Formation of Nontronite from Oxidative Dissolution of Pyrite Disseminated in Precambrian Felsic Metavolcanics of the Southern Iberian Massif (Spain)

Fernández-Caliani, Juan Carlos; Crespo-Feo, E.; Rodas, M.; Barrenechea, José F.; Luque, Francisco

doi:10.1346/ccmn.2004.0520110

Cited by 27 publications

(17 citation statements)

References 35 publications

(15 reference statements)

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“…Nontronite authigenesis in mangrove soils and surface sediments can be possible according to the mechanism proposed by Fernandez-Caliani et al (2004), in which cyclical changes in the redox potential of flooded soils can favor the oxidation of pyrite and subsequent nontronite formation in Si, Mg and Al rich environments. Ferreira (2006) and Otero et al (2006) found similar conditions in the Pai Matos Island soils.…”

Section: Discussionmentioning

confidence: 99%

Smectite in mangrove soils of the State of São Paulo, Brazil

Souza-Júnior

Vidal‐Torrado²,

García‐González

et al. 2010

Sci. agric. (Piracicaba, Braz.)

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Smectitic clay minerals are frequently identified in mangrove soils, but there is little information about their types and origins. Besides their importance in the agronomical and geotechnical areas, smectites play an important environmental role by adsorbing nutrients, organic pollutants and heavy metals. Smectites found in mangrove soils can be of marine or continental detrital origin, or of neoformation origin. Thus, the objective of this study was to identify the types of smectites present in the State of São Paulo mangrove soils (Brazil), and to relate them to their possible origins. Soil samples were taken in five mangroves along the State of Sao Paulo State coast line. The mineral composition of the clay fraction was identified by X-ray Diffractometry (XRD) applying the Greene-Kelly test and by Fourier transform infrared spectroscopy (FTIR). Highlighting the peaks in the 3,560 cm-1 band and in the region near 798 and 820 cm-1, there was a predominance of nontronite in the soil at the Sítio Grande River, Pai Matos Island, Caranguejo Island and Itapanhaú River mangroves, and possibly a lower concentration of ferric montmorillonite in the Escuro River mangrove. Since the continental sediments in these environments are very poor in smectite, the origin of these minerals in the mangrove soils studied is related to sedimentation left by past marine transgressions, to neoformation processes, or yet to a combination of both origins.

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Section: Discussionmentioning

confidence: 99%

Smectite in mangrove soils of the State of São Paulo, Brazil

Souza-Júnior

Vidal‐Torrado²,

García‐González

et al. 2010

Sci. agric. (Piracicaba, Braz.)

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“…The majority of hydrothermal alteration occurs beneath the surface in hypogene conditions. However, mineral assemblages formed under hypogene conditions are often subject to supergene weathering and erosion which can replace some of the metastable hydrothermal minerals under atmospheric pressure and temperature conditions, including dickite, anhydrite, sulfur, and pyrite (Fernández‐Caliani et al, 2004; John et al, 2008; Scott, 1990; Zimbelman et al, 2005). This commonly results in mineral overprint, making interpretations of the original hydrothermal condition, fluid composition, and pH challenging, particularly on complex and long‐lived volcanic systems.…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Alteration on Composite Volcanoes: Mineralogy, Hyperspectral Imaging, and Aeromagnetic Study of Mt Ruapehu, New Zealand

Keresztúri

Schaefer

Miller

et al. 2020

Geochem Geophys Geosyst

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Prolonged volcanic activity can induce surface weathering and hydrothermal alteration that is a primary control on edifice instability, posing a complex hazard with its challenges to accurately forecast and mitigate. This study uses a frequently active composite volcano, Mt Ruapehu, New Zealand, to develop a conceptual model of surface weathering and hydrothermal alteration applicable to long‐lived composite volcanoes. The alteration on Mt Ruapehu was classified using ground samples as non‐altered, supergene argillic, intermediate argillic, and advanced argillic. The first two classes have a paragenesis that is consistent with surficial infiltration and circulation of low‐temperature (<40°C) neutral to mildly acidic fluids, inducing chemical weathering and formation of weathering rims on rock surfaces. The intermediate and advanced argillic alteration formed from hotter (≥100°C) hydrothermal fluids with lower pH, interacting with the andesitic to dacitic host rocks. The distribution of weathering and hydrothermal alteration has been mapped with airborne hyperspectral imaging through image classification, while aeromagnetic data inversion was used to map alteration to up to 500‐m depth. The joint use of hyperspectral imaging complements the geophysical methods since it can spectrally identify hydrothermal alteration mineralogy. This study established a conceptual model of hydrothermal alteration history of Mt Ruapehu, exemplifying a long‐lived and nested active and ancient hydrothermal system. This study's combination approach can be used to indicate the most likely sources of future debris avalanches, which are a significant hazard on Ruapehu.

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“…Nontronite forms during low-temperature alteration of sulfide-bearing felsic metavolcanic rocks, in mesothermal gold veins where argentian gold is associated with iron-and base-metal sulfides, and in epithermal gold-silver deposits (So et al 1995, Ioannou & Spooner 2000, Fernández-Caliani et al 2004. In these mineral deposits, oxidative dissolution of pyrite and hydrolysis of feldspar are supposed to be the common mode of nontronite formation.…”

Section: Introductionmentioning

confidence: 99%

CLAY MINERALOGY AND LA-ICP-MS DATING OF SUPERGENE U-Cu NONTRONITE-BEARING MINERALIZATION AT NABBURG-WOLSENDORF, SOUTHEASTERN GERMANY

Dill

Kaufhold

Weber³

et al. 2010

The Canadian Mineralogist

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Nontronite has been reported from a wide range of mineral deposits on the continent and in marine environments, commonly associated with basic igneous rocks, base-metal sulfides, Fe sulfides, Fe-Mn oxide-hydroxides and gold. This smectite-type phyllosilicate forms during the low-temperature alteration of sulfide-bearing parent material. In contrast, nontronite from veintype fluorite mineralization at Nabburg-Wölsendorf, in southeastern Germany, developed in a sulfur-deficient environment under supergene conditions associated only with uranyl phosphates, mainly uranocircite. It was investigated by XRD, IR spectrometry, XRF, CEC analysis and SEM-EDX. Phyllosilicates and uranium mica are coeval and of Pliocene age. A U-Pb age of 4.0 ± 0.1 Ma was determined using Laser-Ablation -Inductively Coupled Plasma -Mass Spectrometry (LA-ICP-MS). Some younger ages cluster, possibly indicating a multiphase history of crystallization. Both minerals came into existence at temperatures around 30°C when the region underwent pervasive chemical weathering under humid tropical climatic conditions. Uranium was derived from the decomposition of uraninite and coffinite in the veins and from the weathering of U-bearing accessory minerals in the granite, whereas the major elements and barium in uranocircite originated from the alteration of the granitic country-rocks. The vein minerals, e.g., fluorite acted solely as bedrock, but were not involved in this supergene mineralization. Nontronite-uranocircite mineralization can develop in almost all granitic terranes under supergene conditions like those described. The log Al 3+ /H + 3 and log Ca 2+ /H + 2 values are decisive as to whether nontronite, kaolinite or green opal (nontronite plus opal) comes into existence. Both types of supergene alteration minerals, kaolinite and green opal, developed side-by-side with the nontronite-uranocircite mineralization during the Neogene in this area. Uranium-lead dating using the LA-ICP-MS technique serves to constrain the age of this mineralization.

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Formation of Nontronite from Oxidative Dissolution of Pyrite Disseminated in Precambrian Felsic Metavolcanics of the Southern Iberian Massif (Spain)

Cited by 27 publications

References 35 publications

Smectite in mangrove soils of the State of São Paulo, Brazil

Smectite in mangrove soils of the State of São Paulo, Brazil

Hydrothermal Alteration on Composite Volcanoes: Mineralogy, Hyperspectral Imaging, and Aeromagnetic Study of Mt Ruapehu, New Zealand

CLAY MINERALOGY AND LA-ICP-MS DATING OF SUPERGENE U-Cu NONTRONITE-BEARING MINERALIZATION AT NABBURG-WOLSENDORF, SOUTHEASTERN GERMANY

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