A Deep-Water Glauconitization Process on the Ivory Coast—Ghana Marginal Ridge (ODP Site 959): Determination of Fe<sup>3+</sup>-Rich Montmorillonite in Green Grains

Nickel-lateritic ore is the most common source of nickel in Brazil. The Niquelândia deposit, located in State of Goias, is one of the most famous deposits due to the large amounts of nickel associated with both oxidized and mainly silicated ores. The terms oxidized and silicated ores are used to specify two different ores formed exclusively by oxides and silicate (clay) minerals, respectively. The aim of the present study was to characterize thoroughly the silicated ore to identify the Ni-bearing clay minerals and their crystal chemistry in support of developing a better mineral-processing method or optimizing the current one to improve Ni recoveries. X-ray diffraction, chemical analyses, scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy demonstrated that nickel is associated with Ni-rich stevensite and to a lesser extent with Fe-rich montmorillonite. The crystal chemistry performed by FTIR spectroscopy revealed that Ni is present in the octahedral positions, substituting for Mg or Fe, which results in significant chemical and layer-charge heterogeneity in the samples. This heterogeneity seems to be responsible for reduction in Ni recoveries during the hydrometallurgical process.

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“…Another Fe-rich octahedral charged smectite was also described in deep-sea pyrite-rich sediments (Gaudin et al, 2005;Wiewióra et al, 2001).…”

Section: Discussionmentioning

confidence: 77%

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mano

Caner

Petit

et al. 2014

Clays and clay miner.

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“…The term glauconitic is misused to designate green minerals formed in marine environments. Some are totally expandable (Wiewiora et al. , 2001) and should be assigned to nontronite or Fe‐montmorillonite.…”

Section: Discussionmentioning

confidence: 99%

Unusual occurrence of glauconite in a shallow lagoonal environment (Lower Cretaceous, northern Aquitaine Basin, SW France)

2005

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Some minerals are considered to be representative of specific natural environments. Among them glauconite is considered to be formed in marine deep platform conditions. However, the term glauconitic is misused to designate green minerals formed in marine outer‐shelf environments. X‐ray diffraction, scanning electron microscopy and energy‐dispersive X‐ray analyses of individual green materials were carried out leading to the identification of glauconite in the Purbeckian facies. Green glauconite grains predominantly occur as burrow fills and occasionally as faecal pellet replacements. Two depositional environments have been identified from bottom to top of the succession: (1) an argillaceous dolomitic lagoonal sediment formed in saline, shallow water; (2) a marl‐limestone alternation deposited in a brackish water estuary. The crystallochemical properties of the glauconites change abruptly. These findings show that glauconite may form in coastal environments and not only in mid‐shelf to upper deep water platform environments as classically assumed. Moreover, the glauconite composition changes with the chemical conditions imposed by the local environment.

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“…The process of glauconization is often associated with relatively shallow water depths (<1000 m). The core depth of 2347 m is, to our knowledge, one of the deepest water depth where in-situ Glauconite formation has been found yet (see also Wiewiora et al, 2001). …”

Section: Dissolution and Dilution Processesmentioning

confidence: 98%

High Arabian Sea productivity conditions during MIS 13 – odd monsoon event or intensified overturning circulation at the end of the Mid-Pleistocene transition?

et al. 2010

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Abstract. Marine isotope stage (MIS) 13 (∼500 000 years ago) has been recognized as atypical in many paleoclimate records and, in particular, it has been connected to an exceptionally strong summer monsoon throughout the Northern Hemisphere. Here, we present a multi-proxy study of a sediment core taken from the Murray Ridge at an intermediate water depth in the northern Arabian Sea that covers the last 750 000 years. Our results indicate that primary productivity conditions were anomalously high during MIS 13 in the Arabian Sea and led to extreme carbonate dissolution and glauconitization in the deep-sea sediments. These observations could be explained by increased wind driven upwelling of nutrient-rich deep waters and, hence, by the occurrence of an exceptionally strong summer monsoon event during MIS 13, as it was suggested in earlier studies. However, ice core records from Antarctica demonstrate that atmospheric methane concentrations, which are linked to the extent of tropical wetlands, were relatively low during this period. This constitutes a strong argument against an extremely enhanced global monsoon circulation during MIS 13 which, moreover, is in contrast with results of transient climate modelling experiments. As an alternative solution for the aberrant conditions in the Arabian Sea record, we propose that the high primary productivity was probably related to the onset of an intensive meridional overturning circulation in the Atlantic Ocean at the end of the Mid-Pleistocene transition. This may have led to an increased supply of nutrient-rich deep waters into the Indian Ocean euphotic zone, thereby triggering the observed productivity maximum.

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A Deep-Water Glauconitization Process on the Ivory Coast—Ghana Marginal Ridge (ODP Site 959): Determination of Fe³⁺-Rich Montmorillonite in Green Grains

Cited by 35 publications

References 27 publications

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Unusual occurrence of glauconite in a shallow lagoonal environment (Lower Cretaceous, northern Aquitaine Basin, SW France)

High Arabian Sea productivity conditions during MIS 13 – odd monsoon event or intensified overturning circulation at the end of the Mid-Pleistocene transition?

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A Deep-Water Glauconitization Process on the Ivory Coast—Ghana Marginal Ridge (ODP Site 959): Determination of Fe3+-Rich Montmorillonite in Green Grains

Cited by 35 publications

References 27 publications

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Unusual occurrence of glauconite in a shallow lagoonal environment (Lower Cretaceous, northern Aquitaine Basin, SW France)

High Arabian Sea productivity conditions during MIS 13 – odd monsoon event or intensified overturning circulation at the end of the Mid-Pleistocene transition?

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A Deep-Water Glauconitization Process on the Ivory Coast—Ghana Marginal Ridge (ODP Site 959): Determination of Fe³⁺-Rich Montmorillonite in Green Grains