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Pedro H.s. Bastos - One of the best experts on this subject based on the ideXlab platform.
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Mineralogy and Geochemistry of Laterites from the Morro dos Seis Lagos Nb (Ti, REE) Deposit (Amazonas, Brazil).
Ore Geology Reviews, 2017Co-Authors: Arthur L. Giovannini, Luc Barbanson, Artur C. Bastos, Claudio G. Porto, Vitor P. Pereira, Luc Takehara, Pedro H.s. BastosAbstract:The Morro dos Seis Lagos niobium deposit (2897.9 Mt at 2.81 wt.% Nb2O5) is associated with Laterites formed by the weathering of siderite carbonatite. This iron-rich lateritic profile (>100 m in thickness) is divided into six textural and compositional types, which from the top to the base of the sequence is: (1) pisolitic laterite, (2) fragmented laterite, (3) mottled laterite, (4) purple laterite, (5) manganiferous laterite, and (6) brown laterite. All the Laterites are composed mainly of goethite (predominant in the lower and upper varieties) and hematite (predominant in the intermediate types, formed from goethite dehydroxylation). The upper Laterites were reworked, resulting in goethite formation. In the manganiferous laterite (10 m thick), the manganese oxides (mainly hollandite, with associated cerianite) occur as veins or irregular masses, formed in a late event during the development of the lateritic profile, precipitated from a solution with higher oxidation potential than that for Fe oxides, closer to the water table. Siderite is the source for the Mn. The main Nb ore mineral is Nb-rich rutile (with 11.26 – 22.23 wt.% Nb2O5), which occurs in all of the Laterites and formed at expense of a former secondary pyrochlore, together with Ce-pyrochlore (last pyrochore before final breakdown), Nb-rich goethite and minor cerianite. The paragenesis results of lateralization have been extremely intense. Minor Nb-rich brookite formed from Nb-rich rutile occurs as broken spherules with an “oolitic” (or Liesegang ring structure). Nb-rich rutile and Nb-rich brookite incorporate Nb following the [Fe3+ + (Nb, Ta) for 2Ti] substitution and both contain up to 2 wt.% WO3. The Laterites have an average Nb2O5 content of 2.91 wt.% and average TiO2 5.00 wt.% in the upper parts of the sequence. Average CeO2 concentration increases with increasing depth, from 0.12 wt.% in the pisolitic type to 3.50 wt.% in the brown laterite. HREE concentration is very low.
Salvador Gali - One of the best experts on this subject based on the ideXlab platform.
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Discovery of Ni-smectite-rich saprolite at Loma Ortega, Falcondo mining district (Dominican Republic): geochemistry and mineralogy of an unusual case of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite
Mineralium Deposita, 2017Co-Authors: Esperanca Tauler, Thomas Aiglsperger, Joaquín A. Proenza, John F. Lewis, Francisco Longo, Cristina Domenech, Tamara Gallardo, Cristina Villanova-de-benavent, Salvador GaliAbstract:Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-Laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite deposit for Loma Ortega would be more appropriate.
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discovery of ni smectite rich saprolite at loma ortega falcondo mining district dominican republic geochemistry and mineralogy of an unusual case of hybrid hydrous mg silicate clay silicate type ni laterite
Mineralium Deposita, 2017Co-Authors: Esperanca Tauler, Thomas Aiglsperger, Joaquín A. Proenza, John F. Lewis, Francisco Longo, Cristina Villanovadebenavent, Cristina Domenech, Tamara Gallardo, Salvador GaliAbstract:Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-Laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite deposit for Loma Ortega would be more appropriate.
Sanat Kumar Guchhait - One of the best experts on this subject based on the ideXlab platform.
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Geochronology of Laterites
SpringerBriefs in Geography, 2019Co-Authors: Sandipan Ghosh, Sanat Kumar GuchhaitAbstract:There are marked similarities in between Laterites of India and Australia because these continents have moved from polar to tropical palaeolatitudes over the past 80 million years. On the basis of palaeolatitudes and laterite magnetizations, the favourable optimum climate of laterite formation was prevailed in India from Late Cretaceous to Late Tertiary. Consequently, the Laterites in the northern peninsula should be older than those in the south as per drifting of the Indian plate. In this chapter, the age determination, span of lateritization event, and dating data analysis are included to draw significant information about the geochronology of Laterites.
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Laterite and Society
SpringerBriefs in Geography, 2019Co-Authors: Sandipan Ghosh, Sanat Kumar GuchhaitAbstract:The study area is presently characterized as low-relief plateau fringe region where the primary and secondary Laterites are overlain on the Rajmahal Basalts and towards east this lateritic Rarh plain merges with the GBM Delta. Now it is necessary to examine the importance of Laterites in the human society and impact of ferruginous properties in resource utilization. In this section, the economic significance of Laterites, productivity of latosols, potentiality of geotourism, and soil erosion issue are discussed to get few inferences on the significance of laterite to human.
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Palaeogeographic Significance of Laterites
SpringerBriefs in Geography, 2019Co-Authors: Sandipan Ghosh, Sanat Kumar GuchhaitAbstract:Many researchers have reliability on the Laterites and weathered zones as palaeoclimatic indicators and as morpho-stratigraphic markers, because that ferruginous facies were the products or regolith of past weathering processes under suitable geo-climatic conditions which are not prevailing today. The residual laterite profiles of the Bengal Basin are the fossil type formed in past geological ages when climatic conditions were favourable for lateritization. These Laterites were generally formed under an oxic atmosphere in the presence of abundant terrestrial biomass in an acidic environment, elevated atmospheric carbon dioxide, exceptional fossil wood preservation, and intense deep basal weathering of basalts, dolerite, gneiss, sandstones, and Neogene gravelly sediments of Bengal Basin. In this chapter, it is tried to unearth the palaeogenesis, palaeoclimatic implication, and tectono-geomorphic evolution of Laterites in the shelf zone of Bengal Basin.
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Characterization of Secondary Laterite Profiles
SpringerBriefs in Geography, 2019Co-Authors: Sandipan Ghosh, Sanat Kumar GuchhaitAbstract:This section minutely analysed the profiles of low-level or ex situ Laterites which separate the lithological formations of Archaean, Gondwana, and Tertiary gravels from the Sijua and Chuchura Formations (Quaternary Alluvium) deposited over the shelf zone of Bengal Basin between Pliocene and Pleistocene. The secondary Laterites are specifically found as the dissected interfluves in Rampurhat, Illambazar, Bolpur, Kanksa, Ausgram, Bishnupur, Garhbeta, and Kharagpur through the variations of horizons are still observed. The presence of a subsurface layer of kaolinitic clay reddened from above by ferro-colloids and of rounded pebbles of different rocks, gravelly appearance of crust and the general absence of conventional horizons of laterite signify a detrital origin (ex situ) in Rarh Plain.
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modes of formation palaeogene to early quaternary palaeogenesis and geochronology of Laterites in rajmahal basalt traps and rarh bengal of lower ganga basin
2019Co-Authors: Sandipan Ghosh, Sanat Kumar GuchhaitAbstract:The present research work deals with the geomorphic evolution of in situ (primary) and ex situ (secondary) types of Laterites (in West Bengal, eastern part of India) which are found as distinct badland terrain and litho-stratigraphic unit, developed in between the eastern fringe of Chotanagpur Plateau (Rajmahal Basalt Traps, Gondwana sedimentary and Archaean rocks) and the western fringe of Bengal Basin (Rarh Bengal). These Laterites are analyzed here to address perennial unanswered questions about their genesis. What are the different modes of lateritization to classify Laterites? What types of climates produce Laterites? When and where were the particular palaeoclimates that formed Laterites? What can Laterites tell us about palaeoenvironment, palaeogeomorphology and other global events of the past? The field studies, detailed profile analysis of lithofacies, geochemical analysis, characterization of various ferricretes, fossil records and OSL dating have emphasized on the primary and secondary origin of Laterites in West Bengal. The primary Laterites (Palaeogene to Neogene) are genetically related to parent rocks, viz., Rajmahal basalt and Gondwana sandstones, but the secondary Laterites are re-cemented ferruginous materials of fluvial fan-deltaic depositions which are related to Early to Late Quaternary tectono-climatic evolution of north-western Bengal Basin. Here the geochronology of few secondary laterite profiles is determined by OSL dating method in three sample sites, representing Late Quaternary palaeogenesis of Laterites and ferruginized sediments (150–35 ka), i.e. Late Pleistocene. The analysis of in situ and ex situ Laterites signifies drifting of Indian plate through ideal tropics from Palaeogene to Early–Late Quaternary and widespread occurrence of basal chemical weathering under strong, optimum and seasonal tropical wet–dry climate than prevail today in this part of West Bengal. The litho-stratigraphic ferruginous unit of Rarh Bengal (formerly the palaeovalleys of ferruginous depositions) was developed as an inverted relief due to prolong gully erosion and neo-tectonic uplift in between the Chotanagpur Foot-hill Fault and Medinipur–Farraka Fault.
Arthur L. Giovannini - One of the best experts on this subject based on the ideXlab platform.
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Mineralogy and Geochemistry of Laterites from the Morro dos Seis Lagos Nb (Ti, REE) Deposit (Amazonas, Brazil).
Ore Geology Reviews, 2017Co-Authors: Arthur L. Giovannini, Luc Barbanson, Artur C. Bastos, Claudio G. Porto, Vitor P. Pereira, Luc Takehara, Pedro H.s. BastosAbstract:The Morro dos Seis Lagos niobium deposit (2897.9 Mt at 2.81 wt.% Nb2O5) is associated with Laterites formed by the weathering of siderite carbonatite. This iron-rich lateritic profile (>100 m in thickness) is divided into six textural and compositional types, which from the top to the base of the sequence is: (1) pisolitic laterite, (2) fragmented laterite, (3) mottled laterite, (4) purple laterite, (5) manganiferous laterite, and (6) brown laterite. All the Laterites are composed mainly of goethite (predominant in the lower and upper varieties) and hematite (predominant in the intermediate types, formed from goethite dehydroxylation). The upper Laterites were reworked, resulting in goethite formation. In the manganiferous laterite (10 m thick), the manganese oxides (mainly hollandite, with associated cerianite) occur as veins or irregular masses, formed in a late event during the development of the lateritic profile, precipitated from a solution with higher oxidation potential than that for Fe oxides, closer to the water table. Siderite is the source for the Mn. The main Nb ore mineral is Nb-rich rutile (with 11.26 – 22.23 wt.% Nb2O5), which occurs in all of the Laterites and formed at expense of a former secondary pyrochlore, together with Ce-pyrochlore (last pyrochore before final breakdown), Nb-rich goethite and minor cerianite. The paragenesis results of lateralization have been extremely intense. Minor Nb-rich brookite formed from Nb-rich rutile occurs as broken spherules with an “oolitic” (or Liesegang ring structure). Nb-rich rutile and Nb-rich brookite incorporate Nb following the [Fe3+ + (Nb, Ta) for 2Ti] substitution and both contain up to 2 wt.% WO3. The Laterites have an average Nb2O5 content of 2.91 wt.% and average TiO2 5.00 wt.% in the upper parts of the sequence. Average CeO2 concentration increases with increasing depth, from 0.12 wt.% in the pisolitic type to 3.50 wt.% in the brown laterite. HREE concentration is very low.
Esperanca Tauler - One of the best experts on this subject based on the ideXlab platform.
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Discovery of Ni-smectite-rich saprolite at Loma Ortega, Falcondo mining district (Dominican Republic): geochemistry and mineralogy of an unusual case of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite
Mineralium Deposita, 2017Co-Authors: Esperanca Tauler, Thomas Aiglsperger, Joaquín A. Proenza, John F. Lewis, Francisco Longo, Cristina Domenech, Tamara Gallardo, Cristina Villanova-de-benavent, Salvador GaliAbstract:Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-Laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite deposit for Loma Ortega would be more appropriate.
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discovery of ni smectite rich saprolite at loma ortega falcondo mining district dominican republic geochemistry and mineralogy of an unusual case of hybrid hydrous mg silicate clay silicate type ni laterite
Mineralium Deposita, 2017Co-Authors: Esperanca Tauler, Thomas Aiglsperger, Joaquín A. Proenza, John F. Lewis, Francisco Longo, Cristina Villanovadebenavent, Cristina Domenech, Tamara Gallardo, Salvador GaliAbstract:Hydrous Mg silicate-type Ni-laterite deposits, like those in the Falcondo district, Dominican Republic, are dominated by Ni-enriched serpentine and garnierite. Recently, abundant Ni-smectite in the saprolite zone have been discovered in Loma Ortega, one of the nine Ni-laterite deposits in Falcondo. A first detailed study on these Ni-smectites has been performed (μXRD, SEM, EPMA), in addition to a geochemical and mineralogical characterisation of the Loma Ortega profile (XRF, ICP-MS, XRD). Unlike other smectite occurrences in laterite profiles worldwide, the Loma Ortega smectites are trioctahedral and exhibit high Ni contents never reported before. These Ni-smectites may be formed from weathering of pyroxene and olivine, and their composition can be explained by the mineralogy and the composition of the Al-depleted, olivine-rich parent ultramafic rock. Our study shows that Ni-Laterites are mineralogically complex, and that a hydrous Mg silicate ore and a clay silicate ore can be confined to the same horizon in the weathering profile, which has significant implications from a recovery perspective. In accordance, the classification of “hybrid hydrous Mg silicate – clay silicate” type Ni-laterite deposit for Loma Ortega would be more appropriate.
