scholarly journals Distribution and Origin of Clay Minerals During Hydrothermal Alteration of Ore Deposits

10.5772/48312 ◽  
2012 ◽  
Author(s):  
Milo Ren
Keyword(s):  
Clay Minerals ◽  
Hydrothermal Alteration ◽  
Ore Deposits

Nickel-bearing clay minerals: I. Optical spectroscopic study of nickel crystal chemistry

Clay Minerals ◽  
1985 ◽  
Vol 20 (3) ◽  
pp. 367-387 ◽  
Author(s):  
A. Manceau ◽  
G. Calas ◽  
A. Decarreau
Keyword(s):  
Clay Minerals ◽  
Crystal Chemistry ◽  
New Caledonia ◽  
Ore Deposits ◽  
Octahedral Sheet ◽  
Al Content ◽  
Intermediate Phases ◽  
Optical Evidence ◽  
Trioctahedral Smectites ◽  
Nickel Crystal

AbstractNickel crystal chemistry was systematically studied in various phyllosilicates, mainly the natural phases selected from the ‘garnierites’ of the supergene ore deposits of New Caledonia. Minerals which do not usually occur in New Caledonian parageneses were synthesised, as they could represent intermediate phases of genetic importance. In the kerolite-pimelite series, a linear relationship occurred between the ratioI(13,20)/I(02,11)of thehkbands and Ni-content. Diffuse reflectance spectra were used to derive the crystal chemical parameters of Ni. These confirmed its divalent character and its occupation of octahedral sites; the resulting structural distortion was slight and could not be detected in some minerals. There was no optical evidence for Ni atoms in 4-fold coordination. The two main parameters which showed significant variations among the studied phases were site distortion and crystal field stabilization energy (CFSE). Site distortion was at a maximum in trioctahedral smectites and sepiolite. CFSE depended on the mineralogy, crystallinity and chemical composition (Al-content) of the phase. Finally, clay minerals are classified according to the increasing stability of Ni in the octahedral sheet, which has been tentatively related to the geochemical distribution of this element. Secondary minerals are usually enriched vs. primary ones and among them are nepouite and kerolite which exhibit a high CFSE in contrast to sepiolite.

Isotopic age determinations on clay minerals from lavas and tuffs of the Derbyshire orefield

1972 ◽  
Vol 109 (6) ◽  
pp. 501-512 ◽  
Author(s):  
P. R. Ineson ◽  
J. G. Mitchell
Keyword(s):  
Clay Minerals ◽  
Hydrothermal Alteration ◽  
Igneous Rocks ◽  
The Other ◽  
Mineral Deposits ◽  
Isotopic Age ◽  
Hydrothermal Mineralization ◽  
Pumice Tuff ◽  
Southern Section ◽  
Age Determinations

SummaryEpisodic hydrothermal mineralization has previously been recognized in the northern section of the Pennine orefield. Igneous rocks from the southern section (the Derbyshire orefield) have yielded isotopic ages, some of which are thought to represent ages of hydrothermal metasomatism (deuteric or subsequent). In order to ascertain whether epicyclic hydrothermal events gave rise to the Derbyshire mineral deposits, samples of highly altered doleritic lava and pumice tuff were collected adjacent to areas of mineralization. Clay-mineral concentrates from 34 samples were dated by the potassium–argon method. The conclusions drawn from these analyses support a hypothesis of repeated hydrothermal alteration of the clay minerals, reflecting at least two episodes of mineralization, one about 270 m.y., the other about 235 m.y. The geo-chronological significance of these and other results is considered.

Hydrothermal clay mineral formation in a biotite-granite in northern Switzerland

Clay Minerals ◽  
1984 ◽  
Vol 19 (4) ◽  
pp. 579-590 ◽  
Author(s):  
Tj. Peters ◽  
B. Hofmann
Keyword(s):  
Fluid Inclusion ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Electron Microprobe ◽  
Mineral Chemistry ◽  
Biotite Granite ◽  
Mineral Formation ◽  
Fluid Inclusion Data ◽  
Northern Switzerland

AbstractClay minerals of several hydrothermally altered zones in a 1200-m biotite-granite core from a drillhole in northern Switzerland were studied microscopically, by XRD and by electron microprobe. The minerals principally affected by the hydrothermal alteration were plagioclase (An5-An20) and, to a lesser extent, biotite. Illite, regularly interstratified illite-smectite and dioctahedral chlorite-smectite, dioctahedral chlorite, trioctahedral chlorite and kaolinite were detected in the alteration products. Commonly, two or more clay minerals occurred together in pseudomorphs after plagioclase. The mineral chemistry of the clay minerals showed a predominance of the substitution KAl for Si and, to a lesser extent, MgSi for Al. Fluid-inclusion data and the absence of pure smectite and epidote indicated temperatures of ∼200°C for the fluid that caused this alteration.

scholarly journals Mineralogical and Geochemical Control of Altered Andesitic Tuff upon Debris Slide Occurences at Pelangan Area, Southern Mountain of Lombok Island, Indonesia

2016 ◽  
Vol 1 (1) ◽  
pp. 19 ◽  
Author(s):  
Dwi Winarti ◽  
Dwikorita Karnawati ◽  
Hary Christady Hardiyatmo ◽  
Srijono Srijono
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Gold Mineralization ◽  
Slope Instability ◽  
Landslide Area ◽  
Debris Slide ◽  
Argillic Alteration ◽  
Wet Condition ◽  
Lombok Island

Debris slides were recently found in the Pelangan area at Southern Mountain of Lombok Island, Indonesia. Pelangan is well known as the gold mineralization and hydrothermal alteration area. This study is aimed to identify the mineralogy and geochemistry of altered andesitic tuff that controlled slope instability and induced debris slides. For this purpose, it is necessary to prepare the field observation and laboratory analyses. Landslide inventory reveals that the Pelangan debris slides mostly occur in altered andesitic tuff. Based on the outcrop observations in the field, andesitic tuff found around the Pelangan debris slides have been altered in general. The strong intensity of alteration developed by hydrothermal alteration in this study area produces large amount of clay minerals especially montmorillonite, kaolinite, and illite. The abundance of those clay minerals reflect the intermediate argillic alteration. Montmorillonite is a type of clay mineral that easily swells at wet condition and easily shrinkages at dry condition. Swelling of clay mineral destroys intersheet and interlayer bonds, and reduces shear strength. The presence of clay minerals in the altered andesitic tuff of intermediate argillic zone can be considered as one of the factors that induced to the Pelangan debris slides. Further studies on geotechnical and slope stability analysis of the landslide area are crucial to be done for better understanding of the characteristics of the altered rocks inducing hazardous landslides.

Formation de phyllosilicates dans les roches carbonatées cristallines de La Mauricie, Québec

1989 ◽  
Vol 26 (7) ◽  
pp. 1463-1473
Author(s):  
Christian de Kimpe
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Parent Material ◽  
Material Composition ◽  
Mineral Transformation ◽  
Fe Oxides ◽  
Fracture Planes ◽  
Low Degree

The chemical and mineralogical analyses of the disaggregated material collected in the fracture planes of crystalline carbonate outcrops at three sites north of Trois-Rivières, Quebec, showed the formation of expanding phyllosilicates, smectite and vermiculite, mainly at the expense of the ferromagnesian minerals hornblende and augite. The clay minerals are enriched in Fe and Mg with respect to the parent material composition and are associated with the crystalline Fe oxides goethite and lepidocrocite. The moderate to low degree of mineral transformation is accounted for by the slow dissolution of the carbonates. Corrensite, a regularly interstratified clay mineral, was identified in 50% of the samples; it probably resulted from the hydrothermal alteration of phlogopite. Silicate alteration may have been responsible for a fraction of the swelling minerals found in the soils of the area.

The geochronological significance of argon-40/argon-39 age determinations on White Whin from the northern Pennine orefield

1968 ◽  
Vol 307 (1490) ◽  
pp. 251-266 ◽  
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Age Determination ◽  
Hydrothermal Activity ◽  
Work Support ◽  
Natural Isotope ◽  
Minimum Age ◽  
Widespread Phenomenon ◽  
Age Determinations

Controversy regarding the age and character of mineralization in the northern Pennine orefield is reviewed in the context of recent geological and geochronological research in the region, and a number of the unresolved problems are tabulated. A new method of potassium-argon radioisotopic age determination which utilizes the conversion of the natural isotope 39 K in a rock or mineral to the isotope 39 Ar by neutron irradi­ation is described in outline. This method avoids some of the limitations of conventional potassium-argon age determination, and, among other advantages, makes the measurement of the radioages of clay minerals possible. A geochronological and petrological investigation of White Whin samples from the northern Pennine orefield is reported in full, and eighteen new age determinations, mostly upon clay mineral concentrates are presented. The conclusions that can be drawn from this work support a hypothesis of repeated hydrothermal mineralizations within the area of the northern Pennine orefield: the first within the period 284 ± 40 My with subsequent maxima of hydrothermal activity occurring at intervals. At least two of these subsequent episodes have been identified: one around a minimum age of 230 My and another, very important episode occurring around 170 My. Comparison of these results with histograms of (1) all radio­ages of British rocks and (2) radioages from British dolerites and basalts only, suggests that episodic hydrothermal alteration of pre-existing rocks may be a widespread phenomenon in Britain.

Spatial and temporal evolution of hydrothermal alteration at Lavras do Sul, Brazil: evidence from dioctahedral clay minerals

2008 ◽  
Vol 56 (2) ◽  
pp. 222-243 ◽  
Author(s):  
Everton Marques Bongiolo ◽  
Patricia Patrier-Mas ◽  
André Sampaio Mexias ◽  
Daniel Beaufort ◽  
Milton Luiz Laquintinie Formoso
Keyword(s):  
Clay Minerals ◽  
Hydrothermal Alteration ◽  
Temporal Evolution

scholarly journals Alteração hidrotermal de preenchimento de um veio de Rocha Basáltica associada às ametistas - Vila São Gabriel/Planalto, Rio Grande do Sul

1990 ◽  
Vol 12 (12) ◽  
pp. 111
Author(s):  
Rejane Maria Scopel ◽  
Milton Luiz Laquintinie Formoso ◽  
Alain Meurnier ◽  
Patrick Dudoignon
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Alteration ◽  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Secondary Phases ◽  
Geochemical Studies ◽  
Brown Clay

Clay minerals, zeolites, calcite and silica (quartz, opal and chalcedony) are the most common hydrothermal alteration products of the basalts with veins in São Gabriel (Planalto) Region. The petrographic and geochemical studies led to the identification of the secondary phases which fill the veins. From the border to the centre, the filling of the veins comprises: a) brown clay mineral (ferri-montmorillonite), b) prismatic zeolite (heulandite) and/or fibro-radiated saponite/chlorite, and c) interstratiphied saponite/chlorite.

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