include formation of anhydrite nodules and laths, followed by precipitation of dolomite. Later alteration episodes include at least two silica introductions, accompanied by or alternating with two dolomite introductions into the existing gangue assemblages. One introduction of Cu-Co sulfides accompanied the last episode of dolomite alteration, overprinting an earlier generation of ore whose gangue association was unidentifiable. Sulfides and some carbonates were subsequently modified by supergene oxidation, transport, and reprecipitation to 100-200 m depth. Present-day ore distribution resulted from these successive processes. Ore is concentrated in two shale-dominated units on either side of a cavernous silicified dolomite, which is interpreted as the main conduit for the mineralizing fluids. Sulfide ores precipitated at the redox or sulfidation contacts between this dolomite and the shales. Later, supergene fluids dissolved and moved some of the metals, redepositing them as oxides and carbonates. Solubility differences between Cu and Co in supergene conditions caused them to precipitate separately. Thus, modern ore distribution at Tenke-Fungurume results both from original hypogene lithology- and contact-related precipitation and from supergene oxidation, transport, and Cu-Co decoupling. The supergene fluid flow also redistributed gangue minerals such as dolomite, which has an economically important influence on the processing costs of supergene ores.
AB - Two sediment-hosted stratiform Cu-Co deposits in the Tenke-Fungurume district of the Central African Copperbelt were examined to evaluate the alteration history of the ore-hosting Mines Series and its implications for ore distribution and processing. Core logging and petrography, focused on lithology and timing relationships, outlined a complex alteration sequence whose earliest features include formation of anhydrite nodules and laths, followed by precipitation of dolomite. Later alteration episodes include at least two silica introductions, accompanied by or alternating with two dolomite introductions into the existing gangue assemblages. One introduction of Cu-Co sulfides accompanied the last episode of dolomite alteration, overprinting an earlier generation of ore whose gangue association was unidentifiable. Sulfides and some carbonates were subsequently modified by supergene oxidation, transport, and reprecipitation to 100-200 m depth. Present-day ore distribution resulted from these successive processes. Ore is concentrated in two shale-dominated units on either side of a cavernous silicified dolomite, which is interpreted as the main conduit for the mineralizing fluids. Sulfide ores precipitated at the redox or sulfidation contacts between this dolomite and the shales. Later, supergene fluids dissolved and moved some of the metals, redepositing them as oxides and carbonates. Solubility differences between Cu and Co in supergene conditions caused them to precipitate separately. Thus, modern ore distribution at Tenke-Fungurume results both from original hypogene lithology- and contact-related precipitation and from supergene oxidation, transport, and Cu-Co decoupling. The supergene fluid flow also redistributed gangue minerals such as dolomite, which has an economically important influence on the processing costs of supergene ores.
KW - Central African Copperbelt
KW - Gangue acid consumption
KW - Mines Series
KW - Ore distribution
KW - Sediment-hosted deposits
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U2 - 10.1007/s00126-011-0391-2
DO - 10.1007/s00126-011-0391-2
M3 - Article
AN - SCOPUS:84861610831
SN - 0026-4598
VL - 47
SP - 501
EP - 519
JO - Mineralium Deposita
JF - Mineralium Deposita
IS - 5
ER -