Biogenic nanogoethite in the weathering crust of the basalts of Vietnam: Crystal morphology and thermal and magnetic properties

Бортников, Н. С.; Новіков, В. М.; Боева, Н. М.; Gendler, T. S.; Жегалло, Е. А.; Zhukhlistov, A. P.; Соболева, С. В.

doi:10.1134/s1028334x14080108

Cited by 3 publications

(4 citation statements)

References 10 publications

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“…The goethitic coccoidal nano‐balls, which are of diameter not greater than 5 μm observed in the studied clays (Figure 4a), thus indicate their origin through the replacement of organic matter by Fe ions during authigenic stages. The star‐like goethite morphologies are further interpreted in favour of intracellular substitution of coccoid cyanobacteria with goethite (Bortnikov et al, 2014). Considering the above evidences, it is suggested that the studied clays played a crucial role in the diversification and proliferation of early microbial life, facilitating the precipitation of Fe–Mn oxides, owing to their absorbability and organic polymerization catalysing capacity.…”

Section: Discussionmentioning

confidence: 99%

Manganiferous clays of Dharwar Craton, southern peninsular India: Insights on Archean weathering and ore formation processes

Harshitha,

Manikyamba,

Sridhar

et al. 2023

Geological Journal

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Vast clay deposits of Chitradurga and Sandur greenstone belts of the Dharwar Craton, southern peninsular India, hosting pockets of high‐grade manganese (Mn) ore, provide remarkable clues related to the ore‐forming processes and palaeo‐environmental conditions. In this study these Fe–Mn‐rich clays were investigated through mineralogical and geochemical characteristics to comprehend their palaeo‐weathering and genetic constraints and their role in the supergene accumulation of Mn ore. Their mineralogy is characterized by predominant kaolinite, muscovite, birnessite, haematite, goethite, halloysite along with quartz and traces of ilmenite. Chemical indices of alteration and weathering indicate intense weathering conditions under high palaeo‐precipitation rates in a humid, tropical climate under shallow burial conditions and K‐metasomatism. The presence of authigenic kaolinite and absence of illite reflect on diagenesis up to mesodiagenetic stage. Positive to negative Ce anomalies (Ce/Ce* = 0.67–5.93) of these clays suggest varying oxic‐anoxic conditions during their genesis, whereas conspicuous negative Eu anomalies (Eu/Eu* = 0.61–0.99) are attributed to precursor sediment signatures and hydrothermal imprints of the Mn ore. These kaolinite‐rich clays are suggested to have been formed by in situ chemical alteration, whereas kaolinitization of the Fe–Mn‐rich arenaceous and argillaceous sediments was derived from predominant tonalite and felsic provenance in a shallow marine passive margin setting. Based on the morphologies of birnessite, haematite and goethite in the investigated clays, we propose that these clays have played a key role in the oxidation and deposition of Mn (II) from the migrating aqueous solutions and acted as organo‐polymerization templates for the proliferation of ancient microbial life on the planet Earth.

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Section: Discussionmentioning

confidence: 99%

Manganiferous clays of Dharwar Craton, southern peninsular India: Insights on Archean weathering and ore formation processes

Harshitha,

Manikyamba,

Sridhar

et al. 2023

Geological Journal

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“…The other hypothesis is that isomorphism substitution in the phyllosilicate crystals, such as Fe irons replacing Al irons, causes the yellow color of the seal stones. The study conducted X-ray powder diffraction (XRD), Raman, and scanning electron microscopy (SEM) analyses on other stones that are colored by iron oxides and/or hydroxides, such as the weathering crust of basalt and quartzite [5][6][7]. Because the concentration of iron oxides and hydroxides in them is usually high, they have good crystallization and a large grain size, making it easy to identify them as hematite and goethite.…”

Section: Introductionmentioning

confidence: 99%

“…Goethite and hematite are the causes of yellowish and reddish colors in soils [8,9]. Their particle size is usually between 10 and 20 nm [5,6,10,11]. Due to their low contents in soils and the detection limit of XRD, purification is necessary before conducting XRD experiments [9,12].…”

Section: Introductionmentioning

confidence: 99%

“…Due to their low contents in soils and the detection limit of XRD, purification is necessary before conducting XRD experiments [9,12]. They can be observed by transmission electron microscopy (TEM) and detected by the Mössbauer spectrometer after purification when their content is not too low [5,6,9,10]. However, the newly formed (secondary) iron oxides/hydroxides are usually less than 1% in igneous, metamorphic, and sedimentary rocks and soils.…”

Section: Introductionmentioning

confidence: 99%

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The Color Formation of “Lumu Stone” in the Weathering Processes: The Role of Secondary Hematite and Goethite

Zheng

Chen

Han³

et al. 2023

Minerals

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Rocks and minerals buried in the earth’s surface usually undergo weathering processes and change color in the burying environment. A kind of yellow Chinese stamp stone named “Lumu stone”, which is buried in a yellowish weathering crust (yellowish soil), was selected to investigate its color changes in the weathering processes. In this study, the appearance features, mineral components, micromorphology, spectroscopy characteristics, and color causation of the “Lumu stone” were studied by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), an electron probe microanalyzer (EPMA), a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS), and a UV-Visible (UV-Vis) spectrum. The “Lumu stone” usually exhibits a darker yellow outer layer and a lighter yellow core, suggesting that yellow color permeated into the stone from the surface to the core gradually and the color is secondary forming. The results from XRD and SEM show the studied samples are mainly composed of dickite and illite. The individual particles of the dickite and illite are about 2–5 μm, randomly distributing in the three-dimensional space and constituting voids among the particles. The acid pickling experiments using HCl coupled with KSCN confirmed that the mineral phases that caused the yellow color of the matrix are iron oxide and hydroxide. On the other hand, goethite and hematite were observed gathering in the yellow and brown-red cracks on the “Lumu stone” by SEM study. However, iron oxide and hydroxide in the matrix were difficult to observe and detect among the dickite and illite aggregates by SEM and XRD methods. It indicates that they may be nanoscale in size and very low in content. According to the calculation of the second derivative of Kubelka-Munk (K-M) transformed diffuse reflection spectroscopy (DRS) curves obtained from UV-Vis, the characteristic peaks of goethite and hematite were found in the yellow matrix, and their contributions to the color were confirmed. The concentrations of goethite and hematite were calculated to be 0.32 to 1.87 g/kg and 0.22 to 0.93 g/kg in the studied samples, respectively. In this study, a series of methods were employed to detect very low levels of goethite and hematite in the samples undergoing weathering processes. Additionally, nanoscale goethite and hematite were considered newly formed minerals when buried in the weathering processes and may gradually move into the voids among phyllosilicate particles. Therefore, they turned the “Lumu stone” yellow.

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The first find of biogenic nanosiderite in oxidized ferrous quartzite of the Lebedinsk deposit, Kursk Magnetic Anomaly

et al. 2016

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Biogenic nanogoethite in the weathering crust of the basalts of Vietnam: Crystal morphology and thermal and magnetic properties

Cited by 3 publications

References 10 publications

Manganiferous clays of Dharwar Craton, southern peninsular India: Insights on Archean weathering and ore formation processes

Manganiferous clays of Dharwar Craton, southern peninsular India: Insights on Archean weathering and ore formation processes

The Color Formation of “Lumu Stone” in the Weathering Processes: The Role of Secondary Hematite and Goethite

The first find of biogenic nanosiderite in oxidized ferrous quartzite of the Lebedinsk deposit, Kursk Magnetic Anomaly

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