TY - JOUR
T1 - Zinc-rich clays in supergene non-sulfide zinc deposits
AU - Choulet, F.
AU - Buatier, M.
AU - Barbanson, L.
AU - Guégan, R.
AU - Ennaciri, A.
N1 - Funding Information:
The authors are indebted to Managem Company for providing access to the Bou Arhous Mine and for having supported bulk rock analyses in their labs. We also thank Goka Katrawi for CEC measurements and Didier Convert-Gaubier for thin-section preparation. This study benefited from a research grant given by the Région Centre for the 2011–2014 CALAMINES project and from a financial support of Région Franche-Comté through the 2014 “Franco-Suisse” Argzinc project. Access to SEM facilities of the MIMENTO center was made in the frame of cooperative projects in the Renatech network. The authors thank Editor-in-Chief Bernd Lehmann and Associate Editor Hartwig Frimmel for handling manuscript and two anonymous referees, who provided constructive reviews that greatly improved the manuscript.
Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illite, and smectite) present evidence of stratification that reflects internal sedimentation processes during the karst evolution. White clays contain 7-Å clay mineral/smectite irregular interstratified minerals with less than 20 % of smectite layers. Willemite is partially dissolved and is surrounded by authigenic zinc clay minerals. Together with XRD results, WDS analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite. CEC measurements support that zinc is only located within the octahedral sheets. These new results support the following process: (i) dissolution of willemite, leading to release of Si and Zn, (ii) interaction between Zn-Si-rich solutions and residual-detrital clays, and (iii) dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas.
AB - The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illite, and smectite) present evidence of stratification that reflects internal sedimentation processes during the karst evolution. White clays contain 7-Å clay mineral/smectite irregular interstratified minerals with less than 20 % of smectite layers. Willemite is partially dissolved and is surrounded by authigenic zinc clay minerals. Together with XRD results, WDS analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite. CEC measurements support that zinc is only located within the octahedral sheets. These new results support the following process: (i) dissolution of willemite, leading to release of Si and Zn, (ii) interaction between Zn-Si-rich solutions and residual-detrital clays, and (iii) dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas.
KW - Clay minerals
KW - Karst
KW - Morocco
KW - Supergene zinc deposits
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U2 - 10.1007/s00126-015-0618-8
DO - 10.1007/s00126-015-0618-8
M3 - Article
AN - SCOPUS:84944563073
VL - 51
SP - 467
EP - 490
JO - Mineralium Deposita
JF - Mineralium Deposita
SN - 0026-4598
IS - 4
ER -