Allochthonous surface alteration of Ni-laterites

Schellmann, W.

doi:10.1016/0009-2541(89)90044-2

Cited by 18 publications

(8 citation statements)

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“…Pour de nombreux auteurs dont Jolliff et al (1986), la tourmalinite est associée à des intrusions granitiques; elle peut aussi se former par métamorphisme de dépôts de tourmaline. Fieremans et Paepe (1982) (Trescases, 1975;Golightly, 1981;Schellmann, 1989;Freidrich et al, 1990;Marker et al, 1991). La base, autochtone, est issue de l'altération de la roche sous-jacente; alors que la partie sommitale semiautochtone est un mélange de produits ferrugineux issus M. OUANGRAWA Figure 10: Diffractogramme de rayon X de la tourmalinite de la roche ultrabasique et de minéraux provenant des roches acides.…”

Section: Ouangrawaunclassified

L’or, le zircon et la tourmaline : Traceurs de l’origine des materiaux des profils lateritiques d’afrique

Ouangrawa¹,

Yongue²

2009

African Journal of Science and Technology

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Les épais profils latéritiques des zones tropicales sont reconnus comme de vieux sols ayant subi plusieurs cycles d'évolution au cours du temps. Néanmoins, ils contiennent des minéraux peu altérables comme l'or, le zircon et la tourmaline qui résistent au fil des différents processus dynamiques de la surface. Ces minéraux résiduels, utilisés comme traceurs de leur genèse et de leur évolution, permettent d'identifier les matériaux des profils et de démontrer la filiation ou l'absence de filiation avec le substratum basal. En zone soudano-sahélienne au Burkina Faso, dans un environnement aurifère, les transports mécaniques à plus ou moins grande distance ont accumulé l'or et le zircon au dessus de granites stériles. Les transferts chimiques ferrugineux ont cimenté et protégé ce matériel allochtone, formant une cuirasse. En zone tropicale humide au Cameroun, dans un environnement ultrabasique, les transferts chimiques précisément alumineux, à partir des roches acides avoisinantes, ont favorisé l'individualisation des phases manganésifères porteuses de cobalt et de nickel. Ils s'accompagnent de transferts mécaniques mis en évidence par la présence de tourmaline résiduelle dans la partie supérieure des profils, révélée ainsi remaniée semi-autochtone. Mots-clés : Altération supergène-transferts-or-zircon-tourmaline-profil latéritique.

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Section: Ouangrawaunclassified

L’or, le zircon et la tourmaline : Traceurs de l’origine des materiaux des profils lateritiques d’afrique

Ouangrawa¹,

Yongue²

2009

African Journal of Science and Technology

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“…Semi-autochthonous horizons constitute the topmost portion of the weathering covers overlying the ultramafic complexes. They correspond to the "terres rouges" of New Caledonia (Trescases, 1975 ), the "transported limonites" of Golightly (1981 ), the "transported overburden" of Butt and Nickel ( 1981 ) and the "allochthonous surface layers" of Schellmann ( 1989 ). Their geochemical and mineralogical features indicate that they consist of a mixture of autochthonous Fe-Cr-rich ferruginous material and transported AI-Si-Ti-Zr-rich kaolinitic material.…”

Section: The Laterite Covers --Results and Discussionmentioning

confidence: 99%

“…The parameters which favour the enrichment of Ce and other REES in lateritic weathering profiles above ultramafics are: --occurrence of ultramafic Mn-rich rocks and alkaline-peralkaline REE-rich rocks in close spatial association; flOW and accumulation of REE-enriched solutions in the base of small depressions. Semi-autochthonous laterites are not restricted to the depressions of the peridotite karst, but may also occur as extensive weathering covers (Schellmann, 1989). Their camouflaging effect for the identification of ultramafic rocks and related mineralizations is common.…”

Section: Discussionmentioning

confidence: 99%

Control of the distribution of Mn, Co, Zn, Zr, Ti and REEs during the evolution of lateritic covers above ultramafic complexes

Marker¹,

Friedrich

Carvalho³

et al. 1991

Journal of Geochemical Exploration

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Laterites above ultramafic complexes in Brazil and the Philippines consist of in-situ (autochthonous) and partly transported (semi-autochthonous) horizons. Enrichment and distribution of minor and trace elements in the laterites are controlled by weathering processes and the morphology of the peridotite massifs. Mn and Co migrate towards the base of doline-like depressions of the peridotite karst where they precipitate in the ferruginous horizon above the saprolite, due to rising pH and concentration of the solution. Mass balance calculations reveal absolute enrichment of Mn and Co and depletion of Zn and Cr. Semi-autochthonous laterites represent a mixture of Fe-Cr-rich limonitic material derived from ultramafic rocks and Al-Si-Ti-Zr-rich kaolinitic material derived from sialic rocks. They may reveal unusually high contents of A1203, SiO2, TiO2 and Zr, thus camouflaging the underlying ultramafic bedrock. During and after deposition of semi-autochthonous laterites, acidic leaching under humid (sub-) tropical climate leads to the mobilization of REES from the weathering products of sialic rocks. Subsequent migration and precipitation of REES together with Mn at the base of depressions result in concentrations of predominantly Ce which under favourable conditions exceed 0.5 wt.%. High proportions of sialic weathering material in laterites can be expected in geological settings where ultramafic and sialic rocks occur in close spatial association. Enrichment of REES in weathering profiles above ultramafics is favoured by the abundance of weathering material from REErich alkaline rocks like those of the Alkaline Complex of Jacupiranga, Brazil.

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“…Petrography and geochemistry of ultramafic rocks from which Ni laterite deposits developed are documented in Myanmar [20,67,[73][74][75]. In the Central Ophiolite Belt, the weathering profile of the Budaung Ni laterite is developed on serpentinite, likely metamorphosed harzburgite [20].…”

Section: Ultramafic Bedrock Types and Characteristicsmentioning

confidence: 99%

“…Serpentine with a small amount of chromite and magnetite is common in the Budaung bedrock, which contains 36.1 wt.% SiO 2 , 40.2 wt.% MgO, and 0.38 wt.% NiO [20]. The Tagaung Taung Ni laterite deposit of the Eastern Ophiolite Belt was formed on massive serpentinites and peridotites composed of harzburgite and dunite [20,67,[73][74][75]. The main minerals in these rocks are olivine, serpentine, orthopyroxene, smectite, montmorillonite, and minor amounts of enstatite, magnetite, and chromite [20,67,74].…”

Section: Ultramafic Bedrock Types and Characteristicsmentioning

confidence: 99%

Ni(Co) Laterite Deposits of Southeast Asia: A Review and Perspective

Soh Tamehe,

Zhao,

et al. 2024

Minerals

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Southeast Asia has great potential for mineral exploration, and this region is well-known to host huge economic ore deposits located in complex tectonic terranes. Amongst these ore deposits, the Ni(Co) laterite deposits are mainly distributed in Indonesia, the Philippines, and Myanmar. There are two main types of Ni(Co) laterite deposits consisting of hydrous Mg silicate (or garnierite) and oxide ores, with limited development of clay silicate type. These deposits are influenced and controlled by the lithology of ultramafic bedrock, topography, climate, weathering, structures, and tectonic environment. The degree of bedrock serpentinization has an important influence on the grade of Ni laterite ore. Given the growing demand of modern society for Ni(Co) ore resources, deep research should be focused on a better understanding of the genesis of this laterite deposit and geological features of Ni(Co) ore, as well as its exploration applications in southeastern Asia. Improving current research and exploration methods by means of cutting-edge technologies can enhance the understanding of the Ni(Co) enrichment mechanism in weathered laterite and lead to the discovery of new deposits in Southeast Asia. Ni(Co) laterite deposits from this region, especially Indonesia and the Philippines, have the potential to be a source of scandium, rare earth elements, and platinum group elements.

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Allochthonous surface alteration of Ni-laterites

Cited by 18 publications

References 1 publication

L’or, le zircon et la tourmaline : Traceurs de l’origine des materiaux des profils lateritiques d’afrique

L’or, le zircon et la tourmaline : Traceurs de l’origine des materiaux des profils lateritiques d’afrique

Control of the distribution of Mn, Co, Zn, Zr, Ti and REEs during the evolution of lateritic covers above ultramafic complexes

Ni(Co) Laterite Deposits of Southeast Asia: A Review and Perspective

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