Hostname: page-component-848d4c4894-nr4z6 Total loading time: 0 Render date: 2024-06-02T08:56:48.529Z Has data issue: false hasContentIssue false
  • English
  • Français

Kaolin Deposits from the Northern Sector of the Cunene Anorthosite Complex (Southern Angola)

Published online by Cambridge University Press:  01 January 2024

Giovanna Saviano ,
Maurizio Violo ,
Umberto Pieruccini  and
Emidio Tertulliano Lopes da Silva
Giovanna Saviano*
Affiliation:
Dipartimento Ingegneria Chimica dei Materiali, delle Materie Prime e Metallurgia, Université degli Studi di Roma “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy
Maurizio Violo
Affiliation:
Dipartimento Ingegneria Chimica dei Materiali, delle Materie Prime e Metallurgia, Université degli Studi di Roma “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy
Umberto Pieruccini
Affiliation:
Dipartimento di Scienze della Terra, Université di Siena, Via delle Cerchia, 2, Siena, Italy
Emidio Tertulliano Lopes da Silva
Affiliation:
Department of Mineral Engineering, Faculty of Engineering, “A. Neto” University, C.P. 1756 Luanda, Angola
*
*E-mail address of corresponding author: giovanna.saviano@uniromal.it
Get access Rights & Permissions [Opens in a new window]

Abstract

The Mevaiela kaolin deposits are located in the northern part of the anorthositic-gabbro massif within the Cunene complex (southern Angola) and were formed by the alteration of basic anorthosites and gabbros. The Mevaiela area is part of an elevated region which is located between two extensive NNW-SSE fracture systems. Several kaolinite samples were collected from a quarry (main excavation) and from drill-holes as well as from surficial occurrences in the Cunene complex. Chemical analyses, X-ray diffraction, differential thermal analysis, scanning electron microscopy and isotope analyses were performed in order to model the kaolinite occurrences. The alteration of the anorthosite to kaolin approaching the main excavation is characterized by significant decrease in alkaline-earth and transition metals (Ca, Mg, Fe, Co, Ni and Mn) between the average anorthosite and the kaolin. The crystallinity indices suggest that the kaolin contains kaolinite with a reasonably well ordered structure and near the transition between T (triclinic) and pM (pseudo monoclinic).

Mineral exploration tools have been evaluated during this study to assist in future kaolin exploration in the Cunene anorthosite complex.

Isotopic analysis of O and D indicates that Ca-feldspar alteration is essentially due to meteoric fluids, over a different range of temperatures. Furthermore, the presence of quartz-feldspar veinlets in the kaolinite bodies could be the result of hydrothermal activity linked to post-anorthosite granite intrusions of the so-called ‘red granite’. Kaolinite from Cunene plots on or close to the kaolinite line into the ‘warm temperature in tropical region’ area (surficial samples). Samples from drill-holes plot on the left and show the largest displacement from the KS line; these samples also have a relatively reduced δD range of values (−65 to −98%). However, if supergene processes take place in the presence of waters of meteoric origin at temperatures similar to typical surface temperatures, the clays thus formed should plot either in the vicinity of the KS line or be displaced towards lower δO18 and higher δD, depending on both the temperature and relative proportion of clay to water.

Keywords

AngolaClay-forming FluidsCunene Anorthosite ComplexIsotope AnalysesKaolinMafic Rocks
Type
Research Article
Information
Clays and Clay Minerals , Volume 53 , Issue 6 , December 2005 , pp. 674 - 685
Copyright
Copyright © 2005, The Clay Minerals Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ashwal, L.D. and Twist, D., (1994) The Cunene complex, Angola/Namibia: a composite massif-type anorthosite complex Geological Magazine 131 579–591 10.1017/S0016756800012371.CrossRefGoogle Scholar
Bates, R.L. and Jackson, JA e, (1980) Glossary of Geology 2nd edition Virginia, USA American Geological Institute, Falls Church.Google Scholar
Bird, M.I. and Chivas, A.R., (1988) Stable-isotope evidence for low-temperature kaolinitic weathering and post-formational hydrogen-isotope exchange in Permian kaolinites Chemical Geology (Isotope Geoscience Section) 72 249–265 10.1016/0168-9622(88)90028-0.CrossRefGoogle Scholar
Brindley, G.W. and Robinson, K., (1948) Structures of methalloysite Mineralogical Magazine 28 393–406 10.1180/minmag.1948.028.203.01.CrossRefGoogle Scholar
Bristow, C.M., (1990) The genesis of the China Clays of southwest England: a multistage story 27th Annual Meeting of the Clay Minerals Society 27.Google Scholar
Carvalho, H., (1990) Complexo Gabro-Anortositico do SW de Angola/NW da Namibia Istituto de Investigaçâo Cientifica Tropical, série Ciências da Terra, Lisboa 2 1–66.Google Scholar
Comsti, F.A., (1969) Kaolin deposits of Philippines. Proceedings of the Symposium ‘Kaolin Deposits of the World’, B: Overseas Countries 23rd International Geological Congress 16 67–74.Google Scholar
Damiani, L. and Trautman, F., (1969) Les depots de kaolin francais. Proceedings of the symposium ‘Kaolin Deposits of the World’ 23rd International Geological Congress 15 141–178.Google Scholar
Durrance, E.M. Bromley, A.Y. Bristow, C.M. Heath, M.J. and Penman, J.M., (1982) Hydrothermal circulation and post-magmatic changes in granites of south-west England Proceedings of the Usher Society 5 304–320.Google Scholar
Fehn, U., (1985) Post-magmatic convection related to high heat production granites of south-west England: a theoretical study High Heath Production (HHP) Granites, Hydrothermal Circulation and Ore Genesis London Institution of Mining and Metallurgy.Google Scholar
Fei Zheng, Y., (1993) Calculation of oxygen isotope fractionation in hydroxyl-bearing silicates Earth and Planetary Science Letters 120 247–263 10.1016/0012-821X(93)90243-3.CrossRefGoogle Scholar
Fiori, C. Fabbri, B. and Ravaglioli, A., (1989) Materie Prime Ceramiche: Studi, Ricerche e Tecnologie in Italia .Google Scholar
Fornaseri, M., (1980) Lezioni di Geochimica .Google Scholar
Giral-Kacmarcik, S. Savin, S.M. Nahon, D. Girard, J.P. Lucas, Y. and Abel, L.J., (1998) Oxygen isotope geochemistry of kaolinite in laterite-forming processes, Manaus, Amazonas, Brazil Geochimica et Cosmochimica Acta 62 1865–1879 10.1016/S0016-7037(98)00103-3.CrossRefGoogle Scholar
Gomes, C. Velho, J. and Guimarâes, F., (1994) Kaolin deposit of Mevaiela (Angola), alteration product of anorthosite: assessment of kaolin potential for application in paper Applied Clay Science 9 97–106 10.1016/0169-1317(94)90029-9.CrossRefGoogle Scholar
Grimshaw, R.W., (1971) The Chemistry and Physics of Clays and other Ceramic Materials .Google Scholar
Harris, C. Compton, J.S. and Bevington, S.A., (1999) Oxygen and hydrogen isotope composition of kaolinite deposits, Cape Peninsula, South Africa: low-temperature, meteoric origin Economic Geology 94 1353–1366 10.2113/gsecongeo.94.8.1353.CrossRefGoogle Scholar
Hassanipak, A.A. and Eslinger, E., (1985) Mineralogy, crystal —linity, O18/O16, and D/H of Georgia kaolins Clays and Clay Minerals 33 99–106 10.1346/CCMN.1985.0330203.CrossRefGoogle Scholar
Hinckley, D.N., (1954) Variability in “crystallinity” values among the kaolin deposits of the coastal plain of Georgia and South Carolina Clays and Clay Minerals 11 229–235 10.1346/CCMN.1962.0110122.CrossRefGoogle Scholar
Hinckley, D.N., (1963) Variability in ‘crystallinity’ values among the kaolin deposits of the Coastal Plain of Georgia and South Carolina Proceedings of the 11th National Conference — Clays and Clay Minerals 229–235.CrossRefGoogle Scholar
Hunter, D.R. and Urie, J.C., (1969) Kaolin deposits of Swaziland. Proceedings of the Symposium ‘Kaolin Deposits of the World’, B Overseas Countries 23rd International Geological Congress 16 67–74.Google Scholar
IAEA/WMO, Global Network of Isotope in Precipitation the GNIPDatabase (2001).Google Scholar
IAEA, Isotope Hydrology Information System. The ISOHIS Database (2001).Google Scholar
Jasmund, K. and Lagaly, G., (1993) Tonminerale und Tone Berlin Steinkopf Verlag 38 10.1007/978-3-642-72488-6.CrossRefGoogle Scholar
Keller, W.D., (1977) Scan electron micrographs of kaolins collected from diverse environments of origin—IV. Georgia kaolin and kaolinizing source rocks Clays and Clay Minerals 25 311–345 10.1346/CCMN.1977.0250501.CrossRefGoogle Scholar
Keller, W.D., (1977) Scan electron micrographs of kaolins collected from diverse environments of origin—V. Kaolins collected in Australia and Japan on field trips of the sixth and seventh clay conference Clays and Clay Minerals 25 347–364 10.1346/CCMN.1977.0250502.CrossRefGoogle Scholar
Keller, W.D. Galán, E. and Mattias, P.P., (1977) Scan electron micrographs of clays from field trip localities of the VIII International Kaolin Symposium, Spain and Italy Proceedings of the 8th International Kaolin Symposium and Meeting on Alunite .Google Scholar
Köstlin, E.C., (1974) The Cunene basic complex, northern Southwest Africa Contributions to the Precambrian Geology of Southern Africa 15 123–135.Google Scholar
Lawrence, J.R. Taylor, H.P. Jr., (1971) Deuterium and oxygen-18 correlation: Clay minerals and hydroxides in quaternary soils compared to meteoric waters Geochimica et Cosmochimica Acta 35 993–1003 10.1016/0016-7037(71)90017-2.CrossRefGoogle Scholar
Lawrence, J.R. Taylor, H.P. Jr, (1972) Hydrogen and oxygen isotope systematics in weathering profiles Geochimica et Cosmochimica Acta 36 1377–1393 10.1016/0016-7037(72)90068-3.CrossRefGoogle Scholar
Lombardi, G. and Mattias, P., (1987) The kaolin deposits of Italy L’Industria Mineraria 6 1–34.Google Scholar
Longstaffe, F.J. and Hutcheon, I.E., (1989) Stable isotopes as tracers in clastic diagenesis Burial Diagenesis Ottawa, Ontario Mineralogical Association of Canada 201–277.Google Scholar
Mackenzie, R.C. (1972) Differential Thermal Analysis. Vol. 2, Academic Press, London, 1382 pp.Google Scholar
Marumo, K. Matsuhisa, Y. and Nagasawa, K., (1982) Hydrogen and oxygen isotopic compositions of kaolin minerals in Japan Proceedings of the International Clay Conference 1981 Amsterdam Elsevier Science Publishers 315–320.Google Scholar
Marumo, K. Longstaffe, F.J. and Matsubaya, O., (1995) Stable isotope geochemistry of clay minerals from fossil and active hydrothermal systems, southwestern Hokkaido, Japan Geochimica et Cosmochimica Acta 59 2545–2559 10.1016/0016-7037(95)00149-2.CrossRefGoogle Scholar
Mayer, A. Sinigoi, S. Miguel, L.G. Morais, E. and Petrini, R., (2000) Kibaran ages in the Kunene Anorthositic Complex Geoluanda 2000 International Conference 110.Google Scholar
Mizota, C. and Longstaffe, F.G., (1996) Origin of Cretaceous and Oligocene kaolinites from the Iwaizumi clay deposit, Iwate, northeastern Japan Clays and Clay Minerals 44 408–416 10.1346/CCMN.1996.0440310.CrossRefGoogle Scholar
Morais, E. Sinigoi, S. Mayer, A. and Miguel, L.G., (2000) Kunene gabbro-anorthosite Complex: coalescence of discrete crystal mush intrusion Geoluanda 2000 110.Google Scholar
Murray, H.H. and Bailey, S.W., (1989) Kaolin minerals: their genesis and occurrences Hydrous Phyllosilicates Washington, D.C. Mineralogical Society of America 1–25.Google Scholar
Murray, H.H. and Lyons, S.C., (1956) Correlation of paper coating quality with degree of crystalline perfection of kaolinite Clays and Clay Minerals 4 31–40 10.1346/CCMN.1955.0040105.CrossRefGoogle Scholar
O’Neil, J.R. and Kharaka, Y.K., (1976) Hydrogen and oxygen isotope exchange reaction between clay minerals and water Geochimica et Cosmochimica Acta 40 241–246 10.1016/0016-7037(76)90181-2.CrossRefGoogle Scholar
Pickering, S.M. Jr. and Murray, H.H., (1994) Kaolin Industrial Minerals and Rocks Littleton, Colorado, USA. Society of Mining, Metallurgy and Exploration, Inc. 265–277.Google Scholar
Prasad, M.S. Reid, K.J. and Murray, H.H., (1991) Kaolin: processing, properties and applications Applied Clay Science 6 87–119 10.1016/0169-1317(91)90001-P.CrossRefGoogle Scholar
Range, K.J. Range, A. and Weiss, A., (1969) Fire clay type kaolinite or fire clay mineral? Experimental classification of kaolinite-halloysite minerals Proceedings of the International Clay Conference 3–13.Google Scholar
Rye, R.O. Bethke, P.M. and Wasserman, M.D., (1992) The stable isotope geochemistry of acid sulphate alteration Economic Geology and Bulletin of the Society of Economic Geologists 87 225–262 10.2113/gsecongeo.87.2.225.CrossRefGoogle Scholar
Savin, S.M. and Epstein, S., (1970) The oxygen and hydrogen isotope geochemistry of clay minerals Geochimica et Cosmochimica Acta 34 25–42 10.1016/0016-7037(70)90149-3.CrossRefGoogle Scholar
Savin, S.M. and Epstein, S., (1970) The oxygen and hydrogen isotope geochemistry of ocean sediments and shales Geochimica et Cosmochimica Acta 34 43–63 10.1016/0016-7037(70)90150-X.CrossRefGoogle Scholar
Savin, S.M. and Hsieh, J.C.C., (1998) The hydrogen and oxygen isotope geochemistry of pedogenic clay minerals: Principles and theoretical background Geoderma 82 1-3 227–253 10.1016/S0016-7061(97)00103-1.CrossRefGoogle Scholar
Savin, S.M. Lee, M. and Bailey, S.W., (1988) Isotopic studies of phyllosilicates Hydrous Phyllosilicates (exclusive of micas) Washington, D.C. Mineralogical Society of America 189–223 10.1515/9781501508998-012.CrossRefGoogle Scholar
Schenato, F. and Formoso, M.L.L., (1993) Mineralogical and geochemical aspects of the alteration of the Capivarita anorthosite to kaolin (Brasil) Proceedings of the 10th International Clay Conference 1–149.Google Scholar
Seal, R.R. II and Rye, R.O., (1992) Stable isotope study of water-rock interaction and ore formation, Bayhorse base and precious metal district, Idaho Economic Geology 87 271–287 10.2113/gsecongeo.87.2.271.CrossRefGoogle Scholar
Sheppard, S.M.F., (1977) The Cornubian Batholith, south-west England; D/H and O18/O16 studies of kaolinite and other alteration minerals Journal of the Geological Society of London 133 573–591 10.1144/gsjgs.133.6.0573.CrossRefGoogle Scholar
Sheppard, S.M.F. and Gilg, H.A., (1996) Stable isotope geochemistry of clay minerals Clays and Clay Minerals 31 1–24 10.1180/claymin.1996.031.1.01.CrossRefGoogle Scholar
Sheppard, S.M.F. Nielsen, R.L. and Taylor, H.P., (1969) Oxygen and hydrogen isotope ratio of clay minerals from porphyry copper deposits Economic Geology 64 755–777 10.2113/gsecongeo.64.7.755.CrossRefGoogle Scholar
Silva, ATSF Torquato, J.R. and Kawashita, K., (1973) Alguns dados geocronológicos pelo método K/Ar da regiáo de Vila Paiva Conceiro, Quilengues e Chicomba (Angola) Boletin Serviqos de Geologia e Minas de Angola 24 29–46.Google Scholar
Silva, L.C., (1972) Maciço gabro-anortosítico do SW de Angola, observaçôes na regiáo do Pocolo Revue Facultad de Ciências 17 253–277.Google Scholar
Silva, Z.C.G., (1990) Geochemistry of the gabbro-anorthosite complex of southwest Angola Journal of African Earth Sciences 10 683–692 10.1016/0899-5362(90)90034-C.CrossRefGoogle Scholar
Silva, Z.C.G., (1992) Mineralogy and cryptic layering in the Cunene anorthosite complex of SW Angola and Namibia Mineralogical Magazine 56 319–327 10.1180/minmag.1992.056.384.03.CrossRefGoogle Scholar
Suzuoki, T. and Epstein, S., (1976) Hydrogen isotope fractionation between OH-bearing minerals and water Geochimica et Cosmochimica Acta 40 1229–1240 10.1016/0016-7037(76)90158-7.CrossRefGoogle Scholar
Taylor, H.P. Jr, (1974) The application of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition Economic Geology 69 843–883 10.2113/gsecongeo.69.6.843.CrossRefGoogle Scholar
Vermaak, C.F. and Hunter, D.R., (1981) Cunene anorthosite complex Precambrian Geology in the Southern Hemisphere Amsterdam Elsevier 578–590.Google Scholar